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LeMMINGs - IV. The X-ray properties of a statistically complete sample of the nuclei in active and inactive galaxies from the Palomar sample

Williams, DRA, Pahari, M, Baldi, RD, McHardy, IM, Mathur, S, Beswick, RJ, Beri, A, Boorman, P, Aalto, S, Alberdi, A, Argo, MK, Dullo, BT, Fenech, DM, Green, DA, Knapen, JH, Marti-Vidal, I, Moldon, J, Mundell, CG, Muxlow, TWB, Panessa, F , Perez-Torres, M, Saikia, P, Shankar, F, Stevens, IR and Uttley, P (2021) LeMMINGs - IV. The X-ray properties of a statistically complete sample of the nuclei in active and inactive galaxies from the Palomar sample. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 510 (4). pp. 4909-4928. ISSN 0035-8711

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All 280 of the statistically complete Palomar sample of nearby (<120 Mpc) galaxies δ > 20° have been observed at 1.5 GHz as part of the LeMMINGs e-MERLIN legacy survey. Here, we present Chandra X-ray observations of the nuclei of 213 of these galaxies, including a statistically complete sub-set of 113 galaxies in the declination range 40° <δ < 65°. We observed galaxies of all optical spectral types, including ‘active’ galaxies [e.g. low-ionization nuclear emission line regions (LINERs) and Seyferts] and ‘inactive’ galaxies like HII galaxies and absorption line galaxies (ALG). The X-ray flux limit of our survey is 1.65 × 10−14 erg s−1 cm−2 (0.3−10 keV). We detect X-ray emission coincident within 2 arcsec of the nucleus in 150/213 galaxies, including 13/14 Seyferts, 68/77 LINERs, 13/22 ALGs and 56/100 HII galaxies, but cannot completely rule out contamination from non-AGN processes in sources with nuclear luminosities ≲1039 erg s−1. We construct an X-ray Luminosity function (XLF) and find that the local galaxy XLF, when including all active galactic nucleus (AGN) types, can be represented as a single power law of slope −0.54 ± 0.06. The Eddington ratio of the Seyferts is usually 2−4 decades higher than that of the LINERs, ALGs, and HII galaxies, which are mostly detected with Eddington ratios ≲10−3⁠. Using [OIII] line measurements and black hole masses from the literature, we show that LINERs, HII galaxies and ALGs follow similar correlations to low luminosities, suggesting that some ‘inactive’ galaxies may harbour AGN.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: ACCRETION; Astronomy & Astrophysics; BLACK-HOLE MASS; DWARF SEYFERT NUCLEI; FUNDAMENTAL PLANE; GALACTIC NUCLEI; galaxies: active; LOCAL UNIVERSE; LUMINOSITY FUNCTION; Physical Sciences; RADIO-EMISSION; Science & Technology; SEARCH; SPECTRA; X-rays: galaxies; Science & Technology; Physical Sciences; Astronomy & Astrophysics; X-rays: galaxies; galaxies: active; DWARF SEYFERT NUCLEI; BLACK-HOLE MASS; GALACTIC NUCLEI; FUNDAMENTAL PLANE; RADIO-EMISSION; LUMINOSITY FUNCTION; LOCAL UNIVERSE; ACCRETION; SEARCH; SPECTRA; astro-ph.HE; astro-ph.HE; astro-ph.GA; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
SWORD Depositor: A Symplectic
Date Deposited: 01 Nov 2022 10:10
Last Modified: 01 Nov 2022 10:15
DOI or ID number: 10.1093/mnras/stab3310
URI: https://researchonline.ljmu.ac.uk/id/eprint/17984
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