Galaxy Bulges and Their Massive Black Holes: A Review

Abstract

With references to both key and oft-forgotten pioneering works, this article starts by presenting a review into how we came to believe in the existence of massive black holes at the centres of galaxies. It then presents the historical development of the near-linear (black hole)-(host spheroid) mass relation, before explaining why this has recently been dramatically revised. Past disagreement over the slope of the (black hole)-(velocity dispersion) relation is also explained, and the discovery of substructure within the (black hole)-(velocity dispersion) diagram is discussed. As the search for the fundamental connection between massive black holes and their host galaxies continues, the competing array of additional black hole mass scaling relations for samples of predominantly inactive galaxies are presented.

SUPERMASSIVE BLACK HOLES AND THEIR HOST SPHEROIDS. II. THE RED AND BLUE SEQUENCE IN THE MBH–M*,SPH DIAGRAM

“…Pseudo-bulges are notoriously hard to identify (Graham 2013(Graham , 2014(Graham , 2015(Graham , 2016. For example, mergers can create bulges that rotate (e.g., Bekki 2010; Keselman & Nusser 2012), and bars can spin-up classical bulges (e.g., Saha et al 2012;Saha 2015), thus rotation is not a definitive signature of a pseudo-bulge.…”

Searching for intermediate-mass black holes in galaxies with low-luminosity AGN: a multiple-method approach

“…Furthermore, our approach does not require the use of velocity dispersions, and, as such, avoids the issue of offset barred-galaxies/pseudobulges (most galaxies in our sample are barred and have strong indications of pseudobulges) in the M BH -σ diagram, discovered by Graham (2008) and Hu (2008). Nevertheless, we intend to use our multiple method approach to address the issue of the applicability of the M BH -σ relation in the low mass regime and in barred/pseudobulge galaxies (see also discussion in Kormendy & Ho 2013;Graham 2016), in a separate publication.…”

Selection bias in dynamically measured supermassive black hole samples: its consequences and the quest for the most fundamental relation

“…A number of observations and black hole accretion models (e.g., Marconi et al 2004;Merloni 2004;Granato et al 2006;Lapi et al 2006;Zheng et al 2009;Silverman et al 2008;Shankar et al 2009b;Mullaney et al 2012;Lapi et al 2014) suggest some degree of correlation between black hole growth and large-scale star formation. On the other hand, a number of observational and theoretical studies are now showing that the actual coevolution may be more complex to probe observationally, possibly depending on the different evolutionary phases undergone by the host galaxies as well as AGN variability effects (e.g., Hickox et al 2014;Rodighiero et al 2015;Volonteri et al 2015;Graham 2016;Westhues et al 2016, and references therein). Indeed the large scatter measured in the correlation between star formation and X-ray AGN luminosity (Dai et al 2015, and references therein) might simply reflect the large scatter in the intrinsic M bh -Mstar relation (Figure 4), a possible independent sign for velocity dispersion, instead of stellar mass, acting as the main driver of the co-evolution between central black holes and their hosts.…”

“…Indeed, nuclear kinematics of a number of nearby galaxies show the clear signature of a central mass concentration, beyond what can be attributed to the observed stellar population ⋆ E-mail: F.Shankar@soton.ac.uk in the nuclear regions. Black hole masses, M bh , are found to correlate with several global properties of their host galaxies (see, e.g., Ferrarese & Ford 2005;Shankar 2009; Kormendy & Ho 2013;Graham 2016, for reviews), including the stellar and/or bulge mass, velocity dispersion, σ, luminosity, light concentration or Sérsic index (e.g., Magorrian et al 1998;Richstone et al 1998 Kormendy & Ho 2013;McConnell & Ma 2013;Scott et al 2013;Läsker et al 2014;Savorgnan & Graham 2015a;Savorgnan et al 2016;Saglia et al 2016), and the mass of the surrounding dark matter halo (e.g., Ferrarese 2002a; Baes et al 2003;Bogdán & Goulding 2015;Sabra et al 2015). However, while it is true that the number of dynamical black hole mass measurements has increased over the years, such samples still remain relatively small, of the order of ∼ 70 − 80 galaxies.…”