Bulge-forming galaxies with an extended rotating disk at z ∼ 2

Journal Article · Tue Jan 10 04:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/834/2/135· OSTI ID:22869521

Tadaki, Ken-ichi; Genzel, Reinhard; Wisnioski, Emily; Schreiber, Natascha M. Förster; Burkert, Andreas; Lang, Philipp; Tacconi, Linda J.; Lutz, Dieter; Belli, Sirio; Davies, Richard I.; Herrera-Camus, Rodrigo; Mendel, J. Trevor ^[1]; Kodama, Tadayuki; Hatsukade, Bunyo; Hayashi, Masao ^[2]; Wuyts, Stijn ^[3]; Ikarashi, Soh ^[4]; Inoue, Shigeki ^[5]; Kohno, Kotaro ^[6]; Koyama, Yusei ^[7] ; others, and

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1. Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstr., D-85748 Garching (Germany)
2. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
3. Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY (United Kingdom)
4. Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen (Netherlands)
5. Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Chiba 277-8583 (Japan)
6. Institute of Astronomy, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)
7. Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, HI 96720 (United States)

We present 0.″2-resolution Atacama Large Millimeter/submillimeter Array observations at 870 μm for 25 Hα-seleced star-forming galaxies around the main sequence at z = 2.2–2.5. We detect significant 870 μm continuum emission in 16 (64%) of these galaxies. The high-resolution maps reveal that the dust emission is mostly radiated from a single region close to the galaxy center. Exploiting the visibility data taken over a wide uv distance range, we measure the half-light radii of the rest-frame far-infrared emission for the best sample of 12 massive galaxies with log(M{sub *}/M{sub ⊙}) > 11. We find nine galaxies to be associated with extremely compact dust emission with R{sub 1/2,870 μm} < 1.5 kpc, which is more than a factor of 2 smaller than their rest-optical sizes, 〈R{sub 1/2,1.6μm}〉=3.2 kpc, and is comparable with optical sizes of massive quiescent galaxies at similar redshifts. As they have an exponential disk with Sérsic index of 〈n{sub 1.6μm}〉=1.2 in the rest-optical, they are likely to be in the transition phase from extended disks to compact spheroids. Given their high star formation rate surface densities within the central 1 kpc of 〈ΣSFR{sub 1kpc}〉=40 M{sub ⊙} yr{sup −1} kpc{sup −2}, the intense circumnuclear starbursts can rapidly build up a central bulge with ΣM{sub *,1 kpc} > 10{sup 10} M{sub ⊙} kpc{sup −2} in several hundred megayears, i.e., by z ∼ 2. Moreover, ionized gas kinematics reveal that they are rotation supported with an angular momentum as large as that of typical star-forming galaxies at z = 1–3. Our results suggest that bulges are commonly formed in extended rotating disks by internal processes, not involving major mergers.

• OSTI ID: 22869521
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 834; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANGULAR MOMENTUM
COMPARATIVE EVALUATIONS
COSMIC DUST
DENSITY
DISTANCE
EMISSION
GALACTIC EVOLUTION
GALAXIES
PHASE TRANSFORMATIONS
RED SHIFT
RESOLUTION
ROTATION
SPHEROIDS
STARS
SURFACES