The Mass Scale of High-redshift Galaxies:Virial Mass Estimates Calibrated with Stellar Dynamical Models from LEGA-C

Wel, A.V.D. and Houdt, J.V. and Bezanson, R. and Franx, M. and D’Eugenio, F. and Straatman, C. and Bell, E.F. and Muzzin, A. and Sobral, D. and Maseda, M.V. and de Graaff, A. and Holden, B.P. (2022) The Mass Scale of High-redshift Galaxies:Virial Mass Estimates Calibrated with Stellar Dynamical Models from LEGA-C. Astrophysical Journal, 936 (1). ISSN 0004-637X

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Dynamical models for 673 galaxies at z = 0.6-1.0 with spatially resolved (long-slit) stellar kinematic data from LEGA-C are used to calibrate virial mass estimates defined as M vir = K σ ′ ⋆ , int 2 R , with K a scaling factor, σ ′ ⋆ , int the spatially integrated stellar velocity second moment from the LEGA-C survey, and R the effective radius measured from a Sérsic profile fit to Hubble Space Telescope imaging. The sample is representative for M ⋆ > 3 × 1010 M ⊙ and includes all types of galaxies, irrespective of morphology and color. We demonstrate that using R = R sma (the semimajor axis length of the ellipse that encloses 50% of the light) in combination with an inclination correction on σ ′ ⋆ , int produces an unbiased M vir. We confirm the importance of projection effects on σ ′ ⋆ , int by showing the existence of a similar residual trend between virial mass estimates and inclination for the nearby early-type galaxies in the ATLAS3D survey. Also, as previously shown, when using a Sérsic profile-based R estimate, a Sérsic index-dependent correction to account for nonhomology in the radial profiles is required. With respect to analogous dynamical models for low-redshift galaxies from the ATLAS3D survey we find a systematic offset of 0.1 dex in the calibrated virial constant for LEGA-C, which may be due to physical differences between the galaxy samples or an unknown systematic error. Either way, with our work we establish a common mass scale for galaxies across 8 Gyr of cosmic time with a systematic uncertainty of at most 0.1 dex.

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Astrophysical Journal
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16 Sep 2022 08:55
Last Modified:
19 Sep 2023 02:52