TY - JOUR A1 - Zabl, Johannes A1 - Bouche, Nicolas F. A1 - Schroetter, Ilane A1 - Wendt, Martin A1 - Finley, Hayley A1 - Schaye, Joop A1 - Conseil, Simon A1 - Contini, Thierry A1 - Marino, Raffaella Anna A1 - Mitchell, Peter A1 - Muzahid, Sowgat A1 - Pezzulli, Gabriele A1 - Wisotzki, Lutz T1 - MusE GAs FLOw and Wind (MEGAFLOW) BT - II. A study of gas accretion around z approximate to 1 star-forming galaxies with background quasars JF - Monthly notices of the Royal Astronomical Society N2 - We use the MusE GAs FLOw and Wind (MEGAFLOW) survey to study the kinematics of extended disc-like structures of cold gas around z approximate to 1 star-forming galaxies. The combination of VLT/MUSE and VLT/UVES observations allows us to connect the kinematics of the gas measured through MgII quasar absorption spectroscopy to the kinematics and orientation of the associated galaxies constrained through integral field spectroscopy. Confirming previous results, we find that the galaxy-absorber pairs of the MEGAFLOW survey follow a strong bimodal distribution, consistent with a picture of MgII absorption being predominantly present in outflow cones and extended disc-like structures. This allows us to select a bona-fide sample of galaxy-absorber pairs probing these discs for impact paramometers of 10-70 kpc. We test the hypothesis that the disc-like gas is co-rotating with the galaxy discs, and find that for seven out of nine pairs the absorption velocity shares the sign of the disc velocity, disfavouring random orbits. We further show that the data are roughly consistent with inflow velocities and angular momenta predicted by simulations, and that the corresponding mass accretion rates are sufficient to balance the star formation rates. KW - galaxies: evolution KW - galaxies: formation KW - galaxies: haloes KW - galaxies: kinematics and dynamics KW - quasars: absorption lines Y1 - 2019 U6 - https://doi.org/10.1093/mnras/stz392 SN - 0035-8711 SN - 1365-2966 VL - 485 IS - 2 SP - 1961 EP - 1980 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Schroetter, Ilane A1 - Bouche, Nicolas F. A1 - Zabl, Johannes A1 - Contini, Thierry A1 - Wendt, Martin A1 - Schaye, Joop A1 - Mitchell, Peter A1 - Muzahid, Sowgat A1 - Marino, Raffaella Anna A1 - Bacon, Roland A1 - Lilly, Simon J. A1 - Richard, Johan A1 - Wisotzki, Lutz T1 - MusE GAs FLOw andWind (MEGAFLOW) BT - III. Galactic wind properties using background quasars JF - Monthly notices of the Royal Astronomical Society N2 - We present results from our on-going MusE GAs FLOw and Wind (MEGAFLOW) survey, which consists of 22 quasar lines of sight, each observed with the integral field unit MUSE and the UVES spectrograph at the ESO Very Large Telescopes (VLT). The goals of this survey are to study the properties of the circumgalactic medium around z similar to 1 star-forming galaxies. The absorption-line selected survey consists of 79 strong MgII absorbers (with rest-frame equivalent width greater than or similar to 0.3 angstrom) and, currently, 86 associated galaxies within 100 projected kpc of the quasar with stellar masses (M-star) from 109 to 1011 M-circle dot. We find that the cool halo gas traced by MgII is not isotropically distributed around these galaxies from the strong bi-modal distribution in the azimuthal angle of the apparent location of the quasar with respect to the galaxy major axis. This supports a scenario in which outflows are bi-conical in nature and co-exist with a co-planar gaseous structure extending at least up to 60-80 kpc. Assuming that absorbers near the minor axis probe outflows, the current MEGAFLOW sample allowed us to select 26 galaxy-quasar pairs suitable for studying winds. From this sample, using a simple geometrical model, we find that the outflow velocity only exceeds the escape velocity when M-star less than or similar to 4 x 10(9) M-circle dot, implying the cool material is likely to fall back except in the smallest haloes. Finally, we find that the mass loading factor., the ratio between the ejected mass rate and the star formation rate, appears to be roughly constant with respect to the galaxy mass. KW - galaxies: evolution KW - galaxies: formation KW - intergalactic medium KW - quasars: absorption lines Y1 - 2019 U6 - https://doi.org/10.1093/mnras/stz2822 SN - 0035-8711 SN - 1365-2966 VL - 490 IS - 3 SP - 4368 EP - 4381 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Hani, Maan H. A1 - Ellison, Sara L. A1 - Sparre, Martin A1 - Grand, Robert J. J. A1 - Pakmor, Rüdiger A1 - Gómez, Facundo A. A1 - Springel, Volker T1 - The diversity of the circumgalactic medium around z=0 Milky Way-mass galaxies from the Auriga simulations JF - Monthly notices of the Royal Astronomical Society N2 - Galaxies are surrounded by massive gas reservoirs ( i.e. the circumgalactic medium; CGM) which play a key role in their evolution. The properties of the CGM, which are dependent on a variety of internal and environmental factors, are often inferred from absorption line surveys which rely on a limited number of single lines-of-sight. In this work we present an analysis of 28 galaxy haloes selected from the Auriga project, a cosmological magneto-hydrodynamical zoom-in simulation suite of isolated MilkyWay-mass galaxies, to understand the impact of CGM diversity on observational studies. Although the Auriga haloes are selected to populate a narrow range in halo mass, our work demonstrates that the CGM of L-star galaxies is extremely diverse: column densities of commonly observed species span similar to 3-4 dex and their covering fractions range from similar to 5 to 90 per cent. Despite this diversity, we identify the following correlations: 1) the covering fractions ( CF) of hydrogen and metals of the Auriga haloes positively correlate with stellar mass, 2) the CF of H I, C IV, and Si II anticorrelate with active galactic nucleus luminosity due to ionization effects, and 3) the CF of H I, C IV, and Si II positively correlate with galaxy disc fraction due to outflows populating the CGM with cool and dense gas. The Auriga sample demonstrates striking diversity within the CGM of L-star galaxies, which poses a challenge for observations reconstructing CGM characteristics from limited samples, and also indicates that long-term merger assembly history and recent star formation are not the dominant sculptors of the CGM. KW - methods: numerical KW - galaxies: evolution KW - galaxies: haloes Y1 - 2019 U6 - https://doi.org/10.1093/mnras/stz1708 SN - 0035-8711 SN - 1365-2966 VL - 488 IS - 1 SP - 135 EP - 152 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Gong, Chen Chris A1 - Libeskind, Noam I. A1 - Tempel, Elmo A1 - Guo, Quan A1 - Gottloeber, Stefan A1 - Yepes, Gustavo A1 - Wang, Peng A1 - Sorce, Jenny A1 - Pawlowski, Marcel T1 - The origin of lopsided satellite galaxy distribution in galaxy pairs JF - Monthly notices of the Royal Astronomical Society N2 - It is well known that satellite galaxies are not isotropically distributed among their host galaxies as suggested by most interpretations of the Λ cold dark matter (ΛCDM) model. One type of anisotropy recently detected in the Sloan Digital Sky Survey (and seen when examining the distribution of satellites in the Local Group and in the Centaurus group) is a tendency to be so-called lopsided. Namely, in pairs of galaxies (like Andromeda and the Milky Way) the satellites are more likely to inhabit the region in between the pair, rather than on opposing sides. Although recent studies found a similar set-up when comparing pairs of galaxies in ΛCDM simulations indicating that such a set-up is not inconsistent with ΛCDM, the origin has yet to be explained. Here we examine the origin of such lopsided set-ups by first identifying such distributions in pairs of galaxies in numerical cosmological simulations, and then tracking back the orbital trajectories of satellites (which at z = 0 display the effect). We report two main results: first, the lopsided distribution was stronger in the past and weakens towards z = 0. Secondly, the weakening of the signal is due to the interaction of satellite galaxies with the pair. Finally, we show that the z = 0 signal is driven primarily by satellites that are on first approach, who have yet to experience a ‘flyby’. This suggests that the signal seen in the observations is also dominated by dynamically young accretion events. KW - galaxies: evolution KW - galaxies: formation KW - galaxy: kinematics and dynamics KW - Local Group KW - dark matter KW - cosmology: theory Y1 - 2019 U6 - https://doi.org/10.1093/mnras/stz1917 SN - 0035-8711 SN - 1365-2966 VL - 488 IS - 3 SP - 3100 EP - 3108 PB - Oxford Univ. Press CY - Oxford ER -