The processing of raw data from modern astronomical instruments is often carried out nowadays using dedicated software, known as pipelines, largely run in automated operation. In this paper we ...describe the data reduction pipeline of the Multi Unit Spectroscopic Explorer (MUSE) integral field spectrograph operated at the ESO Paranal Observatory. This spectrograph is a complex machine: it records data of 1152 separate spatial elements on detectors in its 24 integral field units. Efficiently handling such data requires sophisticated software with a high degree of automation and parallelization. We describe the algorithms of all processing steps that operate on calibrations and science data in detail, and explain how the raw science data is transformed into calibrated datacubes. We finally check the quality of selected procedures and output data products, and demonstrate that the pipeline provides datacubes ready for scientific analysis.
ABSTRACT
We present results from our on-going MusE GAs FLOw and Wind (MEGAFLOW) survey, which consists of 22 quasar lines of sight, each observed with the integral field unit MUSE and the UVES ...spectrograph at the ESO Very Large Telescopes (VLT). The goals of this survey are to study the properties of the circumgalactic medium around z ∼ 1 star-forming galaxies. The absorption-line selected survey consists of 79 strong Mg ii absorbers (with rest-frame equivalent width ≳0.3 Å) and, currently, 86 associated galaxies within 100 projected kpc of the quasar with stellar masses (M⋆) from 109 to 1011 M⊙. We find that the cool halo gas traced by Mg ii is not isotropically distributed around these galaxies from the strong bi-modal distribution in the azimuthal angle of the apparent location of the quasar with respect to the galaxy major axis. This supports a scenario in which outflows are bi-conical in nature and co-exist with a co-planar gaseous structure extending at least up to 60–80 kpc. Assuming that absorbers near the minor axis probe outflows, the current MEGAFLOW sample allowed us to select 26 galaxy–quasar pairs suitable for studying winds. From this sample, using a simple geometrical model, we find that the outflow velocity only exceeds the escape velocity when M⋆ ≲ 4 × 109 M⊙, implying the cool material is likely to fall back except in the smallest haloes. Finally, we find that the mass loading factor η, the ratio between the ejected mass rate and the star formation rate, appears to be roughly constant with respect to the galaxy mass.
Abstract
As part of our massive spectroscopic survey of 25 Galactic globular clusters with MUSE, we performed multiple epoch observations of NGC 3201 with the aim of constraining the binary fraction. ...In this cluster, we found one curious star at the main-sequence turn-off with radial velocity variations of the order of 100 km s− 1, indicating the membership to a binary system with an unseen component since no other variations appear in the spectra. Using an adapted variant of the generalized Lomb–Scargle periodogram, we could calculate the orbital parameters and found the companion to be a detached stellar-mass black hole with a minimum mass of 4.36 ± 0.41 M⊙. The result is an important constraint for binary and black hole evolution models in globular clusters as well as in the context of gravitational wave sources.
ABSTRACT
Using deep ($11.2\, \rm{h}$) VLT/MUSE data from the MEGAFLOW survey, we report the first detection of extended $\rm{Mg\, \small {II}}$ emission from a galaxy’s halo that is probed by a ...quasar sightline. The $\rm{Mg\, \small {II}}\, \lambda \lambda \, 2796, 2803$ emission around the z = 0.702 galaxy ($\log (M_*/\rm{M_\odot })=10.05_{-0.11}^{+0.15}{}$) is detected out to $\approx 25\, \hbox{kpc}$ from the central galaxy and covers $1.0\times 10^3\, \hbox{kpc}^2$ above a surface brightness of $14\times 10^{-19}\, \rm{erg}\, \rm{s}^{-1}\, \rm{cm}^{-2}\, \rm{arcsec}^{-2}{}$ ($2\, \sigma$; integrated over $1200\, \rm{km\, s}^{-1}= 19\mathring{\rm A}$ and averaged over $1.5\, \rm{arcsec}^{2}$). The $\rm{Mg\, \small {II}}$ emission around this highly inclined galaxy (i ≃ 75 deg) is strongest along the galaxy’s projected minor axis, consistent with the $\rm{Mg\, \small {II}}$ gas having been ejected from the galaxy into a bi-conical structure. The quasar sightline, which is aligned with the galaxy’s minor axis, shows strong $\rm{Mg\, \small {II}}$ absorption ($\hbox{$EW_0^{\lambda 2796}$}{}=1.8{}\, \mathring{\rm A}$) at an impact parameter of $39{}\, \hbox{kpc}$ from the galaxy. Comparing the kinematics of both the emission and the absorption − probed with VLT/UVES − to the expectation from a simple toy model of a bi-conical outflow, we find good consistency when assuming a relatively slow outflow ($v_\rm{out}=130{}\, \rm{km\, s}^{-1}$). We investigate potential origins of the extended $\rm{Mg\, \small {II}}$ emission using simple toy models. With continuum scattering models we encounter serious difficulties in explaining the luminosity of the $\rm{Mg\, \small {II}}$ halo and in reconciling density estimates from emission and absorption. Instead, we find that shocks might be a more viable source to power the extended $\rm{Mg\, \small {II}}$ (and non-resonant $\rm{O\, \small {II}}$) emission.
We use the results from the ALMA large program ASPECS, the spectroscopic survey in the Hubble Ultra Deep Field (HUDF), to constrain CO luminosity functions of galaxies and the resulting redshift ...evolution of (H2). The broad frequency range covered enables us to identify CO emission lines of different rotational transitions in the HUDF at z > 1. We find strong evidence that the CO luminosity function evolves with redshift, with the knee of the CO luminosity function decreasing in luminosity by an order of magnitude from ∼2 to the local universe. Based on Schechter fits, we estimate that our observations recover the majority (up to ∼90%, depending on the assumptions on the faint end) of the total cosmic CO luminosity at z = 1.0-3.1. After correcting for CO excitation, and adopting a Galactic CO-to-H2 conversion factor, we constrain the evolution of the cosmic molecular gas density (H2): this cosmic gas density peaks at z ∼ 1.5 and drops by a factor of to the value measured locally. The observed evolution in (H2), therefore, closely matches the evolution of the cosmic star formation rate density SFR. We verify the robustness of our result with respect to assumptions on source inclusion and/or CO excitation. As the cosmic star formation history can be expressed as the product of the star formation efficiency and the cosmic density of molecular gas, the similar evolution of (H2) and SFR leaves only little room for a significant evolution of the average star formation efficiency in galaxies since z ∼ 3 (85% of cosmic history).
Abstract
We study the physical properties of the ionized gas in local discs using the sample of 38 nearby ∼108.5–11.2 M⊙ Star-Forming Main-Sequence (SFMS) galaxies observed so far as part of the MUSE ...Atlas of Disks (MAD). Specifically, we use all strong emission lines in the MUSE wavelength range 4650–9300 Å to investigate the resolved ionized gas properties on ∼100 pc scales. This spatial resolution enables us to disentangle H ii regions from the diffuse ionized gas (DIG) in the computation of gas metallicities and star formation rates (SFRs) of star-forming regions. The gas metallicities generally decrease with radius. The metallicity of the H ii regions is on average ∼0.1 dex higher than that of the DIG, but the metallicity radial gradient in both components is similar. The mean metallicities within the inner galaxy cores correlate with the total stellar mass of the galaxies. On our < 100 pc scales, we find two correlations previously reported at kpc scales: a spatially resolved mass–metallicity relation (RMZR) and a spatially resolved SFMS (RSFMS). We find no secondary dependence of the RMZR with the SFR density. We find that both resolved relations have a local origin, as they do not depend on the total stellar mass. The observational results of this paper are consistent with the inside-out scenario for the growth of galactic disks.
Context.
Spectroscopic surveys of massive galaxy clusters reveal the properties of faint background galaxies thanks to the magnification provided by strong gravitational lensing.
Aims.
We present a ...systematic analysis of integral-field-spectroscopy observations of 12 massive clusters, conducted with the Multi Unit Spectroscopic Explorer (MUSE). All data were taken under very good seeing conditions (∼0″.6) in effective exposure times between two and 15 h per pointing, for a total of 125 h. Our observations cover a total solid angle of ∼23 arcmin
2
in the direction of clusters, many of which were previously studied by the MAssive Clusters Survey, Frontier Fields (FFs), Grism Lens-Amplified Survey from Space and Cluster Lensing And Supernova survey with
Hubble
programmes. The achieved emission line detection limit at 5
σ
for a point source varies between (0.77–1.5) × 10
−18
erg s
−1
cm
−2
at 7000 Å.
Methods.
We present our developed strategy to reduce these observational data, detect continuum sources and line emitters in the datacubes, and determine their redshifts. We constructed robust mass models for each cluster to further confirm our redshift measurements using strong-lensing constraints, and identified a total of 312 strongly lensed sources producing 939 multiple images.
Results.
The final redshift catalogues contain more than 3300 robust redshifts, of which 40% are for cluster members and ∼30% are for lensed Lyman-
α
emitters. Fourteen percent of all sources are line emitters that are not seen in the available HST images, even at the depth of the FFs (∼29 AB). We find that the magnification distribution of the lensed sources in the high-magnification regime (
μ
= 2–25) follows the theoretical expectation of
N
(
z
) ∝
μ
−2
. The quality of this dataset, number of lensed sources, and number of strong-lensing constraints enables detailed studies of the physical properties of both the lensing cluster and the background galaxies. The full data products from this work, including the datacubes, catalogues, extracted spectra, ancillary images, and mass models, are made available to the community.
We analyze the interstellar medium properties of a sample of 16 bright CO line emitting galaxies identified in the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS) Large Program. ...This CO−selected galaxy sample is complemented by two additional CO line emitters in the UDF that are identified based on their Multi-Unit Spectroscopic Explorer (MUSE) optical spectroscopic redshifts. The ASPECS CO−selected galaxies cover a larger range of star formation rates (SFRs) and stellar masses compared to literature CO emitting galaxies at z > 1 for which scaling relations have been established previously. Most of ASPECS CO-selected galaxies follow these established relations in terms of gas depletion timescales and gas fractions as a function of redshift, as well as the SFR-stellar mass relation ("galaxy main sequence"). However, we find that ∼30% of the galaxies (5 out of 16) are offset from the galaxy main sequence at their respective redshift, with ∼12% (2 out of 16) falling below this relationship. Some CO-rich galaxies exhibit low SFRs, and yet show substantial molecular gas reservoirs, yielding long gas depletion timescales. Capitalizing on the well-defined cosmic volume probed by our observations, we measure the contribution of galaxies above, below, and on the galaxy main sequence to the total cosmic molecular gas density at different lookback times. We conclude that main-sequence galaxies are the largest contributors to the molecular gas density at any redshift probed by our observations (z ∼ 1−3). The respective contribution by starburst galaxies above the main sequence decreases from z ∼ 2.5 to z ∼ 1, whereas we find tentative evidence for an increased contribution to the cosmic molecular gas density from the passive galaxies below the main sequence.
We discuss the nature and physical properties of gas-mass selected galaxies in the ALMA spectroscopic survey (ASPECS) of the Hubble Ultra Deep Field (HUDF). We capitalize on the deep optical ...integral-field spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE) HUDF Survey and multiwavelength data to uniquely associate all 16 line emitters, detected in the ALMA data without preselection, with rotational transitions of carbon monoxide (CO). We identify 10 as CO(2-1) at 1 < z < 2, 5 as CO(3-2) at 2 < z < 3, and 1 as CO(4-3) at z = 3.6. Using the MUSE data as a prior, we identify two additional CO(2-1) emitters, increasing the total sample size to 18. We infer metallicities consistent with (super-)solar for the CO-detected galaxies at z ≤ 1.5, motivating our choice of a Galactic conversion factor between CO luminosity and molecular gas mass for these galaxies. Using deep Chandra imaging of the HUDF, we determine an X-ray AGN fraction of 20% and 60% among the CO emitters at z ∼ 1.4 and z ∼ 2.6, respectively. Being a CO-flux-limited survey, ASPECS-LP detects molecular gas in galaxies on, above, and below the main sequence (MS) at z ∼ 1.4. For stellar masses ≥1010 (1010.5) , we detect about 40% (50%) of all galaxies in the HUDF at 1 < z < 2 (2 < z < 3). The combination of ALMA and MUSE integral-field spectroscopy thus enables an unprecedented view of MS galaxies during the peak of galaxy formation.
ABSTRACT
Using the MEGAFLOW survey, which consists of a combination of MUSE and UVES observations of 22 quasar fields selected to contain strong Mg ii absorbers, we measure the covering fractions of ...C iv and Mg ii as a function of impact parameter b using a novel Bayesian logistic regression method on unbinned data, appropriate for small samples. We also analyse how the C iv and Mg ii covering fractions evolve with redshift. In the MUSE data, we found 215 $z = 1{-}1.5$ O ii emitters with fluxes ${\gt}10^{-17}$ erg s−1 cm−2 and within 250 kpc of quasar sight-lines. Over this redshift path $z = 1{-}1.5$, we have 19 (32) C iv (Mg ii) absorption systems with rest-frame equivalent width (REW) $W_r\gt $ 0.05 Å associated with at least one O ii emitter. The covering fractions of $z\approx 1.2$ C iv (Mg ii) absorbers with mean $W_r\approx$ 0.7 Å (1.0 Å), exceeds 50 per cent within 23$^{+62}_{-16}$ (46$^{+{18}}_{-13}$) kpc. Together with published studies, our results suggest that the covering fraction of C iv (Mg ii) becomes larger (smaller) with time, respectively. For absorption systems that have C iv but not Mg ii, we find in 73 per cent of the cases no O ii counterpart. This may indicate that C iv comes from the intergalactic medium (IGM), i.e. beyond 250 kpc, or that it is associated with lower mass or quiescent galaxies.
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