2010A&A...518A..46T


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.11CEST14:43:30

2010A&A...518A..46T - Astronomy and Astrophysics, volume 518, A46-46 (2010/7-2)

The energy spectrum of anomalous X-ray pulsars and soft gamma-ray repeaters.

TRUEMPER J.E., ZEZAS A., ERTAN U. and KYLAFIS N.D.

Abstract (from CDS):

Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) exhibit characteristic X-ray luminosities (both soft and hard) of around 1035 erg/s and characteristic power-law, hard X-ray spectra extending to about 200 keV. Two AXPs also exhibit pulsed radio emission. Assuming that AXPs and SGRs accrete matter from a fallback disk, we attempt to explain both the soft and the hard X-ray emission as the result of the accretion process. We also attempt to explain their radio emission or the lack of it. We test the hypothesis that the power-law, hard X-ray spectra are produced in the accretion flow mainly by bulk-motion Comptonization of soft photons emitted at the neutron star surface. Fallback disk models invoke surface dipole magnetic fields of 1012 - 1013G, which is what we assume here. Unlike normal X-ray pulsars, for which the accretion rate is highly super-Eddington, the accretion rate is approximately Eddington in AXPs and SGRs and thus the bulk-motion Comptonization operates efficiently. As an illustrative example we reproduce both the hard and the soft X-ray spectra of AXP 4U 0142+61 well using the XSPEC package compTB. Our model seems to explain both the hard and the soft X-ray spectra of AXPs and SGRs, as well as their radio emission or the lack of it, in a natural way. It might also explain the short bursts observed in these sources. On the other hand, it cannot explain the giant X-ray outbursts observed in SGRs, which may result from the conversion of magnetic energy in local multipole fields.

Abstract Copyright:

Journal keyword(s): pulsars: individual: 1E 1841-045 - pulsars: individual: 1RXS J1708-4009 - pulsars: individual: 4U 0142+61 - X-rays: stars - stars: magnetic fields

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 PSR J0146+6145 Psr 01 46 22.21 +61 45 03.8   28.100 25.620     ~ 518 0
2 PSR J1550-5418 Psr 15 50 54.18 -54 18 23.9           ~ 352 1
3 PSR J1708-4008 Psr 17 08 49.0 -40 09 10           ~ 269 0
4 AX J1809.8-1943 Psr 18 09 51.07 -19 43 51.8           ~ 385 0
5 PSR J1841-0456 Psr 18 41 19.29 -04 56 11.4           ~ 239 1
6 BD+53 2790 HXB 22 07 56.2368407539 +54 31 06.405811141 9.4 10.11 9.84 9.64 9.43 O9.5Vep 179 0
7 2E 4673 HXB 23 01 08.14 +58 52 44.5           ~ 597 1
8 NAME Magnificent Seven ? ~ ~           ~ 59 1

    Equat.    Gal    SGal    Ecl

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2021.04.11-14:43:30

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