The Compact, ∼1 kpc Host Galaxy of a Quasar at a Redshift of 7.1

Journal Article · Fri Mar 10 04:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA62AC· OSTI ID:22869223

Venemans, Bram P.; Walter, Fabian; Decarli, Roberto ^[1]; Bañados, Eduardo ^[2]; Hodge, Jacqueline ^[3]; Hewett, Paul; McMahon, Richard G. ^[4]; Mortlock, Daniel J. ^[5]; Simpson, Chris ^[6]

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1. Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
2. The Observatories of the Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
3. Leiden Observatory, Leiden University, P.O. Box 9513, NL2300 RA Leiden (Netherlands)
4. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. Astrophysics Group, Blackett Laboratory, Imperial College London, London, SW7 2AZ (United Kingdom)
6. Gemini Observatory, 670 N. A’ohoku Place, Hilo, HI 96720 (United States)

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [C ii] fine-structure line and the underlying far-infrared (FIR) dust continuum emission in J1120+0641, the most distant quasar currently known (z=7.1). We also present observations targeting the CO(2–1), CO(7–6), and [C i] 369 μm lines in the same source obtained at the Very Large Array and Plateau de Bure Interferometer. We find a [C ii] line flux of F{sub [CII]}=1.11±0.10 Jy km s{sup −1} and a continuum flux density of S{sub 227GHz}=0.53±0.04 mJy beam{sup −1}, consistent with previous unresolved measurements. No other source is detected in continuum or [C ii] emission in the field covered by ALMA (∼ 25″). At the resolution of our ALMA observations (0.″23, or 1.2 kpc, a factor of ∼70 smaller beam area compared to previous measurements), we find that the majority of the emission is very compact: a high fraction (∼80%) of the total line and continuum flux is associated with a region 1–1.5 kpc in diameter. The remaining ∼20% of the emission is distributed over a larger area with radius ≲4 kpc. The [C ii] emission does not exhibit ordered motion on kiloparsec scales: applying the virial theorem yields an upper limit on the dynamical mass of the host galaxy of (4.3±0.9)×10{sup 10} M{sub ⊙}, only ∼20 × higher than the central black hole (BH). The other targeted lines (CO(2–1), CO(7–6), and [C i]) are not detected, but the limits of the line ratios with respect to the [C ii] emission imply that the heating in the quasar host is dominated by star formation, and not by the accreting BH. The star formation rate (SFR) implied by the FIR continuum is 105–340 M{sub ⊙} yr{sup −1}, with a resulting SFR surface density of ∼100–350 M{sub ⊙} yr{sup −1} kpc{sup −2}, well below the value for Eddington-accretion-limited star formation.

• OSTI ID: 22869223
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 837; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
CARBON MONOXIDE
COMPARATIVE EVALUATIONS
COSMIC DUST
COSMOLOGY
EMISSION
FINE STRUCTURE
FLUX DENSITY
GALAXIES
HEATING
INTERFEROMETERS
MASS
QUASARS
RED SHIFT
RESOLUTION
STARS
VIRIAL THEOREM