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PNe as mass tracers
Dark-to-luminous properties of early-type galaxies
Nicola R. Napolitano
Kapteyn Institute Groningen (NL)
ESO workshop: PNe beyond the Milky Way. Garching 19-21 May 2004
PNe as mass tracers
Dark-to-luminous properties of early-type galaxies
Collaborators
PN.S Consortium
N. Douglas
K. Kuijken
M. Arnaboldi
M. Capaccioli
A. Romanowsky
M. Merrifield
H. Merrett
K. Freeman
O. Gerhard
Kapteyn Institute
Un. Leiden
INAF-OAT
INAF-OAC
Un. Nottingham
Un. Nottingham
Un. Nottingham
Mt. Stromlo
Un. Basel
ESO workshop: PNe beyond the Milky Way. Garching 19-21 May 2004
Observed trends of the M/L in early type galaxies
PNe kinematics
Inner stellar kinematics
(long-slit spectroscopy)
When we measure =M/L ratios in galaxies we basicly deal with
dark-to-luminous mass distribution
At every radius, R, (in B band for example):
Mlum MDM
LB
B
Mlum MDM
Mlum
assuming a radially constant stellar mass-to-light radius,
stellar population synthesis models)
B
R
1
MDM R
Mlum R
* (from
dark-to-luminous
mass fraction
In presence of a significant(?) dark halo, this quantity must grow with
the distance from the center:
OK!
HOW MUCH in order to be consistent with LCDM(=NFW+cvir)?
Can we predict the radial run of the M/L in galaxies?
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Stellar syntesis mod
NFW 97
MDM=MDM(Mvir, cvir)
cvir
20
Mvir
1011 Msun
Hernquist (1990)
Mlum=Mlum(Ml,tot,,Re)
0.13
Re 4.5
Bullock et al. (2001)
MDM=MDM(Mvir)
SF
fvir
0.56
kpc
Shen et al. (2003)
Formation efficiency
Ml,tot
Ml,tot
1011 Msun
Mlum=Mlum(Ml,tot)
Mb
Mvir
Ml,tot
1
SF
1
fb
1
Baryon fraction (CMB)
Bennett et al. 2003
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
esf=0.1 (Padmanabhan et al. 04)
esf=0.2 (Fukugita et al. 98)
esf=0.6 (Guzik&Seljak 02
Marinoni&Hudson 02)
Ml,tot = 1.1x1011Msol
M/Ls increase more quickly for decreasing efficiencies and ...
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.1x1011Msol
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.4x1011Msol
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 5x1011Msol
…and M/Ls increase more quickly for increasing masses
Are these trends observed in early-type galaxies?
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 5x1011Msol
NGC 1399
M/L gradients
Predicted M/Ls in LCDM framework
esf
esf=0.1
esf=0.2
esf=0.6
Log Ml,tot
Predicted M/Ls in LCDM framework
Gerhard et al. 01
Magorrian&Ballantyne01
Spread
distribution
esf=0.1
esf=0.2
Plateau
esf=0.6
Log Ml,tot
Predicted M/Ls in LCDM framework
esf=0.1
esf=0.2
esf=0.6
Log Ml,tot
Napolitano et al. 2002
Equilibrium?
Log Ml,tot
Baryon physics in galaxy luminous regions not
accounted in simulation [adiabatic collapse (de
Jong et al. 2003, Dutton et al. 2003)?];
hydrodynamical simulations (Meza et al. 2003,
Wright et al. 2004) found DM not to be
dominant up to 5Re in low-luminosity
compactwith
Inconsistent
galaxies
esf < 0.6 at 95% s.l.
Low concentrations
c=5±2
Halo stripping?
Log Ml,tot
Conclusions
We have a “toy-model” to make predictions of the M/L trend in the LCDM
framework, to be compared with future PNe observations AND other
dynamical tracers (GCs, Xrays, lensing). Thanks to the PN.S statistical
samples of PN radial velocities are reaching the precision which will allow to
discriminate the efficiency of the baryon cooling in galaxies.
We have shown on a sample of 21 galaxies that the M/L gradients by PN and
stellar kinematics are generally in agreement with the LCDM expectations
with some “critical points”:
a) nearly L* galaxies are in conflict with “reasonable” formation efficiency
unless we do not assume low-concentration halos (at odd with collisionless
LCDM simulations, but qualitatively expected in adiabatic collapse picture);
b) low-luminosity/gradients galaxies are tendentially more consistent with very
high formation efficiency (esf0.6) while high-luminosity/gradients galaxies
are spread on all the range of allowed efficiencies (esf=0.1-0.6). The turn-off
point is around Ml,tot =1.2x1011 Msun, i.e. around L* luminosities (MB ~ -20.2).
More (accurate) M/L estimates are needed in order to confirm these results….
FUTURE...
…The PN Spectrograph
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Precisions of 20% at 5-6 Re in order to discriminate models
Such a precisions are expected to be reached with the PN.S
Ml,tot = 1.4x1011Msol
Dichotomy of ETs in
DM properties as well
as in luminous properties?
Turn-off point
MB ~ -20.5
L* galaxies
Such a dichotomy is
observed in X-ray properties
(Pellegrini 1999)
faint
boxy
disky
bright
core
power-law
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
NGC 3379
Ml,tot = 1.1x1011Msol
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.4x1011Msol
NGC 5128
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 5x1011Msol
NGC 1399
…and M/Ls increase more quickly for increasing masses
Are these trends observed in early-type galaxies?
Predicted M/Ls in LCDM framework
esf=0.1
Spread
distribution
esf=0.2
Plateau
esf=0.6
Log Ml,tot
Observed trends of the M/L in early type galaxies
M/L “gradients” for
systems with PNe
kinematics
Observed trends of the M/L in early type galaxies
M/L “gradients”
from PNe kinematics+
systems with extended
long-slit spectroscopy
(out to 2 Re)
PNe have been extensively used in the recent past to constrain the mass
distribution in early-type galaxies up to unprecedented distances from
the galaxy center
Early works were based on poor statistical sample (the reliability of which has
been discussed in Napolitano et al. 2001)
year
1986
1993
1994
1995
1995
1996
1998
2001
GALAXY
M32
N3379
N1399
N5128
N3384
N4406
N1316
N4472
n.PNe
15
29
37
433
68
19
43
24
Rout/Re
6
3.5(6)
5
5
7
3
2.5
5
M/L
6
7
21-45
10
9
13
8
21
M/L*
3
7
9
4
4
8
Recently the improved observation techniques are allowing much larger samples
2001
2003
2003
2003
2004
N4697
N821
N4494
N3379
N5128
535
100 ->150
100 ->250
110 ->300
780
3
5
5
5
15
11
15
6
7
14
9
8
7
4
Observed trends of the M/L in early type galaxies
PNe kinematics
Inner stellar kinematics
(long-slit spectroscopy)
Observed trends of the M/L in early type galaxies
B /*
PNe kinematics
Inner stellar kinematics
(long-slit spectroscopy)
Observed trends of the M/L in early type galaxies
B /*
In order to improve statistics
we have added a sample of
ETGs with extended long-slit
spectroscopy data
Sample of 21 ETGs
Observed trends of the M/L in early type galaxies

/ B/
B*/
**
In order to improve statistics
we have added a sample of
ETGs with extended long-slit
spectroscopy data
Sample of 21 ETGs
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.1x1011Msol
NGC 3379
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.4x1011Msol
NGC 5128
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 5x1011Msol
NGC 3379
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.1x1011Msol
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.4x1011Msol
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 5x1011Msol
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.4x1011Msol
* = 3.5
NGC 5128
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 5x1011Msol
* = 9
NGC 1399
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.5x1011Msol
* = 7
NGC 3379
Stellar population versus dynamical M/L
Predicted M/Ls in LCDM framework
Predicted M/Ls in LCDM framework
2
Napolitano et al. 2002
Equilibrium?
esf=0.6
esf=0.2
Low concentration
c=5±2
esf=0.1
Predicted M/Ls in LCDM framework
Star mass following an Hernquist (1990) profile
NFW dark halos with concentrations by Bullock et al. (2001)
cvir
20
Mvir
1011 Msun
0.13
Luminous mass and dark mass are 1-parameter family models
MDM/Mlum is a 2-parameter quantity: total stellar mass, M* , and virial
mass, Mvir (or concentration cvir).
Predicted M/Ls in LCDM framework
B
R,
R
Hernquist (1990)
Total stellar mass
1
R
MDM
Mlum
out
MDM
Mlum
virial mass
NFW97 profile
Shen et al. (2003)
cvir
20
Bullock et al. (2001)
Mvir
1011 Msun
0.13
Luminous mass and dark mass are 1-parameter family models
MDM/Mlum is a 2-parameter quantity: total stellar mass, M* , and virial
mass, Mvir (or concentration cvir).
in
Predicted M/Ls in LCDM framework
1
R
B
R,
R
MDM
Mlum
out
MDM
Mlum
in
M* and Mvir are related to the efficiency which the baryons cool in stars with,
assuming that the original baryon fraction is the same for all the dark halos
and close to the cosmic value from CBM measurements (Bennett et al. 2003)
where
Star formation efficiency
fvir
Mvir
M
1
SF
1
f bar
1
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.4x1011Msol
* = 3.5
NGC 5128
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 5x1011Msol
* = 9
NGC 1399
Predicted M/Ls in LCDM framework
B
R
1
MDM R
Mlum R
Ml,tot = 1.5x1011Msol
* = 7
NGC 3379