C.D.S. - SIMBAD4 rel 1.7 - 2021.02.26CET17:55:16

2009A&A...508..395R - Astronomy and Astrophysics, volume 508, 395-400 (2009/12-2)

The first cyclotron harmonic of 4U 1538-52.


Abstract (from CDS):

Cyclotron resonant scattering features are an essential tool for studying the magnetic field of neutron stars. The fundamental line provides a measure of the field strength, while the harmonic lines provide information about the structure and configuration of the magnetic field. Until now only a handful of sources are known to display more than one cyclotron line and only two of them have shown a series of harmonics. The aim of this work is to see the first harmonic cyclotron line, confirming the fundamental line at ∼22keV, thus increasing the number of sources with detected harmonic cyclotron lines. To investigate the presence of absorption or emission lines in the spectra, we have combined RXTE and INTEGRAL spectra. We modeled the 3-100keV continuum emission with a power law with an exponential cut off and look for the second absorption feature. We show evidence of an unknown cyclotron line at ∼47keV (the first harmonic) in the phase-averaged X-ray spectra of 4U 1538-52. This line is detected by several telescopes at different epochs, even though the S/N of each individual spectrum is low. We conclude that the line-like absorption is a real feature, and the most straightforward interpretation is that it is the first harmonic, thus making 4U 1538-52 the fifth X-ray pulsar with more than one cyclotron line.

Abstract Copyright:

Journal keyword(s): X-rays: binaries - pulsars: individual: 4U 1538-52

Simbad objects: 3

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Number of rows : 3

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 V* QV Nor HXB 15 42 23.3633078550 -52 23 09.576918639   16.3 14.5     B0.2Ia:e 379 1
2 NAME Nor Arm PoG 16 00 -50.0           ~ 354 0
3 HD 153919 HXB 17 03 56.7728262865 -37 50 38.912077679 6.06 6.78 6.51 6.08 5.90 O6Iafcp 765 1

    Equat.    Gal    SGal    Ecl

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