2015ApJ...813L...7N -
Astrophys. J., 813, L7 (2015/November-1)
Discovery of a strongly lensed massive quiescent galaxy at z = 2.636: spatially resolved spectroscopy and indications of rotation.
NEWMAN A.B., BELLI S. and ELLIS R.S.
Abstract (from CDS):
We report the discovery of RG1M0150, a massive, recently quenched galaxy at z = 2.636 that is multiply imaged by the cluster MACSJ0150.3-1005. We derive a stellar mass of log M* = 11.49 -0.16_+0.10 and a half-light radius of R_e,maj- = 1.8 ± 0.4 Kpc Taking advantage of the lensing magnification, we are able to spatially resolve a remarkably massive yet compact quiescent galaxy at z > 2 in ground-based near-infrared spectroscopic observations using Magellan/FIRE and Keck/MOSFIRE. We find no gradient in the strength of the Balmer absorption lines over 0.6 Re - 1.6 Re which are consistent with an age of 760 Myr. Gas emission in [N ii] broadly traces the spatial distribution of the stars and is coupled with weak Hα emission (log [N ii]/Hα = 0.6 ± 0.2), indicating that OB stars are not the primary ionizing source. The velocity dispersion within the effective radius is σe,stars = 271 ± 41 km/s We detect rotation in the stellar absorption lines for the first time beyond z ∼ 1 Using a two-integral Jeans model that accounts for observational effects, we measure a dynamical mass of log Mdyn = 11.24 ± 0.14 and V/σ = 0.70 +/ 0.21. This is a high degree of rotation considering the modest observed ellipticity of 0.12±0.08, but it is consistent with predictions from dissipational merger simulations that produce compact remnants. The mass of RG1M0150 implies that it is likely to become a slowly rotating elliptical. If it is typical, this suggests that the progenitors of massive ellipticals retain significant net angular momentum after quenching which later declines, perhaps through accretion of satellites.
Abstract Copyright:
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Journal keyword(s):
galaxies: elliptical and lenticular, cD - galaxies: kinematics and dynamics - gravitational lensing: strong
Nomenclature:
NAME RG1M0150 N=1.
Simbad objects:
2
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