The most luminous, merger-free AGNs show only marginal correlation with bar presence

Garland, Izzy and Fahey, Matthew and Simmons, Brooke and Smethurst, Rebecca J and Lintott, Chris and Shanahan, Jesse and Silcock, Maddie and Smith, Josh and Keel, William and Coil, Alison and Tobias, Geron and Kruk, Sandor and Masters, Karen L. and O'Ryan, David and Thorne, Matthew and Wiersema, Klaas (2023) The most luminous, merger-free AGNs show only marginal correlation with bar presence. Monthly Notices of the Royal Astronomical Society, 522 (1). pp. 211-225. ISSN 0035-8711

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Abstract

The role of large-scale bars in the fuelling of active galactic nuclei (AGN) is still debated, even as evidence mounts that black hole growth in the absence of galaxy mergers cumulatively dominates and may substantially influence disc (i.e., merger-free) galaxy evolution. We investigate whether large-scale galactic bars are a good candidate for merger-free AGN fuelling. Specifically, we combine slit spectroscopy and Hubble Space Telescope imagery to characterise star formation rates (SFRs) and stellar masses of the unambiguously disc-dominated host galaxies of a sample of luminous, Type-1 AGN with 0.02 < < 0.24. After carefully correcting for AGN signal, we find no clear difference in SFR between AGN hosts and a stellar mass-matched sample of galaxies lacking an AGN (0.013 < < 0.19), although this could be due to small sample size (AGN = 34). We correct for SFR and stellar mass to minimise selection biases, and compare the bar fraction in the two samples. We find that AGN are marginally (∼ 1.7σ) more likely to host a bar than inactive galaxies, with AGN hosts having a bar fraction, bar = 0.59+0.08 −0.09 and inactive galaxies having a bar fraction, bar = 0.44+0.08 −0.09. However, we find no further differences between SFR- and mass-matched AGN and inactive samples. While bars could potentially trigger AGN activity, they appear to have no further, unique effect on a galaxy’s stellar mass or SFR