A1 Refereed original research article in a scientific journal

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




AuthorsNwaokoro 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

PublisherOXFORD UNIV PRESS

Publication year2021

JournalMonthly Notices of the Royal Astronomical Society

Journal name in sourceMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

Journal acronymMON NOT R ASTRON SOC

Volume502

Issue2

First page 3101

Last page3112

Number of pages12

ISSN0035-8711

DOIhttps://doi.org/10.1093/mnras/stab242

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/58635547


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 x 10-15 erg s-1cm-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*  ≲ 109.5 M). 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 [OIII] line luminosity (above 1040.3ergs-1).


Downloadable publication

This is an electronic reprint of the original article.
This reprint may differ from the original in pagination and typographic detail. Please cite the original version.





Last updated on 2024-26-11 at 19:58