CaltechAUTHORS
  A Caltech Library Service

MAXI J1820+070 with NuSTAR I. An increase in variability frequency but a stable reflection spectrum: coronal properties and implications for the inner disc in black hole binaries

Buisson, D. J. K. and Fabian, A. C. and Barret, D. and Fürst, F. and Gandhi, P. and García, J. A. and Kara, E. and Madsen, K. K. and Miller, J. M. and Parker, M. L. and Shaw, A. W. and Tomsick, J. A. and Walton, D. J. (2019) MAXI J1820+070 with NuSTAR I. An increase in variability frequency but a stable reflection spectrum: coronal properties and implications for the inner disc in black hole binaries. Monthly Notices of the Royal Astronomical Society, 490 (1). pp. 1350-1362. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20190917-134739032

[img] PDF - Published Version
See Usage Policy.

3MB
[img] PDF - Submitted Version
See Usage Policy.

2MB

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20190917-134739032

Abstract

MAXI J1820+070 (optical counterpart ASASSN-18ey) is a black hole candidate discovered through its recent very bright outburst. The low extinction column and long duration at high flux allow detailed measurements of the accretion process to be made. In this work, we compare the evolution of X-ray spectral and timing properties through the initial hard state of the outburst. We show that the inner accretion disc, as measured by relativistic reflection, remains steady throughout this period of the outburst. Nevertheless, subtle spectral variability is observed, which is well explained by a change in coronal geometry. However, characteristic features of the temporal variability – low-frequency roll-over and quasi-periodic oscillation frequency – increase drastically in frequency, as the outburst proceeds. This suggests that the variability time-scales are governed by coronal conditions rather than solely by the inner disc radius. We also find a strong correlation between X-ray luminosity and coronal temperature. This can be explained by electron pair production with a changing effective radius and a non-thermal electron fraction of ∼20 per cent.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stz2681DOIArticle
https://arxiv.org/abs/1909.04688arXivDiscussion Paper
ORCID:
AuthorORCID
Fabian, A. C.0000-0002-9378-4072
Barret, D.0000-0002-0393-9190
Fürst, F.0000-0003-0388-0560
Gandhi, P.0000-0003-3105-2615
García, J. A.0000-0003-3828-2448
Kara, E.0000-0003-0172-0854
Madsen, K. K.0000-0003-1252-4891
Parker, M. L.0000-0002-8466-7317
Tomsick, J. A.0000-0001-5506-9855
Walton, D. J.0000-0001-5819-3552
Additional Information:© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2019 September 20. Received 2019 September 19; in original form 2019 May 31. Published: 27 September 2019. We thank Fiona Harrison for approval of these DDT observations and Karl Forster for their prompt scheduling. DJKB acknowledges financial support from the Science and Technology Facilities Council (STFC). ACF acknowledges support from the ERC Advanced Grant FEEDBACK 340442. AWS is supported by an NSERC Discovery Grant and a Discovery Accelerator Supplement. This work has used data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. This research has used the NuSTARDAS jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA).
Group:NuSTAR, Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)UNSPECIFIED
European Research Council (ERC)340442
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
NASA/JPL/CaltechUNSPECIFIED
Subject Keywords:accretion, accretion discs - black hole physics - X-rays: binaries
Issue or Number:1
Record Number:CaltechAUTHORS:20190917-134739032
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190917-134739032
Official Citation:D J K Buisson, A C Fabian, D Barret, F Fürst, P Gandhi, J A García, E Kara, K K Madsen, J M Miller, M L Parker, A W Shaw, J A Tomsick, D J Walton, MAXI J1820+070 with NuSTAR I. An increase in variability frequency but a stable reflection spectrum: coronal properties and implications for the inner disc in black hole binaries, Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 1, November 2019, Pages 1350–1362, https://doi.org/10.1093/mnras/stz2681
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98683
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Sep 2019 21:43
Last Modified:09 Mar 2020 13:19

Repository Staff Only: item control page