The Sino-French IFU Workshop ---Lijing

PU,SHIBI (pushibi@hotmail.com; pushibi@ynao.ac.cn) --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.

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Density profiles

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Results : Coma galaxies