GAMA/XXL: X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field

E. Nwaokoro; S. Phillipps; A. J. Young; I. Baldry; A. Bongiorno; M. N. Bremer; M. J. I. Brown; L. Chiappetti; R. De Propris; S. P. Driver; A. Elyiv; S. Fotopoulou; P. A. Giles; A. M. Hopkins; B. Maughan; S. McGee; F. Pacaud; M. Pierre; M. Plionis; B. M. Poggianti; C. Vignali

doi:10.1093/mnras/stab242

GAMA/XXL: X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field

E. Nwaokoro, S. Phillipps^*, A. J. Young, I. Baldry, A. Bongiorno, M. N. Bremer, M. J. I. Brown, L. Chiappetti, R. De Propris, S. P. Driver, A. Elyiv, S. Fotopoulou, P. A. Giles, A. M. Hopkins, B. Maughan, S. McGee, F. Pacaud, M. Pierre, M. Plionis, B. M. PoggiantiC. Vignali

^*Corresponding author for this work

Australian Astronomical Optics

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Abstract

Relatively few X-ray sources are known that have low-mass galaxies as hosts. This is an important restriction on studies of active galactic nuclei (AGNs), hence black holes, and of X-ray binaries (XRBs) in low-mass galaxies; addressing it requires very large samples of both galaxies and X-ray sources. Here, we have matched the X-ray point sources found in the XXL-N field of the XXL survey (with an X-ray flux limit of ∼6 × 10^-15 erg s^-1 cm^-2 in the [0.5-2] keV band) to galaxies with redshifts from the Galaxy And Mass Assembly (GAMA) G02 survey field (down to a magnitude limit r = 19.8) in order to search for AGNs and XRBs in GAMA galaxies, particularly those of low optical luminosity or stellar mass (fainter than Mr =-19 or M_∗ ≲ 10^9.5M_⊙). Out of a total of 1200 low-mass galaxies in the overlap region, we find a total of 28 potential X-ray source hosts, though this includes possible background contaminants. From a combination of photometry (optical and infrared colours), positional information, and optical spectra, we deduce that most of the ≃20 X-ray sources genuinely in low-mass galaxies are high-mass X-ray binaries in star-forming galaxies. None of the matched sources in a low-mass galaxy has a BPT classification as an AGN, and even ignoring this requirement, none passes both criteria of close match between the X-ray source position and optical galaxy centre (separation ≤3 arcsec) and high [O iii] line luminosity (above 10^40.3 erg s^-1).

Original language	English
Pages (from-to)	3101-3112
Number of pages	12
Journal	Monthly Notices of the Royal Astronomical Society
Volume	502
Issue number	2
DOIs	https://doi.org/10.1093/mnras/stab242
Publication status	Published - 1 Apr 2021

Bibliographical note

Copyright 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

galaxies: active
galaxies: star formation
X-rays: galaxies

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10.1093/mnras/stab242Licence: CC BY

Publisher version (open access)Final published version, 1.76 MBLicence: CC BY

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Nwaokoro, E., Phillipps, S., Young, A. J., Baldry, I., Bongiorno, A., Bremer, M. N., Brown, M. J. I., Chiappetti, L., De Propris, R., Driver, S. P., Elyiv, A., Fotopoulou, S., Giles, P. A., Hopkins, A. M., Maughan, B., McGee, S., Pacaud, F., Pierre, M., Plionis, M., ... Vignali, C. (2021). GAMA/XXL: X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field. Monthly Notices of the Royal Astronomical Society, 502(2), 3101-3112. https://doi.org/10.1093/mnras/stab242

@article{2874857e121242e68f786a54cee98502,

title = "GAMA/XXL: X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field",

abstract = "Relatively few X-ray sources are known that have low-mass galaxies as hosts. This is an important restriction on studies of active galactic nuclei (AGNs), hence black holes, and of X-ray binaries (XRBs) in low-mass galaxies; addressing it requires very large samples of both galaxies and X-ray sources. Here, we have matched the X-ray point sources found in the XXL-N field of the XXL survey (with an X-ray flux limit of ∼6 × 10-15 erg s-1 cm-2 in the [0.5-2] keV band) to galaxies with redshifts from the Galaxy And Mass Assembly (GAMA) G02 survey field (down to a magnitude limit r = 19.8) in order to search for AGNs and XRBs in GAMA galaxies, particularly those of low optical luminosity or stellar mass (fainter than Mr =-19 or M∗ ≲ 109.5M⊙). Out of a total of 1200 low-mass galaxies in the overlap region, we find a total of 28 potential X-ray source hosts, though this includes possible background contaminants. From a combination of photometry (optical and infrared colours), positional information, and optical spectra, we deduce that most of the ≃20 X-ray sources genuinely in low-mass galaxies are high-mass X-ray binaries in star-forming galaxies. None of the matched sources in a low-mass galaxy has a BPT classification as an AGN, and even ignoring this requirement, none passes both criteria of close match between the X-ray source position and optical galaxy centre (separation ≤3 arcsec) and high [O iii] line luminosity (above 1040.3 erg s-1).",

keywords = "galaxies: active, galaxies: star formation, X-rays: galaxies",

author = "E. Nwaokoro and S. Phillipps and Young, {A. J.} and I. Baldry and A. Bongiorno and Bremer, {M. N.} and Brown, {M. J. I.} and L. Chiappetti and {De Propris}, R. and Driver, {S. P.} and A. Elyiv and S. Fotopoulou and Giles, {P. A.} and Hopkins, {A. M.} and B. Maughan and S. McGee and F. Pacaud and M. Pierre and M. Plionis and Poggianti, {B. M.} and C. Vignali",

note = "Copyright 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

year = "2021",

month = apr,

day = "1",

doi = "10.1093/mnras/stab242",

language = "English",

volume = "502",

pages = "3101--3112",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

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Nwaokoro, E, Phillipps, S, Young, AJ, Baldry, I, Bongiorno, A, Bremer, MN, Brown, MJI, Chiappetti, L, De Propris, R, Driver, SP, Elyiv, A, Fotopoulou, S, Giles, PA, Hopkins, AM, Maughan, B, McGee, S, Pacaud, F, Pierre, M, Plionis, M, Poggianti, BM & Vignali, C 2021, 'GAMA/XXL: X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field', Monthly Notices of the Royal Astronomical Society, vol. 502, no. 2, pp. 3101-3112. https://doi.org/10.1093/mnras/stab242

TY - JOUR

T1 - GAMA/XXL

T2 - X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field

AU - Nwaokoro, E.

AU - Phillipps, S.

AU - Young, A. J.

AU - Baldry, I.

AU - Bongiorno, A.

AU - Bremer, M. N.

AU - Brown, M. J. I.

AU - Chiappetti, L.

AU - De Propris, R.

AU - Driver, S. P.

AU - Elyiv, A.

AU - Fotopoulou, S.

AU - Giles, P. A.

AU - Hopkins, A. M.

AU - Maughan, B.

AU - McGee, S.

AU - Pacaud, F.

AU - Pierre, M.

AU - Plionis, M.

AU - Poggianti, B. M.

AU - Vignali, C.

N1 - Copyright 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2021/4/1

Y1 - 2021/4/1

N2 - Relatively few X-ray sources are known that have low-mass galaxies as hosts. This is an important restriction on studies of active galactic nuclei (AGNs), hence black holes, and of X-ray binaries (XRBs) in low-mass galaxies; addressing it requires very large samples of both galaxies and X-ray sources. Here, we have matched the X-ray point sources found in the XXL-N field of the XXL survey (with an X-ray flux limit of ∼6 × 10-15 erg s-1 cm-2 in the [0.5-2] keV band) to galaxies with redshifts from the Galaxy And Mass Assembly (GAMA) G02 survey field (down to a magnitude limit r = 19.8) in order to search for AGNs and XRBs in GAMA galaxies, particularly those of low optical luminosity or stellar mass (fainter than Mr =-19 or M∗ ≲ 109.5M⊙). Out of a total of 1200 low-mass galaxies in the overlap region, we find a total of 28 potential X-ray source hosts, though this includes possible background contaminants. From a combination of photometry (optical and infrared colours), positional information, and optical spectra, we deduce that most of the ≃20 X-ray sources genuinely in low-mass galaxies are high-mass X-ray binaries in star-forming galaxies. None of the matched sources in a low-mass galaxy has a BPT classification as an AGN, and even ignoring this requirement, none passes both criteria of close match between the X-ray source position and optical galaxy centre (separation ≤3 arcsec) and high [O iii] line luminosity (above 1040.3 erg s-1).

AB - Relatively few X-ray sources are known that have low-mass galaxies as hosts. This is an important restriction on studies of active galactic nuclei (AGNs), hence black holes, and of X-ray binaries (XRBs) in low-mass galaxies; addressing it requires very large samples of both galaxies and X-ray sources. Here, we have matched the X-ray point sources found in the XXL-N field of the XXL survey (with an X-ray flux limit of ∼6 × 10-15 erg s-1 cm-2 in the [0.5-2] keV band) to galaxies with redshifts from the Galaxy And Mass Assembly (GAMA) G02 survey field (down to a magnitude limit r = 19.8) in order to search for AGNs and XRBs in GAMA galaxies, particularly those of low optical luminosity or stellar mass (fainter than Mr =-19 or M∗ ≲ 109.5M⊙). Out of a total of 1200 low-mass galaxies in the overlap region, we find a total of 28 potential X-ray source hosts, though this includes possible background contaminants. From a combination of photometry (optical and infrared colours), positional information, and optical spectra, we deduce that most of the ≃20 X-ray sources genuinely in low-mass galaxies are high-mass X-ray binaries in star-forming galaxies. None of the matched sources in a low-mass galaxy has a BPT classification as an AGN, and even ignoring this requirement, none passes both criteria of close match between the X-ray source position and optical galaxy centre (separation ≤3 arcsec) and high [O iii] line luminosity (above 1040.3 erg s-1).

KW - galaxies: active

KW - galaxies: star formation

KW - X-rays: galaxies

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JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

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ER -

GAMA/XXL: X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field

Abstract

Bibliographical note

Keywords

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