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 ORCID: 0000-0003-0719-9385, 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 et al (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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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).

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
Date of acceptance:	26 January 2021
Date of first compliant Open Access:	17 October 2022
Date Deposited:	17 Oct 2022 13:47
Last Modified:	05 Jul 2025 13:15
DOI or ID number:	10.1093/mnras/stab242
URI:	https://researchonline.ljmu.ac.uk/id/eprint/17862

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