Query : 2010A&A...516A...4P

2010A&A...516A...4P - Astronomy and Astrophysics, volume 516, A4-4 (2010/6-2)

Radially extended kinematics and stellar populations of the massive ellipticals NGC 1600, NGC 4125, and NGC 7619. Constraints on the outer dark halo density profile.


Abstract (from CDS):

We present high quality long slit spectra along the major and minor axes out to 1.5-2Re (14-22kpc) of three bright elliptical galaxies (NGC1600, NGC4125, NGC7619) obtained at the Hobby-Eberly Telescope (HET). We derive stellar kinematic profiles and Lick/IDS indices (Hβ,Mgb,Fe5015, Fe5270, Fe5335, Fe5406). Moreover, for NGC4125 we derive gas kinematics and emission line strengths. We model the absorption line strengths using Simple Stellar Populations models that take into account the variation of [α/Fe] and derive ages, total metallicity and element abundances. Overall, we find that the three galaxies have old and [α/Fe] overabundant stellar populations with no significant gradients. The metallicity is supersolar at the center with a strong negative radial gradient. For NGC4125, several pieces of evidence point to a recent dissipational merger event. We calculate the broad band color profiles with the help of SSP models. All of the colors show sharp peaks at the center of the galaxies, mainly caused by the metallicity gradients, and agree well with the measured colors. Using the Schwarzschild's axisymmetric orbit superposition technique, we model the stellar kinematics to constrain the dark halos of the galaxies. We use the tight correlation between the Mgb strength and local escape velocity to set limits on the extent of the halos by testing different halo sizes. Logarithmic halos - cut at 60kpc - minimize the overall scatter of the Mgb-Vesc relation. Larger cutoff radii are found if the dark matter density profile is decreasing more steeply at large radii.

Abstract Copyright:

Journal keyword(s): galaxies: elliptical and lenticular, cD - Galaxy: abundances - galaxies: kinematics and dynamics - galaxies: individual: NGC4125 - galaxies: individual: NGC7619 - galaxies: individual: NGC1600

VizieR on-line data: <Available at CDS (J/A+A/516/A4): table3.dat table4.dat table6.dat>

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NGC 1600 GiG 04 31 39.858 -05 05 09.97   8.9   10.81   ~ 362 0
2 M 105 LIN 10 47 49.600 +12 34 53.87   10.56 9.76 9.12 8.18 ~ 1438 0
3 NGC 4125 GiP 12 08 06.017 +65 10 26.88 11.14 10.65 9.72     ~ 417 2
4 NGC 7619 GiG 23 20 14.524 +08 12 22.63   12.7       ~ 434 0
5 NGC 7626 rG 23 20 42.524 +08 13 01.43   12.8       ~ 416 1

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