Submitted Abstracts

Sanjay K Reddy Fermion Superfluidity in Compacts Stars Abstract:

Recent theoretical developments in dense matter and neutron star evolution has led to renewed interest in Fermion superfluidity - especially in the strong coupling regime. In this talk I will explore the role Fermion pairing in dense matter inside compact stars and on the phase structure of dense QCD. I will highlight recent work on pairing in asymmetric Fermi systems and on the response of superfluids to external perturbations. I will discuss these result in context of observable aspects compact star structure and evolution.
Anthony L Piro Burst Oscillations and Non-Radial Oscillations of Neutron Stars Abstract:

Accreting neutron stars often show coherent modulations during type I X-ray bursts, called burst oscillations. Recently there has been much theoretical work suggesting that a nonradial mode can serve as an explanation. After reviewing the phenomenology of burst oscillations, I will discuss the basics of shallow ocean waves in the context of neutron stars, including the interesting complications brought about by rotation. We find that a surface wave in the shallow burning layer evolves into a crustal interface wave as the envelope cools, a new and previously uninvestigated phenomenon. This provides frequencies and drifts that match those observed, and furthermore, the drifts can be used as a probe of the neutron star crust. By modeling the pulsed emission we can begin the exciting process of using burst oscillations to learn about the properties of these accreting neutron stars.
Jorge Piekarewicz Neutron-rich nuclei in Heaven and Earth Abstract:

An accurately calibrated relativistic parametrization is introduced to compute the ground state properties of finite nuclei, their linear response, and the structure of neutron stars. Among the predictions of this model are a symmetric nuclear-matter incompressibility of K=230 MeV and a neutron skin thickness in 208Pb of Rn-Rp=0.21 fm. Further, the impact of such a softening on the properties of neutron stars is as follows: the model predicts a limiting neutron star mass of Mmax=1.72 Msun, a radius of R=12.66 km for a ``canonical'' M=1.4 Msun neutron star, and no (nucleon) direct Urca cooling in neutrons stars with masses below M=1.3 Msun.
Andreas Reisenegger Internal dissipation through beta processes and thermal emission from old neutron stars: “rotochemical heating” and constraints on a time-variation of Newton's “constant” of gravity Abstract:

The equilibrium composition of neutron star matter is achieved through weak interactions, which proceed on relatively long time scales. If the density of a matter element is perturbed, it will relax to the new chemical equilibrium through non-equilibrium reactions, which produce entropy that is partly released through neutrino emission, while a similar fraction heats the matter and is eventually radiated as thermal photons. We examined two possible causes of such density perturbations: 1)the reduction in centrifugal force caused by spin-down (particularly in millisecond pulsars), leading to “rotochemical heating” (astro-ph/0502116), and 2)a hypothetical time-variation of the gravitational “constant”, as predicted by some theories of gravity and current cosmological models (“gravitochemical heating”). If only slow weak interactions are allowed in the neutron star (modified Urca reactions, with or without Cooper pairing), “rotochemical heating” can roughly account for the observed ultraviolet emission from the closest millisecond pulsar, PSR J0437-4715, which also provides a constraint on |dG/dt| of the same order as the best available in the literature.
Nanda Rea Evidence for a magnetospheric untwisting in the post-Giant Flare X-ray emission of SGR 1806-20 Abstract:

The Chandra satellite observed the magnetar candidate SGR 1806-20 almost one month after its Giant Flare in December 2004. This was the first X-ray observation after the flare with a high spectral resolution instrument. The X-ray emission of the source strongly suggest that a magnetospheric untwisting took (or is still taking) place, soon after the twist which could have triggered the Giant Flare.
Jacek Niemiec Monte Carlo modeling of radiative transfer in magnetar atmosperes Abstract:

Monte Carlo simulations of radiative transfer in magnetar atmospheres are presented. We include the effects of vacuum polarization, electron and proton scattering, and free-free absorption. Simulations are performed for the atmosphere model with the magnetic field perpendicular and also tilted with respect to the neutron star surface. We show that the average spectrum does not strongly depend on the orientation of the magnetic field. The region of the parameter space where the vacuum absorption-like feature appears in the spectrum is investigated and we analyze the shape of the proton cyclotron line. Our results indicate that the existence of the vacuum polarization feature should be a general property of soft gamma-ray repeaters burst spectra, provided that the energy release takes place at the sufficiently dense region, and the atmosphere scaleheight is large enough. We discuss the existence of such a feature in recent observational data on these sources.
Sebastian Kubis Kaon codensation instability Abstract:

Last years the kaon condensation in neutron stars was explored intensively as it could lead to rapid cooling of the star core. It will be shown that, this type of Bose-Einstein condensate suffers from a serious instability caused by charge fluctation what make many nuclear models unaplicable.
Chris A Engelbrecht Statistical Studies of Pulsar Arrival Times as Probes of Neutron Star Physics Abstract:

Observed arrival times of pulses from neutron stars that operate as pulsars are known to exhibit fluctuations of various kinds, including glitches, microglitches and what is termed 'timing noise'. Advanced statistical methods applied to sequences of arrival times hint at non-random intrinsic signals being present in the arrival time behaviour. Results are shown for selected pulsar data and the potential physics involved in creating the observed behaviour is explored.
Peter G Jonker The extremely faint quiescent NS SXT 1H 1905+00: constrainst on the NS EoS Abstract:

Observations of black hole and neutron star Soft X-ray Transients (SXTs) with Chandra and XMM-Newton turned out to have a profound impact on two important areas of high energy astrophysics. First of all, comparing the quiescent luminosity of neutron star SXTs with that of black hole SXTs it was found that black hole (BH) SXTs are systematically fainter in quiescence than neutron stars (e.g. Narayan, Garcia, & McClintock 1997, Garcia et al. 2001). This has been interpreted as evidence for advection of energy across a BH event horizon. Despite many objections to this interpretation, alternative explanations for the difference in quiescent luminosity, and neutron stars which turned out to be fainter than initially found to be rule, none of the neutron star SXTs is as faint as the BH SXT A 0620-00 in quiescence. Secondly, in observations of neutron star SXTs in quiescence which allow for a spectral study, the spectrum was found to be well-fit by a neutron star atmosphere model (NSA) sometimes supplemented with a power-law component. Well established theories about the time averaged mass accretion rates in neutron star SXTs, the pycnonuclear reactions taking place in the neutron star crust combined with neutron star cooling theory predictions, yield a neutron star core temperature. This hot neutron star core, moderated by the neutron star atmosphere, is thought to be observed during the quiescent phase of neutron star SXTs. In theory, a NSA-fit provides means to measure the mass and radius of the neutron star and hence constrain the equation of state (EoS) of matter at supranuclear densities. The description of the relations between pressure and density of matter (the EoS) under the extreme conditions encountered in neutron stars is one of the ultimate goals of the study of neutron stars. We recently observed the neutron star SXT 1H1905+000 in quiescence with ACIS-S. However, the source was not detected even though the distance and interstellar extinction are well known. This means that the source (thermal) luminosity in the 0.5-10 keV band is lower than 1031 erg s^-1. From this and from the fact that it is known from binary evolution theory that the time averaged mass accretion rate cannot be much less than 10-12 Msun per year, we conclude that the neutron star must be so massive that only EoSs with a nucleonic core can exist.
Sergey B. Popov Population synthesis as a probe of neutron star thermal evolution Abstract:

We propose to use the population synthesis of close-by young neutron stars as an additional test of the cooling curves of these objects. We illustrate our approach. After we apply the new test to nine sets of cooling curves which successfully explain the data points on the Age-Temperature plot, we obtain that only three out of nine (two just marginaly) are in correspondence with the ROSAT data on close-by neutron stars. We discuss advantages and drawbacks of both test and propose future improvements for the population synthesis test. Our conclusion is that the two test together can dicriminate between cooling models much better than any of the tests alone.
David Eichler Understanding Magnetars with Conservative Physics Abstract:

I review recent progress in understanding observations of SGRs and AXPs under the assumptions that they have normal (non-strange) crusts and superfluid cores. Several qualitative manifestations of ultrastrong fields have probably been observed, including the recent 27 December 2004 event, and others remain theoretical possibilities.
Charles J Horowitz Neutron Rich Matter at Subnuclear Densities in Neutron Stars and Supernovae Abstract:

The virial expansion is used to make model independent determinations of the composition, equation of state, and neutrino response of nuclear matter at densities near 1011 to 1013 g cm-3. Experimental nucleon-nucleon, alpha-nucleon, and alpha-alpha scattering phase shifts are used as input. We compare to existing model dependent equations of state such as Lattimer-Swesty and Shen. Our virial expansion corrects nuclear statistical equilibrium (NSE) models for the strong interactions between nuclei and or nucleons. Next, properties of the complex “nuclear pasta” phases in the inner crust of neutron stars are determined with large scale molecular dynamics simulations. Finally, we present an update of the Parity Radius Experiment (PREX) to measure the neutron skin in 208Pb. This has many implications for neutron stars.
Andrew Cumming Constraints on Neutron Star Interior Physics from Long Type I X-ray Bursts Abstract:

Long term monitoring of accreting neutron stars has revealed a new sample of long duration X-ray bursts. They are thought to occur when a thick layer of fuel undergoes a thermonuclear runaway, either carbon in the case of "superbursts", or helium for other "intermediate duration" bursts. I will present a new comparison of theory and observations of long X-ray bursts, including models of both lightcurves and ignition conditions. The observed properties of helium and carbon bursts are reproduced only if the neutrino emission from the core and crust of the star is inefficient. The ignition conditions for these thick layers are extremely sensitive to the thermal profile of the neutron star interior, and provide a new way to probe neutron star cooling, complementary to observations of isolated neutron stars and accreting neutron stars in quiescence.
Silvia Zane XMM-Newton observations of the two Anomalous X-ray pulsars 1E 1048.1-5937 and 1RXS J170849.0-400910 Abstract:

We report the results of XMM-Newton observations of two Anomalous X-ray pulsars: 1E 1048.1-5937 and 1RXS J170849.0-400910. 1E 1048.1-5937 was observed in 2000, 2003, and 2004. The comparison of the three data sets shows an anti-correlation between flux and pulsed fraction, implying that previous estimates of the source energetics based on the assumption of a large and constant pulsed fraction might be significantly underestimated. The source spectrum is well described by a power law plus blackbody model (kT~0.63 keV, photon index \Gamma~ 2.7-3.5) or, alternatively, by the sum of two blackbodies of which the hotter is Comptonized by relativistic electrons. The long term luminosity variation of a factor >2 is accompanied by relatively small variations in the spectral shape. Phase resolved spectroscopy indicates a harder spectrum in correspondence of the pulse maximum. 1RXS J170849.0-400910 was observed in 2003 August and was found at a flux level a factor of about two lower than previous observations.A significant spectral evolution appears to be present, the source exhibiting a much softer spectrum than in the past. Comparison of the present properties with those from archival data shows a clear correlation between the X-ray flux and the spectral hardness. We discuss a possible explanation for the glitches and for the softening of the source emission which followed the flux decrease, in the framework of the magnetar model.
Svetlana Petrova Giant pulses of radio pulsars Abstract:

Giant pulses rank among the most puzzling phenomena in pulsar emission. With the radio intensities up to a few thousand times the average and the characteristic power-law statistics of intensities, giant pulses challenge not only the existing theories of pulsar emission, but also the global picture of the magnetosphere of a neutron star. Probably most exciting feature of giant pulses is their substructure at the timescales down to a few nanoseconds. These so called nanopulses appear the brightest pulses in the Universe, only marginally matching the energetics of a rotation-powered neutron star. A brief review of the observational manifestations of giant pulses and their implications is complemented by the theoretical explanation of this phenomenon in terms of propagation effects in the plasma of pulsar magnetosphere. The mechanism suggested is based on the induced scattering of pulsar radio emission by the plasma particles. It is demonstrated that the observed giant amplifications may result from intensity redistribution between widely spaced frequencies in the course of induced scattering. Then the observed statistics of giant pulse intensities may well be explained by pulse-to-pulse variations of the scattering depth. The photon focusing as a result of induced scattering can account for the nanostructure, removing the problem of exceedingly high brightness temperatures of the nanopulses. The perspectives for further observational and theoretical studies of giant pulse phenomenon are outlined as well.
Jules P Halpern On the Interpretation of Soft X-ray Spectra of Anomalous X-ray Pulsars Abstract:

The X-ray spectra of anomalous X-ray pulsars in the 0.5-10 keV range are conventionally fitted with a two-component model consisting of a soft power law plus a hard blackbody, or less often with a pair of blackbodies or Comptonized blackbodies. I will discuss constraints on these X-ray fits from observations at lower and higher energies, and from complementary information contained in the X-ray pulse profiles. I will examine whether the parameterized fits are consistent with interpretation of a power-law spectrum as Compton upscattering of thermal seed photons from a neutron star, and whether the seed photons themselves are self-consistently included in fitting the spectra. X-ray spectral fitting is sometimes used in estimating distances to AXPs via the column density parameter. The effect of an assumed spectral model on the fitted column density and inferred distance can be important.
Vladimir Usov Thermal emission from hot bare strange stars and their observational appearance Abstract:

Strange stars made almost entirely of deconfined quarks have long been proposed as a possible alternative to neutron stars. Strange quark matter with the density of ~ 5x1014 g cm-3 might exist up to the surface of strange stars. Such bare strange stars (BSSs) differ qualitatively from neutron stars which have the density at the surface (more exactly at the photosphere) of about 0.1-1 g cm-3. This opens observational possibilities to distinguish BSSs from neutrons stars, if indeed the formers exist. We present the results of calculations of the thermal emission of photons and electron-positron pairs from the surface of a hot BSS. Since strange quark matter at the surface of a BSS is bound via strong interaction rather than gravity, such a star is not subject to the Eddington limit in contrast to a neutron star, and its thermal luminosity in photons and pairs may be up to ~ 1052 ergs/s or even more. Using the thermal emission from the surface of a BSS as a boundary condition, we consider numerically the structure of pair winds and the emerging emission from BBSs for total luminosities of L = 1034-1042 ergs/s. We find that for L > 2x1035 ergs/s, photons dominate the emerging emission. As L increases from ~ 1034 to 1042 ergs/s, the mean energy of emergent photons decreases from ~ 400 keV to ~ 40 keV, as the spectrum changes in shape from that of a wide annihilation line to nearly a blackbody spectrum with a high energy (> 100 keV) tail. These results are pertinent to the deduction of the outside appearance of hot BSSs, which might help discern them from neutron stars. Some criteria are suggested for a compact object to be considered as a BSS candidate. Soft gamma-ray repeaters are among such candidates. The bursting activity of a soft gamma-ray repeater may be explained by fast heating of the surface of a BSS up to the temperature of ~ (1-3) x 109 K and its subsequent thermal emission.
Andrey Timokhin Signatures of neutron star oscillations in post-glitch emission of radiopulsars Abstract:

Experimental determination of neutron stars eigenmodes parameters would provide important information about internal structure of the neutron stars. Isolated NSs should be more suitable for such studies, because their power spectra are not contaminated by numerous instabilities in accreted material. The vast majority of known isolated NSs are radiopulsars, in ~ 50 of them glitches are observed. Glitches can excite neutron star oscillations, because they are connected with transfer of rotation energy from one stellar component (core) to another (crust). The main attention in this work is drawn to distortion of pulsar magnetosphere by neutron star oscillations. Pulsar "standard model" of rotating magnetized conducting sphere surrounded by plasma is generalized in its essential parts for the case of oscillating star. Goldreich-Julian charge density, electromagnetic energy losses, as well as polar cap scenario of particle accelerations, are considered. The changes in the Goldreich-Julian charge density due to star pulsations for oscillation modes with high harmonic numbers (l,m) are essential, and will lead to substantially distortion of accelerating electric field in pulsar polar cap. This can result in remarkable changes of individual pulse profiles of radiopulsars. It is shown, that for moderately optimistic scenario of NS's oscillations excitation by the glitch, such changes in pulsar radiation could be detected by contemporary radiotelescopes.
Agnieszka Majczyna Mass, radius, surface gravity and gravitational redshift determination for the neutron star in the X-ray burst source MXB 1728-34 Abstract:

We analyse archival X-ray spectra of MXB 1728-34 obtained in 1996-99 by the instrument PCA on board of the RXTE satellite. X-ray spectra were fitted to our extensive grids of model atmosphere spectra to determine the effective temperature Teff on the neutron star surface, logarithm of surface gravity log(g), and the gravitational redshift z simultaneously. We have chosen fitting by numerical model spectra plus broad gaussian line, modified by interstellar absorption and the absorption on dust. We arbitrarily assume either hydrogen-helium chemical composition of a model atmosphere, or H-He-Fe mixture in solar proportion. The best values of log(g), and z were subsequently used to determine mass and radius of the neutron star. We obtained the best values of the parameters for the neutron star in X-ray burst source MXB 1728-34: mass either M=0.52 or 0.64 Msol (for H-He or H-He-Fe models, respectively), radius and R=5.7 or 5.8 km, log(g)=14.4 or 14.5 and the gravitational redshift z=0.17 or 0.22. Confidence limits are rather large, however, they strongly support the equation of state for strange matter.
Roberto Turolla XMM-Newton Observations of SGR 1806-20 in the Pre-Giant Flare Epoch Abstract:

I present results from XMM-Newton observations of the Soft Gamma-ray Repeater SGR 1806-20. Four pointings were carried out in 2003-2004 and catched the source in different states of activity. During these two years the 2-10 keV flux doubled with respect to the historical level observed previously. The long term raise in luminosity was accompanied by a gradual hardening of the spectrum, with the power-law photon index decreasing from 2.2 to 1.5, and by a growth of the bursting activity. The pulse period measurements obtained in the four observations show a steady increase and are consistent with a high spin-down rate at an average value of 5.5e-10 s/s. The long term behavior of SGR 1806-20 follows the correlation between spectral hardness and spin-down rate previously observed only by comparing different SGRs and AXPs. The relevance of these results for the magnetar scenario, and for the twisted magnetosphere model in particular, are discussed also in the light of post-flare Chandra and XMM observations.
Chengmin Zhang The Bottom magnetic field and magnetosphere evolution of Abstract:

The accretion induced neutron star magnetic field evolution is studied through considering the accretion flow to drag the field lines aside and dilute the polar field strength, and as a result the equatorial field strength increases, which is buried inside the crust on account of the accretion induced global compression of star crust. The main conclusions of model are as follows: (i) the polar field decays with increasing the accreted mass; as dm-1 (ii) The bottom magnetic field strength of about 10^8 G can occur when neutron star magnetosphere radius approaches the star radius, and it depends on the accretion rate as \mdot^{1/2}; (iii) The neutron star magnetosphere radius decreases with accretion until it reaches the star radius, and its evolution is little influenced by the initial field and the accretion rate after the star accreting ~ 0.01 \ms, which implies that the magnetosphere radii of neutron stars in LMXBs would be homogeneous for Z sources and Atoll sources if they accreted the comparable masses. As an extension, the physical effects of the possible strong magnetic zone in the X-ray neutron stars and recycled pulsars are discussed. Moreover, the strong magnetic fields in the binary pulsars PSR 1831-00 and PSR 1718-19 after accreting about half solar mass in the binary accretion phase, 8.7x1010 G and 1.28x1012 G, respectively, can be explained through considering the incomplete frozen flow in the polar zone. As a model's expectation, the existence of the low magnetic field (~ 3x 107 G) neutron stars or millisecond pulsars is suggested.
Bennett Link Neutrino Pulsars Abstract:

Neutron stars are efficient accelerators for bringing charges up to relativistic energies. I show that if positive ions are accelerated to ~ 1 PeV near the surface of a young neutron star, protons interacting with the star's radiation field will produce beamed \mu neutrinos with energies of ~ 50 TeV resulting in certain neutron stars being the brightest neutrino sources at these energies yet proposed. The neutrinos would be roughly coincident with the radio beam, so that if the star is detected as a radio pulsar, the neutrino beam will sweep the Earth; the star would be a ``neutrino pulsar''. Looking for \nu_\mu emission from young neutron stars will provide a valuable probe of the energetics of the neutron star magnetosphere.
Andreas Schmitt Pulsar kicks via spin-1 color superconductivity Abstract:

We propose a new neutrino propulsion mechanism for neutron stars which can lead to strong velocity kicks, needed to explain the observed bimodal velocity distribution of pulsars. The spatial asymmetry in the neutrino emission is naturally provided by a stellar core containing spin-1 color-superconducting quark matter in the A phase. The neutrino propulsion mechanism switches on when the stellar core temperature drops below the transition temperature of this phase.
Ira M Wasserman Nonlinear Saturation of the R-Mode Instability Abstract:

The CFS instability of rotating neutron stars is truncated at a small amplitude by weakly nonlinear couplings among numerous stellar inertial modes. The basic physics of the truncation -- which may apply to other systems with numerous resonances -- will be reviewed. Implications for neutron star rotation will be discussed.
David Lomiashvili On the nature of radio pulsars with long periods Abstract:

It is shown that the drift waves near the light cylinder can cause the modulation of emission with periods of order several seconds. These periods explains the intervals between successive pulses observed in radio pulsars with long periods. The model under consideration gives the possibility to calculate real rotation periods of host neutron stars. They are less than 1 sec for the investigated objects. The magnetic fields at the surface of the neutron star are of order 1011 - 1013 G and equal to the fields usual for known radio pulsars.
Maxim Lyutikov Resonant Cyclotron Scattering and Comptonization in Neutron Star Magnetospheres Abstract:

Resonant cyclotron scattering of the surface radiation in magnetospheres of neutron stars may considerably modify emergent spectra. Resonant tranfer has a number of unusual characteristics: (i) in the limit of high resonant optical depth, cyclotron resonant layer is half opaque, in a sharp contrast to the case of non-resonant scattering; (ii) transmitted flux is on average Compton up-scattered by 1+ 2 betaT, where betaT is a typical thermal velocity in units of the velocity of light; reflected flux has on average the initial frequency. (iii) for both transmitted and reflected fluxes the dispersion of intensity decreases with increasing optical depth; (iv) emerging spectrum is appreciably non-Plankian while narrow spectral features produced at the surface are erased; (v) optical optical photons are less affected by resonant Comptonization than X-rays due to different polarization of normal modes in resonances. We discuss applications to Anomaous X-ray Pulsars and thermally emitting Isolated Neutron Stars
Hans-Thomas Janka Supernova Simulations and Neutron Star Formation Abstract:

The current status of supernova modeling will be reviewed. Improvements in the treatment of neutrino transport and neutrino-matter interactions have advanced the models to a new level of sophistication. Successful and robust explosions by the neutrino-heating mechanism can be reported for progenitors with 8-10 solar masses, and explosions supported by hydrodynamic instabilities seem in reach for stars with masses between 10 and 12 solar masses. State of the art simulations for more massive progenitors are not yet finally conclusive, but offer new and interesting insights into the role of convection, hydrodynamic instabilities, and rotation in supernovae and during neutron star birth.
Patrick Slane Cooling Limits from the Youngest Neutron Stars Abstract:

One of the primary means of constraining the cooling properties of neutron stars, and thus the structure and composition of their deep interiors, is through measurements of their X-ray properties. The youngest neutron stars provided some of the strongest constraints, particularly in cases where the total luminosity is low. However, the X-ray emission from young neutron stars is often dominated by nonthermal emission. Thus, high-sensitivity observations and subsequent spectral modeling are necessary to confidently identify the emission, or limits to the emission, directly from the stellar surface. Here I summarize recent work on establishing the temperature properties of the youngest neutron stars.
Jacco Vink The suprising spectral evolution of the surface emission from RX J0270.4-3125 Abstract:

RX J720.4-3125 is one of the brightest isolated neutrons whose emission is dominated by radiation from the hot surface. The first observations of the source with XMM-Newton and Chandra revealed that the spectrum is best described by a black body spectrum, disappointingly without any features revealing the presence and composition of an atmosphere. Surprisingly, subsequent observations with the gratings of XMM-Newton show that the emission of RX J720.4-3125 is changing with time, which is confirmed by Chandra LETGS observations. However, the spectral shapes observed by Chandra and XMM-Newton do not agree concerning the flux changes at long wavelengths: Both instruments reveal a hardening of the spectrum, but in addition XMM-Newton shows also a decline in flux at long wavelength, not seen with Chandra. Here we will discuss our latest re-analysis of the XMM-Newton observations, in which we incorporate the results of new instrumental calibrations. We will also discuss what can be said about the nature of the spectral change and its cause. For instance, the spectral evolution is hard to reconcile with a simple heating of a hot spot at the surface of the neutron star, or the emergence of an additional hot spot.
Nevin N Weinberg Exposing the Nuclear Burning Ashes of Radius Expansion X-ray Bursts Abstract:

During a type I X-ray burst, the neutron star atmosphere becomes convective and the ashes of nuclear burning get mixed throughout the convective region. We study the evolution of the atmosphere's thermal structure during a burst and show that during bursts with super-Eddington peak luminosities (i.e., radius expansion bursts) the convective region reaches sufficiently low pressure that some ashes of burning get ejected by the bursts' radiation driven wind. Ashes will also reside in the photosphere at the neutron star surface after the wind turns off. We find that the exposed ashes are sufficiently that some will cease to be fully ionized. The resulting atomic spectral line features may be detectable with current X-ray telescopes. A detection would probe the nuclear burning during bursts and might enable a measurement of the gravitational redshift of the neutron star.
Jacco Vink Constraints on the formation of magnetars from associated supernova remnants Abstract:

It is now generally accepted that Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs) are magnetars, i.e. neutron stars with surface magnetic fields of 1014-1015 G. The origin of this magnetic field is uncertain, but one of the hypotheses is that magnetars are born with an initial spin period close to the break-up limit (< 1 ms), which results in a powerful dynamo action, greatly amplifying the seed magnetic field. A neutron star spinning at such a rate has a rotational energy in excess of 1052 erg, and part of that energy will power the supernova through rapid magnetic breaking. In other words it is expected that if magnetars are born with periods of ~ 1 ms their supernova remnants should be very energetic. However, we have investigated two supernova remnants which contain magnetars, Kes 73 (1E 1841-045) and N49 (SGR 0526-66), and they appear to be the results of explosions with the canonical supernova explosion energy of 1051 erg. Converting this to an initial rotation period suggests that the initial period was longer than ~ 6 ms. This poses problems for the theory. However, there is the possibility that the conversion of rotational energy to magnetic field energy is so efficient that ~ 90% of the rotational energy is used to generate an interior magnetic field of ~ 1017 G, far in excess of the surface magnetic field estimated from the spin-down rate.
Andrew Melatos Global, time-dependent flow of a neutron star superfluid Abstract:

The global time-dependent flow of superfluid inside a neutron star has received little theoretical attention in the past, partly thanks to numerical challenges (including visualization), and partly because local processes (e.g. vortex pinning), which set the boundary conditions for the global flow, have taken precedence. In this talk, we describe several new phenomena that emerge when the global problem is considered, driven by differential rotation in the star. (i) A Kelvin-Helmholtz instability occurs at the boundary between the (anisotropic) 3P2 core superfluid and the (isotropic) 1S0 crust superfluid, suddenly transferring circulation (carried by clusters of vortices) to the crust in amounts comparable to those observed during glitches (and in accord with high-resolution laboratory experiments). (ii) Quasiperiodic torque noise ("oscillations") occurs as a natural consequence of the frictionally coupled (Hall-Vinen-Bekharevich-Khalatnikov) flow of normal fluid and superfl! uid inside a sheared spherical shell, as in the stellar inner crust. We present the results of high-resolution, 3-dim hydrodynamic simulations of this flow, which displays a rich structure of Taylor-like vortices, Ekman layers, and meridional currents. (iii) The rectilinear vortex array in the core quickly breaks up into a reconnecting vortex tangle when the meridional flow exceeds a threshold. We present the results of line vortex simulations which show that the mutual friction and tension forces in the HVBK theory decrease suddenly when this happens, exciting jumps and damped oscillations in the torque. These phenomena are related to radio observations of timing irregularities in rotation-powered pulsars.
Martin Durant AXPs in the optical and infrared: new developments. Abstract:

I will review the current set of detections of Anomalous X-ray Pulsars (AXPs) in the optical and infrared, including the new detections of 1E 1048.1-5937 and CXOU J010043.1-721134 and upper limits on 1E 1841-045. I will investigate the possible implications of this suite of data points, briefly discussing uncertainties in variability and reddening. As a possible solution to the latter, I will present a method by which we hope to derive the reddening versus distance relationship towards each of the AXPs. Finally, I will discuss the results of observations with VLT/UltraCam, VLT/ISAAC, and CFHT/PUEO for optical and infrared pulsations.
Peter R. den Hartog Hard X-ray Characteristics of Anomalous X-ray Pulsars: Results from RXTE and INTEGRAL Abstract:

Until recently anomalous X-ray pulsars (AXPs) were known as soft X-ray emitters. This has changed drastically since the discovery of hard X-ray emission (>10 keV) from several AXPs by INTEGRAL (Molkov et al. 2004, Revnivtsev et al. 2004 and den Hartog et al. 2004). Kuiper et al. (2004) discovered pulsed emission in the same energy range using RXTE (PCA and HEXTE) data. Currently four AXPs (1RXS J170849.0-400910, 1E 1841-045, 4U 0142+614 and 1E 2259+586) have been detected, some of them showing emission up to 200 keV. The spectra exhibit extremely hard power laws with photon indices < 1.0 and with apparent luminosities 2-3 orders of magnitude above the rotational energy loss. The origin of this behaviour is not yet understood. An overview containing the current observational status in the temporal and the spectral domains as well as future prospects of AXPs at high energies is presented.
James M. Lattimer Neutron Star Structure and Neutron-Rich Matter Abstract:

The liquid-droplet equations of state of LPRL (Lattimer, Pethick, Ravenhall & Lamb) and LS (Lattimer & Swesty) are extended to incorporate better descriptions of the nuclear surface, the neutron skin of nuclei, and density-dependent effective nucleon masses, and are generalized to include both non-relativistic potential and relativistic field-theoretical nucleon-nucleon interactions. Laboratory measurements of nuclear masses, giant resonances, and neutron skin thicknesses provide some constraints to the models. Nevertheless, some basic parameters of the nucleon-nucleon interactions, conveniently expressed as the nuclear incompressibility, the nuclear symmetry energy (and its density dependence), and the specific heats of both bulk nuclear matter and the nuclear surface, are not yet adequately determined. Implications of uncertainties in these parameters for the structure of the crusts of neutron stars, including possible pasta phases, are discussed. Astronomical constraints from observations of neutron star thermal emissions and the timing of radio pulsars (i.e., mass, glitch, and moment of inertia measurements) are explored.
Samina S Masood Degenerate Fermi Gas in Neutron Stars Abstract:

We study the properties of degenerate fermi gas of electrons, protons and neutrons in the neutron stars. We find the degeneracy conditions in the intense magnetic field for highly dense systems. The equation of state of neutron stars help to investigate the properties of neutron stars in a bit more detail. We investigate the individual behavior of these degenerate gases depending on their location in the neutron stars.
Samina S Masood Neutrinos in the Strong Magnetic Field Abstract:

We discuss the properties of the neutrinos in hot and dense medium of magnetized electron gas. The change in the properties of neutrinos makes it easier to learn more about the compact objects. We describe the possibel implications of our results on the stellar objects.
Deborah N. Aguilera Color-spin locking phase in two-flavor quark matter for compact star phenomenology Abstract:

We study a spin-1 single flavor color superconducting phase which results from a color-spin locking (CSL) interaction in two-flavor quark matter. This phase is particularly interesting for compact star cooling applications since the CSL phase may survive under charge neutrality constraints implying a mismatch between up- and down-quark chemical potentials which can destroy the scalar diquark condensate. CSL gaps are evaluated within an NJL model and they are found to be consistent with cooling phenomenology if a density dependent coupling constant is used.
Ariel Zhitnitsky Quantum Anomalies and Topological Currents in Dense Matter Abstract:

We derive an anomalous effective Lagrangian describing the interactions of light particles such as axions, photons and superfluid phonons in the dense matter background. This effective Lagrangian, among other things, imlies that some nontrivial persistent non dissipating currents and charge densities may be formed in the dense matter. We speculate that these effects may influence such phenomena as neutron star kicks, glitches, cooling rate...
George Pavlov Central Compact Objects in Supernova Remnants Abstract:

X-ray observations show puzzling compact objects near centers of some SNRs. Having X-ray luminosities in a range of 1032 - 1034 erg/s, they have not been seen in radio, optical, and gamma-ray bands, and they do not show pulsar wind nebulae expected for active radio and/or gamma-ray pulsars. Their X-ray spectra are predominantly thermal, with temperatures of a few million kelvins and emitting areas much smaller than the surface area of a neutron star. About eight such sources are currently known, and it is not clear whether they constitute a uniform class or it is a collection of physically different objects. It seems plausible that at least some of these sources are related to magnetars, but no firm confirmation of this hypothesis has been obtained. I will give an overview of the available observations of the whole class and discuss possible interpretations of their properties. I will also present our recent deep X-ray and optical observations of two best-studied (and most puzzling) CCOs, with most distinct properties: the central source of the Cas A SNR and the famous 1E 1207-5209 in the SNR G296.5+10.0. The Cas A CCO is the youngest member of this class, and its properties most strongly resemble those of magnetars, although its period has not been detected yet. In contrast, 1E 1207-5209 shows pulsation with a period of about 424 ms, which varies with time nonmonotonically, possibly because it is in a wide binary system with a low-mass companion. This is the only CCO from which spectral lines have been detected, which provides an opportunity to measure the gravitational redshift at the neutron star surface. I will discuss the properties and possible interpretations of these puzzling lines.
Frank Haberl Nearby radio-quiet isolated neutron stars with strong magnetic fields Abstract:

Presently seven radio-quiet isolated neutron stars with thermal X-ray emission are known. Their X-ray spectra are characterized by soft blackbody-like emission (kT ~ 45-120 eV) without indication for harder, non-thermal components. These stars apparently show no radio emission and no association with supernova remnants. Five of them exhibit pulsations in their X-ray flux with periods in the range of 3.45 s to 11.37 s. XMM-Newton observations revealed broad absorption lines in the X-ray spectra which may be caused by cyclotron resonance absorption of protons or heavy ions. I'll review our present knowledge about this group of isolated neutron stars with particular emphasis on their X-ray properties.
Divas Sanwal Neutron Stars at X-ray Wavelengths: NASA's Constellation-X Mission Abstract:

Among the most important topics in Neutron Star (NS) astrophysics is the equation of state of the matter in their interiors. Observations in X-rays wavelengths with the improved sensitivity and spectral resolution provided by Chandra and XMM-Newton have greatly enhanced our understanding of NSs. We have discovered long sought spectral lines from NSs, increased the number of NSs detected in X-rays and started to perform phase-resolved spectroscopy of NS to map the surface and differentiate among the different emission components. The Constellation-X observatory is being developed to perform spatially resolved high-resolution X-ray spectroscopy. This talk focuses on the driving science behind this mission, which is one of two flagship missions in NASA's Beyond Einstein program. A general overview of the observatory's capabilities and basic technology will also be given. Constellation-X would provide an opportunity to study Neutron Star with high sensitivity and spectral resolution. I will also present the projections into the impact on Neutron Star astrophysics with the Constellation-X observatory.
Morten Stejner The gap between a strange star core and crust Abstract:

The detailed structure of the gap caused by a strong electric field between the quark matter core and nuclear crust of a strange star is studied for a wide range of parameters.
Anna L Watts Spin evolution in LMXBs and accreting millisecond pulsars Abstract:

One of the outstanding questions of neutron star physics is why all known sources spin at rates far below the maximum predicted by nuclear theory. Candidate mechanisms for limiting spin include gravitational wave emission and magnetosphere/accretion disk interaction. I will discuss aspects of spin braking and present results from an ongoing study that aims to diagnose the governing torques using spin variability. Prospects for gravitational wave detection will also be addressed.
Lilia Ferrario Implications of the birth period - magnetic field relationship in the for the origin of magnetic fields in pulsars. Abstract:

We model the recent results from the 1374 MHZ Parkes Multibeam Survey to investigate the magnetic field distribution and the birth period distribution of pulsars as a function of magnetic field. Using population synthesis calculations we relate these to the magnetic properties of their progenitor stars on the main sequence exploring the hypothesis that the fields in neutron stars are of fossil origin. We show that the observations of radio pulsars can be explained by the fossil hypothesis if the mean field of their progenitors is of about 15 Gauss.The required distribution implies that the vast majority of main sequence stars will have fields well below the current detectability limit, while the implied high field extrapolation of the distribution naturally explains the magnetars. We also show that as with the magnetic white dwarfs, there is evidence from the radio pulsars that there is a tendency for the stronger field pulsars to be born as slower rotators, and argue that this may be a characteristic that can be used to distinguish between the fossil and dynamo models for the origin of fields in compact stars.
Christian Motch Optical Properties and origin of Radio-Quiet X-ray Dim Isolated Neutron Stars Abstract:

ROSAT has discovered a small group of X-ray emitting isolated neutron stars (INS) characterised by a lack of radio emission and a soft thermal-like X-ray spectrum. Weak interstellar absorption indicates relatively small distances of a few hundred parsecs and the absence of nearby SNR suggests middle-age objects or old neutron stars re-heated by accretion from the interstellar medium. Their proximity and the absence of strong non-thermal activity make them unique laboratories for testing radiative properties of neutron star surfaces, high gravity and high magnetic field physics. Most of these INS have optical counterparts from which contraints on the surface emitting properties can be derived. Optical imaging also allows sensitive searches for proper motion which can provide information on space velocity and birth place. I will report on the current problems faced by the modelling of the optical to X-ray energy distributions and will discuss the evolutionary status, age and origin of this particular population.
Jes Madsen Probing quark matter in compact stars with cosmic rays Abstract:

I will review the properties of small lumps of quark matter ("strangelets") and the possibility of detecting them in cosmic rays as a result of binary compact star collisions. An ongoing search in lunar soil as well as a coming search from the International Space Station will be described.
Matthew I van Adelsberg Effect of Vacuum Polarization on Thermal Emission from Strongly Magnetized Neutron Stars Abstract:

In highly magnetized neutron stars, surface magnetic field strengths can approach or exceed B > 1014 G. In such strong fields, vacuum polarization can have a substantial impact on the thermal spectrum of these objects, modifying the dielectric properties of the neutron star atmosphere and inducing a narrow resonance feature into the photon opacity. Recent studies investigating vacuum polarization and neutron star atmospheres have focused on the effect of resonant mode conversion, in which a photon encountering the resonance under adiabatic conditions changes polarization states. It has been found that mode conversion affects the thermal spectrum of the NS atmosphere, leading to suppression of the proton cyclotron feature and softening of the high energy continuum. In previous studies, the mode conversion effect has been treated approximately, assuming either complete conversion or no conversion of photons at the resonance. Also, near the vacuum resonance, the usual d! escription of radiative transfer based on photon modes breaks down. Here we present an accurate treatment of the mode conversion effect by constructing self-consistent models of radiative transfer which take into account the probability of photon conversion at the resonance as well as transfer of photon Stokes parameters. The results of such calculations are found to be intermediate between the two limiting cases of complete conversion and no conversion. We discuss the implications of our calculation to observations of isolated neutron stars; in particular, whether the effect of vacuum polarization on the proton cyclotron line can be used to understand recently observed absorption features from several sources.
Edward Brown The cooling of quasi-persistent neutron star transients Abstract:

Neutron star transients with outburst durations of several years allow observations to constrain the cooling rate of the heated neutron star crust. Pycnonuclear reactions in the crust heat the neutron star interior and can elevate the crust temperature considerably with respect to that of the core if the thermal conductivity is sufficiently low. For various scenarios of the physics of the crust and core, we have computed families of quiescent lightcurves for different outburst durations, accretion rates, and quiescent intervals. I will compare these lightcurves with observations, and highlight recent efforts to compute the nuclear reaction chains in the crust for a realistic distribution of rp-process ashes. The unstable ignition of carbon, which powers superbursts, is strongly dependent on the temperature in the neutron star crust and is thus also sensitive to the physics of the crust and core. Interestingly, KS1731-260 had at least one superburst during its protracted accr! etion outburst but also had a rapidly declining quiescent luminosity. I will compare the superburst ignition conditions from our time-dependent calculations with observations.
Herman L Marshall Searches for Absorption Lines in Neutron Star Atmospheres Abstract:

There have been many observations of neutron stars with high resolution X-ray spectrometers where the primary goal was to observe narrow absorption features that could then be used to determine the surface redshift. To date, there is still only one reported detection. I will summarize results from many of the observations using the Chandra grating spectrometers, including X-ray bursters, magnetars, and weakly magnetized isolated neutron stars. I will describe some of the difficulties involved and what efforts may be required.
Frederick M Walter On the Parallax of Geminga Abstract:

Geminga is one of the seminal sources for high energy astrophysics. It is a radio-quiet X-ray and gamma-ray pulsar, and one of the strongest sources of pulsed gamma ray emission in the sky. Its spectrum features a soft thermal component and a hard tail. Its characteristic age is 340,000 years, and it may have been born in the Orion OB1 association. Carraveo et al (1996) claimed a distance of 157 (+59, -34) pc using a parallax determination based on 3 HST WFPC2 images. Given the importance of this object for understanding the high energy radiation processes in magnetized neutron stars, we decided to confirm the parallax using an optimized set of HST/ACS images. We obtained deep V-band images in September 2003, March and September 2004, and March 2005, at the extrema of the parallactic shift of Geminga. As of this writing, we are analyzing the images and coming to terms with the instrumental anomalies of the ACS. We expect to report a preliminary parallax of Geminga. Collaborators on this work include Jacqueline Faherty, James Lattimer, and George Pavlov. This work is supported by a grant from the Space Telescope Science Institute.
Sanjib S Gupta Deep Crustal Reactions Abstract:

I will present results from coupling a realistic reaction network with newly calculated electron capture rates to composition-dependent thermal transport of the Neutron Star crust. From the ashes of rp-process burning on the accreting Neutron Star we follow the sequences of electron captures in a multizone model and the resulting composition changes. Photodisintegration rearrangement and the effect of the resultant heating are also calculated self-consistently with the thermal transport.
Andrei M Beloborodov Magnetospheres of Magnetars Abstract:

Properties of magnetar magnetospheres will be reviewed. Then a model of their persistent nonthermal emission will be presented, which relates emission to the electric circuit in a twisted magnetosphere. A self-consistent model of plasma dynamics in the circuit allows one to answer basic questions: What are the magnetospheric particles? What are their temperature and density? What is the dissipation rate in the magnetosphere? How and where is the observed nonthermal emission produced?
Anatoly Spitkovsky Magnetospheres of neutron stars Abstract:

Rotating magnetized neutron stars generate enormous electric fields near the surface and populate their magnetospheres with relativistic plasma. The detailed structure of pulsar and magnetar magnetospheres has remained an unsolved problem for a long time. Understanding the magnetospheric structure is crucial for determining the neutron star energy loss rate and its radiative properties. In this talk I present the time-dependent numerical solution of pulsar magnetospheric structure in the limit of force-free relativistic MHD. Both aligned and oblique dipole case are addressed, paying particular attention to the spontaneous formation of current sheets in the magnetosphere. The numerical method is applicable to generic differentially rotating magnetized configurations and is further used to study magnetospheres of magnetars, both in the quescent state, and during rapid field reconfiguration in flares.
Alaa I. Ibrahim Burst Observations from the Two Neighboring Magnetars SGR 1806-20 and XTE J1810-197 Abstract:

XTE J1810-197 is a newly discovered magnetar with a new flavor of being transient (Ibrahim et al. 2004). Monitoring observations revealed that the source emitted a few X-ray bursts that appear to show different properties than most SGR bursts (Woods et al. 2005). We confront these bursts with those from SGR sources, especially SGR 1806-20, and discuss the implications of the results to a number of open questions on magnetars including whether SGR and AXP bursts are intrinsically different and the presence of spectral line feature in some magnetar bursts. Ibrahim, A. et al. 2004, ApJ, 609, L21 Woods, P. et al. 2005, ApJ, in press
Sergio Campana Powering neutron star binary transients during quiescence: to accrete or not to accrete Abstract:

Binary neutron star transients are systems that shine as the brightest sources in the sky for limited periods (months) and then for years return to their quiescent (low-luminosity) state. During quiescence accretion might still powering the observed X-ray luminosity, even if difficulties exist. Different mechanisms from accretion onto the neutron star surface have been put forword over the last years, involving propeller accretion, cooling of the (heated) neutron star or conversion into X-rays of the spin down power of a re-activated radio pulsar. This is particularly intriguiing in those (few) systems showing pulsations during the outburst phase. Here we will present results obtained with XMM-Newton, Chandra and VLT on the quiescent state of a few of these systems. Circumstantial evidence in favor of a re-activated radio pulsar can be found in SAX J1808.4-3658 from the very high optical emission with respect to the brown dwarf companion. Long and short term variability prop! erties of X-ray flux add further arguments in favour of this mechanism.
Dany Page Strange Stars: where are they ? Abstract:

Strange Stars, i.e., compact stars made of self-bound quark matter, are an intriguing alternative to "neutron" stars. To date there is not yet any convincing evidence either in favor or against their existence. I'll argue that if Strange Stars exist then the most massive compact stars in LMXB should be strange stars, and vice-versa, if these are not Strange Stars then Strange Stars do not exist. Models of thermal evolution of massive Strange Stars in LMXBs, in particular superbursting sources and SXRTs, could give an answer to this question.
David Nice Highlights of Recent Binary Pulsar Observations at Arecibo Abstract:

I will describe some recent results of binary and millisecond pulsar observations with the Arecibo radio telescope. Topics to be described include (1) the surprisingly high mass (2.1+-0.2 solar masses) of PSR J0751+1807 and a possible inverse correlation between pulsar mass and orbital period, (2) the surprisingly low proper motion of the Hulse-Taylor binary PSR B1913+16, and (3) first results from the PALFA survey, a deep pulsar search along the Galactic plane.
Marten H van Kerkwijk Absorption lines in the spectra of nearby neutron stars Abstract:

Over the last year, photospheric absorption features - likely due to hydrogen in strongly magnetized atmospheres - have been found in X-ray spectra taken with XMM and Chandra for three nearby neutron stars. I will discuss what we have learned from those observations and describe the new puzzles they have posed. I will also present initial results from our large, 300 ks Chandra programme on one of the brightest sources.
David L Kaplan Searching for Compact Objects in Supernova Remnants Abstract:

We have undertaken a census of the central sources in supernova remnants (SNRs) within 5 kpc. For SNRs that have no evidence for a central source (i.e. shell-type remnants), we have begun a search for new sources with the Chandra X-ray Obervatory. This search consists of X-ray imaging, followed by deep optical, infrared, and radio observations to reject contaminating sources.
David L Kaplan Constraining the Properties of Isolated Neutron Stars Through Astrometry and Abstract:

We will discuss the results of dedicated programs that use high-precision optical astrometry and phase-coherent X-ray timing to measure the distances, proper motions, ages, and magnetic field strengths of nearby, isolated neutron stars.
Andrey Timokhin High resolution numerical modeling Abstract:

I consider the force-free magnetosphere of aligned rotator. Its structure is well described by the Grad-Shafranov equation for poloidal magnetic field, so-called "pulsar equation". I developed multigrid code for solution of the pulsar equation with high numerical resolution. On the fine numerical grid current layer along the last closed field line could be accurately incorporated into numerical procedure and all physical properties of the solution such as Goldreich-Julian charge density, drift velocity, energy losses etc. could be accurately calculated. Here I report results of the simulations. Among other interesting properties, the solution is not unique, i.e. the position of the last closed field line, and, hence, the pulsar energy losses, are not determined by the global magnetospheric structure and depends on kinetic of electromagnetic cascades. I discuss the properties of the solutions and their implications for pulsars. I propose a model for pulsar magnetosphere evolution. In the frame of this model values of the pulsar braking index less than 3 can be easily explained.
Krishna Rajagopal A Hot Water Bottle for Aging Neutron Stars? Abstract:

We understand many of the properties of the densest phase of quark matter rigorously from first principles QCD. However, the nature of the second-most-dense phase of quark matter remains unclear. A recently proposed candidate for this phase features both neutrino emissivity and specific heat that are parametrically enhanced relative to those of all other proposed phases of dense matter -- quark or nuclear. If present within a layer of a neutron star, it would control the cooling of the star. The neutrino-dominated cooling would look like standard Direct-URCA as the two enhancements cancel, but old stars, say tens of millions of years and older, would stay orders of magnitude warmer than in any other scenario. Most of my talk will consist of explaining this abstract. At the end, I will explain why it currently remains unclear whether this hot water bottle phase really is the second-densest form of quark matter, and will discuss an alternative possibility.
Kaya Mori A Unique Neutron Star: Detailed Spectral and Theoretical Analysis of 1E1207.4-5209 Abstract:

1E1207.4-5209 is unique because it is the only isolated neutron star with multiple spectral features. We present our detailed analysis of the 260 ksec XMM-Newton data focusing on the putative absorption features at 2.1 and 2.8 keV reported by Bignami et al. 2003. Our statistical tests show the 3rd and 4th feature are insignificant, and only the two broad absorption features previously reported are significant. We have also confirmed that the residuals are consistent in strength and position with the instrument Au-M residuals observed in 3C273. We also present the results from our recent phase-resolved spectral analysis of 1E1207. At the end, we discuss our model for the two absorption features in terms of atomic transition lines from highly-ionized Oxygen or Neon and compare that picture with other competing models. Future high resolution spectroscopy is essential to elucidate the surface composition of 1E1207 and to understand why 1E1207 is unique compared to other isolated neutron stars.
Ingrid Stairs Timing the Double-pulsar System Abstract:

I will present the current status of the timing solution for the double pulsar J0737-3039, and will discuss future observables, including the prospect of measuring a neutron-star moment of inertia through the spin-orbit contribution the advance of periastron.
Jennifer Parry Analysis of PSR B1828-11 Profile Variations Abstract:

We present an analysis of high-resolution Parkes observations of the precessing pulsar B1828-11. The data cover the 1000-day periodicity evident in the timing residuals. This study aims to determine whether the profile variations also show evidence for a 1000We present an analysis of high-resolution Parkes observations of the precessing pulsar B1828-11. The data cover the 1000-day periodicity evident in the timing residuals. This study aims to determine whether the profile variations also show evidence for a 1000-day periodicity in addition to the known 500- and 250-day variations. We also present initial results in mapping the emission region of this pulsar, incorporating the mode-changing effects that are evident at each epoch.
Robert E Rutledge Neutron Star Radii: At the Crossroads Abstract:

Transient Low Mass X-ray Binaries in quiesence have offered a primary means to measure neutron star radii. In this talk, I will review the theory which motivated the investigation of these sources for neutron star radius measurements, the observational status of this direction, what we have learned so far in the era of high throughput X-ray spectroscopy, and where we can expect these observations to take us.
Philip Chang Atomic Transition Lines During Type I X-Ray Bursts Abstract:

The discovery of the first atomic transition lines from a bursting neutron star (NS) by Cottam, Paerels and Mendez is the solid measurement of gravitational redshift from a NS surface. I will review the observation and discuss the basic physics of the neutron star atmosphere and line formation in this context. I will highlight the important effects of Stark broadening, resonant scattering and NLTE effects (level population) on the formation of the Fe H\alpha and Ly\alpha lines. With the inclusion of these effects, I reproduce the appropriate equivalent width of the observed line with Fe columns that are consistent with solar metallicity accretion. I also compare the fully relativisitic rotationally broadened line profile to the data and find that the NS spin is \nu_{\rm s}\sin i (R/10\,{\rm km}) = 32-28+52\,{\rm Hz} with 95% confidence, in agreement with the 44.7 Hz spin detected by Villarreal and Strohmayer. However, fine structure splitting of the line precludes a meaningful constraint on the radius of this NS. Finally I highlight future prospects for detecting other features on more rapidly rotationing NSs and their application in determining both the redshift and radius to contraint the nuclear equation of state.
Olivier R Espinosa Neutrino emission rates in highly magnetized neutron stars Abstract:

Magnetars are a subclass of neutron stars whose intense soft-gamma-ray bursts and quiescent X-ray emission are believed to be powered by the decay of a strong internal magnetic field. We reanalyze neutrino emission in such stars in the plausibly relevant regime in which the Landau band spacing delta-E of both protons and electrons is much larger than kT (where k is the Boltzmann constant and T is the temperature), but still much smaller than the Fermi energies. Focusing on the direct Urca process, we find that the emissivity oscillates as a function of density or magnetic field, peaking when the Fermi level of the protons or electrons lies about 3kT above the bottom of any of their Landau bands. The oscillation amplitude is comparable to the average emissivity when delta-E is roughly the geometric mean of kT and the Fermi energy (excluding mass), i. e., at fields much weaker than required to confine all particles to the lowest Landau band. Since the density and magnetic field strength vary continuously inside the neutron star, there will be alternating surfaces of high and low emissivity. Globally, these oscillations tend to average out, making it unclea! r whether there will be any observable effects.
Igor A Shovkovy Phase diagram of dense QCD with and without neutrino trapping Abstract:

We study the phase diagram of dense, locally neutral three-flavor quark matter within the framework of the Nambu--Jona-Lasinio model. In the analysis, dynamically generated quark masses are taken into account self-consistently. The phase diagrams in the plane of temperature and quark chemical potential, as well as in the plane of temperature and neutrino chemical potential are presented. We show that neutrino trapping favors two-flavor color superconductivity and disfavors color-flavor-locked phase at imtermediate densities of matter. The implications of these results for the evolution of protoneutron stars are briefly discussed.
Marjorie E Gonzalez Pulsed X-ray emission from the young, high magnetic field radio pulsar PSR J1119-6127 Abstract:

We report the first detection of pulsed X-ray emission from the radio pulsar PSR J1119-6127 using XMM-Newton. The pulsar has a characteristic age of 1,700 yrs and inferred surface dipole magnetic field strength of 4.1 x 1013 G. In the 0.5-2.0 keV range, the emission shows a single, narrow pulse with a very high pulsed fraction of ~ 70%. No pulsations are detected in the 2.0-10.0 keV range, where we derive an upper limit for the pulsed fraction of 28%. The pulsed emission is well described by a thermal blackbody model with a high temperature of ~ 2.4 x 106 K. Atmospheric models result in problematic estimates for the distance/emitting area. PSR J1119-6127 is now the radio pulsar with smallest characteristic age from which thermal X-ray emission has been detected. The observed combination of temporal and spectral characteristics provide an excellent test site for current models of thermal emission from neutron stars.
Feryal Özel Constraining Neutron Star Masses and Radii Using High Resolution Spectra Abstract:

While recent X-ray missions provide us with high resolution spectra of thermally emitting neutron stars, the largest uncertainties in determining neutron star masses and radii from from these spectra are still theoretical. In order to obtain accurate constraints, (i) the surface layers of neutron stars need to be modeled in detail, (ii) the effects of strong gravity and rotation on surface emission need to be taken into account, and (iii) possible temperature non-uniformity and unknown emission geometry need to be addresses. In this talk, I will discuss recent models of neutron star surface layers and the general relativistic effects on the surface, pointing out the uncertainties in mass-radius determination arising from each. I will then show how combining timing information of neutron stars with their spectra reduces greatly the uncertainties arising from general relativistic and geometrical effects. Finally, I will discuss how combining several different spectral and timing measurements of X-ray sources provides us with complementary and the most promising method for accurate determination of neutron star masses and radii, as well as minimizes observational uncertainties such as source distances.
Vicky Kaspi Observational Properties of Magnetars Abstract:

I will review recent observational results concerning magnetars.
Rene Breton PSR J1744-3922: a puzzle for standard binary pulsar evolution Abstract:

Although only 5-10% of the known population of pulsars consists of binary systems, they comprise the vast majority of the so-called millisecond pulsars (MSPs). This fact leads to the interpretation that most MSPs were formerly slower pulsars that got spun up after accreting matter from their companion. We report on the study of PSR J1744-3922 , a binary pulsar exhibiting a rather strange combination of characteristics in comparison with other MSPs: a long spin period (172 ms), a high magnetic field (1.7e10 G), a short orbital period (4.6 h) and a light companion (Mmin = 0.08 Msol). Interestingly, J1744-3922 also experiences sporadic lacks of radio emission, first thought to be a intrinsic phenomenon called “nulling” (Faulkner et al. 2004); however, a statistical analysis indicates a marginal correlation between the radio modulation and the orbital phase. Altogether, these properties are not explained by any of the standard evolution models and this suggests that J1744-! 3922 underwent a peculiar evolution history. A close examination at the binary pulsar population reveals evidence of a few other systems having similar orbital and spin characteristics. We therefore propose the addition of a new subclass of binary pulsars and discuss some plausible evolution channels leading to their atypical properties.
Bülent KIZILTAN Neutron Star Physics with GLAST Abstract:

The Gamma Ray Large Area Space Telescope (GLAST) will provide us with a new window on the galactic neutron star population and a unique opportunity to understand the pulsar emission physics and geometry. We will review the general capabilities of GLAST and the expected contribution to our understanding of neutron star physics.
Eric Gotthelf Further Evidence of a Power Threshold for Generation of a Pulsar Wind Nebula Abstract:

Analysis of newly archived Chandra X-ray data on energetic rotation-powered pulsars support previous conclusions of a spin-down power threshold for generating a pulsar wind nebulae (PWN). The X-ray flux ratio FPWN/FPSR measured from newly available data on several pulsars with \dot E \equiv I\omega\dot\omega < \dot Ec \approx 4 x 1036 erg s-1 are all found to be greatly reduced in magnitude compared to their more energetic counterparts. As an empirical rule, all pulsars with spin-down power greater then this threshold are found to be X-ray bright, manifest a distinct pulsar wind nebula, and are associated with a supernova event. For pulsars with \dot E < \dot Ec, the X-ray flux ratio FPWN/FPSR on average is an order-of-magnitude less. The reason for this cut-off is unknown. However, this result is evidently more general, as observations at radio wavelengths also show that only the most energetic rotation-powered pulsars display a PWN (Frail \& Scharringhausen 1997; Gaensler et al. 2000) while less energetic pulsars with \dot E < \dot E_c generally do not. The only exception so far is PSR J0908-4913, a pulsar with very weak, barely resolved radio emission (FPWN/FPSR < 0.06 @ 1.2--2.2 GHz; Gaensler et al. 1998). Thus the radio result is consistent with the X-ray finding of a threshold for generating a bright PWN based on the spin-down power of a pulsar. The latest findings will be discussed.
Tomasz Bulik Moments of inertia of the components of binary pulsar J0737-3039 Abstract:

he moment of inertia of the pulsar A in the binary pulsar J0737-3039 will soon be measurable through detailed measurements of the periastron advanc. We present the calculation of the moment of inertia of neutron stars with the masses of the components of the binary pulsar J0737-3039 for a broad range of nuclear equations of state and discuss the implications of such measurement for constraining the nuclear matter equation of state.
Anna L Watts Rapid X-ray oscillations in magnetar giant flares Abstract:

Israel and co-authors recently reported the detection of high frequency QPOs in the December 2004 giant flare from the magnetar SGR 1806-20. They suggested that the QPOs may have their origin in torsional vibrations of the neutron star crust. In this talk we report the discovery of similar high frequency oscillations in the August 1998 giant flare of SGR 1900+14. We discuss our findings in the light of the torsional mode model and show that if the stars have similar masses then the magnetic field of SGR 1806-20 must be about twice as large as that of SGR 1900+14, which is broadly consistent with magnetic field estimates from pulse timing. We also show how detailed mode identifications could lead to constraints on the nuclear equation of state.
Sergei Popov Soft gamma repeaters outside the Local group Abstract:

We propose that the best sites to search for SGRs outside the Local group are galaxies with active massive star formation. Different possibilities to observe SGR activity from these sites are discussed. In particular we searched for giant flares from nearby galaxies (~ 2 -- 4 Mpc) M82, M83, NGC 253, and NGC 4945 in the BATSE data. No candidates alike giant SGR flares were found. The absence of such detections implies that the rate of giant flares with energy release in the initial spike above 0.5 \cdot 1044 erg is less then 1/25 yr-1 in our Galaxy. However, hyperflares similar to the one of 27 December 2004 can be observed from larger distances. Nevertheless, we do not see any significant excess of short GRBs from the Virgo galaxy cluster and from galaxies Arp 299 and NGC 3256 with extremely high star formation rate. This implies that the galactic rate of hyperflares with energy release ~ 1046 erg is less than ~ 10-3 yr-1. With this constraint the fraction of possible extragalactic SGR hyperflares among BATSE short GRBs should not exceed few percents. We present a list of short GRBs coincident with galaxies mentioned above, and discuss the possibility that some of them are SGR hyperflares. We propose that the best target for ! observations of extragalactic SGR flares by {\it Swift} is the Virgo cluster.
Sergei Popov Magnetars origin and progenitors with enhanced rotation Abstract:

Among a dozen known magnetar candidates there are no binary objects. As an estimate of a fraction of binary neutron stars is about 10% it is reasonable to address the question of solitarity of magnetars, to estimate theoretically the fraction of binary objects among them, and to mark o probable companions. We present population synthesis calculations of binary systems. Our goal is to estimate the number of neutron stars originated from progenitors with enhanced rotation, as such compact objects can be expected to have large magnetic fields, ie. they can be magnetars. The fraction of such neutron stars in our calculations is about 13-16%. Most of these objects are isolated due to coalescences of components prior to a neutron star formation, or due to a system disruption after a supernova explosion. The fraction of such neutron stars in survived binaries is about 1% or lower. Their most numerous companions are black holes.
Marcel Agueros Candidate Isolated Neutron Stars and Other Optically Blank X-ray Fields Identified from the RASS and SDSS Abstract:

We describe a selection algorithm based on a cross-correlation of the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) that identifies X-ray error circles devoid of plausible optical counterparts to the SDSS m=22 mag depth. We quantitatively characterize these error circles as optically blank; they may host isolated neutron stars (INSs) or other similarly exotic X-ray sources such as radio-quiet BL Lacs, obscured AGN, etc. Our search excludes the 99.9% of error circles that contain more common X-ray emitting subclasses. We find 14 candidates, 12 of which are new, a number consistent with predictions from INS population models.
Denis Leahy The interpretation of the pulse shapes of the ms accreting pulsar SAXJ1808-3654 Abstract:

The accreting millisecond pulsar (401 Hz pulse frequency) has a pulse shape which depends significantly on energy. Since it is spinning rapidly, special relativistic effects as well as light-bending effects due to general relativity, need to be considered when modeling its pulse profile. Poutanen and Gierlinski (2003 MNRAS, 343, 1301) have modeled the pulse profile during one RXTE observation using Schwarzchild metric light-bending and special relativistic corrections. Here is described modeling of the pulse profiles with two generalizations: 1. 3 different RXTE observations with different pulse shapes are analyzed; 2. the model is generalized to include light time-travel delays. Both of the above significantly affect the conclusions derived about the emitting region and also the derived mass and radius of the neutron star in SAXJ1808-36.
Denis Leahy On modeling the pulse shape of Her X-1 Abstract:

Her X-1 exhibits a 35-day cycle of intensity and pulse shape changes. The 35-day cycle has been long understood as caused by a precessing accretion disk which intermittently obscures the radiation from the pulsar. The pulse shape changes were first successfully explained by Scott, Leahy and Wilson (2000 ApJ, 539, 392), and detailed models for the intensity vs. 35-day cycle were produced by Leahy (2002 MNRAS, 334, 847). A pulse shape model incorporating the pencil beam plus reverse fan beam configuration was constructed by Leahy (2004 MNRAS, 348, 932) and used to constrain the mass and radius of the neutron star (Leahy 2004 ApJ, 613, 517). Here some further generalizations of the model are described.
Rene Breton Eclipse Study of the Double Pulsar System Abstract:

The double pulsar system PSR J0737-3039 offers an unprecedented opportunity for studying neutron star magnetospheres. This system presents favourable orbital inclination which makes the faster pulsar, "A", being eclipsed when its slower companion, "B", passes in front. High time resolution light curves at 820 MHz revealed modulation of the pulsed flux intensity of "A" correlated with the spin phase of "B" (McLaughlin et al. 2004). We report on preliminary results from a detailed study of the eclipses confirming that modulation also exists at other radio frequencies. We found modulation modes linked to the fundamental and the first harmonic of pulsar "B" spin frequency. These features should allow us to probe the magnetosphere of "B" in the plane intersecting our line of sight.
Olivier R Espinosa Neutrino emission from highly magnetized neutron star matter (revisited) Abstract:

We reanalyze neutrino emission from strongly magnetized neutron stars in the plausibly relevant regime in which the Landau band spacing \Delta E of both protons and electrons is much larger than kT (where k is the Boltzmann constant and T is the temperature), but still much smaller than the Fermi energies. Focusing on the direct Urca process, we find that the emissivity oscillates as a function of density or magnetic field, peaking when the Fermi level of the protons or electrons lies about ~ 3 kT above the bottom of any of their Landau bands. The oscillation amplitude is comparable to the average emissivity when \Delta E is roughly the geometric mean of kT and the Fermi energy (excluding mass), i. e., at fields much weaker than required to confine all particles to the lowest Landau band. Since the density and magnetic field strength vary continuously inside the neutron star, there will be alternating surfaces of high and low emissivity. Globally, these oscillations tend to average out, making it unclear whether there will be any observable effects.