The Formation of Dwarf Early-Type Galaxies. Reynier Peletier Kapteyn Astronomical Institute, Groningen

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1 The Formation of Dwarf Early-Type Galaxies Reynier Peletier Kapteyn Astronomical Institute, Groningen

2 From Kormendy et al. (2009) Definition of dwarf ellipticals: -15 < MB < -18 Here to be discussed the Low Surface Brightness Branch (green), named Spheroids by Kormendy+

3 Quenched Dwarfs have Large Companions Isolated Quenched Galaxies (Geha et al. 2012; NASA-SDSS Atlas) Binggeli, Sandaga & Tammann 1988

4 Questions to answer: - How are dwarf ellipticals formed and how do they evolve? - Why are there no isolated dwarf ellipticals? Possible ways to find the answers: - Studying the Star Formation History of dwarf ellipticals - Studying the Internal Motions of their stars - Studying Scaling Relations of these galaxies

5 Questions to answer: - How are dwarf ellipticals formed and how do they evolve? - Why are there no isolated dwarf ellipticals? Possible ways to find the answers: - Studying the Star Formation History of dwarf ellipticals - Studying the Internal Motions of their stars - Studying Scaling Relations of these galaxies

6 Are de's smaller versions of E's? 2MASS 2MASS SDSS VCC 1316 (M87) VCC 1912

7 λre versus the ellipticity for all 260 ATLAS3D galaxies. Emsellem E et al. MNRAS 2011;414: Davies (DEFIS)

8 λr for dwarfs in the literature: Geha et al Toloba et al. 2009

9 de(di) de(bc)

10 The SMAKCED Survey of Virgo des SMAKCED (Stellar content, Mass and Kinematics of Cluster Dwarfs): Photometry (IR+Opt) + Long slit Spectroscopy of 39 dwarf in the Virgo Cluster (see also Janz et al. 2012,14) Spectroscopy: representative sample of 39 galaxies out of complete sample of 100 with photometry. Deep major axis spectroscopy, ~ A, R~3000 (Toloba et al. 2011, 2012) (Toloba et al. 2014, submitted to ApJ)

11 SMAKCED Collaborators: Elisa Toloba, Alessandro Boselli, Thorsten Lisker, Raja Guha Thakurta, Glenn van de Ven, Jesus Falcon Barroso, Agnieszka Rys, Mark den Brok, Samuel Boissier, Gerhard Hensler, Joachim Janz, Eija Laurikainen, Sanjaya Paudel, Heikki Salo, Josh Simon, Eric Emsellem, Javier Gorgas, Sami Niemi, Josh Adams, Andrew Benson.

12 1. Rotational Support

13 λre versus ellipticity for all 260 ATLAS3D galaxies.

14 λre versus ellipticity for all 260 ATLAS3D galaxies. and for SMAKCED Dwarfs Dwarfs show both fast and slow rotators. Dwarf ellipticals, compared to massive galaxies, tend to be less rotationally Supported. Radial trend visible.

15 Now including CALIFA Spiral Galaxies

16 Is there a trend of λr with clustercentric distance? Rys et al SAURON IFU SMAKCED Toloba et al. 2014

17 We find: - dwarf ellipticals show a range in λr: there are both slow and fast rotators. - there is a small dependence of λr with clustercentric distance.

18 2. Kinematically Decoupled Cores

19

20 How many other KDCs are there in dwarf ellipticals? One detected in VCC 510 (Thomas et al. 2006)

21 Some statistics (Toloba et al. 2014, ApJ): - number of KDCs in dwarfs (Virgo): 5.9 +/- 2.4% = 4/71 - number of KDCs in large E/S0 (ATLAS3D): 8.1 +/- 1.8% (Krajnovic et al. 2011, KDC+CRC) Very similar!

22 3. Some scaling relations

23

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25 Why this dichotomy? Why are Slow Rotators either very massive or dwarfs?

26 Consequences for formation scenarios 1. Properties of KDCs similar to those in large galaxies (e.g. stellar populations). So, formation mechanism similar. 2. Could KDCs be due to harassment (close interactions)? Does not seem to be possible, since its effects mostly visible In the outer parts (beyond 1.5 eff. radii, Gonzalez-Garcia et al. 2005). 3. Dwarf-dwarf merger, or accretion of large amounts of gas: difficult in cluster-environment (Boselli et al. 2008) So, maybe it is easier to make KDCs than is generally thought.

27 But: - de have exponential surface brightness profiles (Caon+ 1991) - many de show photometric remnants from disk structures (Lisker+ 2006,7) So, violent mergers not likely Kormendy et al. 2009

28 Why do dwarf ellipticals have such low λr?

29 Why do dwarf ellipticals have such low λr? Maybe their progenitors have low λr.

30 Koleva et al BCDs MgI FeI 0 CaII FeI CaII FeI CaII 0 0 TiI 1.4 NaD 3 0 Flux Wavelength, Å 8800 MK+ 2014

31 [Fe/H] Age, Gyr σ, km s 1 v, km s 1 Norm. flux Koleva et al. 2014: BCDs might have low λr N S Mk324major Mrk324 I band R, arcsec 5 10 Mrk324 (B-I) mag

32 Questions to answer: - How are dwarf ellipticals formed and how do they evolve? - Why are there no isolated dwarf ellipticals? They evolve from star forming dwarfs that lose their gas through ram pressure stripping, and some interactions when falling into the cluster environment. How KDCs are formed is still not clear at all.

33 Hard questions: 1. Why do dwarf ellipticals sometimes have KDCs? 2. Why are most Sd/Sm fully rotationally supported, while in star forming dwarfs they appear to be more dispersion supported? 3. Why have dwarf ellipticals exponential surface brightness profiles?