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

Nwaokoro, E, Phillipps, S, Young, AJ, Baldry, I, Bongiorno, A, Bremer, MN, Brown, MJ, 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 and 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). pp. 3101-3112. ISSN 0035-8711

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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).

Item Type: Article
Uncontrolled Keywords: ACTIVE GALACTIC NUCLEI; Astronomy & Astrophysics; BINARIES; CHANDRA; DATA RELEASE; DWARF GALAXIES; EMISSION-LINE; galaxies: active; galaxies: star formation; MASS ASSEMBLY GAMA; Physical Sciences; SCALING RELATIONS; Science & Technology; STAR-FORMATION; SUPERMASSIVE BLACK-HOLES; X-rays: galaxies; Science & Technology; Physical Sciences; Astronomy & Astrophysics; galaxies: active; galaxies: star formation; X-rays: galaxies; MASS ASSEMBLY GAMA; ACTIVE GALACTIC NUCLEI; SUPERMASSIVE BLACK-HOLES; STAR-FORMATION; EMISSION-LINE; DATA RELEASE; DWARF GALAXIES; SCALING RELATIONS; BINARIES; CHANDRA; Astronomy & Astrophysics; 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Royal Astronomical Society
SWORD Depositor: A Symplectic
Date Deposited: 17 Oct 2022 13:47
Last Modified: 17 Oct 2022 13:47
DOI or ID number: 10.1093/mnras/stab242
URI: https://researchonline.ljmu.ac.uk/id/eprint/17862
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