ON THE RELATION BETWEEN CIRCULAR VELOCITY AND CENTRAL VELOCITY DISPERSION IN HSB AND LSB GALAXIES

1
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

2
Introduction
? A possible relation between bulge ?c and disk
Vc was found by Whitmore et al. (1979) studying a
sample of spiral galaxies. They inferred from Vc
/ ?c ? 1.7 that halo and bulge are dynamically
separate components.
3
Whitmore et al. 1979
4
Introduction
? A possible relation between bulge ?c and disk
Vc was found by Whitmore et al. (1979) studying a
sample of spiral galaxies. They inferred from Vc
/ ?c ? 1.7 that halo and bulge are dynamically
separate components. ? Gerhard et al. (2001)
derived the Vc- ?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,
5
Gerhard et al. 2001
6
Introduction
? A possible relation between bulge ?c and disk
Vc was found by Whitmore et al. (1979) studying a
sample of spiral galaxies. They inferred from Vc
/ ?c ? 1.7 that halo and bulge are dynamically
separate components. ? Gerhard et al. (2001)
derived the Vc- ?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 Vc-
?c relation. It was interpreted as a relation
between the mass of the DM halo and SMBH.
7
ellipticals spirals
Ferrarese 2002
8
Sample selection
We enlarged the sample so far studied, namely
? 38 Sa-Scd Ferrarese 2002 optical/HI RCs
from literature ? 12 Sb-Sc Baes et al. 2003
optical RCs ? 20 E0-E2 Kronawitter et al.
2000 stellar dynamicsby including ? 17
S0/a-Sab Corsini et al. 1999, 2003 optical
RCs ? 33 Sb-Sbc Vega et al. 2001 Pizzella
et al. 2004 optical RCs ? 11 LSB Sa-Sc
Pizzella et al. 2005 optical RCs ? 5 Es
Bertola et al. 1993 HI RCs from literature
9
NGC6925 HSB Sbc
Pizzella et al. 2004
10
ESO206-G14 LSB Sc
Pizzella et al. 2005
11
Measuring Vc

• Es from either the flat part of HI RC or
  dynamical modeling to test against
  model-depend biases ? HSB/LSBs from the
  flat part of gas RC V(R) A R B
  with A ? 2 km s-1 kpc-1 for R ? 0.35 R25
  instead of Vc V(Rlast) with Rlast ?
  R25

12
warped rising asymmetric not extended
Corsini et al. 2003
13
Pizzella et al. 2005
14
Measuring ?c

• Es from aperture measurements of the stellar
  velocity dispersion corrected to re/8
  ? HSB/LSBs from stellar velocity dispersion
  profile with no aperture correction
  

15
Pizzella et al. 2004
16
The Vc-?c relation for HSBs and Es
The sample consists of ? 40 HSB spirals
(Rlast ? 0.8 R25 ) ? 24 ellipticals 19 Vc
from stellar dynamics (Rlast ? 0.5 R25 )
5 Vc from HI kinematics
(Rlast ? 3 R25 )We fitted a straight line to
the data of HSBs and Es taking into account the
errors on Vc and ?c
17
ellipticals HI ellipticals HSB spirals
18
The MBH - MDM relation
? ?c is related to MBH according to the
MBH - ?c relation (Ferrarese Ford 2004)
? Vc is related to MDM since Vc
correlates with Vvir (e.g., Vc / Vvir 1.8,
Seljak 2002) and Vvir determines MDM
(e.g., Bullock et al. 2001)
19
? the Vc- ?c relation translates into a MBH - MDM
relation with some caveats ? MBH- ?c
for spirals ? MBH- ?c extrapolation to ?c ? 50
km/s ? uncertainties in the MDM - Vc conversion
20
The Vc-?c relation for LSBs
The sample consists of ? 8 LSB spirals (Rlast
? 1.2 R25 ) According to KS test the
distribution of normalized scatter of LSBs is
different from that of HSBs and Es. We fitted
a straight line to the data of LSBs taking into
account the errors on Vc and ?c
21
ellipticals HI ellipticals HSB spirals
22
ellipticals HI ellipticals HSB spirals LSB spirals
23
(No Transcript)
24
(No Transcript)
25
Conclusions
? Vc - ?c relation for 40 HSBs, 24 Es, and 8
LSBs with flat RCs.? Vc - ?c relation for
HSBs is linear out to ?c ? 50 km/s. ? Es with
Vc based on dynamical models or directly derived
from from HI RCs follow the same relation as
HSBs. ? LSBs follow a different Vc- ?c
relation. This suggests that DM halos of LSBs
host smaller SMBHs and were less affected by
baryon collapse with respect to their HSB
counterparts.
26
(No Transcript)
27
Pizzella et al. 2005
28
HI optical
Ferrarese 2002
29
ellipticals HI ellipticals HSB spirals
30
ellipticals HI ellipticals HSB spirals LSB spirals
31
(No Transcript)