AstroSat view of 'Clocked' burster GS 1826-238: broad-band spectral nature of persistent and burst emission during soft state

被引:6
作者
Agrawal, Vivek K. [1 ]
Nandi, Anuj [1 ]
Katoch, Tilak [2 ]
机构
[1] UR Rao Satellite Ctr, Space Astron Grp, ISITE Campus, Bangalore 560037, Karnataka, India
[2] Tata Inst Fundamental Res, Dept Astron & Astrophys, Homi Bhabha Rd, Mumbai 400005, Maharashtra, India
关键词
accretion; accretion discs; X-rays: binaries; X-rays: individual: GS 1826-238; X-RAY-SPECTRUM; BEPPOSAX OBSERVATIONS; HARD TAIL; ATOLL; EVOLUTION; REFLECTION; 4U-1705-44; X-1;
D O I
10.1093/mnras/stac2579
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
In this paper, we have carried out a detailed study of the 'Clocked' burster GS 1826 - 238 using similar to 90 ks broad-band (0.7-60.0 keV) data obtained with AstroSat observatory. The source was observed during a soft spectral state and traced a 'banana' type track in the colour-colour diagram (CCD). We find that a combination of thermal component (multi-colour disc/bbodyrad) and Comptonized component is statistically good description for all the sections of the track in the CCD. The corona becomes optically thick (tau increases from similar to 5 to 21) and cooler (kT(e) decreases from similar to 4.8 to 2.2 keV) as the source moves up in the 'banana' branch. Probably cooling is caused by increase in the supply of soft-seed photons from the disc/boundary-layer. Reflection signature is observed at upper 'banana' branch of the source. Two type-I X-ray bursts are detected during the AstroSat observations. During the bursts, hard X-rays increased unlike previous observations where a reduction in hard X-rays is observed during the bursts. Decrease in the electron temperature and increase in the optical depth are observed during the bursts. The power spectral density of all the sections of the CCD can be represented by a pure power-law component. The strength of this component increases from similar to 1 percent to 4.5 percent as the source moves up in the 'banana' track. Search for burst oscillations gave a null result. We discuss the implications of our results in the context of previous findings.
引用
收藏
页码:194 / 205
页数:12
相关论文
共 45 条
[1]   AstroSat/LAXPC view of GX 17+2: spectral evolution along the Z-track [J].
Agrawal, V. K. ;
Nandi, Anuj ;
Ramadevi, M. C. .
ASTROPHYSICS AND SPACE SCIENCE, 2020, 365 (02)
[2]   Spectral and timing properties of atoll source 4U 1705-44: LAXPC/AstroSat results [J].
Agrawal, V. K. ;
Nandi, Anuj ;
Girish, V. ;
Ramadevi, M. C. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2018, 477 (04) :5437-5446
[3]   X-ray spectral evolution of the extragalactic Z source LMC X-2 [J].
Agrawal, V. K. ;
Misra, R. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2009, 398 (03) :1352-1360
[4]   X-ray spectral evolution of low-mass X-ray binary GX 349+2 [J].
Agrawal, VK ;
Sreekumar, P .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2003, 346 (03) :933-939
[5]   X-ray variability with spectral state transitions in NS-LMXBs observed with MAXI/GSC and Swift/BAT [J].
Asai, Kazumi ;
Mihara, Tatehiro ;
Matsuoka, Masaru ;
Sugizaki, Mutsumi .
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN, 2015, 67 (05)
[6]   Hard X-ray emission from low-mass X-ray binaries [J].
Barret, D ;
Olive, JF ;
Boirin, L ;
Done, C ;
Skinner, GK ;
Grindlay, JE .
ASTROPHYSICAL JOURNAL, 2000, 533 (01) :329-351
[7]   The broad band X-ray/hard X-ray spectra of accreting neutron stars [J].
Barret, D .
X-RAY AND GAMMA-RAY SIGNATURES OF BLACK HOLES AND WEAKLY MAGNETIZED NEUTRON STARS, 2001, 28 (2-3) :307-321
[8]   A peculiar spectral state transition of 4U 1705-44: When an atoll looks like a Z [J].
Barret, D ;
Olive, JF .
ASTROPHYSICAL JOURNAL, 2002, 576 (01) :391-401
[9]   THE HARD X-RAY BEHAVIOR OF AQL X-1 DURING TYPE-I BURSTS [J].
Chen, Yu-Peng ;
Zhang, Shu ;
Zhang, Shuang-Nan ;
Ji, Long ;
Torres, Diego F. ;
Kretschmar, Peter ;
Li, Jian ;
Wang, Jian-Min .
ASTROPHYSICAL JOURNAL LETTERS, 2013, 777 (01)
[10]   BeppoSAX view of the NS-LMXB GS 1826-238 [J].
Cocchi, M. ;
Farinelli, R. ;
Paizis, A. .
ASTRONOMY & ASTROPHYSICS, 2011, 529