TY - JOUR A1 - Zaritsky, Dennis A1 - Courtois, Helene A1 - Munoz-Mateos, Juan-Carlos A1 - Sorce, Jenny A1 - Erroz-Ferrer, S. A1 - Comeron, S. A1 - Gadotti, D. A. A1 - Gil De Paz, A. A1 - Hinz, J. L. A1 - Laurikainen, E. A1 - Kim, T. A1 - Laine, J. A1 - Menendez-Delmestre, K. A1 - Mizusawa, T. A1 - Regan, M. W. A1 - Salo, H. A1 - Seibert, M. A1 - Sheth, K. A1 - Athanassoula, E. A1 - Bosma, A. A1 - Cisternas, M. A1 - Ho, Luis C. A1 - Holwerda, B. T1 - The baryonic Tully-Fisher relationship for S(4)G galaxies and the "condensed" baryon fraction of galaxies JF - The astronomical journal N2 - 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. KW - galaxies: evolution KW - galaxies: formation KW - galaxies: fundamental parameters KW - galaxies: stellar content KW - galaxies: structure Y1 - 2014 U6 - https://doi.org/10.1088/0004-6256/147/6/134 SN - 0004-6256 SN - 1538-3881 VL - 147 IS - 6 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Bouche, Nicolas A1 - Finley, H. A1 - Schroetter, I. A1 - Murphy, M. T. A1 - Richter, Philipp A1 - Bacon, Roland A1 - Contini, Thierry A1 - Richard, J. A1 - Wendt, Martin A1 - Kamann, S. A1 - Epinat, Benoit A1 - Cantalupo, Sebastiano A1 - Straka, Lorrie A. A1 - Schaye, Joop A1 - Martin, C. L. A1 - Peroux, C. A1 - Wisotzki, Lutz A1 - Soto, K. A1 - Lilly, S. A1 - Carollo, C. M. A1 - Brinchmann, Jarle A1 - Kollatschny, W. T1 - POSSIBLE SIGNATURES OF A COLD-FLOW DISK FROM MUSE USING A z similar to 1 GALAXY-QUASAR PAIR TOWARD SDSS J1422-0001 JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - 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. KW - galaxies: evolution KW - galaxies: formation KW - intergalactic medium KW - quasars: individual (SDSS J142253.31-000149) Y1 - 2016 U6 - https://doi.org/10.3847/0004-637X/820/2/121 SN - 0004-637X SN - 1538-4357 VL - 820 SP - 1872 EP - 1882 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Wisotzki, Lutz A1 - Bacon, Roland A1 - Blaizot, J. A1 - Brinchmann, Jarle A1 - Herenz, Edmund Christian A1 - Schaye, Joop A1 - Bouche, Nicolas A1 - Cantalupo, Sebastiano A1 - Contini, Thierry A1 - Carollo, C. M. A1 - Caruana, Joseph A1 - Courbot, J. -B. A1 - Emsellem, E. A1 - Kamann, S. A1 - Kerutt, Josephine Victoria A1 - Leclercq, F. A1 - Lilly, S. J. A1 - Patricio, V. A1 - Sandin, C. A1 - Steinmetz, Matthias A1 - Straka, Lorrie A. A1 - Urrutia, Tanya A1 - Verhamme, A. A1 - Weilbacher, Peter Michael A1 - Wendt, Martin T1 - Extended Lyman alpha haloes around individual high-redshift galaxies revealed by MUSE JF - Science N2 - 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. KW - galaxies: high-redshift KW - galaxies: evolution KW - galaxies: formation KW - cosmology: observations KW - intergalactic medium Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201527384 SN - 1432-0746 VL - 587 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Schroetter, I. A1 - Bouche, Nicolas A1 - Wendt, Martin A1 - Contini, Thierry A1 - Finley, H. A1 - Pello, R. A1 - Bacon, Roland A1 - Cantalupo, Sebastiano A1 - Marino, Raffaella Anna A1 - Richard, J. A1 - Lilly, S. J. A1 - Schaye, Joop A1 - Soto, K. A1 - Steinmetz, Matthias A1 - Straka, Lorrie A. A1 - Wisotzki, Lutz T1 - MUSE GAS FLOW AND WIND (MEGAFLOW). I. FIRST MUSE RESULTS ON BACKGROUND QUASARS JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - 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. KW - galaxies: evolution KW - galaxies: formation KW - intergalactic medium KW - quasars: individual (SDSS J213748+001220, SDSS J215200+062516) Y1 - 2016 U6 - https://doi.org/10.3847/1538-4357/833/1/39 SN - 0004-637X SN - 1538-4357 VL - 833 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Hani, Maan H. A1 - Sparre, Martin A1 - Ellison, Sara L. A1 - Torrey, Paul A1 - Vogelsberger, Mark T1 - Galaxy mergers moulding the circum-galactic medium BT - I. The impact of a major merger JF - Monthly notices of the Royal Astronomical Society N2 - 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. KW - methods: numerical KW - galaxies: evolution KW - galaxies: haloes KW - galaxies: interactions Y1 - 2017 U6 - https://doi.org/10.1093/mnras/stx3252 SN - 0035-8711 SN - 1365-2966 VL - 475 IS - 1 SP - 1160 EP - 1176 PB - Oxford Univ. Press CY - Oxford ER - TY - THES A1 - Bekeraitė, Simona T1 - Distribution functions of rotating galaxies T1 - Verteilungsfunktionen rotierender Galaxien BT - an Integral Field Spectroscopy perspective BT - eine Perspektive der Integrale-Feld-Spektroskopie N2 - The work done during the PhD studies has been focused on measurements of distribution functions of rotating galaxies using integral field spectroscopy observations. Throughout the main body of research presented here we have been using CALIFA (Calar Alto Legacy Integral Field Area) survey stellar velocity fields to obtain robust measurements of circular velocities for rotating galaxies of all morphological types. A crucial part of the work was enabled by well-defined CALIFA sample selection criteria: it enabled reconstructing sample-independent distributions of galaxy properties. In Chapter 2, we measure the distribution in absolute magnitude - circular velocity space for a well-defined sample of 199 rotating CALIFA galaxies using their stellar kinematics. Our aim in this analysis is to avoid subjective selection criteria and to take volume and large-scale structure factors into account. Using stellar velocity fields instead of gas emission line kinematics allows including rapidly rotating early type galaxies. Our initial sample contains 277 galaxies with available stellar velocity fields and growth curve r-band photometry. After rejecting 51 velocity fields that could not be modelled due to the low number of bins, foreground contamination or significant interaction we perform Markov Chain Monte Carlo (MCMC) modelling of the velocity fields, obtaining the rotation curve and kinematic parameters and their realistic uncertainties. We perform an extinction correction and calculate the circular velocity v_circ accounting for pressure support a given galaxy has. The resulting galaxy distribution on the M_r - v_circ plane is then modelled as a mixture of two distinct populations, allowing robust and reproducible rejection of outliers, a significant fraction of which are slow rotators. The selection effects are understood well enough that the incompleteness of the sample can be corrected and the 199 galaxies can be weighted by volume and large-scale structure factors enabling us to fit a volume-corrected Tully-Fisher relation (TFR). More importantly, we also provide the volume-corrected distribution of galaxies in the M_r - v_circ plane, which can be compared with cosmological simulations. The joint distribution of the luminosity and circular velocity space densities, representative over the range of -20 > M_r > -22 mag, can place more stringent constraints on the galaxy formation and evolution scenarios than linear TFR fit parameters or the luminosity function alone. In Chapter 3, we measure one of the marginal distributions of the M_r - v_circ distribution: the circular velocity function of rotating galaxies. The velocity function is a fundamental observable statistic of the galaxy population, being of a similar importance as the luminosity function, but much more difficult to measure. We present the first directly measured circular velocity function that is representative between 60 < v_circ < 320 km s^-1 for galaxies of all morphological types at a given rotation velocity. For the low mass galaxy population 60 < v_circ < 170 km s^-1, we use the HIPASS velocity function. For the massive galaxy population 170 < v_circ < 320 km s^-1, we use stellar circular velocities from CALIFA. The CALIFA velocity function includes homogeneous velocity measurements of both late and early-type rotation-supported galaxies. It has the crucial advantage of not missing gas-poor massive ellipticals that HI surveys are blind to. We show that both velocity functions can be combined in a seamless manner, as their ranges of validity overlap. The resulting observed velocity function is compared to velocity functions derived from cosmological simulations of the z = 0 galaxy population. We find that dark matter-only simulations show a strong mismatch with the observed VF. Hydrodynamic Illustris simulations fare better, but still do not fully reproduce observations. In Chapter 4, we present some other work done during the PhD studies, namely, a method that improves the precision of specific angular measurements by combining simultaneous Markov Chain Monte Carlo modelling of ionised gas 2D velocity fields and HI linewidths. To test the method we use a sample of 25 galaxies from the Sydney-AAO Multi-object Integral field (SAMI) survey that had matching ALFALFA HI linewidths. Such a method allows constraining the rotation curve both in the inner regions of a galaxy and in its outskirts, leading to increased precision of specific angular momentum measurements. It could be used to further constrain the observed relation between galaxy mass, specific angular momentum and morphology (Obreschkow & Glazebrook 2014). Mathematical and computational methods are presented in the appendices. N2 - Die Arbeit, die während dises Promotionsstudiums durchgeführt wurde, konzentrierte sich auf die Messungen von Verteilungsfunktionen rotierender Galaxien, unter Verwendung von integralen Feldspektroskopiebeobachtungen. Im Rahmen der hier vorgestellten Hauptforschung haben wir CALIFA (Calar Alto Legacy Integral Field Area) mit stellaren Geschwindigkeitsfeldern verwendet, um robuste Messungen von Kreisförmigen Geschwindigkeiten für rotierende Galaxien aller Morphologien zu erhalten. Der entscheidende Teil dieser Arbeit wurde durch wohl definierte CALIFA-Probenselektionskriterien ermöglicht: Es ermöglichte die Rekonstruktion von probenunabhängigen Verteilungen von Galaxieneigenschaften. In Kapitel 2 messen wir die Verteilung in absoluten Magnituden für eine wohldefinierte Stichprobe von 199 rotierenden CALIFA-Galaxien unter Berücksichtigung ihrer stellaren Kinematik. Die Selektionseffekte sind verstanden genug damit die Unvollständigkeit der Probe korrigiert werden kann und uns ermöglichen eine volumenkorrigierte Tully-Fisher-Relation (TFR) anzupassen. Noch wichtiger ist es, dass wir auch die volumenkorrigierte Verteilung von Galaxien in der Mr -vcirc Ebene bereitstellen, die mit kosmologischen Simulationen verglichen werden können. In Kapitel 3 messen wir die Kreisgeschwindigkeitsfunktion der rotierenden Galaxien. Die Geschwindigkeitsfunktion ist eine fundamentale, beobachtbare Messgröße der Galaxienpopulationen, welche von ähnlicher Bedeutung ist wie die Helligkeitsfunktion, aber viel schwerer zu messen ist. Wir präsentieren die erste direkt gemessene Kreisgeschwindigkeitsfunktion, die bei einer gegebenen Rotationsgeschwindigkeit zwischen 60 < vcirc < 320 km s ^-1 für Galaxien aller morphologischen Typen repräsentativ ist. Für die Galaxienpopulation mit niedrigen Massen verwenden wir die HIPASSGeschwindigkeitsfunktion. Für die massiven Galaxienpopulationen verwenden wir stellare Kreisgeschwindigkeiten von CALIFA. Die CALIFA-Geschwindigkeitsfunktion umfasst homogene Geschwindigkeitsmessungen sowohl der späten als auch der frühen Rotations-gestützten Galaxien. Wir zeigen, dass beide Geschwindigkeitsfunktionen nahtlos kombiniert werden können, da sich ihre Gültigkeitsbereiche überschneiden. Die resultierende beobachtete Geschwindigkeitsfunktion wird mit Geschwindigkeitsfunktionen verglichen, die von kosmologischen Simulationen bei lokale Galaxien abgeleitet sind. Wir finden, dass dunkle Materie-Simulationen und hydrodynamische Illustris Simulationen reproduzieren immer noch nicht vollständig die Beobachtungen. In Kapitel 4 stellen wir einige andere Arbeiten vor, die während der Promotion durchgeführt wurden. Mathematische und rechnerische Methoden werden in den Anhängen dargestellt. KW - galaxies: kinematics and dynamics KW - Galaxien: Kinematik und Dynamik KW - galaxies: statistics KW - galaxies: evolution KW - Galaxien: Statistiken KW - Galaxien: Evolution Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-420950 ER - TY - JOUR A1 - Finley, Hayley A1 - Bouche, Nicolas A1 - Contini, Thierry A1 - Epinat, Benoit A1 - Bacon, Roland A1 - Brinchmann, Jarle A1 - Cantalupo, Sebastiano A1 - Erroz-Ferrer, Santiago A1 - Marino, Aella Anna A1 - Maseda, Michael A1 - Richard, Johan A1 - Schroetter, Ilane A1 - Verhamme, Anne A1 - Weilbacher, Peter Michael A1 - Wendt, Martin A1 - Wisotzki, Lutz T1 - Galactic winds with MUSE: A direct detection of Fe II* emission from a z=1.29 galaxy JF - Astronomy and astrophysics : an international weekly journal N2 - 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. KW - galaxies: evolution KW - galaxies: formation KW - galaxies: starburst KW - galaxies: ISM KW - ISM: jets and outflows KW - ultraviolet: ISM Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201730428 SN - 1432-0746 VL - 605 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Bustamante, Sebastian A1 - Sparre, Martin A1 - Springel, Volker A1 - Grand, Robert J. J. T1 - Merger-induced metallicity dilution in cosmological galaxy formation simulations JF - Monthly notices of the Royal Astronomical Society N2 - 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. KW - methods: numerical KW - galaxies: interactions KW - galaxies: star formation KW - galaxies: evolution Y1 - 2018 U6 - https://doi.org/10.1093/mnras/sty1692 SN - 0035-8711 SN - 1365-2966 VL - 479 IS - 3 SP - 3381 EP - 3392 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Davidzon, Iary A1 - Ilbert, Olivier A1 - Faisst, Andreas L. A1 - Sparre, Martin A1 - Capak, Peter L. T1 - An Alternate Approach to Measure Specific Star Formation Rates at 2 < z < 7 JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - 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. KW - galaxies: evolution KW - galaxies: high-redshift KW - galaxies: star formation Y1 - 2018 U6 - https://doi.org/10.3847/1538-4357/aaa19e SN - 0004-637X SN - 1538-4357 VL - 852 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Paalvast, M. A1 - Verhamme, A. A1 - Straka, L. A. A1 - Brinchmann, J. A1 - Herenz, Edmund Christian A1 - Carton, D. A1 - Gunawardhana, M. L. P. A1 - Boogaard, L. A. A1 - Cantalupo, S. A1 - Contini, T. A1 - Epinat, Benoit A1 - Inami, H. A1 - Marino, R. A. A1 - Maseda, M. V. A1 - Michel-Dansac, L. A1 - Muzahid, S. A1 - Nanayakkara, T. A1 - Pezzulli, Gabriele A1 - Richard, J. A1 - Schaye, Joop A1 - Segers, M. C. A1 - Urrutia, Tanya A1 - Wendt, Martin A1 - Wisotzki, Lutz T1 - Properties and redshift evolution of star-forming galaxies with high [0 III]/[O II] ratios with MUSE at 0.28 < z < 0.85 JF - Astronomy and astrophysics : an international weekly journal N2 - 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. KW - galaxies: evolution KW - galaxies: ISM KW - galaxies: abundances KW - ISM: structure KW - ISM: kinematics and dynamics KW - dark ages, reionization, first stars Y1 - 2018 U6 - https://doi.org/10.1051/0004-6361/201832866 SN - 0004-6361 SN - 1432-0746 VL - 618 PB - EDP Sciences CY - Les Ulis ER -