A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT

Murray Brightman; Jean-Marie Hameury; Jean-Pierre Lasota; Ranieri D. Baldi; Gabriele Bruni; Jenna M. Cann; Hannah Earnshaw; Felix Fürst; Marianne Heida; Amruta Jaodand; Margaret Lazzarini; Matthew J. Middleton; Dominic J. Walton; Kimberly A. Weaver

doi:10.3847/1538-4357/acd18a

A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT

Murray Brightman, Jean-Marie Hameury, Jean-Pierre Lasota, Ranieri D. Baldi, Gabriele Bruni, Jenna M. Cann, Hannah Earnshaw, Felix Fürst, Marianne Heida, Amruta Jaodand, Margaret Lazzarini, Matthew J. Middleton, Dominic J. Walton, Kimberly A. Weaver

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Abstract

Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources; however, there is growing evidence to suggest a large fraction of these sources are transient. Here we present a sample of five newly reported transient ULXs in the galaxies NGC 4945, NGC 7793, and M81 serendipitously discovered in Swift/XRT observations. Swift monitoring of these sources have provided well-sampled lightcurves, allowing for us to model the lightcurves with the disk-instability model of Hameury & Lasota, which implies durations of 60–400 days and that the mass-accretion rate through the disk is close to or greater than the Eddington rate. Of the three source regions with prior Hubble Space Telescope imaging, color–magnitude diagrams of the potential stellar counterparts show varying ages of the possible stellar counterparts. Our estimation of the rates of these sources in these three galaxies is 0.4–1.3 yr−1. We find that, while persistent ULXs dominate the high end of galaxy luminosity functions, the number of systems that produce ULX luminosities are likely dominated by transient sources.

Original language	English
Article number	51
Pages (from-to)	1-16
Number of pages	16
Journal	The Astrophysical Journal
Volume	951
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/acd18a
Publication status	Published - 3 Jul 2023

Keywords

Transient sources
X-ray sources
Ultraluminous x-ray sources
X-ray transient sources

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10.3847/1538-4357/acd18aLicence: CC BY

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© 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/
Final published version, 3.86 MBLicence: CC BY

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Brightman, M., Hameury, J.-M., Lasota, J.-P., Baldi, R. D., Bruni, G., Cann, J. M., Earnshaw, H., Fürst, F., Heida, M., Jaodand, A., Lazzarini, M., Middleton, M. J., Walton, D. J., & Weaver, K. A. (2023). A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT. The Astrophysical Journal, 951(1), 1-16. Article 51. https://doi.org/10.3847/1538-4357/acd18a

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title = "A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT",

abstract = "Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources; however, there is growing evidence to suggest a large fraction of these sources are transient. Here we present a sample of five newly reported transient ULXs in the galaxies NGC 4945, NGC 7793, and M81 serendipitously discovered in Swift/XRT observations. Swift monitoring of these sources have provided well-sampled lightcurves, allowing for us to model the lightcurves with the disk-instability model of Hameury & Lasota, which implies durations of 60–400 days and that the mass-accretion rate through the disk is close to or greater than the Eddington rate. Of the three source regions with prior Hubble Space Telescope imaging, color–magnitude diagrams of the potential stellar counterparts show varying ages of the possible stellar counterparts. Our estimation of the rates of these sources in these three galaxies is 0.4–1.3 yr−1. We find that, while persistent ULXs dominate the high end of galaxy luminosity functions, the number of systems that produce ULX luminosities are likely dominated by transient sources.",

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author = "Murray Brightman and Jean-Marie Hameury and Jean-Pierre Lasota and Baldi, {Ranieri D.} and Gabriele Bruni and Cann, {Jenna M.} and Hannah Earnshaw and Felix F{\"u}rst and Marianne Heida and Amruta Jaodand and Margaret Lazzarini and Middleton, {Matthew J.} and Walton, {Dominic J.} and Weaver, {Kimberly A.}",

note = "{\textcopyright} 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/",

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month = jul,

day = "3",

doi = "10.3847/1538-4357/acd18a",

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Brightman, M, Hameury, J-M, Lasota, J-P, Baldi, RD, Bruni, G, Cann, JM, Earnshaw, H, Fürst, F, Heida, M, Jaodand, A, Lazzarini, M, Middleton, MJ, Walton, DJ & Weaver, KA 2023, 'A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT', The Astrophysical Journal, vol. 951, no. 1, 51, pp. 1-16. https://doi.org/10.3847/1538-4357/acd18a

TY - JOUR

T1 - A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT

AU - Brightman, Murray

AU - Hameury, Jean-Marie

AU - Lasota, Jean-Pierre

AU - Baldi, Ranieri D.

AU - Bruni, Gabriele

AU - Cann, Jenna M.

AU - Earnshaw, Hannah

AU - Fürst, Felix

AU - Heida, Marianne

AU - Jaodand, Amruta

AU - Lazzarini, Margaret

AU - Middleton, Matthew J.

AU - Walton, Dominic J.

AU - Weaver, Kimberly A.

N1 - © 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/

PY - 2023/7/3

Y1 - 2023/7/3

N2 - Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources; however, there is growing evidence to suggest a large fraction of these sources are transient. Here we present a sample of five newly reported transient ULXs in the galaxies NGC 4945, NGC 7793, and M81 serendipitously discovered in Swift/XRT observations. Swift monitoring of these sources have provided well-sampled lightcurves, allowing for us to model the lightcurves with the disk-instability model of Hameury & Lasota, which implies durations of 60–400 days and that the mass-accretion rate through the disk is close to or greater than the Eddington rate. Of the three source regions with prior Hubble Space Telescope imaging, color–magnitude diagrams of the potential stellar counterparts show varying ages of the possible stellar counterparts. Our estimation of the rates of these sources in these three galaxies is 0.4–1.3 yr−1. We find that, while persistent ULXs dominate the high end of galaxy luminosity functions, the number of systems that produce ULX luminosities are likely dominated by transient sources.

AB - Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources; however, there is growing evidence to suggest a large fraction of these sources are transient. Here we present a sample of five newly reported transient ULXs in the galaxies NGC 4945, NGC 7793, and M81 serendipitously discovered in Swift/XRT observations. Swift monitoring of these sources have provided well-sampled lightcurves, allowing for us to model the lightcurves with the disk-instability model of Hameury & Lasota, which implies durations of 60–400 days and that the mass-accretion rate through the disk is close to or greater than the Eddington rate. Of the three source regions with prior Hubble Space Telescope imaging, color–magnitude diagrams of the potential stellar counterparts show varying ages of the possible stellar counterparts. Our estimation of the rates of these sources in these three galaxies is 0.4–1.3 yr−1. We find that, while persistent ULXs dominate the high end of galaxy luminosity functions, the number of systems that produce ULX luminosities are likely dominated by transient sources.

KW - Transient sources

KW - X-ray sources

KW - Ultraluminous x-ray sources

KW - X-ray transient sources

UR - http://www.scopus.com/inward/record.url?scp=85164355120&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/acd18a

DO - 10.3847/1538-4357/acd18a

M3 - Article

SN - 0004-637X

VL - 951

SP - 1

EP - 16

JO - The Astrophysical Journal

JF - The Astrophysical Journal

IS - 1

M1 - 51

ER -

A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT

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