@article{ZaritskyCourtoisMunozMateosetal.2014, author = {Zaritsky, Dennis and Courtois, Helene and Munoz-Mateos, Juan-Carlos and Sorce, Jenny and Erroz-Ferrer, S. and Comeron, S. and Gadotti, D. A. and Gil De Paz, A. and Hinz, J. L. and Laurikainen, E. and Kim, T. and Laine, J. and Menendez-Delmestre, K. and Mizusawa, T. and Regan, M. W. and Salo, H. and Seibert, M. and Sheth, K. and Athanassoula, E. and Bosma, A. and Cisternas, M. and Ho, Luis C. and Holwerda, B.}, title = {The baryonic Tully-Fisher relationship for S(4)G galaxies and the "condensed" baryon fraction of galaxies}, series = {The astronomical journal}, volume = {147}, journal = {The astronomical journal}, number = {6}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-6256}, doi = {10.1088/0004-6256/147/6/134}, pages = {11}, year = {2014}, abstract = {We combine data from the Spitzer Survey for Stellar Structure in Galaxies, a recently calibrated empirical stellar mass estimator from Eskew et al., and an extensive database of Hi spectral line profiles to examine the baryonic Tully-Fisher (BTF) relation. We find (1) that the BTF has lower scatter than the classic Tully-Fisher (TF) relation and is better described as a linear relationship, confirming similar previous results, (2) that the inclusion of a radial scale in the BTF decreases the scatter but only modestly, as seen previously for the TF relation, and (3) that the slope of the BTF, which we find to be 3.5 +/- 0.2 (Delta log M-baryon/Delta log v(c)), implies that on average a nearly constant fraction (similar to 0.4) of all baryons expected to be in a halo are "condensed" onto the central region of rotationally supported galaxies. The condensed baryon fraction, M-baryon/M-total, is, to our measurement precision, nearly independent of galaxy circular velocity (our sample spans circular velocities, vc, between 60 and 250 km s(-1), but is extended to v(c) similar to 10 km s(-1) using data from the literature). The observed galaxy-to-galaxy scatter in this fraction is generally <= a factor of 2 despite fairly liberal selection criteria. These results imply that cooling and heating processes, such as cold versus hot accretion, mass loss due to stellar winds, and active galactic nucleus driven feedback, to the degree that they affect the global galactic properties involved in the BTF, are independent of halo mass for galaxies with 10 < v(c) < 250 km s(-1) and typically introduce no more than a factor of two range in the resulting M-baryon/M-total. Recent simulations by Aumer et al. of a small sample of disk galaxies are in excellent agreement with our data, suggesting that current simulations are capable of reproducing the global properties of individual disk galaxies. More detailed comparison to models using the BTF holds great promise, but awaits improved determinations of the stellar masses.}, language = {en} } @article{ZablBoucheSchroetteretal.2019, author = {Zabl, Johannes and Bouche, Nicolas F. and Schroetter, Ilane and Wendt, Martin and Finley, Hayley and Schaye, Joop and Conseil, Simon and Contini, Thierry and Marino, Raffaella Anna and Mitchell, Peter and Muzahid, Sowgat and Pezzulli, Gabriele and Wisotzki, Lutz}, title = {MusE GAs FLOw and Wind (MEGAFLOW)}, series = {Monthly notices of the Royal Astronomical Society}, volume = {485}, journal = {Monthly notices of the Royal Astronomical Society}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stz392}, pages = {1961 -- 1980}, year = {2019}, abstract = {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.}, language = {en} } @article{WisotzkiBaconBlaizotetal.2016, author = {Wisotzki, Lutz and Bacon, Roland and Blaizot, J. and Brinchmann, Jarle and Herenz, Edmund Christian and Schaye, Joop and Bouche, Nicolas and Cantalupo, Sebastiano and Contini, Thierry and Carollo, C. M. and Caruana, Joseph and Courbot, J. -B. and Emsellem, E. and Kamann, S. and Kerutt, Josephine Victoria and Leclercq, F. and Lilly, S. J. and Patricio, V. and Sandin, C. and Steinmetz, Matthias and Straka, Lorrie A. and Urrutia, Tanya and Verhamme, A. and Weilbacher, Peter Michael and Wendt, Martin}, title = {Extended Lyman alpha haloes around individual high-redshift galaxies revealed by MUSE}, series = {Science}, volume = {587}, journal = {Science}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201527384}, pages = {27}, year = {2016}, abstract = {We report the detection of extended Ly alpha emission around individual star-forming galaxies at redshifts z = 3-6 in an ultradeep exposure of the Hubble Deep Field South obtained with MUSE on the ESO-VLT. The data reach a limiting surface brightness (1 sigma) of similar to 1 x 10(-19) erg s(-1) cm(-2) arcsec(-2) in azimuthally averaged radial profiles, an order of magnitude improvement over previous narrowband imaging. Our sample consists of 26 spectroscopically confirmed Ly alpha-emitting, but mostly continuum-faint (m(AB) greater than or similar to 27) galaxies. In most objects the Ly alpha emission is considerably more extended than the UV continuum light. While five of the faintest galaxies in the sample show no significantly detected Ly alpha haloes, the derived upper limits suggest that this is due to insufficient S/N. Ly alpha haloes therefore appear to be ubiquitous even for low-mass (similar to 10(8)-10(9) M-circle dot) star-forming galaxies at z > 3. We decompose the Ly alpha emission of each object into a compact component tracing the UV continuum and an extended halo component, and infer sizes and luminosities of the haloes. The extended Ly alpha emission approximately follows an exponential surface brightness distribution with a scale length of a few kpc. While these haloes are thus quite modest in terms of their absolute sizes, they are larger by a factor of 5-15 than the corresponding rest-frame UV continuum sources as seen by HST. They are also much more extended, by a factor similar to 5, than Ly alpha haloes around low-redshift star-forming galaxies. Between similar to 40\% and greater than or similar to 90\% of the observed Ly alpha flux comes from the extended halo component, with no obvious correlation of this fraction with either the absolute or the relative size of the Ly alpha halo. Our observations provide direct insights into the spatial distribution of at least partly neutral gas residing in the circumgalactic medium of low to intermediate mass galaxies at z > 3.}, language = {en} } @article{WendtBoucheZabletal.2021, author = {Wendt, Martin and Bouche, Nicolas F. and Zabl, Johannes and Schroetter, Ilane and Muzahid, Sowgat}, title = {MusE GAs FLOw and Wind V. The dust/metallicity-anisotropy of the circum-galactic medium}, series = {Monthly notices of the Royal Astronomical Society}, volume = {502}, journal = {Monthly notices of the Royal Astronomical Society}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stab049}, pages = {3733 -- 3745}, year = {2021}, abstract = {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.}, language = {en} } @article{SchroetterBoucheZabletal.2019, author = {Schroetter, Ilane and Bouche, Nicolas F. and Zabl, Johannes and Contini, Thierry and Wendt, Martin and Schaye, Joop and Mitchell, Peter and Muzahid, Sowgat and Marino, Raffaella Anna and Bacon, Roland and Lilly, Simon J. and Richard, Johan and Wisotzki, Lutz}, title = {MusE GAs FLOw andWind (MEGAFLOW)}, series = {Monthly notices of the Royal Astronomical Society}, volume = {490}, journal = {Monthly notices of the Royal Astronomical Society}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stz2822}, pages = {4368 -- 4381}, year = {2019}, abstract = {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.}, language = {en} } @article{SchroetterBoucheWendtetal.2016, author = {Schroetter, I. and Bouche, Nicolas and Wendt, Martin and Contini, Thierry and Finley, H. and Pello, R. and Bacon, Roland and Cantalupo, Sebastiano and Marino, Raffaella Anna and Richard, J. and Lilly, S. J. and Schaye, Joop and Soto, K. and Steinmetz, Matthias and Straka, Lorrie A. and Wisotzki, Lutz}, title = {MUSE GAS FLOW AND WIND (MEGAFLOW). I. FIRST MUSE RESULTS ON BACKGROUND QUASARS}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {833}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/833/1/39}, pages = {17}, year = {2016}, abstract = {The physical properties of galactic winds are one of the keys to understand galaxy formation and evolution. These properties can be constrained thanks to background quasar lines of sight (LOS) passing near star-forming galaxies (SFGs). We present the first results of the MusE GAs FLOw and Wind survey obtained from two quasar fields, which have eight Mg II absorbers of which three have rest equivalent width greater than 0.8 angstrom. With the new Multi Unit Spectroscopic Explorer (MUSE) spectrograph on the Very Large Telescope (VLT), we detect six (75\%) Mg II host galaxy candidates within a radius of 30. from the quasar LOS. Out of these six galaxy-quasar pairs, from geometrical argument, one is likely probing galactic outflows, where two are classified as "ambiguous,"two are likely probing extended gaseous disks and one pair seems to be a merger. We focus on the wind-pair and constrain the outflow using a high-resolution quasar spectra from the Ultraviolet and Visual Echelle Spectrograph. Assuming the metal absorption to be due to ga;s flowing out of the detected galaxy through a cone along the minor axis, we find outflow velocities in the order of approximate to 150 km s(-1) (i.e., smaller than the escape velocity) with a loading factor, eta = M-out/SFR, of approximate to 0.7. We see evidence for an open conical flow, with a low-density inner core. In the future, MUSE will provide us with about 80 multiple galaxy-quasar pairs in two dozen fields.}, language = {en} } @article{RichterWinkelWakkeretal.2018, author = {Richter, Philipp and Winkel, Benjamin and Wakker, Bart P. and Pingel, N. M. and Fox, Andrew J. and Heald, G. and Walterbos, Rene A. M. and Fechner, C. and Ben Bekhti, N. and Gentile, G. and Zschaechner, Laura}, title = {Circumgalactic Gas at Its Extreme}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {868}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/aae838}, pages = {12}, year = {2018}, abstract = {We present a detailed analysis of the absorption properties of one of the tidal gas streams around the "Whale" galaxy NGC 4631 in the direction of the quasar 2MASS J12421031+3214268. Our study is based on ultraviolet spectral data obtained with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST) and 21cm-data from the HALOGAS project and the Green Bank Telescope (GBT). We detect strong H I Ly alpha absorption in the velocity range +550 to +800 km s(-1) related to gas from a NGC 4631 tidal stream known as Spur 2. We measure a column density of log (N(H I/cm(-2))) = 18.68 +/- 0.15, indicating that the quasar sightline traces the outer boundary of Spur 2 as seen in the 21 cm data. Metal absorption in Spur 2 is detected in the lines of O I, C II, Si II, and Si III in a complex absorption pattern that reflects the multiphase nature of the gas. We find that the average neutral gas fraction in Spur 2 toward 2MASS J12421031+3214268 is only 14\%. This implies that ionized gas dominates the total mass of Spur 2, which then may comprise more than 10(9)M(circle dot). No significant depletion of Si is observed, showing that Spur 2 does not contain significant amounts of dust. From the measured O I/H I column density ratio, we determine an alpha abundance in Spur 2 of 0.131(-0.05)(+0.07) solar ([alpha/H] = -0.90 +/- 0.16), which is substantially lower than what is observed in the NGC 4631 disk. The low metallicity and low dust content suggest that Spur 2 represents metal-deficient gas stripped off a gas-rich satellite galaxy during a recent encounter with NGC 4631.}, language = {en} } @article{PaalvastVerhammeStrakaetal.2018, author = {Paalvast, M. and Verhamme, A. and Straka, L. A. and Brinchmann, J. and Herenz, Edmund Christian and Carton, D. and Gunawardhana, M. L. P. and Boogaard, L. A. and Cantalupo, S. and Contini, T. and Epinat, Benoit and Inami, H. and Marino, R. A. and Maseda, M. V. and Michel-Dansac, L. and Muzahid, S. and Nanayakkara, T. and Pezzulli, Gabriele and Richard, J. and Schaye, Joop and Segers, M. C. and Urrutia, Tanya and Wendt, Martin and Wisotzki, Lutz}, title = {Properties and redshift evolution of star-forming galaxies with high [0 III]/[O II] ratios with MUSE at 0.28 < z < 0.85}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {618}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {0004-6361}, doi = {10.1051/0004-6361/201832866}, pages = {15}, year = {2018}, abstract = {We present a study of the [O III]/[O II] ratios of star-forming galaxies drawn from Multi-Unit Spectroscopic Explorer (MUSE) data spanning a redshift range 0.28 < z < 0.85. Recently discovered Lyman continuum (LyC) emitters have extremely high oxygen line ratios: [O III]lambda 5007/[O II]lambda lambda 3726, 3729 > 4. Here we aim to understand the properties and the occurrences of galaxies with such high line ratios. Combining data from several MUSE Guaranteed Time Observing (GTO) programmes, we select a population of star-forming galaxies with bright emission lines, from which we draw 406 galaxies for our analysis based on their position in the z-dependent star formation rate (SFR) stellar mass (M*) plane. Out of this sample 15 are identified as extreme oxygen emitters based on their [O III]/[O II] ratios (3.7\%) and 104 galaxies have [O III]/[O II] > 1 (26\%). Our analysis shows no significant correlation between M*, SFR, and the distance from the SFR M, relation with [O III]/[O II]. We find a decrease in the fraction of galaxies with [O III]/[O II] > 1 with increasing M*, however, this is most likely a result of the relationship between [O III]/[O II] and metallicity, rather than between [O III]/[O II] and M. We draw a comparison sample of local analogues with < z > 0.03 from the Sloan Digital Sky Survey, and find similar incidence rates for this sample. In order to investigate the evolution in the fraction of high [O III]/[O II] emitters with redshift, we bin the sample into three redshift subsamples of equal number, but find no evidence for a dependence on redshift. Furthermore, we compare the observed line ratios with those predicted by nebular models with no LyC escape and find that most of the extreme oxygen emitters can be reproduced by low metallicity models. The remaining galaxies are likely LyC emitter candidates.}, language = {en} } @article{HaniSparreEllisonetal.2017, author = {Hani, Maan H. and Sparre, Martin and Ellison, Sara L. and Torrey, Paul and Vogelsberger, Mark}, title = {Galaxy mergers moulding the circum-galactic medium}, series = {Monthly notices of the Royal Astronomical Society}, volume = {475}, journal = {Monthly notices of the Royal Astronomical Society}, number = {1}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stx3252}, pages = {1160 -- 1176}, year = {2017}, abstract = {Galaxies are surrounded by sizeable gas reservoirs which host a significant amount of metals: the circum-galactic medium (CGM). The CGM acts as a mediator between the galaxy and the extragalactic medium. However, our understanding of how galaxy mergers, a major evolutionary transformation, impact the CGM remains deficient. We present a theoretical study of the effect of galaxy mergers on the CGM. We use hydrodynamical cosmological zoom-in simulations of a major merger selected from the Illustris project such that the z = 0 descendant has a halo mass and stellar mass comparable to the Milky Way. To study the CGM we then re-simulated this system at a 40 times better mass resolution, and included detailed post-processing ionization modelling. Our work demonstrates the effect the merger has on the characteristic size of the CGM, its metallicity, and the predicted covering fraction of various commonly observed gas-phase species, such as H I, C IV, and O VI. We show that merger-induced outflows can increase the CGM metallicity by 0.2-0.3 dex within 0.5 Gyr post-merger. These effects last up to 6 Gyr post-merger. While the merger increases the total metal covering fractions by factors of 2-3, the covering fractions of commonly observed UV ions decrease due to the hard ionizing radiation from the active galactic nucleus, which we model explicitly. Our study of the single simulated major merger presented in this work demonstrates the significant impact that a galaxy interaction can have on the size, metallicity, and observed column densities of the CGM.}, language = {en} } @article{HaniEllisonSparreetal.2019, author = {Hani, Maan H. and Ellison, Sara L. and Sparre, Martin and Grand, Robert J. J. and Pakmor, R{\"u}diger and G{\´o}mez, Facundo A. and Springel, Volker}, title = {The diversity of the circumgalactic medium around z=0 Milky Way-mass galaxies from the Auriga simulations}, series = {Monthly notices of the Royal Astronomical Society}, volume = {488}, journal = {Monthly notices of the Royal Astronomical Society}, number = {1}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stz1708}, pages = {135 -- 152}, year = {2019}, abstract = {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.}, language = {en} } @article{GongLibeskindTempeletal.2019, author = {Gong, Chen Chris and Libeskind, Noam I. and Tempel, Elmo and Guo, Quan and Gottloeber, Stefan and Yepes, Gustavo and Wang, Peng and Sorce, Jenny and Pawlowski, Marcel}, title = {The origin of lopsided satellite galaxy distribution in galaxy pairs}, series = {Monthly notices of the Royal Astronomical Society}, volume = {488}, journal = {Monthly notices of the Royal Astronomical Society}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stz1917}, pages = {3100 -- 3108}, year = {2019}, abstract = {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.}, language = {en} } @article{FinleyBoucheContinietal.2017, author = {Finley, Hayley and Bouche, Nicolas and Contini, Thierry and Epinat, Benoit and Bacon, Roland and Brinchmann, Jarle and Cantalupo, Sebastiano and Erroz-Ferrer, Santiago and Marino, Aella Anna and Maseda, Michael and Richard, Johan and Schroetter, Ilane and Verhamme, Anne and Weilbacher, Peter Michael and Wendt, Martin and Wisotzki, Lutz}, title = {Galactic winds with MUSE: A direct detection of Fe II* emission from a z=1.29 galaxy}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {605}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201730428}, pages = {15}, year = {2017}, abstract = {Emission signatures from galactic winds provide an opportunity to directly map the outflowing gas, but this is traditionally challenging because of the low surface brightness. Using very deep observations (27 h) of the Hubble Deep Field South with the Multi Unit Spectroscopic Explorer (MUSE) instrument, we identify signatures of an outflow in both emission and absorption from a spatially resolved galaxy at z = 1.29 with a stellar mass M-star = 8 x 10(9) M-circle dot, star formation rate SFR = 77(-25)(+40) M-circle dot yr(-1), and star formation rate surface brightness Sigma(SFR) = 1.6 M-circle dot kpc(-2) within the [OII] lambda lambda 3727, 3729 half-light radius R-1/2, ([OII]) = 2.76 +/- 0.17 kpc. From a component of the strong resonant Mg II and Fe II absorptions at -350 km s(-1), we infer a mass outflow rate that is comparable to the star formation rate. We detect non-resonant Fe II* emission, at lambda 2365, lambda 2396, lambda 2612, and lambda 2626, at 1.2-2.4-1.5-2.7 x 10-(18) erg s(-1) cm(-2) respectively. The flux ratios are consistent with the expectations for optically thick gas. By combining the four non-resonant Fe II* emission lines, we spatially map the Fe II* emission from an individual galaxy for the first time. The Fe II* emission has an elliptical morphology that is roughly aligned with the galaxy minor kinematic axis, and its integrated half-light radius, R-1/2, (Fe II*) = 4.1 +/- 0.4 kpc, is 70\% larger than the stellar continuum (R-1/2,(star) similar or equal to 2.34 +/- 0.17) or the [O II] nebular line. Moreover, the Fe II* emission shows a blue wing extending up to -400 km s(-1), which is more pronounced along the galaxy minor kinematic axis and reveals a C-shaped pattern in a p - v diagram along that axis. These features are consistent with a bi-conical outflow.}, language = {en} } @article{DavidzonIlbertFaisstetal.2018, author = {Davidzon, Iary and Ilbert, Olivier and Faisst, Andreas L. and Sparre, Martin and Capak, Peter L.}, title = {An Alternate Approach to Measure Specific Star Formation Rates at 2 < z < 7}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {852}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/aaa19e}, pages = {11}, year = {2018}, abstract = {We trace the specific star formation rate (sSFR) of massive star-forming galaxies (greater than or similar to 10(10)M(circle dot)) from z similar to 2 to 7. Our method is substantially different from previous analyses, as it does not rely on direct estimates of star formation rate, but on the differential evolution of the galaxy stellar mass function (SMF). We show the reliability of this approach by means of semianalytical and hydrodynamical cosmological simulations. We then apply it to real data, using the SMFs derived in the COSMOS and CANDELS fields. We find that the sSFR is proportional to (1 + z)(1.1) (+/-) (0.2) at z > 2, in agreement with other observations but in tension with the steeper evolution predicted by simulations from z similar to 4 to 2. We investigate the impact of several sources of observational bias, which, however, cannot account for this discrepancy. Although the SMF of high-redshift galaxies is still affected by significant errors, we show that future large-area surveys will substantially reduce them, making our method an effective tool to probe the massive end of the main sequence of star-forming galaxies.}, language = {en} } @article{BustamanteSparreSpringeletal.2018, author = {Bustamante, Sebastian and Sparre, Martin and Springel, Volker and Grand, Robert J. J.}, title = {Merger-induced metallicity dilution in cosmological galaxy formation simulations}, series = {Monthly notices of the Royal Astronomical Society}, volume = {479}, journal = {Monthly notices of the Royal Astronomical Society}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/sty1692}, pages = {3381 -- 3392}, year = {2018}, abstract = {Observational studies have revealed that galaxy pairs tend to have lower gas-phase metallicity than isolated galaxies. This metallicity deficiency can be caused by inflows of low-metallicity gas due to the tidal forces and gravitational torques associated with galaxy mergers, diluting the metal content of the central region. In this work we demonstrate that such metallicity dilution occurs in state-of-the-art cosmological simulations of galaxy formation. We find that the dilution is typically 0.1 dex for major mergers, and is noticeable at projected separations smaller than 40 kpc. For minor mergers the metallicity dilution is still present, even though the amplitude is significantly smaller. Consistent with previous analysis of observed galaxies we find that mergers are outliers from the fundamental metallicity relation, with deviations being larger than expected for a Gaussian distribution of residuals. Our large sample of mergers within full cosmological simulations also makes it possible to estimate how the star formation rate enhancement and gas consumption timescale behave as a function of the merger mass ratio. We confirm that strong starbursts are likely to occur in major mergers, but they can also arise in minor mergers if more than two galaxies are participating in the interaction, a scenario that has largely been ignored in previous work based on idealised isolated merger simulations.}, language = {en} } @article{BoucheFinleySchroetteretal.2016, author = {Bouche, Nicolas and Finley, H. and Schroetter, I. and Murphy, M. T. and Richter, Philipp and Bacon, Roland and Contini, Thierry and Richard, J. and Wendt, Martin and Kamann, S. and Epinat, Benoit and Cantalupo, Sebastiano and Straka, Lorrie A. and Schaye, Joop and Martin, C. L. and Peroux, C. and Wisotzki, Lutz and Soto, K. and Lilly, S. and Carollo, C. M. and Brinchmann, Jarle and Kollatschny, W.}, title = {POSSIBLE SIGNATURES OF A COLD-FLOW DISK FROM MUSE USING A z similar to 1 GALAXY-QUASAR PAIR TOWARD SDSS J1422-0001}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {820}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/0004-637X/820/2/121}, pages = {1872 -- 1882}, year = {2016}, abstract = {We use a background quasar to detect the presence of circumgalactic gas around a z = 0.91 low-mass star-forming galaxy. Data from the new Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope show that the galaxy has a dust-corrected star formation rate (SFR) of 4.7 +/- 2.0. M-circle dot yr(-1), with no companion down to 0.22 M-circle dot yr(-1) (5 sigma) within 240 h(-1) kpc ("30"). Using a high-resolution spectrum of the background quasar, which is fortuitously aligned with the galaxy major axis (with an azimuth angle alpha of only 15 degrees), we find, in the gas kinematics traced by low-ionization lines, distinct signatures consistent with those expected for a "cold-flow disk" extending at least 12 kpc (3 x R-1/2). We estimate the mass accretion rate M-in to be at least two to three times larger than the SFR, using the geometric constraints from the IFU data and the H (I) column density of log N-H (I)/cm(-2) similar or equal to 20.4 obtained from a Hubble Space Telescope/COS near-UV spectrum. From a detailed analysis of the low-ionization lines (e.g., Zn II, Cr II, Ti II, MnII, Si II), the accreting material appears to be enriched to about 0.4 Z(circle dot) (albeit with large uncertainties: log Z/Z(circle dot) = -0.4 +/- 0.4), which is comparable to the galaxy metallicity (12 + log O/H = 8.7 +/- 0.2), implying a large recycling fraction from past outflows. Blueshifted Mg II and Fe II absorptions in the galaxy spectrum from the MUSE data reveal the presence of an outflow. The Mg II and Fe II absorption line ratios indicate emission infilling due to scattering processes, but the MUSE data do not show any signs of fluorescent Fe II* emission.}, language = {en} }