Resolving the physics of quasar Lyα nebulae (RePhyNe): I. Constraining quasar host halo masses through circumgalactic medium kinematics

doi:10.1093/mnras/stad2682

Resolving the physics of quasar Lyα nebulae (RePhyNe): I. Constraining quasar host halo masses through circumgalactic medium kinematics

2023-09-06

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DOI：10.1093/mnras/stad2682

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Ly alpha nebulae ubiquitously found around z > 2 quasars can supply unique constraints on the properties of the circumgalactic medium, such as its density distribution, provided the quasar halo mass is known. We present a new method to constrain quasar halo masses based on the line-of-sight velocity dispersion maps of Ly alpha nebulae. By using MUSE-like mock observations obtained from cosmological hydrodynamic simulations under the assumption of maximal quasar fluorescence, we show that the velocity dispersion radial profiles of Ly alpha emitting gas are strongly determined by gravity and that they are thus self-similar with respect to halo mass when rescaled by the virial radius. Through simple analytical arguments and by exploiting the kinematics of He II 1640 angstrom emission for a set of observed nebulae, we show that Ly alpha radiative transfer effects plausibly do not change the shape of the velocity dispersion profiles but only their normalization without breaking their self-similarity. Taking advantage of these results, we define the variable eta(140-200)(40-100) as the ratio of the median velocity dispersion in two specifically selected annuli and derive an analytical relation between eta 140-20040-100 and the halo mass which can be directly applied to observations. We apply our method to 37 observed quasar Ly alpha nebulae at 3 < z < 4.7 and find that their associated quasars are typically hosted by similar to 10(12.16 +/- 0.14) M-circle dot haloes independent of redshift within the explored range. This measurement, which is completely independent of clustering methods, is consistent with the lowest mass estimates based on quasar autocorrelation clustering at z similar to 3 and with quasar-galaxies cross-correlation results.

Keywords:

galaxies: evolution

galaxies: haloes

galaxies: high-redshift

galaxies: kinematics and dynamics

quasars: general

Resolving the physics of quasar Lyα nebulae (RePhyNe): I. Constraining quasar host halo masses through circumgalactic medium kinematics

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