The Sino-French IFU Workshop ---Lijing PU,SHIBI --Yunnan Observatory (Group BPS) Zhanwen,Han R.P.Saglia, J.Thomas, R.Bender (MPE) 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 superposition technique (Schwarzschild 1979) and Mgb- V esc correlation  The measurement of stellar kinematics and stellar populations  Results – a novel method constraints on the outer dark halo profile  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- V esc Improved ? EXP 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 V esc )

 Dynamical models measure the potential profiles (V esc ) 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)

4, The dark matter halo The dark matter halo used is the cored logarithmic (LOG) halo profile (Binney & Tremaine 1987) we introduce a cut-off radius r cut 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 (V esc ) are derived. EXP

Methods: Dynamical models --Thomas et al (2004,2005,2007) 6, Suppose Mgb follows V esc, fitting Mgb and V esc 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 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: 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 – V esc Constraints on the size of dark halo (NGC1600,NGC4125,NGC7619) 1,Dynamics models 2,Suppose Mgb follows V esc, Fitting log (Mgb) and V esc 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 density profiles systematically varies with R e from Chandra X-ray observatory of 10 galaxies. (From α= 2 for systems with R e =4 kpc to α= 1.2 for systems with R e > 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