2009MNRAS.398..561W

Query : 2009MNRAS.398..561W

2009MNRAS.398..561W - Mon. Not. R. Astron. Soc., 398, 561-574 (2009/September-2)

Stellar velocity profiles and line strengths out to four effective radii in the early-type galaxies NGC3379 and 821.

WEIJMANS A.-M., CAPPELLARI M., BACON R., DE ZEEUW P.T., EMSELLEM E., FALCON-BARROSO J., KUNTSCHNER H., McDERMID R.M., VAN DEN BOSCH R.C.E. and VAN DE VEN G.

Abstract (from CDS):

We use the integral-field spectrograph SAURON to measure the stellar line-of-sight velocity distribution and absorption line strengths out to four effective radii (Re) in the early-type galaxies NGC 3379 and 821. With our newly developed observing technique, we can now probe these faint regions in galaxies that were previously not accessible with traditional long-slit spectroscopy. We make optimal use of the large field-of-view and high throughput of the spectrograph: by adding the signal of all ∼1400 lenslets into one spectrum, we obtain sufficient signal-to-noise in a few hours of observing time to reliably measure the absorption line kinematics and line strengths out to large radius.

We find that the line strength gradients previously observed within 1 Re remain constant out to at least 4 Re, which puts constraints on the merger histories of these galaxies. The stellar halo populations are old and metal poor. By constructing orbit-based Schwarzschild dynamical models, we find that dark matter is necessary to explain the observed kinematics in NGC 3379 and 821, with 30-50 per cent of the total matter being dark within 4 Re. The radial anisotropy in our best-fitting halo models is less than in our models without halo, due to differences in orbital structure. The halo also has an effect on the Mgb-Vescrelation: its slope is steeper when a dark matter halo is added to the model.


Abstract Copyright: © 2009 The Authors. Journal compilation © 2009 RAS

Journal keyword(s): galaxies: elliptical and lenticular, cD - galaxies: haloes - galaxies: individual: NGC 3379 - galaxies: individual: NGC 821 - galaxies: kinematics and dynamics - dark matter

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NGC 821 AG? 02 08 21.1358498040 +10 59 41.832436704   12.210 11.310 10.739 9.744 ~ 592 0
2 M 105 LIN 10 47 49.600 +12 34 53.87   10.56 9.76 9.12 8.18 ~ 1504 0
3 NGC 3384 GiG 10 48 16.8855574392 +12 37 45.371165844   10.0       ~ 617 1
4 NGC 4494 GiP 12 31 24.0391348536 +25 46 30.071664120   10.55 9.74     ~ 491 0

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