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

D. R.A. Williams, M. Pahari, R. D. Baldi, I. M. McHardy, S. Mathur, R. J. Beswick, A. Beri, P. Boorman, S. Aalto, A. Alberdi, M. K. Argo, B. T. Dullo, D. M. Fenech, D. A. Green, J. H. Knapen, I. Martí-Vidal, J. Moldon, C. G. Mundell, T. W.B. Muxlow, F. PanessaM. Pérez-Torres, P. Saikia, F. Shankar, I. R. Stevens, P. Uttley

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6 Citations (SciVal)


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 le gac y surv e y. Here, we present Chandr a 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 H II galaxies and absorption line galaxies (ALG). The X-ray flux limit of our surv e y 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 H II galaxies, but cannot completely rule out contamination from non-AGN processes in sources with nuclear luminosities ≲ 10 39 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 H II galaxies, which are mostly detected with Eddington ratios ≲ 10 -3 . Using [ O III ] line measurements and black hole masses from the literature, we show that LINERs, H II galaxies and ALGs follow similar correlations to low luminosities, suggesting that some 'inactive' galaxies may harbour AGN.

Original languageEnglish
Pages (from-to)4909-4928
Number of pages20
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date17 Nov 2021
Publication statusPublished - 1 Mar 2022

Bibliographical note

Publisher Copyright:
© 2021 The Author(s).


  • Galaxies: Active
  • X-rays: Galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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