2016/08/31 by Ken-ichi Tadaki, Reinhard Genzel, Tadayuki Kodama +24 · 130 citations
Physics and Astronomy · #Angular momentum #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Bulge #Elliptical galaxy #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy rotation curve #Lenticular galaxy #Luminous infrared galaxy #Peculiar galaxy #Star formation #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/834/2/135
published in The Astrophysical Journal 834(2), 135 (IOP Publishing) · 11 pages, 6 figures, 2 tables, accepted for publication in ApJ
openalex created_date 2016/09/16 · arxiv created 2016/10/25 · openalex publication_date 2017/01/09 · arxiv updated 2017/01/18 · openalex updated_date 2026/08/05
ABSTRACT We present 0.″2-resolution Atacama Large Millimeter/submillimeter Array observations at 870 μ m for 25 H α -seleced star-forming galaxies around the main sequence at z = 2.2–2.5. We detect significant 870 μ m 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 * / M ⊙ ) > 11. We find nine galaxies to be associated with extremely compact dust emission with R 1/2,870 μ m < 1.5 kpc, which is more than a factor of 2 smaller than their rest-optical sizes, , and is comparable with optical sizes of massive quiescent galaxies at similar redshifts. As they have an exponential disk with Sérsic index of 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 M ⊙ yr −1 kpc −2 , the intense circumnuclear starbursts can rapidly build up a central bulge with Σ M *,1 kpc > 10 10 M ⊙ kpc −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.