A submillimeter galaxy illuminating its circumgalactic medium: Lyα scattering in a cold, clumpy outflow
- Center for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)
- Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
- Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
- School of Physics, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)
- XMM SOC, ESAC, Apartado 78, E-28691 Villanueva de la Canada, Madrid (Spain)
- Department of Physics and Atmospheric Science, Dalhousie University Halifax, NS B3H 3J5 (Canada)
- Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
- Virginia Polytechnic Institute and State University Department of Physics, MC 0435, 910 Drillfield Drive, Blacksburg, VA 24061 (United States)
- Joint Astronomy Centre, 660 North A'ohoku Place University Park, Hilo, HI 96720 (United States)
- UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
- Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)
- Kapteyn Institute, University of Groningen, PO Box 800, 9700 AV Groningen (Netherlands)
We report the detection at 850 μm of the central source in SSA22-LAB1, the archetypal 'Lyman-α Blob' (LAB), a 100 kpc scale radio-quiet emission-line nebula at z = 3.1. The flux density of the source, S {sub 850} = 4.6 ± 1.1 mJy, implies the presence of a galaxy or group of galaxies with a total luminosity of L {sub IR} ≈ 10{sup 12} L {sub ☉}. The position of an active source at the center of a ∼50 kpc radius ring of linearly polarized Lyα emission detected by Hayes et al. suggests that the central source is leaking Lyα photons preferentially in the plane of the sky, which undergo scattering in H I clouds at a large galactocentric radius. The Lyα morphology around the submillimeter detection is reminiscent of a biconical outflow, and the average Lyα line profiles of the two 'lobes' are dominated by a red peak, which is expected for a resonant line emerging from a medium with a bulk velocity gradient that is outflowing relative to the line center. Taken together, these observations provide compelling evidence that the central active galaxy (or galaxies) is responsible for a large fraction of the extended Lyα emission and morphology. Less clear is the history of the cold gas in the circumgalactic medium being traced by Lyα: is it mainly pristine material accreting into the halo that has not yet been processed through an interstellar medium (ISM), now being blown back as it encounters an outflow, or does it mainly comprise gas that has been swept-up within the ISM and expelled from the galaxy?.
- OSTI ID:
- 22365046
- Journal Information:
- Astrophysical Journal, Vol. 793, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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