AstroSat observations of GRO J2058+42 during the 2019 outburst

Abstract

We present results from AstroSat observation of the recent outburst of GRO J2058+42, an X-ray pulsar in a Be-binary system. The source was observed on April 10, 2019 by LAXPC and SXT instruments on AstroSat during its declining phase of the latest giant outburst. Light curves showed a strong pulsation of the pulsar with a period of 194.2201 \pm 0.0016 s, and a spin-up rate of (1.65\pm0.06)\times10^{-11} Hz s^{-1}. Intermittent flaring was detected in light curves between 3--80 keV energy band with increase in intensity by up to 1.8 times its average intensity. Pulse profiles obtained between 3--80 keV energy band of the pulsar showed strong dependence on energy. A broad peak was observed in the power density spectrum of the source consistently during AstroSat observations with its peak oscillation frequency of 0.090 Hz along with its higher harmonics, which may be due to quasi-periodic oscillations, a commonly observed phenomenon in transient X-ray pulsars, during their outburst. AstroSat observation also detected cyclotron absorption features in its spectrum corresponding to (9.7--14.4) keV, (19.3--23.8) keV and (37.8--43.1) keV. The pulse phase resolved spectroscopy of the source showed phase dependent variation in its energy and relative strength of these features. The spectrum was well fitted with an absorbed black-body, a Fermi Dirac cut-off model and alternatively with an absorbed CompTT model. Both these models were combined with a Fe-line and three Gaussian absorption lines to account for observed cyclotron resonance scattering features in the spectrum.

arXiv comment22 pages, 22 figures, 3 tables, Accepted for publication in Astrophysical Journal

References in corpus (50)

• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Observations of Accreting Pulsars
• Statistics: Handle with Care, Detecting Multiple Model Components with the Likelihood Ratio Test
• Millisecond Oscillations in X-Ray Binaries
• Be/X-ray binaries
• The Swift/BAT Hard X-ray Transient Monitor
• Magnetic Fields of Accreting X-Ray Pulsars with the Rossi X-Ray Timing Explorer
• A natural explanation for periodic X-ray outbursts in Be/X-ray binaries
• Cyclotron lines in highly magnetized neutron stars
• Calibration of the Large Area X-ray Proportional Counter (LAXPC) instrument on-board AstroSat
• Viscous Effects on the Interaction between the Coplanar Decretion Disc and the Neutron Star in Be/X-Ray Binaries
• A reflection model for the cyclotron lines in the spectra of X-ray pulsars
• Completing the puzzle of the 2004-2005 outburst in V0332+53: the brightening phase included
• Study of the accreting pulsar 4U 0115+634 with a bulk and thermal Comptonization model
• Pulse phase resolved analysis of the HMXB Cen X-3 over two binary orbits
• Discovery of a Third Harmonic Cyclotron Resonance Scattering Feature in the X-ray Spectrum of 4U 0115+63
• The variable cyclotron line in GX 301-2
• Confirmation of Two Cyclotron Lines in Vela X-1
• A new Comptonization model for low-magnetized accreting neutron stars in low mass X-ray binaries
• Maximum likelihood fitting of X-ray power density spectra: Application to high-frequency quasi-periodic oscillations from the neutron star X-ray binary 4U1608-522
• Recent X-ray measurements of the accretion-powered pulsar 4U 1907+09
• RXTE Discovery of Multiple Cyclotron Lines during the 2004 December Outburst of V0332+53
• INTEGRAL observations of Her X-1
• The 0.1-100 keV Spectrum of LMC X-4 in the High State: Evidence for a High Energy Cyclotron Absorption Line
• INTEGRAL observations of V0332+53 in outburst
• Luminosity-dependent changes of the cyclotron line energy and spectral hardness in Cep X-4
• On the radiation beaming of bright X-ray pulsars and constraints on neutron star mass-radius relation
• Identification of the optical counterparts of high-mass X-ray binaries through optical photometry and spectroscopy
• Broadband spectroscopy using two Suzaku observation of the HMXB GX 301-2
• NuSTAR Detection Of A Cyclotron Line In The Supergiant Fast X-ray Transient IGR J17544-2619
• Cyclotron resonant scattering feature simulations. II. Description of the CRSF simulation process
• NuSTAR Discovery of a cyclotron line in KS 1947+300
• BeppoSAX observations of the X-ray pulsar MAXI J1409-619 in low state: discovery of cyclotron resonance features
• Energy-Dependent Harmonic Ratios of the Cyclotron Features of X0331+53 in the 2004-2005 Outburst
• The Be/X-ray Binary Swift J1626.6-5156 as a Variable Cyclotron Line Source
• Suzaku Observations of Hercules X-1 : Measurements of the Two Cyclotron Harmonics
• Discovery of a pulse-phase-transient cyclotron line in the X-ray pulsar GROJ2058+42
• Discovery of the 198 s X-ray Pulsar GRO J2058+42
• Cyclotron Resonance Energies and Orbital Elements of Accretion Pulsar 4U 0115+63 During the Giant Outburst in 2008
• Confirmation of a High Magnetic Field in GRO J1008-57
• On the cyclotron line in Cep X-4
• NuSTAR discovery of a cyclotron line in the accreting X-ray pulsar IGR J16393-4643
• Discovery of a Be/X-ray Binary Consistent with the Position of GRO J2058+42
• Discovery of new quasi-periodic oscillations in the X-ray transient source V~0332+53
• RXTE-PCA observations of 1A 1118--61: timing and spectral studies during an outburst
• Detection of fundamental and first harmonic cyclotron line in X-ray pulsar Cep X-4
• Pulse Phase Variation of Cyclotron Line in HMXB 4U 1907+09 with ASTROSAT LAXPC
• Discovery of a QPO in the X-ray pulsar 1A 1118-615: correlated spectral and aperiodic variability
• Statistical properties of twin kHz QPO in neutron star LMXBs
• Detection of a variable QPO at ~41 mHz in the Be/X-ray transient pulsar 4U 0115+634

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• Large Area X-ray Proportional Counter (LAXPC) in Orbit Performance : Calibration, background, analysis software
• Revealing the nature of the transient source MAXI J0637-430 through spectro-temporal analysis
• Catalog of the Galactic population of X-ray pulsars in High-mass X-ray binary systems
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• The X-ray pulsar XTE J1858+034 observed with NuSTAR and Fermi/GBM: spectral and timing characterization plus a cyclotron line
• The Galactic high mass X-ray binary population with Fermi -LAT
• Science with the $AstroSat$ Soft X-ray Telescope: an overview
• Long-term optical variability of the Be/X-ray binary GRO J2058+42
• LAXPC instrument onboard AstroSat: Five exciting years of new scientific results specially on X-ray Binaries
• Monte-Carlo simulations on possible collimation effects of outflows to fan-beamed emission of ultraluminous accreting X-ray pulsars
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