Browsing by Author "Mahler, G."

Now showing 1 - 6 of 6
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    Faint end of the z ∼ 3-7 luminosity function of Lyman-alpha emitters behind lensing clusters observed with MUSE
    (2019) de La Vieuville, G.; Bina, D.; Pello, R.; Mahler, G.; Richard, J.; Drake, A. B.; Herenz, E. C.; Bauer, F. E.; Clement, B.; Lagattuta, D.; Laporte, N.; Martinez, J.; Patricio, V.; Wisotzki, L.; Zabl, J.; Bouwens, R. J.; Contini, T.; Garel, T.; Guiderdoni, B.; Marino, R. A.; Maseda, M. V.; Matthee, J.; Schaye, J.; Soucail, G.
    Contact. This paper presents the results obtained with the Multi-Unit Spectroscopic Explorer (MUSE) at the ESOVery Large Telescope on the faint end of the Lyman-alpha luminosity function (LF) based on deep observations of four lensing clusters. The goal of our project is to set strong constraints on the relative contribution of the Lyman-alpha emitter (LAE) population to cosmic reionization.
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    Molecular gas budget of strongly magnified low-mass star-forming galaxies at cosmic noon
    (2024) Catán Valenzuela, Victoria Sofia; González López, Jorge; Solimano Gambardella, Manuel Antonio; Barrientos, Luis Felipe; Afruni, A.; Aravena, M.; Bayliss, M.; Hernández, J. A.; Ledoux, C.; Mahler, G.; Sharon, K.; Tejos, N.
    Aims. The aim of this study is to investigate the molecular gas content of strongly magnified low-mass star-forming galaxies (SFGs) around the cosmic noon period (z ∼ 2) through observations of carbon monoxide (CO) emission lines and dust continuum emission, both of which serve as tracers of molecular gas (H2). Methods. We observed 12 strongly lensed arcs with the Atacama Compact Array (ACA) to detect CO mid-J rotational transitions and dust continuum. Thanks to the strong lensing, we were able to probe the previously understudied low-mass regime. With a compiled set of observations, we recalibrated empirical relations between star formation rate density (ΣSFR) and the CO line ratios. We derived galaxy properties using spectral energy distribution fitting (SED). We also performed galaxy stacking to combine faint signals. In all cases, molecular gas masses were estimated using both tracers. Results. We detected CO emission in 3 of the 12 arcs and dust continuum emission in another 3. The obtained H2 masses indicate that most of these galaxies (M* < 1010.7 M⊙) have lower molecular gas fractions and shorter depletion times compared to expectations from established scaling relations at these redshifts. We explored several possible explanations for this gas deficit, including uncertainties in mass estimates, effects of low-metallicity environments, larger atomic gas reservoirs in low-mass systems, and the possibility that these represent low-mass analogs of main sequence starburst (MS SBs) galaxies that are undergoing sustained star formation due to gas compaction despite low overall gas fractions. Conclusions. We conclude that these mass and metallicity regimes present a molecular gas deficit. Our results suggest that this deficit is likely due to a significant amount of atomic gas, which our stacking indicates is about 91% of the total gas. However, this estimation might be an upper limit, as the possibility remains that our galaxies contain CO-dark gas.
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    MUSE observations towards the lensing cluster A2744: Intersection between the LBG and LAE populations at z ∼ 3-7
    (2020) de La Vieuville, G.; Pello, R.; Richard, J.; Mahler, G.; Leveque, L.; Bauer, F. E.; Lagattuta, D. J.; Blaizot, J.; Contini, T.; Guaita, L.; Kusakabe, H.; Laporte, N.; Martinez, J.; Maseda, M., V; Schaerer, D.; Schmidt, K. B.; Verhamme, A.
    We present a study of the intersection between the populations of star forming galaxies selected as either Lyman break galaxies (LBGs) or Lyman-alpha emitters (LAEs) in the redshift range 2.9-6.7 and within the same volume of universe sampled by the Multi-Unit Spectroscopic Explorer (MUSE) behind the Hubble Frontier Fields lensing cluster A2744. We define three samples of star-forming galaxies: LBG galaxies with an LAE counterpart (92 galaxies), LBG galaxies without an LAE counterpart (408 galaxies), and LAE galaxies without an LBG counterpart (46 galaxies). All these galaxies are intrinsically faint because of the lensing nature of the sample (M-1500 >=-20.5). The fraction of LAEs among all selected star-forming galaxies increases with redshift up to z similar to 6 and decreases for higher redshifts, in agreement with previous findings. The evolution of LAE/LBG populations with UV magnitude and Ly alpha luminosity shows that the LAE selection is able to identify intrinsically UV faint galaxies with M-1500 >=-15 that are typically missed in the deepest lensing photometric surveys. The LBG population seems to fairly represent the total population of star-forming galaxies down to M-1500 similar to-15. Galaxies with M-1500<-17 tend to have SFRLy alpha-17, including galaxies only detected by their Ly alpha emission, with a large scatter. These trends, previously observed in other samples of star-forming galaxies at high-z, are seen here for very faint M-1500 similar to-15 galaxies; that is, much fainter than in previous studies. The present results show no clear evidence for an intrinsic difference between the properties of the two populations selected as LBG and/or LAE. The observed trends could be explained by a combination of several phenomena, like the existence of different star-formation regimes, the dust content, the relative distribution and morphology of dust and stars, or the stellar populations.
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    Probing 3D structure with a large MUSE mosaic : extending the mass model of Frontier Field Abell 370
    (2019) Lagattuta, D. J.; Richard, J.; Bauer, Franz Erik; Clement, B.; Mahler, G.; Soucail, G.; Carton, D.; Kneib, J. P.; Laporte, Nicolás; Martínez, J.; Patricio, V.; Payne, A. V.; Pello, R.; Schmidt, K. B.; De La Vieuville, G.
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    Probing the faint-end luminosity function of Lyman-alpha emitters at 3 < z < 7 behind 17 MUSE lensing clusters
    (2023) Thai, T. T.; Tuan-Anh, P.; Pello, R.; Goovaerts, I.; Richard, J.; Claeyssens, A.; Mahler, G.; Lagattuta, D.; de la Vieuville, G.; Salvador-Sole, E.; Garel, T.; Bauer, F. E.; Jeanneau, A.; Clement, B.; Matthee, J.
    Context. This paper presents a study of the galaxy Lyman-alpha luminosity function (LF) using a large sample of 17 lensing clusters observed by the Multi Unit Spectroscopic Explorer (MUSE) at the ESO Very Large Telescope (VLT). The magnification resulting from strong gravitational lensing by clusters of galaxies and MUSE spectroscopic capabilities allows for blind detections of LAEs without any photometric pre-selection, reaching the faint luminosity regime. Aims. The present work aims to constrain the abundance of Lyman-alpha emitters (LAEs) and quantify their contribution to the total cosmic reionization budget. Methods. We selected 600 lensed LAEs behind these clusters in the redshift range of 2.9 < z < 6.7, covering four orders of magnitude in magnification-corrected Ly-alpha luminosity (39.0 < log(L)[erg s(-1)] < 43.0). These data were collected behind lensing clusters, indicating an increased complexity in the computation of the LF to properly account for magnification and dilution effects. We applied a non-parametric V-max method to compute the LF to carefully determine the survey volume where an individual source could have been detected. The method used in this work follows the recipes originally developed in previous works, with some improvements to better account for the effects of lensing when computing the effective volume. Results. The total co-moving volume at 2.9 < z < 6.7 in the present survey is similar to 50 10(3) Mpc(3). Our LF points in the bright end (log(L) [erg s(-1)] > 42) are consistent with those obtained from blank field observations. In the faint luminosity regime, the density of sources is well described by a steep slope, alpha similar to -2 for the global redshift range. Up to log(L) [erg s(-1)] similar to 41, the steepening of the faint end slope with redshift, suggested in earlier works, is observed, but the uncertainties are still large. A significant flattening is observed towards the faintest end, for the highest redshift bins, namely, log(L)[erg s(-1)] < 41. Conclusions. When taken at face value, the steep slope at the faint-end causes the star formation rate density (SFRD) to dramatically increase with redshift, implying that LAEs could play a major role in the process of cosmic reionization. The flattening observed towards the faint end for the highest redshift bins still requires further investigation. This turnover is similar to the one observed for the UV LF at z >= 6 in lensing clusters, with the same conclusions regarding the reliability of current results. Improving the statistical significance of the sample in this low-luminosity high-redshift regime is a difficult endeavour that may lead to potentially valuable leads in understanding the process of reionization.
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    Spatially Resolved Outflows in a Seyfert Galaxy at z = 2.39
    (2019) Fischer, Travis C.; Rigby, J. R.; Mahler, G.; Gladders, M.; Sharon, K.; Florian, M.; Kraemer, S.; Bayliss, M.; Dahle, H.; Barrientos, L. Felipe; Lopez, S.; Tejos, N.; Johnson, T.; Wuyts, E.
    We present the first spatially resolved analysis of rest-frame optical and UV imaging and spectroscopy for a lensed galaxy at z = 2.39 hosting a Seyfert active galactic nucleus (AGN). Proximity to a natural guide star has enabled observations with high signal-to-noise ratio using Very Large Telescope SINFONI + adaptive optics (AO) of rest-frame optical diagnostic emission lines, which exhibit an underlying broad component with full width at half maximum similar to 700 km s(-1) in both the Balmer and forbidden lines. Measured line ratios place the outflow robustly in the region of the ionization diagnostic diagrams associated with AGNs. This unique opportunity-combining gravitational lensing, AO guiding, redshift, and AGN activity-allows for a magnified view of two main tracers of the physical conditions and structure of the interstellar medium in a star-forming galaxy hosting a weak AGN at Cosmic Noon. By analyzing the spatial extent and morphology of the Ly alpha and dust-corrected H alpha emission, disentangling the effects of star formation and AGN ionization on each tracer, and comparing the AGN-induced mass outflow rate to the host star formation rate, we find that the AGN does not significantly impact the star formation within its host galaxy.