| |
 |
| Paper: |
Hydrogen or Helium atmospheres for quiescent accreting neutron stars in globular clusters? |
| Volume: |
470, 370 Years of Astronomy in Utrecht |
| Page: |
181 |
| Authors: |
Servillat, M. |
| Abstract: |
Through the study of the quiescent X-ray emission of neutron stars in
low-mass X-ray binaries it is possible to constrain the chemical
composition of the neutron star atmosphere and the possible equation
of state of dense matter. Using deep Chandra observations, I
report the spectral analysis of a neutron star in the globular cluster
M28. For the first time for this kind of object, different atmosphere
models composed of hydrogen, helium or carbon are used. The carbon
model can be ruled out, and the derived mass and radius are clearly
distinct depending on the composition
of the atmosphere. The hydrogen model gives masses/radii consistent
with the canonical values of 1.4 M☉ and 10 km, and would allow for
the presence of exotic matter inside neutron stars. On the other hand,
the helium model provides solutions with higher masses/radii,
consistent with the stiffest equations of state. Measurements of
neutron star masses/radii by spectral fitting should consider the
possibility of heavier element atmospheres, which produce larger
masses/radii for the same data, unless the composition of the accretor
is known independently. |
|
|
|
|
|
