Details

Autor(en) / Beteiligte

• 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
• Poggianti, B M
• Vignali, C

Titel

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

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2021-04, Vol.502 (2), p.3101-3112

Ort / Verlag

Oxford University Press

Erscheinungsjahr

2021

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 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 $M_* \lesssim 10^{9.5}\, \mathrm{M}_{\odot }$). 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).