Sub-kiloparsec ALMA imaging of compact star-forming galaxies at z ∼ 2.5: revealing the formation of dense galactic cores in the progenitors of compact quiescent galaxies
- University of California, Berkeley, Berkeley, CA (United States)
- Universidad Complutense de Madrid, Madrid (Spain)
- Pennsylvania State University, University Park, PA (United States)
- University of California, Santa Cruz, Santa Cruz, CA (United States)
- The Hebrew University, Jerusalem (Israel)
- Santa Cruz Institute for Particle Physics, Santa Cruz, CA (United States)
- Colby College, Waterville, ME (United States)
- European Southern Observatory, Casilla, Santiago (Chile)
- Kavli Institute for the Physics of the Universe (Japan)
- North American ALMA Science Center, National Radio Astronomy Observatory, Charlottesville, VA (United States)
We present spatially resolved Atacama Large Millimeter/submillimeter Array (ALMA) 870 μm dust continuum maps of six massive, compact, dusty star-forming galaxies at z ∼ 2.5. These galaxies are selected for their small rest-frame optical sizes (r{sub e,F160W}∼1.6 kpc) and high stellar mass densities that suggest that they are direct progenitors of compact quiescent galaxies at z ∼ 2. The deep observations yield high far-infrared (FIR) luminosities of L{sub IR}=10{sup 12.3−12.8} L{sub ⊙} and star formation rates (SFRs) of SFR = 200–700 M {sub ⊙} yr{sup −1}, consistent with those of typical star-forming “main sequence” galaxies. The high spatial resolution (FWHM ∼ 0.″12–0.″18) ALMA and Hubble Space Telescope photometry are combined to construct deconvolved, mean radial profiles of their stellar mass and (UV+IR) SFR. We find that the dusty, nuclear IR–SFR overwhelmingly dominates the bolometric SFR up to r ∼ 5 kpc, by a factor of over 100× from the unobscured UV–SFR. Furthermore, the effective radius of the mean SFR profile (r{sub e,SFR}∼1 kpc) is ∼30% smaller than that of the stellar mass profile. The implied structural evolution, if such nuclear starburst last for the estimated gas depletion time of Δt = ±100 Myr, is a 4× increase of the stellar mass density within the central 1 kpc and a 1.6× decrease of the half-mass–radius. This structural evolution fully supports dissipation-driven, formation scenarios in which strong nuclear starbursts transform larger, star-forming progenitors into compact quiescent galaxies.
- OSTI ID:
- 22868764
- Journal Information:
- Astrophysical Journal Letters, Vol. 827, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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