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A NuSTAR and Swift view of the hard state of MAXI J1813−095

Jiang, Jiachen and Buisson, Douglas J. K. and Dauser, Thomas and Fabian, Andrew C. and Fürst, Felix and Gallo, Luigi C. and Harrison, Fiona A. and Parker, Michael L. and Steiner, James F. and Tomsick, John A. and Ubach, Santiago and Walton, Dominic J. (2022) A NuSTAR and Swift view of the hard state of MAXI J1813−095. Monthly Notices of the Royal Astronomical Society, 514 (2). pp. 1952-1960. ISSN 0035-8711. doi:10.1093/mnras/stac1401.

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We present an analysis of the NuSTAR and Swift spectra of the black hole candidate MAXI J1813−095 in a failed-transition outburst in 2018. The NuSTAR observations show evidence of reflected emission from the inner region of the accretion disc. By modelling the reflection component in the spectra, we find a disc inner radius of Rᵢₙ < 7 r₉. This result suggests that either a slightly truncated disc or a non-truncated disc forms at a few per cent of the Eddington limit in MAXI J1813−095. Our best-fitting reflection models indicate that the geometry of the innermost accretion remains consistent during the period of NuSTAR observations. The spectral variability of MAXI J1813−095 from multi-epoch observations is dominated by the variable photon index of the Comptonization emission.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemHEASARC website Itemreflionx model Itemrelxill model
Jiang, Jiachen0000-0002-9639-4352
Buisson, Douglas J. K.0000-0002-5341-6929
Dauser, Thomas0000-0003-4583-9048
Fabian, Andrew C.0000-0002-9378-4072
Fürst, Felix0000-0003-0388-0560
Harrison, Fiona A.0000-0003-2992-8024
Parker, Michael L.0000-0002-8466-7317
Steiner, James F.0000-0002-5872-6061
Tomsick, John A.0000-0001-5506-9855
Walton, Dominic J.0000-0001-5819-3552
Additional Information:© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Received: 19 September 2021. Revision received: 15 May 2022. Accepted: 15 May 2022. Published: 20 May 2022. This paper was written during the worldwide COVID-19 pandemic in 2020–2022. We acknowledge the hard work of all the health care workers around the world. We would not be able to finish this paper without their protection. JJ acknowledges support from the Leverhulme Trust, the Isaac Newton Trust, and St Edmund’s College, University of Cambridge. DATA AVAILABILITY. All the data can be downloaded from the HEASARC website at The reflionx and relxill models used in this work are available for downloads at and
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Leverhulme TrustUNSPECIFIED
Isaac Newton TrustUNSPECIFIED
University of CambridgeUNSPECIFIED
Subject Keywords:accretion, accretion discs, black hole physics, X-rays: binaries
Issue or Number:2
Record Number:CaltechAUTHORS:20220712-629762000
Persistent URL:
Official Citation:Jiachen Jiang, Douglas J K Buisson, Thomas Dauser, Andrew C Fabian, Felix Fürst, Luigi C Gallo, Fiona A Harrison, Michael L Parker, James F Steiner, John A Tomsick, Santiago Ubach, Dominic J Walton, A NuSTAR and Swift view of the hard state of MAXI J1813−095, Monthly Notices of the Royal Astronomical Society, Volume 514, Issue 2, August 2022, Pages 1952–1960,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115516
Deposited By: George Porter
Deposited On:13 Jul 2022 18:42
Last Modified:13 Jul 2022 18:42

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