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  - Chen, Hsiao-Wen
A1  - Johnson, Sean D.
A1  - Straka, Lorrie A.
A1  - Zahedy, Fakhri S.
A1  - Schaye, Joop
A1  - Muzahid, Sowgat
A1  - Bouche, Nicolas
A1  - Cantalupo, Sebastiano
A1  - Marino, Raffaella Anna
A1  - Wendt, Martin
T1  - Characterizing circumgalactic gas around massive ellipticals at z approximate to 0.4-III.
BT  - the galactic environment of a chemically pristine Lyman limit absorber
JF  - Monthly notices of the Royal Astronomical Society
N2  - This paper presents a study of the galactic environment of a chemically pristine (<0.6 per cent solar metallicity) Lyman Limit system (LLS) discovered along the sightline towards QSO SDSSJ 135726.27+043541.4 (Z(QSO) = 1.233) at projected distance d = 126 physical kpc (pkpc) from a luminous red galaxy (LRG) at z = 0.33. Combining deep Hubble Space Telescope images, MUSE integral field spectroscopic data, and wide-field redshift survey data has enabled an unprecedented, ultradeep view of the environment around this LRG-LLS pair. A total of 12 galaxies, including the LRG, are found at d less than or similar to 400 pkpc and line-of-sight velocity Delta v < 600 km S-1 of the LLS, with intrinsic luminosity ranging from 0.001 L-* to 2 L-* and a corresponding stellar mass range of M-star approximate to 10(7-11) M-circle dot. All 12 galaxies contribute to a total mass of M-star = 1.6 x 10(11) M-circle dot with approximate to 80 per cent contained in the LRG. The line-of-sight velocity dispersion of these galaxies is found to be sigma (group) = 230 km s(-1) with the centre of mass at d(group) = 118 pkpc and line-of-sight velocity offset of Delta v(group) = 181 km s(-1) from the LLS. Three of these are located at d less than or similar to 100 pkpc from the LLS, and they are all faint with intrinsic luminosity less than or similar to 0.02 L-* and gas-phase metallicity of approximate to 10 per cent solar in their interstellar medium. The disparity in the chemical enrichment level between the LLS and the group members suggests that the LLS originates in infalling intergalactic medium and that parts of the intergalactic gas near old and massive galaxies can still remain chemically pristine through the not too distant past.
KW  - galaxies: elliptical and lenticular, cD
KW  - galaxies: formation
KW  - intergalactic medium
KW  - quasars: absorption lines
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/sty3513
SN  - 0035-8711
SN  - 1365-2966
VL  - 484
IS  - 1
SP  - 431
EP  - 441
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
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  - Tepper-Garcia, Thor
A1  - Richter, Philipp
A1  - Schaye, Joop
T1  - Absorption signatures of warm-hot gas at low redshift - ne viii
JF  - Monthly notices of the Royal Astronomical Society
N2  - At z < 1 a large fraction of the baryons is thought to reside in diffuse gas that has been shock-heated to high temperatures (10 (5)-10 (6) K). Absorption by the 770.41, 780.32 A doublet of Ne viii in quasar spectra represents a unique tool to study this elusive warm-hot phase. We have developed an analytic model for the properties of Ne viii absorbers that allows for an inhomogeneous metal distribution. Our model agrees with the predictions of a simulation from the OverWhelmingly Large Simulations project indicating that the average line-of-sight metal-filling fraction within the absorbing gas is low (c(L) similar to 0.1). Most of the Ne viii in our model is produced in low-density, collisionally ionized gas (n(H) = 10(-6)-10(-4) cm(-3), T = 10 (5)-10 (6) K). Strong Ne viii absorbers (log(10)(N-NeVIII/cm(-2))14), like those recently detected by Hubble Space Telescope/Cosmic Origins Spectrograph, are found to arise in higher density gas (n(H) greater than or similar to 10(-4) cm(-3), T approximate to 5 x 10 (5) K). Ne viii cloudlets harbour only 1 per cent of the cosmic baryon budget. The baryon content of the surrounding gas (which has similar densities and temperatures as the Ne viii cloudlets) is a factor c(-1)L higher. We conclude that Ne viii absorbers are robust probes of shock-heated diffuse gas, but that spectra with signal-to-noise ratios S/N > 100 would be required to detect the bulk of the baryons in warm-hot gas.
KW  - methods: analytical
KW  - methods: numerical
KW  - galaxies: formation
KW  - intergalactic medium
KW  - quasars: absorption lines
KW  - cosmology: theory
Y1  - 2013
U6  - https://doi.org/10.1093/mnras/stt1712
SN  - 0035-8711
SN  - 1365-2966
VL  - 436
IS  - 3
SP  - 2063
EP  - 2081
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Tepper-Garcia, Thorsten
A1  - Richter, Philipp
A1  - Schaye, Joop
A1  - Booth, C. M.
A1  - Vecchia, Claudio Dalla
A1  - Theuns, Tom
A1  - Wiersma, Robert P. C.
T1  - Absorption signatures of warm-hot gas at low redshift o vi
JF  - Monthly notices of the Royal Astronomical Society
N2  - We investigate the origin and physical properties of O vi absorbers at low redshift (z = 0.25) using a subset of cosmological, hydrodynamical simulations from the OverWhelmingly Large Simulations (OWLS) project. Intervening O vi absorbers are believed to trace shock-heated gas in the warm-hot intergalactic medium (WHIM) and may thus play a key role in the search for the missing baryons in the present-day Universe. When compared to observations, the predicted distributions of the different O vi line parameters (column density, Doppler parameter, rest equivalent width W-r) from our simulations exhibit a lack of strong O vi absorbers, a discrepancy that has also been found by Oppenheimer & Dave. This suggests that physical processes on subgrid scales (e.g. turbulence) may strongly influence the observed properties of O vi systems. We find that the intervening O vi absorption arises mainly in highly metal enriched (10-1 < Z/Z(circle dot) less than or similar to 1) gas at typical overdensities of 1 < /<<>> less than or similar to 102. One-third of the O vi absorbers in our simulation are found to trace gas at temperatures T < 105 K, while the rest arises in gas at higher temperatures, most of them around T = 105.3 +/- 0.5 K. These temperatures are much higher than inferred by Oppenheimer & Dave, probably because that work did not take the suppression of metal-line cooling by the photoionizing background radiation into account. While the O vi resides in a similar region of (, T)-space as much of the shock-heated baryonic matter, the vast majority of this gas has a lower metal content and does not give rise to detectable O vi absorption. As a consequence of the patchy metal distribution, O vi absorbers in our simulations trace only a very small fraction of the cosmic baryons (< 2 per cent) and the cosmic metals. Instead, these systems presumably trace previously shock-heated, metal-rich material from galactic winds that is now mixing with the ambient gas and cooling. The common approach of comparing O vi and H i column densities to estimate the physical conditions in intervening absorbers from QSO observations may be misleading, as most of the H i (and most of the gas mass) is not physically connected with the high-metallicity patches that give rise to the O vi absorption.
KW  - methods: numerical
KW  - galaxies: formation
KW  - intergalactic medium
KW  - quasars: absorption lines
KW  - cosmology: theory
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-2966.2010.18123.x
SN  - 0035-8711
VL  - 413
IS  - 1
SP  - 190
EP  - 212
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Tepper-Garcia, Thorsten
A1  - Richter, Philipp
A1  - Schaye, Joop
A1  - Booth, C. M.
A1  - Dalla Vecchia, Claudio
A1  - Theuns, Tom
T1  - Absorption signatures of warm-hot gas at low redshift: broad H?i Lya absorbers
JF  - Monthly notices of the Royal Astronomical Society
N2  - We investigate the physical state of H?i absorbing gas at low redshift (z = 0.25) using a subset of cosmological, hydrodynamic simulations from the OverWhelmingly Large Simulations project, focusing in particular on broad (bHI=40 km s-1) H?i Lya absorbers (BLAs), which are believed to originate in shock-heated gas in the warm-hot intergalactic medium (WHIM). Our fiducial model, which includes radiative cooling by heavy elements and feedback by supernovae and active galactic nuclei, predicts that by z = 0.25 nearly 60?per cent of the gas mass ends up at densities and temperatures characteristic of the WHIM and we find that half of this fraction is due to outflows. The standard H?i observables (distribution of H?i column densities NH?I, distribution of Doppler parameters bHI, bHINH?I correlation) and the BLA line number density predicted by our simulations are in remarkably good agreement with observations. BLAs arise in gas that is hotter, more highly ionized and more enriched than the gas giving rise to typical Lya forest absorbers. The majority of the BLAs arise in warm-hot [log?(T/?K) similar to 5] gas at low (log?? < 1.5) overdensities. On average, thermal broadening accounts for at least 60?per cent of the BLA linewidth, which in turn can be used as a rough indicator of the thermal state of the gas. Detectable BLAs account for only a small fraction of the true baryon content of the WHIM at low redshift. In order to detect the bulk of the mass in this gas phase, a sensitivity at least one order of magnitude better than achieved by current ultraviolet spectrographs is required. We argue that BLAs mostly trace gas that has been shock heated and enriched by outflows and that they therefore provide an important window on a poorly understood feedback process.
KW  - methods: numerical
KW  - galaxies: formation
KW  - intergalactic medium
KW  - quasars: absorption lines
KW  - cosmology: theory
Y1  - 2012
U6  - https://doi.org/10.1111/j.1365-2966.2012.21545.x
SN  - 0035-8711
VL  - 425
IS  - 3
SP  - 1640
EP  - 1663
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Turner, Monica L.
A1  - Schaye, Joop
A1  - Crain, Robert A.
A1  - Theuns, Tom
A1  - Wendt, Martin
T1  - Observations of metals in the z approximate to 3.5 intergalactic medium and comparison to the EAGLE simulations
JF  - Monthly notices of the Royal Astronomical Society
N2  - We study the z approximate to 3.5 intergalactic medium (IGM) by comparing new, high-quality absorption spectra of eight QSOs with < z(QSO)> = 3.75, to virtual observations of the Evolution and Assembly of Galaxies and their Environments (EAGLE) cosmological hydrodynamical simulations. We employ the pixel optical depth method and uncover strong correlations between various combinations of H I, C III, C IV, Si III, Si IV, and O VI. We find good agreement between many of the simulated and observed correlations, including tau(O) (VI) (tau(H) (I)). However, the observed median optical depths for the tau(C) (IV) (tau(H) (I)) and tau(Si) (IV) (tau(H) (I)) relations are higher than those measured from the mock spectra. The discrepancy increases from up to approximate to 0.1 dex at tau(H) (I) = 1 to approximate to 1 dex at tau(H) (I) = 10(2), where we are likely probing dense regions at small galactocentric distances. As possible solutions, we invoke (a) models of ionizing radiation softened above 4 Ryd to account for delayed completion of He II reionization; (b) simulations run at higher resolution; (c) the inclusion of additional line broadening due to unresolved turbulence; and (d) increased elemental abundances; however, none of these factors can fully explain the observed differences. Enhanced photoionization of H I by local sources, which was not modelled, could offer a solution. However, the much better agreement with the observed O VI(H I) relation, which we find probes a hot and likely collisionally ionized gas phase, indicates that the simulations are not in tension with the hot phase of the IGM, and suggests that the simulated outflows may entrain insufficient cool gas.
KW  - galaxies: formation
KW  - intergalactic medium
KW  - quasars: absorption lines
Y1  - 2016
U6  - https://doi.org/10.1093/mnras/stw1816
SN  - 0035-8711
SN  - 1365-2966
VL  - 462
SP  - 2440
EP  - 2464
PB  - Oxford Univ. Press
CY  - Oxford
ER  -