44 research outputs found
The MUSE-Wide Survey: A first catalogue of 831 emission line galaxies
We present a first instalment of the MUSE-Wide survey, covering an area of
22.2 arcmin (corresponding to 20% of the final survey) in the
CANDELS/Deep area of the Chandra Deep Field South. We use the MUSE integral
field spectrograph at the ESO VLT to conduct a full-area spectroscopic mapping
at a depth of 1h exposure time per 1 arcmin pointing. We searched for
compact emission line objects using our newly developed LSDCat software based
on a 3-D matched filtering approach, followed by interactive classification and
redshift measurement of the sources. Our catalogue contains 831 distinct
emission line galaxies with redshifts ranging from 0.04 to 6. Roughly one third
(237) of the emission line sources are Lyman emitting galaxies with , only four of which had previously measured spectroscopic redshifts.
At lower redshifts 351 galaxies are detected primarily by their [OII] emission
line (), 189 by their [OIII] line (), and 46 by their H line (). Comparing our spectroscopic redshifts to photometric redshift estimates
from the literature, we find excellent agreement for with a median
of only and an outlier rate of 6%, however a
significant systematic offset of and an outlier rate of 23%
for Ly emitters at . Together with the catalogue we also release
1D PSF-weighted extracted spectra and small 3D datacubes centred on each of the
831 sources.Comment: 24 pages, 14 figures, accepted for publication in A&A, data products
are available for download from http://muse-vlt.eu/science/muse-wide-survey/
and later via the CD
The MUSE-Wide Survey: Survey Description and First Data Release
We present the MUSE-Wide survey, a blind, 3D spectroscopic survey in the
CANDELS/GOODS-S and CANDELS/COSMOS regions. Each MUSE-Wide pointing has a depth
of 1 hour and hence targets more extreme and more luminous objects over 10
times the area of the MUSE-Deep fields (Bacon et al. 2017). The legacy value of
MUSE-Wide lies in providing "spectroscopy of everything" without photometric
pre-selection. We describe the data reduction, post-processing and PSF
characterization of the first 44 CANDELS/GOODS-S MUSE-Wide pointings released
with this publication. Using a 3D matched filtering approach we detected 1,602
emission line sources, including 479 Lyman- (Lya) emitting galaxies
with redshifts . We cross-match the emission line
sources to existing photometric catalogs, finding almost complete agreement in
redshifts and stellar masses for our low redshift (z < 1.5) emitters. At high
redshift, we only find ~55% matches to photometric catalogs. We encounter a
higher outlier rate and a systematic offset of z0.2 when
comparing our MUSE redshifts with photometric redshifts. Cross-matching the
emission line sources with X-ray catalogs from the Chandra Deep Field South, we
find 127 matches, including 10 objects with no prior spectroscopic
identification. Stacking X-ray images centered on our Lya emitters yielded no
signal; the Lya population is not dominated by even low luminosity AGN. A total
of 9,205 photometrically selected objects from the CANDELS survey lie in the
MUSE-Wide footprint, which we provide optimally extracted 1D spectra of. We are
able to determine the spectroscopic redshift of 98% of 772 photometrically
selected galaxies brighter than 24th F775W magnitude. All the data in the first
data release - datacubes, catalogs, extracted spectra, maps - are available on
the website https://musewide.aip.de. [abridged]Comment: 25 pages 15+1 figures. Accepted, A&A. Comments welcom
The MUSE-Wide survey: Three-dimensional clustering analysis of Lyman- emitters at
We present an analysis of the spatial clustering of 695 Ly-emitting
galaxies (LAE) in the MUSE-Wide survey. All objects have spectroscopically
confirmed redshifts in the range . We employ the K-estimator of
Adelberger et al. (2005), adapted and optimized for our sample. We also explore
the standard two-point correlation function approach, which is however less
suited for a pencil-beam survey such as ours. The results from both approaches
are consistent. We parametrize the clustering properties by, (i) modelling the
clustering signal with a power law (PL), and (ii) adopting a Halo Occupation
Distribution (HOD) model. Applying HOD modeling, we infer a large-scale bias of
at a median redshift of the number of
galaxy pairs , while the PL analysis
results in
(Mpc and ). The
implied typical dark matter halo (DMH) mass is
. We study
possible dependencies of the clustering signal on object properties by
bisecting the sample into disjoint subsets, considering Ly luminosity,
UV absolute magnitude, Ly equivalent width, and redshift as variables.
We find a suggestive trend of more luminous Ly emitters residing in
more massive DMHs than their lower Ly luminosity counterparts. We also
compare our results to mock LAE catalogs based on a semi-analytic model of
galaxy formation and find a stronger clustering signal than in our observed
sample. By adopting a galaxy-conserving model we estimate that the LAEs in the
MUSE-Wide survey will typically evolve into galaxies hosted by halos of
at redshift zero,
suggesting that we observe the ancestors of present-day galaxy groups.Comment: Accepted for publication in A&A. 22 pages, 20 figures, 4 table
Equivalent widths of Lyman emitters in MUSE-Wide and MUSE-Deep
The aim of this study is to better understand the connection between the
Lyman rest-frame equivalent width (EW) and spectral properties as
well as ultraviolet (UV) continuum morphology by obtaining reliable EW
histograms for a statistical sample of galaxies and by assessing the fraction
of objects with large equivalent widths. We used integral field spectroscopy
from MUSE combined with broad-band data from the Hubble Space Telescope (HST)
to measure EW. We analysed the emission lines of Lyman
emitters (LAEs) detected in the full MUSE-Wide (one hour exposure time) and
MUSE-Deep (ten hour exposure time) surveys and found UV continuum counterparts
in archival HST data. We fitted the UV continuum photometric images using the
Galfit software to gain morphological information on the rest-UV emission and
fitted the spectra obtained from MUSE to determine the double peak fraction,
asymmetry, full-width at half maximum, and flux of the Lyman line. The
two surveys show different histograms of Lyman EW. In MUSE-Wide,
of objects have EW \r{A}, while this fraction is only
in MUSE-Deep and for the full sample. This includes objects
without HST continuum counterparts (one-third of our sample), for which we give
lower limits for EW. The object with the highest securely measured EW
has EW \r{A} (the highest lower limit being EW \r{A}).
We investigate the connection between EW and Lyman spectral or UV
continuum morphological properties. The survey depth has to be taken into
account when studying EW distributions. We find that in general, high
EW objects can have a wide range of spectral and UV morphological
properties, which might reflect that the underlying causes for high EW
values are equally varied. (abridged)Comment: 28 pages, 21 + 1 figures, 7 + 1 tables, accepted for publication in
A&
Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at 1.5 < z < 6.4
Rest-frame ultraviolet (UV) emission lines probe electron densities, gas-phase abundances, metallicities, and ionization parameters of the emitting star-forming galaxies and their environments. The strongest main UV emission line, Lyα, has been instrumental in advancing the general knowledge of galaxy formation in the early universe. However, observing Lyα emission becomes increasingly challenging at zââłâ6 when the neutral hydrogen fraction of the circumgalactic and intergalactic media increases. Secondary weaker UV emission lines provide important alternative methods for studying galaxy properties at high redshift. We present a large sample of rest-frame UV emission line sources at intermediate redshift for calibrating and exploring the connection between secondary UV lines and the emitting galaxiesâ physical properties and their Lyα emission. The sample of 2052 emission line sources with 1.5â<âzâ<â6.4 was collected from integral field data from the MUSE-Wide and MUSE-Deep surveys taken as part of Guaranteed Time Observations. The objects were selected through untargeted source detection (i.e., no preselection of sources as in dedicated spectroscopic campaigns) in the three-dimensional MUSE data cubes. We searched optimally extracted one-dimensional spectra of the full sample for UV emission features via emission line template matching, resulting in a sample of more than 100 rest-frame UV emission line detections. We show that the detection efficiency of (non-Lyα) UV emission lines increases with survey depth, and that the emission line strength of HeâŻIIλ1640 Ă
, [OâŻIII] λ1661 + OâŻIII] λ1666, and [SiâŻIII] λ1883 + SiâŻIII] λ1892 correlate with the strength of [CâŻIII] λ1907 + CâŻIII] λ1909. The rest-frame equivalent width (EW0) of [CâŻIII] λ1907 + CâŻIII] λ1909 is found to be roughly 0.22 ± 0.18 of EW0(Lyα). We measured the velocity offsets of resonant emission lines with respect to systemic tracers. For CâŻIVλ1548 + CâŻIVλ1551 we find that ÎvCâŻIV âČ 250 km sâ1, whereas ÎvLyα falls in the range of 250â500 km sâ1 which is in agreement with previous results from the literature. The electron density ne measured from [SiâŻIII] λ1883 + SiâŻIII] λ1892 and [CâŻIII] λ1907 + CâŻIII] λ1909 line flux ratios is generally < 105 cmâ3 and the gas-phase abundance is below solar at 12â
+â
log10(O/H)â8. Lastly, we used âPhotoIonization Model Probability Density Functionsâ to infer physical parameters of the full sample and individual systems based on photoionization model parameter grids and observational constraints from our UV emission line searches. This reveals that the UV line emitters generally have ionization parameter log10(U)ââââ2.5 and metal mass fractions that scatter around Zâââ10â2, that is Zâââ0.66âZâ. Value-added catalogs of the full sample of MUSE objects studied in this work and a collection of UV line emitters from the literature are provided with this paper
Where Cosmic Dawn Breaks First: Mapping the Primordial Overdensity Powering a z 9 Ionized Bubble
Where Cosmic Dawn Breaks First: Mapping the Primordial Overdensity Powering a z 9 Ionized Bubble
Models of cosmic reionization predict that the earliest star-forming systems develop in primordial overdensities which, in turn, create ionized bubbles. With time, these bubbles grow and coalesce until the intergalactic medium is fully ionized. Since Lyman-alpha photons originating in these protoclusters can propagate freely through ionized gas, the highest redshift Lyman Alpha emitters (LAEs) act as valuable tracers of early ionized bubbles. We present evidence that the highest redshift LAE, EGSz8p7 (z=8.68), is likely embedded in such an overdensity. Collectively, in all of HST's deep fields, blank fields and gravitationally-lensed fields spanning >1000 arcmin^2 there are ~30 photometric candidates at z~9, yet a third lie within 3.75' (10 cMpc) of EGSz8p7. To confirm and exploit this extraordinary early overdensity we seek systemic redshifts and diagnostic features only JWST can provide. We propose blind, grism spectroscopy to map the ionized bubble around EGSz8p7 using the [OIII] doublet. A blind survey is optimal for determining a complete census of EGSz8p7's physical neighbors. Spitzer/IRAC color excesses at z>8 imply extreme [OIII] EWs (~6000 A) ensuring efficient use of JWST. Stellar population modeling of the sources around EGSz8p7 may give us the strongest constraints yet on when star-formation first commenced after the Big Bang (i.e., cosmic dawn). Our spectra will likewise constrain the ionizing photon production efficiency, a key unknown in reionization calculations. Our observing strategy is designed for maximum legacy value with a footprint overlapping the CEERS ERS survey and use of the wide F444W grism that will guarantee additional
The MUSE-Wide survey: a measurement of the Ly α emitting fraction among z > 3 galaxies
Large scale structure and cosmolog