Velocity dispersion measurements of dwarf galaxies in the Coma cluster - implications for the structure of the fundamental plane

Abstract

We present intermediate‐resolution spectroscopic data for a set of dwarf and giant galaxies in the Coma cluster, with −20.6 < MR < −15.7. The photometric and kinematic properties of the brighter galaxies can be cast in terms of parameters which present little scatter with respect to a set of scaling relations known as the fundamental plane. To determine the form of these fundamental scaling relations at lower luminosities, we have measured velocity dispersions for a sample comprising 69 galaxies on the border of the dwarf and giant regime. Combining these data with our photometric survey, we find a tight correlation of luminosity and velocity dispersion, L∝σ2.0, substantially flatter than the Faber–Jackson relation characterizing giant elliptical galaxies. In addition, the variation of mass‐to‐light (M/L) ratio with velocity dispersion is quite weak in our dwarf sample: M/L∝σ0.2. Our overall results are consistent with theoretical models invoking large‐scale mass removal and subsequent structural readjustment, e.g. as a result of galactic winds.

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

“…One of these is the M BH -s relation (Ferrarese & Merritt 2000;Gebhardt et al 2000), which can be described with a single power law (M BH 5 6 s µ -) over a wide range in velocity dispersion (70 350 km s 1 --, e.g., Graham et al 2011;McConnell et al 2011;. The other is the L sph -s relation, which has long been known to be a "double power law," with L sph 5 6 s µ -at the luminous end 5 (Schechter 1980;Malumuth & Kirshner 1981;Lauer et al 2007b;von der Linden et al 2007;Liu et al 2008)and L sph 2 s µ at intermediate and faint luminosities (Davies et al 1983;Held et al 1992;de Rijcke et al 2005;Matković & Guzmán 2005;Balcells et al 2007;Chilingarian et al 2008;Forbes et al 2008;Cody et al 2009;Tortora et al 2009 When Graham (2012) pointed out this overlooked inconsistency between these linear and bent relations, he identified two different populations of galaxies, namely the core-Sérsic spheroids Trujillo et al 2004) and the Sérsic spheroids 6 , and attributed the change in slope (from super-quadratic to linear) to their different formation mechanisms. In this scenario, core-Sérsic spheroids are built in dry merger events where the black hole and the bulge grow at the same pace, increasing their mass in lock steps (M L BH sph 1 µ ), whereas Sérsic spheroids originate from gas-rich processes in which the mass of the black hole increases more rapidly than the mass of its host spheroid (M L BH sph 2.5 µ ).…”

Galaxy Bulges and Their Massive Black Holes: A Review

“…ies have since shown that this result holds from the lowest luminosity dwarf elliptical galaxies up to M B ≈ −20 to −21 mag (Held et al 1992;de Rijcke et al 2005;Matković & Guzmán 2005;Balcells et al 2007b;Lauer et al 2007;Chilingarian et al 2008;Forbes et al 2008;Cody et al 2009;Tortora et al 2009;Kourkchi et al 2012). This explained why past samples of intermediateto-bright early-type galaxies had a slope of around 4, or 3 (Tonry 1981), and confirmed the observation by Binney (1982) and Farouki et al (1983) that a single power-law was not appropriate to describe the distribution of earlytype galaxies in the L-σ diagram.…”

The Host Galaxies of Low-Mass Black Holes

“…Matković & Guzmán (2005) and Cody et al (2009) study the Faber-Jackson relation for what they refer to as "dwarf early-type" galaxies in the Coma cluster with R-band magnitudes ranging from −22.0 to −17.5 mag and −20.7 to −15.6 mag or I-band magnitudes of ∼ − 23.2 to −16.8 mag (Fukugita et al 1995). According to their positions in the fundamental plane (e.g., Graham & Guzmán 2003), these galaxies obey our definition of spheroidal galaxies.…”