TY  - JOUR
A1  - Wendt, Martin
A1  - Bouche, Nicolas F.
A1  - Zabl, Johannes
A1  - Schroetter, Ilane
A1  - Muzahid, Sowgat
T1  - MusE GAs FLOw and Wind V. The dust/metallicity-anisotropy of the circum-galactic medium
JF  - Monthly notices of the Royal Astronomical Society
N2  - We investigate whether the dust content of the circum-galactic medium (CGM) depends on the location of the quasar sightline with respect to the galaxy major-axis using 13 galaxy-Mg II absorber pairs (9-81 kpc distance) from the MusE GAs FLOw and Wind (MEGAFLOW) survey at 0.4 < z < 1.4. The dust content of the CGM is obtained from [Zn/Fe] using ultraviolet and visual echelle spectrograph data. When a direct measurement of [Zn/Fe] is unavailable, we estimate the dust depletion from a method that consists in solving for the depletion from multiple singly ionized ions (e.g. Mn II, Cr II, and Zn II) since each ion depletes on dust grains at different rates. We find a positive correlation between the azimuthal angle and [Zn/Fe] with a Pearson's gamma = 0.70 +/- 0.14. The sightlines along the major axis show [Zn/Fe] < 0.5, whereas the [Zn/Fe] is > 0.8 along the minor axis. These results suggest that the CGM along the minor axis is on average more metal enriched (by approximate to 1 dex) than the gas located along the major axis of galaxies provided that dust depletion is a proxy for metallicity. This anisotropic distribution is consistent with recent results on outflow and accretion in hydro-dynamical simulations.
KW  - galaxies: evolution
KW  - galaxies: formation
KW  - intergalactic medium
KW  - quasars:
KW  - absorption lines
Y1  - 2021
U6  - https://doi.org/10.1093/mnras/stab049
SN  - 0035-8711
SN  - 1365-2966
VL  - 502
IS  - 3
SP  - 3733
EP  - 3745
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Bouma, Sietske Jeltje Deirdre
A1  - Richter, Philipp
A1  - Wendt, Martin
T1  - The relation between Ly alpha absorbers and local galaxy filaments
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. The intergalactic medium (IGM) is believed to contain the majority of baryons in the universe and to trace the same dark matter structure as galaxies, forming filaments and sheets. Ly alpha absorbers, which sample the neutral component of the IGM, have been extensively studied at low and high redshift, but the exact relation between Ly alpha absorption, galaxies, and the large-scale structure is observationally not well constrained.Aims. In this study, we aim at characterising the relation between Ly alpha absorbers and nearby over-dense cosmological structures (galaxy filaments) at recession velocities Delta v <= 6700 km s(-1) by using archival observational data from various instruments.Methods. We analyse 587 intervening Ly alpha absorbers in the spectra of 302 extragalactic background sources obtained with the Cosmic Origins Spectrograph (COS) installed on the Hubble Space Telescope (HST). We combine the absorption line information with galaxy data of five local galaxy filaments from the V8k catalogue.Results. Along the 91 sightlines that pass close to a filament, we identify 215 (227) Ly alpha absorption systems (components). Among these, 74 Ly alpha systems are aligned in position and velocity with the galaxy filaments, indicating that these absorbers and the galaxies trace the same large-scale structure. The filament-aligned Ly alpha absorbers have a similar to 90% higher rate of incidence (d?/dz=189 for log N(HI) >= 13.2) and a slightly shallower column density distribution function slope (-beta=-1.47) relative to the general Ly alpha population at z=0, reflecting the filaments' matter over-density. The strongest Ly alpha absorbers are preferentially found near galaxies or close to the axis of a filament, although there is substantial scatter in this relation. Our sample of absorbers clusters more strongly around filament axes than a randomly distributed sample would do (as confirmed by a Kolmogorov-Smirnov test), but the clustering signal is less pronounced than for the galaxies in the filaments.
KW  - galaxies: halos
KW  - intergalactic medium
KW  - quasars: absorption lines
KW  - large-scale structure of Universe
KW  - techniques: spectroscopic
KW  - ultraviolet: general
Y1  - 2021
U6  - https://doi.org/10.1051/0004-6361/202039786
SN  - 0004-6361
SN  - 1432-0746
VL  - 647
PB  - EDP Sciences
CY  - Les Ulis
ER  -