Program
|
Central Compact Objects in Supernova Remnants
George Pavlov
Pennsylvania State University
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.
Go back to the program page
|