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MAGAZ3NE: High Stellar Velocity Dispersions for Ultramassive Quiescent Galaxies at z ≳ 3

Forrest, Ben and Wilson, Gillian and Muzzin, Adam and Marchesini, Danilo and Cooper, M. C. and Marsan, Z. Cemile and Annunziatella, Marianna and McConachie, Ian and Zaidi, Kumail and Gomez, Percy and Urbano Stawinski, Stephanie M. and Chang, Wenjun and De Lucia, Gabriella and La Barbera, Francesco and Lubin, Lori and Nantais, Julie and Peña, Theodore and Saracco, Paolo and Surace, Jason and Stefanon, Mauro (2022) MAGAZ3NE: High Stellar Velocity Dispersions for Ultramassive Quiescent Galaxies at z ≳ 3. Astrophysical Journal, 938 (2). Art. No. 109. ISSN 0004-637X. doi:10.3847/1538-4357/ac8747.

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In this work, we publish stellar velocity dispersions, sizes, and dynamical masses for eight ultramassive galaxies (UMGs; log(M_*/M_⊙) > 11), z ≳ 3) from the Massive Ancient Galaxies At z > 3 NEar-infrared (MAGAZ3NE) Survey, more than doubling the number of such galaxies with velocity dispersion measurements at this epoch. Using the deep Keck/MOSFIRE and Keck/NIRES spectroscopy of these objects in the H and K bandpasses, we obtain large velocity dispersions of ∼400 km s⁻¹ for most of the objects, which are some of the highest stellar velocity dispersions measured and ∼40% larger than those measured for galaxies of similar mass at z ∼ 1.7. The sizes of these objects are also smaller by a factor of 1.5–3 compared to this same z ∼ 1.7 sample. We combine these large velocity dispersions and small sizes to obtain dynamical masses. The dynamical masses are similar to the stellar masses of these galaxies, consistent with a Chabrier initial mass function (IMF). Considered alongside previous studies of massive quiescent galaxies across 0.2 < z < 4.0, there is evidence for an evolution in the relation between the dynamical mass–stellar mass ratio and velocity dispersion as a function of redshift. This implies an IMF with fewer low-mass stars (e.g., Chabrier IMF) for massive quiescent galaxies at higher redshifts in conflict with the bottom-heavy IMF (e.g., Salpeter IMF) found in their likely z ∼ 0 descendants, though a number of alternative explanations such as a different dynamical structure or significant rotation are not ruled out. Similar to data at lower redshifts, we see evidence for an increase of IMF normalization with velocity dispersion, though the z ≳ 3 trend is steeper than that for z ∼ 0.2 early-type galaxies and offset to lower dynamical-to-stellar mass ratios.

Item Type:Article
Related URLs:
URLURL TypeDescription
Forrest, Ben0000-0001-6003-0541
Wilson, Gillian0000-0002-6572-7089
Muzzin, Adam0000-0002-9330-9108
Marchesini, Danilo0000-0001-9002-3502
Cooper, M. C.0000-0003-1371-6019
Marsan, Z. Cemile0000-0002-7248-1566
Annunziatella, Marianna0000-0002-8053-8040
McConachie, Ian0000-0002-2446-8770
Zaidi, Kumail0000-0002-1163-7790
Gomez, Percy0000-0003-0408-9850
Urbano Stawinski, Stephanie M.0000-0001-8169-7249
Chang, Wenjun0000-0003-2144-2943
De Lucia, Gabriella0000-0002-6220-9104
La Barbera, Francesco0000-0003-1181-6841
Lubin, Lori0000-0003-2119-8151
Nantais, Julie0000-0002-7356-0629
Peña, Theodore0000-0002-0033-5041
Saracco, Paolo0000-0003-3959-2595
Surace, Jason0000-0001-7291-0087
Stefanon, Mauro0000-0001-7768-5309
Additional Information:This material is based upon work supported by the National Science Foundation under Cooperative Agreement No. AST-2009442. We gratefully acknowledge support from the NASA Astrophysics Data Analysis Program (ADAP) through grant numbers 80NSSC17K0019 and NNX16AN49G, the National Science Foundation through grants AST-1517863 and AST-2205189 and HST program numbers GO-15294 and GO-16300 provided by NASA through grants from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. Data presented herein were obtained using the UCI Remote Observing Facility, made possible by a generous gift from John and Ruth Ann Evans. Some of the material presented in this paper is based upon work supported by the National Science Foundation under grant No. 1908422. P.S. acknowledges support by the grant PRIN-INAF-2019 B.F. also thanks B. Lemaux, A. Pillepich, and L. Lewis for helpful discussions and input, as well as the authors of the codes referenced below, upon which this work has relied heavily. Thanks to the anonymous referee as well, whose comments improved the manuscript. Software: Astropy (Robitaille et al. 2013; Price-Whelan et al. 2018), FAST++ (Schreiber et al. 2018b), grizli (, IPython (Pérez & Granger 2007), Matplotlib (Hunter 2007), Molecfit (Smette et al. 2015; Kausch et al. 2015), MosfireDRP (, NumPy (Harris et al. 2020), pPXF (Cappellari 2017), PyPeit (Prochaska et al. 2020).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Istituto Nazionale di Astrofisica (INAF)
Issue or Number:2
Record Number:CaltechAUTHORS:20221031-575177800.28
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117665
Deposited By: Research Services Depository
Deposited On:09 Nov 2022 20:05
Last Modified:11 Nov 2022 18:38

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