ON THE RELATION BETWEEN CIRCULAR VELOCITY AND CENTRAL VELOCITY DISPERSION IN HSB AND LSB GALAXIES E.M. Corsini, A. Pizzella, E. Dalla Bontà, F.Bertola Dipartimento di Astronomia, Università di Padova, Italy L. Coccato Kapteyn Astronomical Institute, Groningen, The Netherlands M. Sarzi Physics Department, University of Oxford, UK

Introduction  A possible relation between bulge  c and disk V c was found by Whitmore et al. (1979) studying a sample of spiral galaxies. They inferred from V c /  c  1.7 that halo and bulge are dynamically separate components.

Whitmore et al. 1979

Introduction  A possible relation between bulge  c and disk V c was found by Whitmore et al. (1979) studying a sample of spiral galaxies. They inferred from V c /  c  1.7 that halo and bulge are dynamically separate components.  Gerhard et al. (2001) derived the V c -  c relation for a sample of giant, nearly round and almost non-rotating ellipticals. It was explained as an indication of near dynamical homology of these galaxies,

Gerhard et al. 2001

Introduction  A possible relation between bulge  c and disk V c was found by Whitmore et al. (1979) studying a sample of spiral galaxies. They inferred from V c /  c  1.7 that halo and bulge are dynamically separate components.  Gerhard et al. (2001) derived the V c -  c relation for a sample of giant, nearly round and almost non-rotating ellipticals. It was explained as an indication of near dynamical homology of these galaxies.  Ferrarese (2002) and Baes et al. (2003) found that ellipticals and spirals define a common V c -  c relation. It was interpreted as a relation between the mass of the DM halo and SMBH.

Ferrarese 2002 ellipticals spirals

Sample selection We enlarged the sample so far studied, namely  38 Sa-Scd = Ferrarese 2002; optical/HI RC’s from literature  12 Sb-Sc = Baes et al. 2003; optical RC’s  20 E0-E2 = Kronawitter et al. 2000; stellar dynamics by including  17 S0/a-Sab = Corsini et al. 1999, 2003; optical RC’s  33 Sb-Sbc = Vega et al. 2001; Pizzella et al. 2004; optical RC’s  11 LSB Sa-Sc = Pizzella et al. 2005; optical RC’s  5 E’s = Bertola et al. 1993; HI RC’s from literature

Pizzella et al NGC6925 HSB Sbc

Pizzella et al ESO206-G14 LSB Sc

Measuring V c  E’s: from either the flat part of HI RC or dynamical modeling to test against model-depend biases  HSB/LSB’s: from the flat part of gas RC V(R) = A R + B with |A|  2 km s -1 kpc -1 for R  0.35 R 25 instead of V c = V(R last ) with R last  R 25

warped rising asymmetric not extended Corsini et al. 2003

Pizzella et al. 2005

Measuring  c  E’s: from aperture measurements of the stellar velocity dispersion corrected to r e /8  HSB/LSB’s: from stellar velocity dispersion profile with no aperture correction

Pizzella et al. 2004

The V c -  c relation for HSB’s and E’s The sample consists of  40 HSB spirals (R last  0.8 R 25 )  24 ellipticals 19 = V c from stellar dynamics (R last  0.5 R 25 ) 5 = V c from HI kinematics (R last  3 R 25 ) We fitted a straight line to the data of HSB’s and E’s taking into account the errors on V c and  c

ellipticals HI ellipticals HSB spirals

The M BH - M DM relation   c is related to M BH according to the M BH -  c relation (Ferrarese & Ford 2004)  V c is related to M DM since V c correlates with V vir (e.g., V c / V vir = 1.8, Seljak 2002) and V vir determines M DM (e.g., Bullock et al. 2001)

 the V c -  c relation translates into a M BH - M DM relation with some caveats  M BH -  c for spirals  M BH -  c extrapolation to  c  50 km/s  uncertainties in the M DM - V c conversion

The V c -  c relation for LSB’s The sample consists of  8 LSB spirals (R last  1.2 R 25 ) According to KS test the distribution of normalized scatter of LSB’s is different from that of HSB’s and E’s. We fitted a straight line to the data of LSB’s taking into account the errors on V c and  c

ellipticals HI ellipticals HSB spirals

ellipticals HI ellipticals HSB spirals LSB spirals

Conclusions  V c -  c relation for 40 HSB’s, 24 E’s, and 8 LSB’s with flat RC’s.  V c -  c relation for HSB’s is linear out to  c  50 km/s.  E’s with V c based on dynamical models or directly derived from from HI RC’s follow the same relation as HSB’s.  LSB’s follow a different V c -  c relation. This suggests that DM halos of LSB’s host smaller SMBH’s and were less affected by baryon collapse with respect to their HSB counterparts.

Pizzella et al. 2005

HI optical Ferrarese 2002

ellipticals HI ellipticals HSB spirals

ellipticals HI ellipticals HSB spirals LSB spirals