Abell 1201: detection of an ultramassive black hole in a strong gravitational lens

Abstract

Supermassive black holes (SMBHs) are a key catalyst of galaxy formation and evolution, leading to an observed correlation between SMBH mass MBH and host galaxy velocity dispersion σe. Outside the local Universe, measurements of MBH are usually only possible for SMBHs in an active state: limiting sample size and introducing selection biases. Gravitational lensing makes it possible to measure the mass of non-active SMBHs. We present models of the $z$ = 0.169 galaxy-scale strong lens Abell 1201. A cD galaxy in a galaxy cluster, it has sufficient ‘external shear’ that a magnified image of a $z$ = 0.451 background galaxy is projected just ∼1 kpc from the galaxy centre. Using multiband Hubble Space Telescope imaging and the lens modelling software PYAUTOLENS, we reconstruct the distribution of mass along this line of sight. Bayesian model comparison favours a point mass with MBH = 3.27 ± 2.12 × 1010 M⊙ (3σ confidence limit); an ultramassive black hole. One model gives a comparable Bayesian evidence without an SMBH; however, we argue this model is nonphysical given its base assumptions. This model still provides an upper limit of MBH ≤ 5.3 × 1010 M⊙, because an SMBH above this mass deforms the lensed image ∼1 kpc from Abell 1201’s centre. This builds on previous work using central images to place upper limits on MBH, but is the first to also place a lower limit and without a central image being observed. The success of this method suggests that surveys during the next decade could measure thousands more SMBH masses, and any redshift evolution of the MBH−σe relation. Results are available at https://github.com/Jammy2211/autolens_abell_1201.

Hidden Cooling Flows in clusters of Galaxies II: a wider sample

“…Examples in our sample include NGC1600 and the central galaxy of A85, Holm 15A, with 1.7 × 10 10 M ⊙ and 4 × 10 10 M ⊙ black holes, respectively. Other BCGs have very high mass black hole including that of the BCG of A1201 for which a gravitationally lensed arc reveals a central mass of 3 × 10 10 M ⊙ (Nightingale et al 2023).…”

Bayesian Synthesis of Astrometric Wobble and Total Light Curves in Close Binary Supermassive Black Holes

“…Informed by these findings, we are encouraged to extend our exploration to binary CB-SMBHs with subannual orbital periods, within the upper mass range ∼10 10 M e (Magorrian et al 1998;Ghisellini et al 2009;McConnell et al 2012;Valtonen et al 2012;Hlavacek-Larrondo et al 2013;Walker et al 2014;Ferré-Mateu et al 2015;Ghisellini et al 2015;Liu et al 2015;Zuo et al 2015;Saturni et al 2016;Thomas et al 2016;Yıldırım et al 2016;Dullo et al 2017;Ge et al 2019;Mehrgan et al 2019;Jeram et al 2020;Onken et al 2020;Mejía-Restrepo et al 2022;Eilers et al 2023;Nightingale et al 2023).…”

Observational Tests of Active Galactic Nuclei Feedback: An Overview of Approaches and Interpretation

“…The presence of supermassive black holes (SMBHs) at the centre of galaxies, including our own Milky Way, is confirmed by the measurements of the motions of stars and gas in galaxy centres, and by the gravitational lensing signatures within multi-wavelength images (e.g., [1][2][3][4][5]). These black holes (BHs) grow through periods of gas accretion, which are known as Active Galactic Nuclei (AGN), and are identified using observations across the electromagnetic spectrum [6][7][8].…”