We carried out a detailed strong lensing analysis of a sub-sample of eight galaxy clusters of the Cluster Lensing And Supernova survey with Hubble (CLASH) in the redshift range of zcluster = 0.23 − ...0.59 using extensive spectroscopic information, primarily from the Multi Unit Spectroscopic Explorer (MUSE) archival data and complemented with CLASH-VLT redshift measurements. The observed positions of the multiple images of strongly lensed background sources were used to constrain parametric models describing the cluster total mass distributions. Different models were tested in each cluster depending on the complexity of its mass distribution and on the number of detected multiple images. Four clusters show more than five spectroscopically confirmed multiple image families. In this sample, we did not make use of families that are only photometrically identified in order to reduce model degeneracies between the values of the total mass of a cluster source redshifts, in addition to systematics due to the potential misidentifications of multiple images. For the remaining four clusters, we used additional families without any spectroscopic confirmation to increase the number of strong lensing constraints up to the number of free parameters in our parametric models. We present spectroscopic confirmation of 27 multiply lensed sources, with no previous spectroscopic measurements, spanning over the redshift range of zsrc = 0.7 − 6.1. Moreover, we confirm an average of 48 galaxy members in the core of each cluster thanks to the high efficiency and large field of view of MUSE. We used this information to derive precise strong lensing models, projected total mass distributions, and magnification maps. We show that, despite having different properties (i.e. number of mass components, total mass, redshift, etc.), the projected total mass and mass density profiles of all clusters have very similar shapes when rescaled by independent measurements of M200c and R200c. Specifically, we measured the mean value of the projected total mass of our cluster sample within 10 (20)% of R200c to be 0.13 (0.32) of M200c, with a remarkably small scatter of 5 (6)%. Furthermore, the large number of high-z sources and the precise magnification maps derived in this work for four clusters add up to the sample of high-quality gravitational telescopes to be used to study the faint and distant Universe.
We search for the presence of bright Ly
α
emitters among
Spitzer
SMUVS galaxies at
z
> 2.9 making use of homogeneous MUSE spectroscopic data. Although these data only cover a small region of ...COSMOS, MUSE has the unique advantage of providing spectral information over the entire field, without the need of target pre-selection. This results in an unbiased detection of all the brightest Ly
α
emitters among the SMUVS sources, which by design are stellar-mass selected galaxies. Within the studied area, ∼14% of the SMUVS galaxies at
z
> 2.9 have Ly
α
fluxes
F
λ
≳ 7 × 10
−18
erg s
−1
cm
−2
. These Ly
α
emitters are characterized by three types of emission, 47% show a single-line profile, 19% present a double peak or a blue bump, and 31% show a red tail. One object (3%) shows both a blue bump and a red tail. We also investigate the spectral energy distribution (SED) properties of the SMUVS galaxies that are MUSE detected and those that are not. After stellar mass matching the two populations, we find that the MUSE detected galaxies have generally lower extinction than SMUVS-only objects, while there is no clear intrinsic difference in the mass and age distributions of the two samples. For the MUSE-detected SMUVS galaxies, we compare the instantaneous star formation rate lower limit obtained from the Ly
α
line with its past average derived from SED fitting, and find evidence for rejuvenation in some of our oldest objects. In addition, we study the spectra of those Ly
α
emitters that are not detected in SMUVS in the same field. We find that of the emission line profiles shown 67% have a single line, 3% a blue bump, and 30% a red tail. The difference in profile distribution could be ascribed to the fainter Ly
α
luminosities of the MUSE sources not detected in SMUVS and an intrinsically different mass distribution. Finally, we search for the presence of galaxy associations using the spectral redshifts. The integral coverage of MUSE reveals that these associations are 20 times more likely than what is derived from all the other existing spectral data in COSMOS, which is biased by target pre-selection.
We present a detailed strong lensing analysis of the massive and distant (
z
= 0.870) galaxy cluster ACT-CL J0102−4915 (ACT0102, also known as El Gordo), taking advantage of new spectroscopic data ...from the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope and archival imaging from the
Hubble
Space Telescope. Thanks to the MUSE data, we were able to measure secure redshifts for 374 single objects, including 23 multiply lensed galaxies, and 167 cluster members of ACT0102. We used the observed positions of 56 multiple images, along with their new spectroscopic redshift measurements, as constraints for our strong lensing model. Remarkably, some multiple images are detected out to a large projected distance of ≈1 Mpc from the brightest cluster galaxy, allowing us to estimate a projected total mass value of 1.84
−0.04
+0.03
× 10
15
M
⊙
within that radius. We find that we need two extended cluster mass components, the mass contributions from the cluster members and the additional lensing effect of a foreground (
z
= 0.633) group of galaxies, to predict the positions of all multiple images with a root mean square offset of 0″
.
75. The main cluster-scale mass component is centred very close to the brightest cluster galaxy, and the other extended mass component is located in the north-west region of the cluster. These two mass components have very similar values of mass projected within 300 kpc of their centres, namely 2.29
−0.10
+0.09
× 10
14
M
⊙
and 2.10
−0.09
+0.08
× 10
14
M
⊙
, in agreement with the major merging scenario of ACT0102. We make publicly available the lens model, including the magnification maps and posterior distributions of the model parameter values, as well as the full spectroscopic catalogue containing all redshift measurements obtained with MUSE.
We present a detailed strong lensing analysis of the massive and distant (z = 0.870) galaxy cluster ACT-CL J0102−4915 (ACT0102, also known as El Gordo), taking advantage of new spectroscopic data ...from the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope and archival imaging from the Hubble Space Telescope. Thanks to the MUSE data, we were able to measure secure redshifts for 374 single objects, including 23 multiply lensed galaxies, and 167 cluster members of ACT0102. We used the observed positions of 56 multiple images, along with their new spectroscopic redshift measurements, as constraints for our strong lensing model. Remarkably, some multiple images are detected out to a large projected distance of ≈1 Mpc from the brightest cluster galaxy, allowing us to estimate a projected total mass value of 1.84−0.04+0.03 × 1015 M⊙ within that radius. We find that we need two extended cluster mass components, the mass contributions from the cluster members and the additional lensing effect of a foreground (z = 0.633) group of galaxies, to predict the positions of all multiple images with a root mean square offset of 0″.75. The main cluster-scale mass component is centred very close to the brightest cluster galaxy, and the other extended mass component is located in the north-west region of the cluster. These two mass components have very similar values of mass projected within 300 kpc of their centres, namely 2.29−0.10+0.09 × 1014 M⊙ and 2.10−0.09+0.08 × 1014 M⊙, in agreement with the major merging scenario of ACT0102. We make publicly available the lens model, including the magnification maps and posterior distributions of the model parameter values, as well as the full spectroscopic catalogue containing all redshift measurements obtained with MUSE.
A&A 633, A159 (2020) We search for bright Ly$\rm \alpha$ emitters among Spitzer SMUVS galaxies at
z > 2.9 with homogeneous MUSE data. Although it only covers a small region of
COSMOS, MUSE has the ...unique advantage of providing spectral information over
the entire field, without the need of target pre-selection. This gives an
unbiased detection of all the brightest Ly$\rm \alpha$ emitters among SMUVS
sources, which by design are stellar-mass selected galaxies. Within the studied
area, ~14% of the SMUVS galaxies at z > 2.9 have Ly$\rm \alpha$ fluxes F$\rm
_\lambda$ > 7 x 10$^{-18}$ erg s$^{-1}$ cm$^{-2}$. These Ly$\rm \alpha$
emitters are characterized by three types of emission, 47% show a single line
profile, 19% present a double peak or a blue bump and 31% show a red tail. One
object (3%) shows both a blue bump and a red tail. We also investigate the
spectral energy distribution (SED) properties of the SMUVS MUSE-detected
galaxies and MUSE non-detections. After stellar-mass matching both populations,
we find that MUSE detected galaxies have generally lower extinction than
SMUVS-only objects, while there is no clear intrinsic difference in the mass
and age distributions. For the MUSE-detected SMUVS galaxies, we compare the
instantaneous SFR lower limit given by Ly$\rm \alpha$ flux with its past
average derived from SED fitting, and find evidence for rejuvenation in some of
our oldest objects. We also study the spectra of those Ly$\rm \alpha$ emitters
which are not detected in SMUVS in the same field. We find different
distributions of the emission line profiles, which could be ascribed to the
fainter Ly$\rm \alpha$ luminosities of the MUSE-only sources and an
intrinsically different mass distribution. Finally, we search for the presence
of galaxy associations. MUSE's integral coverage is 20 times more likely to
find associations than all other existing spectral data in COSMOS, biased by
target pre-selection.
We present a detailed strong lensing analysis of the massive and distant (\(z=0.870\)) galaxy cluster ACT-CL J0102\(-\)4915 (ACT0102, also known as El Gordo), taking advantage of new spectroscopic ...data from the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope, and archival imaging from the Hubble Space Telescope. Thanks to the MUSE data, we measure secure redshifts for 374 single objects, including 23 multiply lensed galaxies, and 167 cluster members of ACT0102. The observed positions of 56 multiple images, along with their new spectroscopic redshift measurements, are used as constraints for our strong lensing model. Remarkably, some multiple images are detected out to a large projected distance of \(\approx 1\) Mpc from the brightest cluster galaxy, allowing us to estimate a projected total mass value of \(1.84_{-0.04}^{+0.03} \times 10^{15}\, \rm M_{\odot}\) within that radius. We find that we need two extended cluster mass components, the mass contributions from the cluster members and the additional lensing effect of a foreground (\(z=0.633\)) group of galaxies, to predict the positions of all multiple images with a root mean square offset of \(0.75"\). The main cluster-scale mass component is centered very closely to the brightest cluster galaxy and the other extended mass component is located in the north-west region of the cluster. These two mass components have very similar values of mass projected within 300 kpc from their centers, namely \(2.29_{-0.10}^{+0.09}\times10^{14}\,\rm M_{\odot}\) and \(2.10_{-0.09}^{+0.08}\times10^{14}\,\rm M_{\odot}\), in agreement with the major merging scenario of ACT0102. We make publicly available the lens model, including the magnification maps and posterior distributions of the model parameter values, as well as the full spectroscopic catalogue containing all redshift measurements obtained with MUSE.
We tested the implementation of different IMFs in our model for the chemical evolution of ellipticals, with the aim of reproducing the observed relations of Fe/H and Mg/Fe abundances with galaxy mass ...in a sample of early-type galaxies selected from the SPIDER-SDSS catalog. Abundances in the catalog were derived from averaged spectra, obtained by stacking individual spectra according to central velocity dispersion, as a proxy of galaxy mass. We tested initial mass functions already used in a previous work, as well as two new models, based on low-mass tapered ("bimodal") IMFs, where the IMF becomes either (1) bottom-heavy in more massive galaxies, or (2) is time-dependent, switching from top-heavy to bottom-heavy in the course of galactic evolution. We found that observations could only be reproduced by models assuming either a constant, Salpeter IMF, or a time-dependent distribution, as other IMFs failed. We further tested the models by calculating their M/L ratios. We conclude that a constant, time-independent bottom-heavy IMF does not reproduce the data, especially the increase of the \(\alpha/Fe\) ratio with galactic stellar mass, whereas a variable IMF, switching from top to bottom-heavy, can match observations. For the latter models, the IMF switch always occurs at the earliest possible considered time, i.e. \(t_{\text{switch}}= 0.1\) Gyr.
We search for bright Ly\(\rm \alpha\) emitters among Spitzer SMUVS galaxies at z > 2.9 with homogeneous MUSE data. Although it only covers a small region of COSMOS, MUSE has the unique advantage of ...providing spectral information over the entire field, without the need of target pre-selection. This gives an unbiased detection of all the brightest Ly\(\rm \alpha\) emitters among SMUVS sources, which by design are stellar-mass selected galaxies. Within the studied area, ~14% of the SMUVS galaxies at z > 2.9 have Ly\(\rm \alpha\) fluxes F\(\rm _\lambda\) > 7 x 10\(^{-18}\) erg s\(^{-1}\) cm\(^{-2}\). These Ly\(\rm \alpha\) emitters are characterized by three types of emission, 47% show a single line profile, 19% present a double peak or a blue bump and 31% show a red tail. One object (3%) shows both a blue bump and a red tail. We also investigate the spectral energy distribution (SED) properties of the SMUVS MUSE-detected galaxies and MUSE non-detections. After stellar-mass matching both populations, we find that MUSE detected galaxies have generally lower extinction than SMUVS-only objects, while there is no clear intrinsic difference in the mass and age distributions. For the MUSE-detected SMUVS galaxies, we compare the instantaneous SFR lower limit given by Ly\(\rm \alpha\) flux with its past average derived from SED fitting, and find evidence for rejuvenation in some of our oldest objects. We also study the spectra of those Ly\(\rm \alpha\) emitters which are not detected in SMUVS in the same field. We find different distributions of the emission line profiles, which could be ascribed to the fainter Ly\(\rm \alpha\) luminosities of the MUSE-only sources and an intrinsically different mass distribution. Finally, we search for the presence of galaxy associations. MUSE's integral coverage is 20 times more likely to find associations than all other existing spectral data in COSMOS, biased by target pre-selection.
We carry out a detailed strong lensing analysis of a sub-sample of eight galaxy clusters of the CLASH survey, in the redshift range of \( z_{\rm cluster} = 0.23-0.59\), using extensive spectroscopic ...information, primarily MUSE archival data complemented with CLASH-VLT redshift measurements. Different models are tested in each cluster depending on the complexity of its mass distribution and on the number of detected multiple images. Four clusters show more than five spectroscopically confirmed multiple image families. In this sample, we do not make use of families that are only photometrically identified, in order to reduce model degeneracies and systematics due to the potential misidentifications of some multiple images. We present spectroscopic confirmation of 27 multiply lensed sources, with no previous spectroscopic measurements, spanning over the redshift range of \(z_{\rm src}=0.7-6.1\). Moreover, we confirm an average of \(48\) galaxy members in the core of each cluster, thanks to the high efficiency and large field of view of MUSE. Despite having different properties (i.e., number of mass components, total mass, redshift, etc), the projected total mass and mass density profiles of all clusters have very similar shapes, when rescaled by independent measurements of \(M_{200c}\) and \(R_{200c}\). Specifically, we measure the mean value of the projected total mass of our cluster sample within 10 (20)% of \(R_{200c}\) to be 0.13 (0.32) of \(M_{200c}\), with a remarkably small scatter of 5 (6)%. Furthermore, the large number of high-z sources and the precise magnification maps derived in this work for four clusters add up to the sample of high-quality gravitational telescopes to be used to study the faint and distant Universe. The strong lensing models and the full redshift catalogues from MUSE are publicly available.
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