MUSEQuBES: calibrating the redshifts of Ly α emitters using stacked circumgalactic medium absorption profiles

Journal Article · Fri May 15 00:00:00 EDT 2020 · Monthly Notices of the Royal Astronomical Society

DOI:https://doi.org/10.1093/mnras/staa1347· OSTI ID:1634250

Muzahid, Sowgat  ^[1]; Schaye, Joop  ^[2]; Marino, Raffaella Anna ^[3]; Cantalupo, Sebastiano  ^[3]; Brinchmann, Jarle ^[4]; Contini, Thierry ^[5]; Wendt, Martin  ^[6]; Wisotzki, Lutz ^[7]; Zabl, Johannes  ^[8]; Bouché, Nicolas ^[8]; Akhlaghi, Mohammad ^[9]; Chen, Hsiao-Wen  ^[10]; Claeyssens, Adélaîde ^[8]; Johnson, Sean ^[11]; Leclercq, Floriane ^[12]; Maseda, Michael  ^[2]; Matthee, Jorryt  ^[3]; Richard, Johan ^[8]; Urrutia, Tanya ^[7]; Verhamme, Anne ^[13]

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1. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany, Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
2. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
3. Department of Physics, ETH Zürich, Wolfgang-Pauli-Strasse 27, CH-8093 Zürich, Switzerland
4. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands, Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, P-T4150-762 Porto, Portugal
5. Institut de Recherche en Astrophysique et Planétologie (IRAP), Universit’e de Toulouse, CNRS, UPS, F-31400 Toulouse, France
6. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany, Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str 24/25, D-14476 Golm, Germany
7. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany
8. Univ Lyon, Univ Lyon1, Ens de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, F-69230 Saint-Genis-Laval, France
9. Instituto de Astrofísica de Canarias, C/ Vía Lâctea, E-38200 La Laguna, Tenerife, Spain, Facultad de Física, Universidad de La Laguna, Avda. Astrofísico Fco. Sânchez s/n, 38200 La Laguna, Tenerife, Spain
10. Department of Astronomy & Astrophysics, The University of Chicago, Chicago, IL 60637, USA
11. Department of Astrophysical Science, Princeton University, 4 Ivy Lane, Princeton, NJ 08644, USA, The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101, USA
12. Univ Lyon, Univ Lyon1, Ens de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, F-69230 Saint-Genis-Laval, France, Observatoire de Genéve, Université de Genéve, 51 Ch. des Maillettes, CH-1290 Versoix, Switzerland
13. Observatoire de Genéve, Université de Genéve, 51 Ch. des Maillettes, CH-1290 Versoix, Switzerland

ABSTRACT Ly α emission lines are typically found to be redshifted with respect to the systemic redshifts of galaxies, likely due to resonant scattering of Ly α photons. Here, we measure the average velocity offset for a sample of 96 z ≈ 3.3 Ly α emitters (LAEs) with a median Ly α flux (luminosity) of $${\approx}10^{-17}~\rm erg~cm^{-2}~s^{-1}$$ ($${\approx}10^{42}~\rm erg~s^{-1}$$) and a median star formation rate (SFR) of ≈1.3 $$\rm M_{\odot }~yr^{-1}$$ (not corrected for possible dust extinction), detected by the Multi-Unit Spectroscopic Explorer as part of our MUSEQuBES circumgalactic medium (CGM) survey. By postulating that the stacked CGM absorption profiles of these LAEs, probed by eight background quasars, must be centred on the systemic redshift, we measure an average velocity offset, Voffset = 171\pm 8 km s−1, between the Ly α emission peak and the systemic redshift. The observed Voffset is lower by factors of ≈1.4 and ≈2.6 compared to the velocity offsets measured for narrow-band-selected LAEs and Lyman break galaxies, respectively, which probe galaxies with higher masses and SFRs. Consistent with earlier studies based on direct measurements for individual objects, we find that the Voffset is correlated with the full width at half-maximum of the red peak of the Ly α line, and anticorrelated with the rest-frame equivalent width. Moreover, we find that Voffset is correlated with SFR with a sub-linear scaling relation, $$V_{\rm offset}\propto \rm SFR^{0.16\pm 0.03}$$. Adopting the mass scaling for main-sequence galaxies, such a relation suggests that Voffset scales with the circular velocity of the dark matter haloes hosting the LAEs.

• Sponsoring Organization: USDOE Office of Nuclear Energy (NE), Nuclear Fuel Cycle and Supply Chain
• OSTI ID: 1634250
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Vol. 496 Journal Issue: 2; ISSN 0035-8711
• Publisher: Oxford University Press
• Country of Publication: United Kingdom
• Language: English