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AstroSat and Chandra view of the high soft state of 4U 1630-47 (4U 1630-472): evidence of the disk wind and a rapidly spinning black hole

AstroSat and Chandra view of the high soft state of 4U 1630-47 (4U 1630-472): evidence of the disk wind and a rapidly spinning black hole
AstroSat and Chandra view of the high soft state of 4U 1630-47 (4U 1630-472): evidence of the disk wind and a rapidly spinning black hole

We present the X-ray spectral and timing analysis of the transient black hole X-ray binary 4U 1630-47, observed with the AstroSat, Chandra, and MAXI space missions during its soft X-ray outburst in 2016. The outburst, from the rising phase until the peak, is detected neither in hard X-rays (15-50 keV) by the Swift/BAT nor in radio. Such nondetection, along with the source behavior in the hardness-intensity and color-color diagrams obtained using MAXI data, confirms that both Chandra and AstroSat observations were performed during the HS spectral state. The High Energy Grating (HEG) spectrum from the Chandra High-Energy Transmission Grating Spectrometer shows two strong, moderately blueshifted absorption lines at keV and keV, which are produced by Fe xxv and Fe xxvi in a low-velocity ionized disk wind. The corresponding outflow velocity is determined to be 366 ±56 km s-1. Separate spectral fits of Chandra/HEG, AstroSat/SXT+LAXPC, and Chandra/HEG+AstroSat/SXT+LAXPC data show that the broadband continuum can be well described with a relativistic disk blackbody model, with a disk flux fraction of ∼0.97. Based on the best-fit continuum spectral modeling of Chandra, AstroSat, and Chandra+AstroSat joint spectra and using the Markov chain Monte Carlo simulations, we constrain the spectral hardening factor at and the dimensionless black hole spin parameter at 0.92 ±0.04 within the 99.7% confidence interval. Our conclusion of a rapidly spinning black hole in 4U 1630-47 using the continuum spectrum method is in agreement with a previous finding applying the reflection spectral fitting method.

accretion, accretion disks, methods: data analysis, stars: black holes, X-rays: binaries, X-rays: individual (4U 1630)
0004-637X
Pahari, Mayukh
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Bhattacharyya, Sudip
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Rao, A. R.
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Bhattacharya, Dipankar
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Vadawale, Santosh V.
d9f63a07-cf3c-4ca5-b3c4-c5a2077c08b2
Dewangan, Gulab C.
0062ef4f-8422-4085-a1de-8c72f472843c
McHardy, I. M.
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Gandhi, Poshak
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Corbel, Stéphane
930a0c59-7a82-4166-8c78-5a1a4b80e4c2
Schulz, Norbert S.
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Altamirano, Diego
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Pahari, Mayukh
37a1bc53-be32-4688-91a3-2469a4bf0e78
Bhattacharyya, Sudip
e4617c49-b9fe-405e-99f0-aa3ab42c0aa1
Rao, A. R.
c8c754e9-ee73-48bd-8959-cfbcf1eb83f4
Bhattacharya, Dipankar
857e8ba4-bbbf-4107-9eb3-ab152969dc3a
Vadawale, Santosh V.
d9f63a07-cf3c-4ca5-b3c4-c5a2077c08b2
Dewangan, Gulab C.
0062ef4f-8422-4085-a1de-8c72f472843c
McHardy, I. M.
4f215137-9cc4-4a08-982e-772a0b24c17e
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Corbel, Stéphane
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Schulz, Norbert S.
df42e3b4-22dc-4f2e-a263-31f39dfe795c
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b

Pahari, Mayukh, Bhattacharyya, Sudip, Rao, A. R., Bhattacharya, Dipankar, Vadawale, Santosh V., Dewangan, Gulab C., McHardy, I. M., Gandhi, Poshak, Corbel, Stéphane, Schulz, Norbert S. and Altamirano, Diego (2018) AstroSat and Chandra view of the high soft state of 4U 1630-47 (4U 1630-472): evidence of the disk wind and a rapidly spinning black hole. Astrophysical Journal, 867 (2), [86]. (doi:10.3847/1538-4357/aae53b).

Record type: Article

Abstract

We present the X-ray spectral and timing analysis of the transient black hole X-ray binary 4U 1630-47, observed with the AstroSat, Chandra, and MAXI space missions during its soft X-ray outburst in 2016. The outburst, from the rising phase until the peak, is detected neither in hard X-rays (15-50 keV) by the Swift/BAT nor in radio. Such nondetection, along with the source behavior in the hardness-intensity and color-color diagrams obtained using MAXI data, confirms that both Chandra and AstroSat observations were performed during the HS spectral state. The High Energy Grating (HEG) spectrum from the Chandra High-Energy Transmission Grating Spectrometer shows two strong, moderately blueshifted absorption lines at keV and keV, which are produced by Fe xxv and Fe xxvi in a low-velocity ionized disk wind. The corresponding outflow velocity is determined to be 366 ±56 km s-1. Separate spectral fits of Chandra/HEG, AstroSat/SXT+LAXPC, and Chandra/HEG+AstroSat/SXT+LAXPC data show that the broadband continuum can be well described with a relativistic disk blackbody model, with a disk flux fraction of ∼0.97. Based on the best-fit continuum spectral modeling of Chandra, AstroSat, and Chandra+AstroSat joint spectra and using the Markov chain Monte Carlo simulations, we constrain the spectral hardening factor at and the dimensionless black hole spin parameter at 0.92 ±0.04 within the 99.7% confidence interval. Our conclusion of a rapidly spinning black hole in 4U 1630-47 using the continuum spectrum method is in agreement with a previous finding applying the reflection spectral fitting method.

Text
AstroSat and Chandra View of the High Soft State of 4U 1630-47 (4U 1630-472) Evidence of the Disk Wind and a Rapidly Spinning Black Hole - Accepted Manuscript
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Accepted/In Press date: 27 September 2018
e-pub ahead of print date: 2 November 2018
Published date: 10 November 2018
Additional Information: Author, Altamirano has confirmed that the record on Arxiv is the AM
Keywords: accretion, accretion disks, methods: data analysis, stars: black holes, X-rays: binaries, X-rays: individual (4U 1630)

Identifiers

Local EPrints ID: 426797
URI: http://eprints.soton.ac.uk/id/eprint/426797
ISSN: 0004-637X
PURE UUID: 14b554ea-9956-455f-90eb-ccb2634c386c
ORCID for Poshak Gandhi: ORCID iD orcid.org/0000-0003-3105-2615
ORCID for Diego Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

Catalogue record

Date deposited: 12 Dec 2018 17:30
Last modified: 07 Oct 2020 02:06

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Contributors

Author: Mayukh Pahari
Author: Sudip Bhattacharyya
Author: A. R. Rao
Author: Dipankar Bhattacharya
Author: Santosh V. Vadawale
Author: Gulab C. Dewangan
Author: I. M. McHardy
Author: Poshak Gandhi ORCID iD
Author: Stéphane Corbel
Author: Norbert S. Schulz

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