EVIDENCE FOR A CLUMPY, ROTATING GAS DISK IN A SUBMILLIMETER GALAXY AT z = 4

By J. Hodge, C. Carilli, F. Walter, F. Walter, W. D. de Blok, D. Riechers, E. Daddi, L. Lentati. 2012

140 citations recorded by the source corpus.

We present Karl G. Jansky Very Large Array observations of the CO(2–1) emission in the z = 4.05 submillimeter galaxy (SMG) GN20. These high-resolution data allow us to image the molecular gas at 1.3 kpc resolution just 1.6 Gyr after the big bang. The data reveal a clumpy, extended gas reservoir, 14 ± 4 kpc in diameter, in unprecedented detail. A dynamical analysis shows that the data are consistent with a rotating disk of total dynamical mass 5.4 ± 2.4 × 1011 M☉. We use this dynamical mass estimate to constrain the CO-to-H2 mass conversion factor (αCO), finding αCO = 1.1 ± 0.6 M☉(K km s−1 pc2)−1. We identify five distinct molecular gas clumps in the disk of GN20 with masses a few percent of the total gas mass, brightness temperatures of 16–31K, and surface densities of >3200–4500 × (αCO/0.8) M☉ pc−2. Virial mass estimates indicate they could be self-gravitating, and we constrain their CO-to-H2 mass conversion factor to be <0.2–0.7 M☉(K km s−1 pc2)−1. A multiwavelength comparison demonstrates that the molecular gas is concentrated in a region of the galaxy that is heavily obscured in the rest-frame UV/optical. We investigate the spatially resolved gas excitation and find that the CO(6–5)/CO(2–1) ratio is constant with radius, consistent with star formation occurring over a large portion of the disk. We discuss the implications of our results in the context of different fueling scenarios for SMGs.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/8291e3866036f8432f8e87af5316f2a14d0b707b

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In Astronomy and Astrophysics

1. D. Narayanan
2. F. Walter
3. C. Casey
4. D. M. Alexander
5. A. Cooray
6. R. Ivison
7. C. Carilli
8. L. Hernquist

In Instrumentation

1. D. Narayanan
2. C. Casey
3. D. M. Alexander
4. A. Cooray
5. E. Daddi
6. F. Walter
7. R. Ivison
8. I. Smail

Citations in the corpus

• REGULARITY UNDERLYING COMPLEXITY: A REDSHIFT-INDEPENDENT DESCRIPTION OF THE CONTINUOUS VARIATION OF GALAXY-SCALE MOLECULAR GAS PROPERTIES IN THE MASS-STAR FORMATION RATE PLANE (2013, unknown): “…is accurately constrained by Herschel and millimetric continuum observations (see Magdis et al. 2012b for a detailed listing), and (ii) CO(J=1→0) line fluxes from the (J)VLA (for GN20; see Carilli et al. 2010, Hodge et al. 2012) and the Green Bank Telescope (for SMMJ21350102 and HERMES J105751.”
• SUBMILLIMETER GALAXIES AS PROGENITORS OF COMPACT QUIESCENT GALAXIES (2014, unknown): “…of z ∼ 6 (Capak et al. 2008; Schinnerer et al. 2008; Daddi et al. 2009a,b; Knudsen et al. 2010; Carilli et al. 2010, 2011; Riechers et al. 2010; Cox et al. 2011; Combes et al. 2012; Yun et al. 2012; Smolčić et al. 2012a; Micha lowski et al. 2012b; Hodge et al. 2012, 2013a; Riechers et al. 2013).”
• Cool Gas in High-Redshift Galaxies (2013, background): “A long observation using the JVLA in early science of the CO (2–1) emission (Hodge et al. 2012) shows that the CO is distributed in a disk with a diameter ∼ 14kpc (Fig.”
• KILOPARSEC-SCALE DUST DISKS IN HIGH-REDSHIFT LUMINOUS SUBMILLIMETER GALAXIES (2016, background): “…2012; Hodge et al. 2013b) was too poor (>1′′) to sufficiently resolve high–redshift galaxies except for in a handful of cases (e.g., Younger et al. 2008; Hodge et al. 2012), recently there have been some first attempts to constrain the sizes of larger samples of SMGs – as well as massive dusty…”
• AN ALMA SURVEY OF SUB-MILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: PHYSICAL PROPERTIES DERIVED FROM ULTRAVIOLET-TO-RADIO MODELING (2015, background): “…happen if the stars/dust geometry in the galaxies is very different than what is assumed in the models, for example if most of the restframe UV/optical light comes from a region that is physically separated from where the bulk of the infrared/sub-mm emission originates (e.g., Hodge et al. 2012).”
• AN ALMA SURVEY OF SUBMILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: SOURCE CATALOG AND MULTIPLICITY (2013, background): “J CO transitions (Ivison et al. 2010b, 2011; Riechers et al. 2011a,b; Hodge et al. 2012), it would be too extended to detect in a map with our median rms sensitivity of 0.4mJybeam−1.”
• GRAVITATIONAL LENS MODELS BASED ON SUBMILLIMETER ARRAY IMAGING OF HERSCHEL-SELECTED STRONGLY LENSED SUB-MILLIMETER GALAXIES AT z > 1.5 (2013, background): “There is even observational evidence based on dynamical models that disk-like systems exist at high redshift (Hodge et al. 2012).”
• AN ALMA SURVEY OF SUBMILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: THE REDSHIFT DISTRIBUTION AND EVOLUTION OF SUBMILLIMETER GALAXIES (2013, background): “One of the main results from our ALESS survey is that the “robust” Radio/1.4 Ghz and MIPS/24µm identifications for the multiwavelength counterpart to the original LABOCA detection were only 80 per cent correct, and 45 per cent complete (Hodge et al. 2012).”
• CO excitation of normal star forming galaxies out to $z=1.5$ as regulated by the properties of their interstellar medium (2014, methodology): “2ab sources close to BzK-21000; Daddi et al 2009a; Carilli et al 2010; Hodge et al 2012; 2013; Tan et al 2014).”
• Dusty Star Forming Galaxies at High Redshift (2014, background): “…for rotating molecular disks in even extremely bright SMGs and quasars (e.g Tacconi et al., 2008; Bothwell et al., 2010; Carilli et al., 2010; Hodge et al., 2012; Deane et al., 2013)), while other studies have found more seemingly disrupted systems when examining the velocity contours…”