@article{WisotzkiBaconBrinchmannetal.2018,
  author    = {Wisotzki, Lutz and Bacon, R. and Brinchmann, J. and Cantalupo, S. and Richter, Philipp and Schaye, J. and Schmidt, Kasper Borello and Urrutia, Tanya and Weilbacher, Peter Michael and Akhlaghi, M. and Bouche, N. and Contini, T. and Guiderdoni, B. and Herenz, E. C. and Inami, H. and Kerutt, Josephine Victoria and Leclercq, F. and Marino, R. A. and Maseda, M. and Monreal-Ibero, A. and Nanayakkara, T. and Richard, J. and Saust, R. and Steinmetz, Matthias and Wendt, Martin},
  title     = {Nearly all the sky is covered by Lyman-alpha emission around high-redshift galaxies},
  series = {Nature : the international weekly journal of science},
  volume    = {562},
  journal   = {Nature : the international weekly journal of science},
  number    = {7726},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {0028-0836},
  doi       = {10.1038/s41586-018-0564-6},
  pages     = {229 -- 232},
  year      = {2018},
  abstract  = {Galaxies are surrounded by large reservoirs of gas, mostly hydrogen, that are fed by inflows from the intergalactic medium and by outflows from galactic winds. Absorption-line measurements along the lines of sight to bright and rare background quasars indicate that this circumgalactic medium extends far beyond the starlight seen in galaxies, but very little is known about its spatial distribution. The Lyman-alpha transition of atomic hydrogen at a wavelength of 121.6 nanometres is an important tracer of warm (about 104 kelvin) gas in and around galaxies, especially at cosmological redshifts greater than about 1.6 at which the spectral line becomes observable from the ground. Tracing cosmic hydrogen through its Lyman-a emission has been a long-standing goal of observational astrophysics(1-3), but the extremely low surface brightness of the spatially extended emission is a formidable obstacle. A new window into circumgalactic environments was recently opened by the discovery of ubiquitous extended Lyman-alpha emission from hydrogen around high-redshift galaxies(4,5). Such measurements were previously limited to especially favourable systems(6-8) or to the use of massive statistical averaging(9,10) because of the faintness of this emission. Here we report observations of low-surface-brightness Lyman-alpha emission surrounding faint galaxies at redshifts between 3 and 6. We find that the projected sky coverage approaches 100 per cent. The corresponding rate of incidence (the mean number of Lyman-alpha emitters penetrated by any arbitrary line of sight) is well above unity and similar to the incidence rate of high-column-density absorbers frequently detected in the spectra of distant quasars(11-14). This similarity suggests that most circumgalactic atomic hydrogen at these redshifts has now been detected in emission.},
  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{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{KoesterkeHamannUrrutia2001,
  author    = {Koesterke, Lars and Hamann, Wolf-Rainer and Urrutia, Tanya},
  title     = {Line-Profile Variability in the Wolf-Rayet Stars WR 135 and WR 111},
  year      = {2001},
  abstract  = {We have obtained time-resolved observations of line-profile variations of the two Wolf-Rayet stars WR 135 and WR 111. The spectra, taken during two consecutive nights, cover a broad range from 4470 to 6590 Ang. The profile variability of the C iii emission line at 5696 Ang in WR 135 is shown in detail. The principal difficulties to constrain the velocity law from the frequency drift of discrete spectral features is discussed, emphasizing the crucial dependence on the adopted location of the line-emission region, and the possible necessity to distinguish between the motion of structures and the flow of the matter. - Full access to the observational data is provided via anonymous file transfer.},
  language  = {en}
}