2016MNRAS.456..538Y -
Mon. Not. R. Astron. Soc., 456, 538-553 (2016/February-2)
The massive dark halo of the compact early-type galaxy NGC 1281.
YILDIRIM A., VAN DEN BOSCH R.C.E., VAN DE VEN G., DUTTON A., LASKER R., HUSEMANN B., WALSH J.L., GEBHARDT K., GULTEKIN K. and MARTIN-NAVARRO I.
Abstract (from CDS):
We investigate the compact, early-type galaxy NGC 1281 with integral field unit observations to map the stellar line-of-sight velocity distribution (LOSVD) out to five effective radii and construct orbit-based dynamical models to constrain its dark and luminous matter content. Under the assumption of mass-follows-light, the H-band stellar mass-to-light ratio (M/L) is Υ{sstarf} = 2.7±0.1 Υ☉, and higher than expected from our stellar population synthesis fits with either a canonical Kroupa (Υ{sstarf} = 1.3 Υ☉) or Salpeter (Υ{sstarf} = 1.7 Υ☉) stellar initial mass function. Such models also cannot reproduce the details of the LOSVD. Models with a dark halo recover the kinematics well and indicate that NGC 1281 is dark matter dominated, making up ∼ 90 per cent of the total enclosed mass within the kinematic bounds. Parametrized as a spherical NFW profile, the dark halo mass is 11.5 ≤ log(MDM/M☉) ≤ 11.8 and the stellar M/L is 0.6 ≤ Υ{sstarf}/Υ☉ ≤ 1.1. However, this M/L is lower than predicted by its old stellar population. Moreover, the halo mass within the kinematic extent is 10 times larger than expected based on Λ-cold-dark-matter predictions, and an extrapolation yields cluster-sized dark halo masses. Adopting Υ{sstarf} = 1.7 Υ☉ yields more moderate dark halo virial masses, but these models fit the kinematics worse. A non-NFW model might solve the discrepancy between the unphysical consequences of the best-fitting dynamical models and models based on more reasonable assumptions for the dark halo and stellar M/L, which are disfavoured according to our parameter estimation.
Abstract Copyright:
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
Journal keyword(s):
galaxies: elliptical and lenticular, cD - galaxies: haloes - galaxies: kinematics and dynamics - galaxies: structure - dark matter
Status at CDS
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Simbad objects:
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