Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

The MUSE Ultra Deep Field (MUDF) VIII. The cool gas distribution surrounding galaxies at redshifts z ~ 0.5-2

Edoardo Santo, Michele Fumagalli, Seok-Jun Chang, Max Gronke, Rajeshwari Dutta, Matteo Fossati, Mitchell Revalski, Marc Rafelski

Abstract

We use deep MUSE data from the MUDF survey to investigate the cool gas around galaxies at redshifts 0.5 < z < 2. We constructed two samples: one sample for a down-the-barrel analysis, probing outflows via MgII absorption against galaxy continua, and the other sample for projected galaxy pairs to examine the gas around the foreground galaxies in the transverse direction. From down-the-barrel stacked spectra, we detected blueshifted MgII absorption, indicative of outflows, in which the absorption strength increases with stellar mass and star formation rate. Lower-mass galaxies exhibit weaker absorption, but higher outflow velocities, whereas higher-mass systems retain more cool gas with slower outflows. In the transverse direction, the absorption of MgII decreases with the impact parameter, following a shallow profile. Comparing observations with radiative transfer models, we found that extrapolating an expanding halo model constrained with down-the-barrel measurements to halo scales overestimates the observed equivalent widths, likely due to the outflow geometry and the absence of the interstellar medium in the model. Our results highlight that mass, outflow geometry, and gas retention shape the cool circumgalactic medium, and that the combination of absorption and emission diagnostics provides powerful constraints on the properties of the cold halo gas.

The MUSE Ultra Deep Field (MUDF) VIII. The cool gas distribution surrounding galaxies at redshifts z ~ 0.5-2

Abstract

We use deep MUSE data from the MUDF survey to investigate the cool gas around galaxies at redshifts 0.5 < z < 2. We constructed two samples: one sample for a down-the-barrel analysis, probing outflows via MgII absorption against galaxy continua, and the other sample for projected galaxy pairs to examine the gas around the foreground galaxies in the transverse direction. From down-the-barrel stacked spectra, we detected blueshifted MgII absorption, indicative of outflows, in which the absorption strength increases with stellar mass and star formation rate. Lower-mass galaxies exhibit weaker absorption, but higher outflow velocities, whereas higher-mass systems retain more cool gas with slower outflows. In the transverse direction, the absorption of MgII decreases with the impact parameter, following a shallow profile. Comparing observations with radiative transfer models, we found that extrapolating an expanding halo model constrained with down-the-barrel measurements to halo scales overestimates the observed equivalent widths, likely due to the outflow geometry and the absence of the interstellar medium in the model. Our results highlight that mass, outflow geometry, and gas retention shape the cool circumgalactic medium, and that the combination of absorption and emission diagnostics provides powerful constraints on the properties of the cold halo gas.
Paper Structure (14 sections, 3 equations, 10 figures, 2 tables)

This paper contains 14 sections, 3 equations, 10 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Observations and sample selection
  3. The MUSE Ultra Deep Field dataset
  4. Sample selection
  5. Continuum normalization
  6. The cool gas along the line of sight to MUDF galaxies
  7. Observed MgII stacking spectra
  8. Radiative transfer modeling
  9. Spectral features and galaxy properties
  10. The cool gas in the halos of MUDF galaxies via galaxy pairs
  11. Absorption profile in galaxy halos
  12. Individual detections and EW distribution
  13. Comparison with model predictions
  14. Summary and conclusions

Figures (10)

  • Figure 1: Distribution of the continuum S/N for the MUSE spectra of the 84 galaxies included in the down-the-barrel subsample (left panel) and of the 360 galaxies used for the transverse analysis, divided into bins of impact parameter: $b \leq 40\,\rm kpc$ (P1), $40\,\rm kpc < b \leq 65\,\rm kpc$ (P2), $65\,\rm kpc < b \leq 90\,\rm kpc$ (P3), and $90\,\rm kpc < b \leq 110\,\rm kpc$ (P4; right panel).
  • Figure 2: Distributions of redshift (left), stellar mass (center), and SFR (right) of galaxies selected for the down-the-barrel analysis. As described in the text, these sources all have S/N > 5 in the spectral region surrounding Mg II. The dashed lines represent the median values of each distribution.
  • Figure 3: $M_\star-z$ diagram of the parent sample (blue dots) and the selected subsample for the down-the-barrel analysis (cyan dots). The horizontal dashed black line at log $(M_\star/{\rm M_\odot}) = 8.5$ represents the limit we adopted for building a mass-limited sample (see Sect . \ref{['sec:dtb_1']}).
  • Figure 4: Distributions of redshift (left), stellar mass (center), and SFR (right) of the f/g galaxy sample.
  • Figure 5: Stack of all MgII down-the-barrel spectra (gray data points) and best-fit simulated spectra from RT-scat, assuming the gas as a smooth medium (blue line) and as a clumpy medium (red line).
  • ...and 5 more figures