The Sino-French IFU Workshop ---Lijing PU,SHIBI ([email protected];...
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Transcript of The Sino-French IFU Workshop ---Lijing PU,SHIBI ([email protected];...
The Sino-French IFU Workshop ---Lijing
PU,SHIBI ([email protected]; [email protected]) --Yunnan Observatory (Group BPS)Zhanwen,HanR.P.Saglia, J.Thomas, R.Bender (MPE)2010.11.10
Extended stellar kinematics and populations of early-type galaxies: Constraints on the outer dark halo density profile
PU,S.B et al. 2010,A&A, 516,A4
Outline Introduction Sample selection-NGC1600,NGC4125,NGC7619, 19 early-type
galaxies in the Coma cluster. Method –The axisymmetric Schwarzschild’s orbits superposi
tion technique (Schwarzschild 1979) and Mgb-Vesc correlation The measurement of stellar kinematics and stellar population
s Results – a novel method constraints on the outer dark halo p
rofile Discussion
Introduction
Dark matter halo around galaxies
Radial velocity of planetary nebular and globular cluster
Density and temperature profiles of X-ray halos
Gravitational lensing effects
Stellar kinematics
Mass profile Beyond the last kinematic data point
Mgb- Vesc Improved
Improved
??
EXPEXP
According to the standard closed-box models of chemical enrichment,the metallicity is a function of the yields and of how much of gas has
been locked after star formation has ceased (Tinsley 1980)-- the deeper potential is , the easier it is to retain gas in the galaxies. So far, the
metallicity is a function of the local potential (local escape velocity Vesc)
Dynamical models measure the potential profiles (Vesc)
1, Measure the luminosity density from HST, SDSS and 2MASS images
2, The photometric data for the modelling are deprojected into a three-dimensional, axisymmetric distribution with specified inclination using the program of Magorrian (1999)
3, Construct the mass profiles-the total density consists of the stellar mass density and a dark matte halo
Methods:Dynamical models --Thomas et al (2004,2005,2007)
Methods:Dynamical models --Thomas et al (2004,2005,2007)
4, The dark matter halo The dark matter halo used is the cored logarithmic (LOG) halo p
rofile (Binney & Tremaine 1987)
we introduce a cut-off radius rcut and modify the density profile 5, Fit the kinematics data using dynamical models and searching for the best-fit model for each cut-off radii. Therefore,
a number of potential profiles (Vesc) are derived.
222
222
)(
3
4)(
rr
rr
G
Vr
c
ccLOG
)exp()()(2
2
cutLOGcut r
rrr EXP
Methods:Dynamical models --Thomas et al (2004,2005,2007)
6, Suppose Mgb follows Vesc, fitting Mgb and Vesc to a straight-line --- Measured the cut off radius
NOTE:The kinematics of Coma galaxie are taken from Mehlert et al. (2000,2003) and Coccato et al. 2010.
Kinematics Profile
Using the Fourier Correlation Quotient method (FCQ) (Bender 1990), we derived the kinematics of NGC1600,NGC4125, NGC7619 from the long slit spectra carried by the Hobby-Eberly Telecope (HET)
Line strength indices
The index measured in EW is:
And the index measured in Magnitude is:
dF
FEW
C
I
2
1
1
2
112
1log5.2
dF
FMag
C
I
Burstein et al. (1984); Worthey et al. (1994); Trager et al. (1998)
Lick indices
SSP
Stellar populations
Stellar population model: Thomas et al (2003)
Method :
LICK
Results: Mgb – Vesc Constraints on the size of dark halo (NGC1600,NGC4125,NGC7619)
1,Dynamics models
2,Suppose Mgb follows Vesc, Fitting log (Mgb) and Vesc to a straight-line
3, Searching for the best-fitting
Constrain the mass profile
Discussion From the strong-lensing models, Halkola (2007) found the cut off radii
of field galaxies is 66 kpc, for cluster galaxies is 64 kpc Humphrey (2010) found the negative logarithmic slope, α,of mass den
sity profiles systematically varies with Re from Chandra X-ray observatory of 10 galaxies. (From α= 2 for systems with Re=4 kpc to α= 1.2 for systems with Re > 30 kpc.)
We will investigate the degeneracy between cut-off and outer density slope (NFW and Jaffe profiles with cutoff)
Future work: Further investigate the correlation between mass profiles and galaxies type, luminosity, or environment, consider further galaxies with Coma galaxies data.
Thanks!
Introduction
Scott et al (2009b)
Davies et al 1993
where :
For the spherical density distribution ,the gravitation potential Ф is :
Therefore, at each radius the local escape velocity is sensitive to the total mass density profile up to large radii.
BACK
Density profiles
Back
Results : Coma galaxies