ALMA resolves the first strongly-lensed Optical/NIR-dark galaxy

Abstract

We present high-resolution ($\lesssim 0.1$arcsec) ALMA observations of the strongly-lensed galaxy HATLASJ113526.2-01460 at redshift $z\sim 3.1$ discovered in the Gama 12${}^{\mathrm{th}}$ field of the Herschel-ATLAS survey. The gravitationally lensed system is remarkably peculiar in that neither the background source nor the foreground lens show a clearly detected optical/NIR emission. We perform accurate lens modeling and source morphology reconstruction in three different (sub-)mm continuum bands, and in the C[II] and CO(8-7) spectral lines. The modeling indicates a foreground lensing (likely elliptical) galaxy with mass $\gtrsim 10^{11}{M}_{\odot }$ at $z\gtrsim 1.5$, while the source (sub-)mm continuum and line emissions are amplified by factors $\mu \sim 6-13$. We estimate extremely compact sizes $\lesssim 0.5$ kpc for the star-forming region and $\lesssim 1$ kpc for the gas component, with no clear evidence of rotation or of ongoing merging events. We perform broadband SED-fitting and retrieve the intrinsic de-magnified physical properties of the source, which is found to feature a very high star-formation rate $\gtrsim 10^3{M}_{\odot }$ yr${}^{-1}$, that given the compact sizes is on the verge of the Eddington limit for starbursts; the radio luminosity at 6 cm from available EVLA observations is consistent with the star-formation activity. The galaxy is found to be extremely rich in gas $\sim 10^{11}{M}_{\odot }$ and dust $\gtrsim 10^9{M}_{\odot }$. The stellar content $\lesssim 10^{11}{M}_{\odot }$ places the source well above the main sequence of starforming galaxies, indicating that the starburst is rather young with estimated age $\sim 10^8$ yr. Our results indicate that the overall properties of HATLASJ113526.2-01460 are consistently explained by in-situ galaxy formation and evolution scenarios.

17 Pages, 12 Figures, 7 Tables. Submitted to ApJ

References in corpus (32)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• A Dust-Obscured Massive Maximum-Starburst Galaxy at a Redshift of 6.34
• The Detection of a Population of Submillimeter-Bright, Strongly-Lensed Galaxies
• Galaxy growth in a massive halo in the first billion years of cosmic history
• The SCUBA-2 Cosmology Legacy Survey: ALMA resolves the rest-frame far-infrared emission of sub-millimeter galaxies
• ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description
• The Herschel-ATLAS Data Release 1 Paper I: Maps, Catalogues and Number Counts
• The nature of the [CII] emission in dusty star-forming galaxies from the SPT survey
• The Herschel-ATLAS: a sample of 500μm-selected lensed galaxies over 600 square degrees
• Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z~2-4 as probed by multi-J CO lines
• The Spatially Resolved [CII] Cooling Line Deficit in Galaxies
• ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Search for [CII] line and dust emission in 6<z<8 galaxies
• Galaxy Evolution in the Radio Band: The Role of Starforming Galaxies and Active Galactic Nuclei
• A dusty compact object bridging galaxies and quasars at cosmic dawn
• PyAutoLens: Open-Source Strong Gravitational Lensing
• CANDELS: Elevated Black Hole Growth in the Progenitors of Compact Quiescent Galaxies at z~2
• COLDz: A High Space Density of Massive Dusty Starburst Galaxies ~1 Billion Years after the Big Bang
• Illuminating the dark side of cosmic star formation two billion years after the Big Bang
• Strong FUV fields drive the [CII]/FIR deficit in z~3 dusty, star-forming galaxies
• CO emission in distant galaxies on and above the main sequence
• The Herschel Bright Sources (HerBS): Sample definition and SCUBA-2 observations
• Lens Models of Herschel-Selected Galaxies From High-Resolution Near-IR Observations
• A new estimate of the cosmic star formation density from a radio-selected sample, and the contribution of $H$-dark galaxies at $z\ge 3$
• Very compact millimeter sizes for composite star-forming/AGN submillimeter galaxies
• A High-Resolution Investigation of the Multi-Phase ISM in a Galaxy during the First Two Billion Years
• A census of optically dark massive galaxies in the early Universe from magnification by lensing galaxy clusters
• The Herschel-ATLAS: magnifications and physical sizes of $500\mu$m-selected strongly lensed galaxies
• Where do quasar hosts lie with respect to the size-mass relation of galaxies?
• An ALMA view of 11 Dusty Star Forming Galaxies at the peak of Cosmic Star Formation History
• Herschel-ATLAS Data Release III: Near-infrared counterparts in the South Galactic Pole field -- Another 100,000 submillimetre galaxies

Cited by in corpus (6)

• GalaPy, the highly optimised C++/Python spectral modelling tool for galaxies -- I. Library presentation and photometric fitting
• The mass-dependent UVJ diagram at cosmic noon: A challenge for galaxy evolution models and dust radiative transfer
• The Way of Water: ALMA resolves H2O emission lines in a strongly lensed dusty star-forming galaxy at z $\sim$ 3.1
• PRUSSIC III -- ALMA and NOEMA survey of dense gas in high-redshift star-forming galaxies
• Strong gravitational lensing with upcoming wide-field radio surveys
• Uncovering the absorbed atomic Universe with the [OI]63um line