MUSEQuBES: Calibrating the redshifts of Lyman-{alpha} emitters using stacked circumgalactic medium absorption profiles. (arXiv:1910.03593v1 [astro-ph.GA])

MUSEQuBES: Calibrating the redshifts of Lyman-{alpha} emitters using stacked circumgalactic medium absorption profiles. (arXiv:1910.03593v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Muzahid_S/0/1/0/all/0/1">Sowgat Muzahid</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schaye_J/0/1/0/all/0/1">Joop Schaye</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marino_R/0/1/0/all/0/1">Raffaella Anna Marino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cantalupo_S/0/1/0/all/0/1">Sebastiano Cantalupo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brinchmann_J/0/1/0/all/0/1">Jarle Brinchmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Contini_T/0/1/0/all/0/1">Thierry Contini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wendt_M/0/1/0/all/0/1">Martin Wendt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wisotzki_L/0/1/0/all/0/1">Lutz Wisotzki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zabl_J/0/1/0/all/0/1">Johannes Zabl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bouche_N/0/1/0/all/0/1">Nicolas Bouch&#xe9;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Akhlaghi_M/0/1/0/all/0/1">Mohammad Akhlaghi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_H/0/1/0/all/0/1">Hsiao-Wen Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Claeyssens_A/0/1/0/all/0/1">Ad&#xe9;laide Claeyssens</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Johnson_S/0/1/0/all/0/1">Sean Johnson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leclercq_F/0/1/0/all/0/1">Floriane Leclercq</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maseda_M/0/1/0/all/0/1">Michael Maseda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matthee_J/0/1/0/all/0/1">Jorryt Matthee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Richard_J/0/1/0/all/0/1">Johan Richard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Urrutia_T/0/1/0/all/0/1">Tanya Urrutia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Verhamme_A/0/1/0/all/0/1">Anne Verhamme</a>

Lyman-alpha (Lyalpha) emission lines are typically found to be redshifted
with respect to the systemic redshifts of galaxies, likely due to resonant
scattering of Lyalpha photons. Here we measure the average velocity offset for
a sample of 96 z ~ 3.3 Lyalpha emitters (LAEs) with a median Lyalpha flux
(luminosity) of ~10^{-17} erg cm^{-2} s^{-1} (~10^{42} erg s^{-1}) and a median
unobscured star formation rate (SFR) of ~1.3 Msun/yr, 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 8 background quasars, must be centered on the systemic
redshift, we measure an average velocity offset, Voffset = 169 pm 10 km/s,
between the Lyalpha 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 Lyalpha line, and anti-correlated with the rest-frame equivalent width.
Moreover, we find that Voffset is correlated with SFR with a sub-linear scaling
relation, Voffset ~ 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 halos hosting the LAEs.

Lyman-alpha (Lyalpha) emission lines are typically found to be redshifted
with respect to the systemic redshifts of galaxies, likely due to resonant
scattering of Lyalpha photons. Here we measure the average velocity offset for
a sample of 96 z ~ 3.3 Lyalpha emitters (LAEs) with a median Lyalpha flux
(luminosity) of ~10^{-17} erg cm^{-2} s^{-1} (~10^{42} erg s^{-1}) and a median
unobscured star formation rate (SFR) of ~1.3 Msun/yr, 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 8 background quasars, must be centered on the systemic
redshift, we measure an average velocity offset, Voffset = 169 pm 10 km/s,
between the Lyalpha 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 Lyalpha line, and anti-correlated with the rest-frame equivalent width.
Moreover, we find that Voffset is correlated with SFR with a sub-linear scaling
relation, Voffset ~ 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 halos hosting the LAEs.

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