Orientation effects on cool gas absorption from gravitational-arc tomography of a z = 0.77 disc galaxy

Abstract

We use spatially-resolved spectroscopy of a distant giant gravitational arc to test orientation effects on Mg ii absorption equivalent width (EW) and covering fraction (〈κ〉) in the circumgalactic medium of a foreground star-forming galaxy (G1) at z ∼ 0.77. Forty-two spatially-binned arc positions uniformly sample impact parameters (D) to G1 between 10 and 30 kpc and azimuthal angles α between 30○ and 90○ (minor axis). We find an EW-D anti-correlation, akin to that observed statistically in quasar absorber studies, and an apparent correlation of both EW and 〈κ〉 with α, revealing a non-isotropic gas distribution. In line with our previous results on Mg ii kinematics suggesting the presence of outflows in G1, at minimum a simple 3-D static double-cone model (to represent the trace of bipolar outflows) is required to recreate the EW spatial distribution. The D and α values probed by the arc cannot confirm the presence of a disc, but the data highly disfavor a disc alone. Our results support the interpretation that the EW-α correlation observed statistically using other extant probes is partly shaped by bipolar metal-rich winds.

Directly constraining the spatial coherence of the z ∼ 1 circumgalactic medium

“…Previous works (e.g., Schroetter et al 2019) found a segregation of absorbers along the galaxy minor and major axis, suggesting that the cool CGM could be described by a wind plus disk model. In particular, Fernandez-Figueroa et al (2022) found a dependence of the EW strength on the azimuthal angle for one of the three MUSE fields analyzed in this work, SGAS J1226+2152, although the effect is diluted when considering the three fields together, as we see in Sect. 2.4.…”

“…Only successful fits are considered. Also, as we are using an updated selection criterion, these maps are different from those in Lopez et al (2018Lopez et al ( , 2020 and (Fernandez-Figueroa et al 2022).…”

“…The technique, referred to as "arc-tomography", uses resolved spectroscopy of giant gravitational arcs as background sources, which are observed with integral-field spectrographs such as VLT/MUSE (Bacon et al 2010). The observations enable studies of the cool CGM distribution and kinematics (as traced by Mg ii absorption) of single galaxies (e.g., Lopez et al 2018Lopez et al , 2020Tejos et al 2021;Fernandez-Figueroa et al 2022) in an unprecedented fashion by directly mapping its properties across the arc. In the present work, we use this unique dataset (hereafter "ARCTOMO data") combined with the predictions from empirical models to constrain the cool CGM coherence scale, which is defined in the same way as in Rubin et al (2018b).…”

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

“…These studies have confirmed the need for a multiphase CGM but have not been able, given the sparseness of background sources, to directly probe the detailed morphology and physical properties (such as the density and 'clumpiness') of the CGM. This limitation can partly be mitigated by using lensed background quasars which afford multiple sight lines through one halo's CGM (Smette et al 1992 ;Monier, Turnshek & Lupie 1998 ;Rauch et al 2001 ;Ellison et al 2004 ;Zahedy et al 2016 ;Rubin et al 2018 ) or gravitational arc tomography (Lopez et al 2018 ;Mortensen et al 2021 ;Tejos et al 2021 ;Bordoloi et al 2022 ;Fernandez-Figueroa et al 2022 ). The situation has changed in recent years due to new, highly sensitive instrumentation, such as the Multi-Unit Spectroscopic Explorer (MUSE) on the ESO Very Large Telescope (VLT) (Bacon et al 2010 ) and the Keck Cosmic Web Imager (KCWI) (Martin et al 2010 ;Morrissey et al 2018 ) which can reach sensitivity levels that are at least one order of magnitude deeper than previously possible.…”