Stellar Kinematics and Structural Properties of Virgo Cluster Dwarf Early-Type Galaxies From the Smakced Project. Iii. Angular Momentum and Constraints on Formation Scenarios

Abstract

We analyze the stellar kinematics of 39 dwarf early-type galaxies (dEs) in the Virgo cluster. Based on the specific stellar angular momentum λ Re and the ellipticity, we find 11 slow rotators and 28 fast rotators. The fast rotators in the outer parts of the Virgo cluster rotate significantly faster than fast rotators in the inner parts of the cluster. Moreover, 10 out of the 11 slow rotators are located in the inner 3 • (D < 1 Mpc) of the cluster. The fast rotators contain subtle disky structures that are visible in high-pass filtered optical images, while the slow rotators do not exhibit these structures. In addition, two of the dEs have kinematically decoupled cores and four more have emission partially filling in the Balmer absorption lines. These properties suggest that Virgo cluster dEs may have originated from late-type star-forming galaxies that were transformed by the environment after their infall into the cluster. The correlation between λ Re and the clustercentric distance can be explained by a scenario where low luminosity star-forming galaxies fall into the cluster, their gas is rapidly removed by ram pressure stripping, although some of it can be retained in their core, their star-formation is quenched but their stellar kinematics are preserved. After a long time in the cluster and several passes through its center, the galaxies are heated up and transformed into slow rotating dEs.

The Next Generation Virgo Cluster Survey Xvi: The Angular Momentum of Dwarf Early-Type Galaxies From Globular Cluster Satellites

“…The x-shapes found for VCC1261, VCC1528, and VCC1545 in the g-band residual images are typical of disky and boxy isophotes (see Figure 10). These three dEs are slow rotators based on the stellar rotation speed estimate by Toloba et al (2014aToloba et al ( , 2015. See Table 1 for a summary of the main properties of these dEs.…”

“…The stellar kinematics are available for VCC1545 and VCC1861. While VCC1545 rotates at a speed of ∼25km s −1 (Chilingarian 2009), VCC1861 is not rotating (its stellar rotation is 5.3 ± 2.5 km s −1 ; Toloba et al 2011Toloba et al , 2014aToloba et al , 2015. See Table 1 for a summary of the main properties of these dEs.…”

“…Kinematics can be more revealing than morphology, and indeed dEs with similar structural properties can have very different rotation speeds (Pedraz et al 2002;Simien & Prugniel 2002;Geha et al 2002Geha et al , 2003van Zee et al 2004;Chilingarian 2009;Toloba et al 2009Toloba et al , 2011Toloba et al , 2014aToloba et al , 2014bToloba et al , 2015Ryś et al 2013Ryś et al , 2014. Regarding their stellar populations, they span a wide range of subsolar metallicities, from [M/H]∼−0.1 to −1.5, and old ages, from 1 to 14 Gyr (Michielsen et al 2008;Paudel et al 2010;Koleva et al 2011;Toloba et al 2014a).…”

“…However, this galaxy class is rather heterogeneous. Thus, some of the dEs-for instance, those that show subtle spiral structures-are likely to come from a progenitor population that was transformed by the cluster environment where they reside (e.g., Kormendy 1985;Moore et al 1998;Mastropietro et al 2005;Boselli et al 2008Boselli et al , 2014Toloba et al 2009Toloba et al , 2012Toloba et al , 2015Kormendy & Bender 2012).…”

New Spectroscopic Technique Based on Coaddition of Surface Brightness Fluctuations: NGC 4449 and Its Stellar Tidal Stream

“…However, this can only be applied to relatively bright objects (m < 24 r mag arcsec −2 ), which limits the study of the internal properties of spatially resolved galaxies to nearby objects. Some examples of integrated light spectroscopic studies of spatially resolved dwarf galaxies are reported in Geha et al (2002Geha et al ( , 2003, de Rijcke et al (2005), Koleva et al (2009), Toloba et al (2009Toloba et al ( , 2011Toloba et al ( , 2014aToloba et al ( , 2014bToloba et al ( , 2015, and Ryś et al (2013). Here we describe a new spectroscopic technique that allows for kinematic and metallicity studies of faint satellites and streams beyond the Local Group and up to a distance of ∼4 Mpc.…”