Browsing by Author "Finley, Hayley"

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    Dark Galaxy Candidates at Redshift ∼3.5 Detected with MUSE
    (London : Institute of Physics Publ., 2018) Anna Marino, Raffaella; Cantalupo, Sebastiano; Lilly, Simon J.; Gallego, Sofia G.; Straka, Lorrie A.; Borisova, Elena; Pezzulli, Gabriele; Bacon, Roland; Brinchmann, Jarle; Carollo, C. Marcella; Caruana, Joseph; Conseil, Simon; Contini, Thierry; Diener, Catrina; Finley, Hayley; Inami, Hanae; Leclercq, Floriane; Muzahid, Sowgat; Richard, Johan; Schaye, Joop; Wendt, Martin; Wisotzki, Lutz
    Recent theoretical models suggest that the early phase of galaxy formation could involve an epoch when galaxies are gas rich but inefficient at forming stars: a "dark galaxy" phase. Here, we report the results of our Multi-Unit Spectroscopic Explorer (MUSE) survey for dark galaxies fluorescently illuminated by quasars at z > 3. Compared to previous studies which are based on deep narrowband (NB) imaging, our integral field survey provides a nearly uniform sensitivity coverage over a large volume in redshift space around the quasars as well as full spectral information at each location. Thanks to these unique features, we are able to build control samples at large redshift distances from the quasars using the same data taken under the same conditions. By comparing the rest-frame equivalent width (EW0) distributions of the Lyα sources detected in proximity to the quasars and in control samples, we detect a clear correlation between the locations of high-EW0 objects and the quasars. This correlation is not seen in other properties, such as Lyα luminosities or volume overdensities, suggesting the possible fluorescent nature of at least some of these objects. Among these, we find six sources without continuum counterparts and EW0 limits larger than 240 ∗ that are the best candidates for dark galaxies in our survey at z > 3.5. The volume densities and properties, including inferred gas masses and star formation efficiencies, of these dark galaxy candidates are similar to those of previously detected candidates at z ≈2.4 in NB surveys. Moreover, if the most distant of these are fluorescently illuminated by the quasar, our results also provide a lower limit of t =60 Myr on the quasar lifetime.
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    The MUSE Hubble Ultra Deep Field Survey : XII. Mg II emission and absorption in star-forming galaxies
    (Les Ulis : EDP Sciences, 2018) Feltre, Anna; Bacon, Roland; Tresse, Laurence; Finley, Hayley; Carton, David; Blaizot, Jérémy; Bouché, Nicolas; Garel, Thibault; Inami, Hanae; Boogaard, Leindert A.; Brinchmann, Jarle; Charlot, Stéphane; Chevallard, Jacopo; Contini, Thierry; Michel-Dansac, Leo; Mahler, Guillaume; Marino, Raffaella A.; Maseda, Michael V.; Richard, Johan; Schmidt, Kasper B.; Verhamme, Anne
    The physical origin of the near-ultraviolet Mg II emission remains an underexplored domain, unlike more typical emission lines that are detected in the spectra of star-forming galaxies. We explore the nebular and physical properties of a sample of 381 galaxies between 0.70 < z < 2.34 drawn from the MUSE Hubble Ultra Deep Survey. The spectra of these galaxies show a wide variety of profiles of the Mg II λλ2796, 2803 resonant doublet, from absorption to emission. We present a study on the main drivers for the detection of Mg II emission in galaxy spectra. By exploiting photoionization models, we verified that the emission-line ratios observed in galaxies with Mg II in emission are consistent with nebular emission from HII regions. From a simultaneous analysis of MUSE spectra and ancillary Hubble Space Telescope information through spectral energy distribution fitting, we find that galaxies with Mg II in emission have lower stellar masses, smaller sizes, bluer spectral slopes, and lower optical depth than those with absorption. This leads us to suggest that Mg II emission is a potential tracer of physical conditions that are not merely related to those of the ionized gas. We show that these differences in Mg II emission and absorption can be explained in terms of a higher dust and neutral gas content in the interstellar medium (ISM) of galaxies showing Mg II in absorption, which confirms the extreme sensitivity of Mg II to the presence of the neutral ISM. We conclude with an analogy between the Mg II doublet and the Ly α line that lies in their resonant nature. Further investigations with current and future facilities, including the James Webb Space Telescope, are promising because the detection of Mg II emission and its potential connection with Lyα could provide new insights into the ISM content in the early Universe.
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    The tully-fisher relation in dense groups at z ∼ 0.7 in the MAGIC survey
    (Les Ulis : EDP Sciences, 2021) Abril-Melgarejo, Valentina; Epinat, Benoît; Mercier, Wilfried; Contini, Thierry; Boogaard, Leindert A.; Brinchmann, Jarle; Finley, Hayley; Michel-Dansac, Léo; Ventou, Emmy; Amram, Philipe; Krajnović, Davor; Mahler, Guillaume; Pineda, Juan C.B.; Richard, Johan
    Context. Galaxies in dense environments are subject to interactions and mechanisms that directly affect their evolution by lowering their gas fractions and consequently reducing their star-forming capacity earlier than their isolated counterparts. Aims. The aim of our project is to get new insights into the role of environment in the stellar and baryonic content of galaxies using a kinematic approach, through the study of the Tully-Fisher relation (TFR). Methods. We study a sample of galaxies in eight groups, over-dense by a factor larger than 25 with respect to the average projected density, spanning a redshift range of 0.5 < z < 0.8 and located in ten pointings of the MAGIC MUSE Guaranteed Time Observations program. We perform a morpho-kinematics analysis of this sample and set up a selection based on galaxy size, [O » II]λλ3727,3729 emission line doublet signal-to-noise ratio, bulge-to-disk ratio, and nuclear activity to construct a robust kinematic sample of 67 star-forming galaxies. Results. We show that this selection considerably reduces the number of outliers in the TFR, which are predominantly dispersion-dominated galaxies. Similar to other studies, we find that including the velocity dispersion in the velocity budget mainly affects galaxies with low rotation velocities, reduces the scatter in the relation, increases its slope, and decreases its zero-point. Including gas masses is more significant for low-mass galaxies due to a larger gas fraction, and thus decreases the slope and increases the zero-point of the relation. Our results suggest a significant offset of the TFR zero-point between galaxies in low- and high-density environments, regardless of the kinematics estimator used. This can be interpreted as a decrease in either stellar mass by ∼0.05 - 0.3 dex or an increase in rotation velocity by ∼0.02 - 0.06 dex for galaxies in groups, depending on the samples used for comparison. We also studied the stellar and baryon mass fractions within stellar disks and found they both increase with stellar mass, the trend being more pronounced for the stellar component alone. These fractions do not exceed 50%. We show that this evolution of the TFR is consistent either with a decrease in star formation or with a contraction of the mass distribution due to the environment. These two effects probably act together, with their relative contribution depending on the mass regime. © V. Abril-Melgarejo et al. 2021.