2015A&A...573A..53K


C.D.S. - SIMBAD4 rel 1.7 - 2020.09.26CEST15:13:16

2015A&A...573A..53K - Astronomy and Astrophysics, volume 573A, 53-53 (2015/1-1)

The neutron star in HESS J1731-347: Central compact objects as laboratories to study the equation of state of superdense matter.

KLOCHKOV D., SULEIMANOV V., PUEHLHOFER G., YAKOVLEV D.G., SANTANGELO A. and WERNER K.

Abstract (from CDS):

Central compact objects (CCOs) in supernova remnants are isolated thermally emitting neutron stars (NSs). They are most probably characterized by a magnetic field strength that is roughly two orders of magnitude lower than that of most of the radio and accreting pulsars. The thermal emission of CCOs can be modeled to obtain constraints on the physical parameters of the star such as its mass, radius, effective temperature, and chemical composition. The CCO in HESSJ1731-347 is one of the brightest objects in this class. Starting from 2007, it was observed several times with different X-ray satellites. Here we present our analysis of two new XMM-Newton observations of the source performed in 2013 which increase the total exposure time of the data available for spectral analysis by a factor of about five compared to the analyses presented before. We use our numerical spectral models for carbon and hydrogen atmospheres to fit the spectrum of the CCO. From our fits, we derive constraints on the physical parameters of the emitting star such as its mass, radius, distance, and effective temperature. We also use the new data to derive new upper limits on the source pulsations and to confirm the absence of a long-term flux and spectral variability. The analysis shows that atmosphere models are clearly preferred by the fit over the blackbody spectral function. Under the assumption that the X-ray emission is uniformly produced by the entire star surface (supported by the lack of pulsations), hydrogen atmosphere models lead to uncomfortably large distances of the CCO, above 7-8kpc. On the other hand, the carbon atmosphere model formally excludes distances above 5-6kpc and is compatible with the source located in the Scutum-Crux (∼3kpc) or Norma-Cygnus (∼4.5kpc) Galactic spiral arm. We provide and discuss the corresponding confidence contours in the NS mass-radius plane. The measured effective temperature indicates that the NS is exceptionally hot for the estimated age of ∼30kyr. We discuss possible cooling scenarios to explain this property, as well as possible additional constraints on the star mass and radius from cooling theory.

Abstract Copyright:

Journal keyword(s): stars: neutron - stars: atmospheres

Simbad objects: 14

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Number of rows : 14

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 PSR J0357+32 Psr 03 57 52.161 +32 05 23.63           ~ 75 0
2 RX J0822.0-4300 X 08 22 27.00 -43 10 27.0           ~ 29 1
3 NAME Pup A SNR 08 24 07 -42 59.8           ~ 523 1
4 SNR G295.5+09.7 SNR 12 09 40 -52 25.0           ~ 258 1
5 PSR J1210-5226 Psr 12 10 00.88 -52 26 28.4           ~ 205 1
6 NAME Crux-Scutum Spiral Arm reg 12 30 -60.0           ~ 278 0
7 NAME Crux Arm PoG 12 30 -60.0           ~ 83 0
8 NAME Nor Arm PoG 16 00 -50.0           ~ 344 0
9 SNR G353.6-00.7 SNR 17 31 55.0 -34 42 36           ~ 99 0
10 XMMU J173203.3-344518 X 17 32 03.3 -34 45 18           ~ 26 0
11 PSR J1741-2054 Psr 17 41 57.282 -20 54 04.11           ~ 93 1
12 SNR G033.6+00.1 SNR 18 52 29.000 +00 38 42.00           ~ 242 1
13 NAME Cas A SNR 23 23 24.000 +58 48 54.00           ~ 2433 1
14 NAME Norma-Cygnus Arm reg ~ ~           ~ 75 0

    Equat.    Gal    SGal    Ecl

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2020.09.26-15:13:16

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