- ID:
- ivo://CDS.VizieR/J/ApJ/839/L11
- Title:
- HST strong lensing analysis of PLCKG287.0+32.9
- Short Name:
- J/ApJ/839/L11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since galaxy clusters sit at the high end of the mass function, the number of galaxy clusters both massive and concentrated enough to yield particularly large Einstein radii poses useful constraints on cosmological and structure formation models. To date, less than a handful of clusters are known to have Einstein radii exceeding ~40" (for a source at z_s_~2, nominally). Here, we report an addition to that list of the Sunyaev-Zel'dovich (SZ) selected cluster, PLCKG287.0+32.9 (z=0.38), the second-highest SZ-mass (M500) cluster from the Planck catalog. We present the first strong-lensing analysis of the cluster, identifying 20 sets of multiply imaged galaxies and candidates in new Hubble Space Telescope (HST) data, including a long, l~22" giant arc, as well as a quadruply imaged, apparently bright (magnified to J_F110W_=25.3 AB), likely high-redshift dropout galaxy at z_phot_=6.90 [6.13-8.43] (95% C.I.). Our analysis reveals a very large critical area (1.55arcmin^2^, z_s_~2), corresponding to an effective Einstein radius of {theta}_E_~42". The model suggests the critical area will expand to 2.58arcmin^2^ ({theta}_E_~54") for sources at z_s_~10. Our work adds to recent efforts to model very massive clusters toward the launch of the James Webb Space Telescope, in order to identify the most useful cosmic lenses for studying the early universe. Spectroscopic redshifts for the multiply imaged galaxies and additional HST data will be necessary for refining the lens model and verifying the nature of the z~7 dropout.
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- ID:
- ivo://CDS.VizieR/J/ApJ/848/37
- Title:
- HST UV-IR photometry in CLASH galaxy clusters
- Short Name:
- J/ApJ/848/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new method for photometering objects in galaxy clusters. We introduce a mode-filtering technique for removing spatially variable backgrounds, improving both detection and photometric accuracy (roughly halving the scatter in the red sequence compared to previous catalogs of the same clusters). This method is based on robustly determining the distribution of background pixel values and should provide comparable improvement in photometric analysis of any crowded fields. We produce new multiwavelength catalogs for the 25 CLASH cluster fields in all 16 bandpasses from the UV through the near-IR, as well as rest-frame magnitudes. A comparison with spectroscopic values from the literature finds a ~30% decrease in the redshift deviation from previously released CLASH photometry. This improvement in redshift precision, in combination with a detection scheme designed to maximize purity, yields a substantial upgrade in cluster member identification over the previous CLASH galaxy catalog. We construct luminosity functions for each cluster, reliably reaching depths of at least 4.5mag below M* in every case, and deeper still in several clusters. We measure M* , {alpha}, and their redshift evolution, assuming the cluster populations are coeval, and find little to no evolution of {alpha}{<~}-0.9<~{alpha}{<~}-0.8, and M* values consistent with passive evolution. We present a catalog of galaxy photometry, photometric and spectroscopic redshifts, and rest-frame photometry for the full fields of view of all 25 CLASH clusters. Not only will our new photometric catalogs enable new studies of the properties of CLASH clusters, but mode-filtering techniques, such as those presented here, should greatly enhance the data quality of future photometric surveys of crowded fields.
- ID:
- ivo://CDS.VizieR/J/ApJ/800/18
- Title:
- HST/WFC3 observations of z~7-8 galaxies in A2744
- Short Name:
- J/ApJ/800/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exploiting the power of gravitational lensing, the Hubble Frontier Fields (HFF) program aims at observing six massive galaxy clusters to explore the distant universe far beyond the limits of blank field surveys. Using the complete Hubble Space Telescope observations of the first HFF cluster A2744, we report the detection of 50 galaxy candidates at z~7 and eight candidates at z~8 in a total survey area of 0.96arcmin^2^ in the source plane. Three of these galaxies are multiply imaged by the lensing cluster. Using an updated model of the mass distribution in the cluster we were able to calculate the magnification factor and the effective survey volume for each galaxy in order to compute the ultraviolet galaxy luminosity function (LF) at both redshifts 7 and 8. Our new measurements reliably extend the z~7 UV LF down to an absolute magnitude of M_UV_~-15.5. We find a characteristic magnitude of M_UV_^*^=-20.90_-0.73_^+0.90^mag and a faint-end slope {alpha}=-2.01_-0.28_^+0.20^, close to previous determinations in blank fields. We show here for the first time that this slope remains steep down to very faint luminosities of 0.01L^*^. Although prone to large uncertainties, our results at z~8 also seem to confirm a steep faint-end slope below 0.1L^*^. The HFF program is therefore providing an extremely efficient way to study the faintest galaxy populations at z>7 that would otherwise be inaccessible with current instrumentation. The full sample of six galaxy clusters will provide even better constraints on the buildup of galaxies at early epochs and their contribution to cosmic reionization.
- ID:
- ivo://CDS.VizieR/J/ApJ/843/41
- Title:
- HST/WFC3 obs. of z~2-8 galaxies in 4 HFF clusters
- Short Name:
- J/ApJ/843/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide the first observational constraints on the sizes of the faintest galaxies lensed by the Hubble Frontier Fields (HFF) clusters. Ionizing radiation from faint galaxies likely drives cosmic reionization, and the HFF initiative provides a key opportunity to find such galaxies. However, we cannot assess their ionizing emissivity without a robust measurement of their sizes, since this is key to quantifying both their prevalence and the faint- end slope to the UV luminosity function. Here we provide the first size constraints with two new techniques. The first utilizes the fact that the detectability of highly magnified galaxies as a function of shear is very dependent on a galaxy's size. Only the most compact galaxies remain detectable in high-shear regions (versus a larger detectable size range for low shear), a phenomenon we quantify using simulations. Remarkably, however, no correlation is found between the surface density of faint galaxies and the predicted shear, using 87 high-magnification ({mu}=10-100) z~2-8 galaxies seen behind the first four HFF clusters. This can only be the case if faint (~-15mag) galaxies have significantly smaller sizes than more luminous galaxies, i.e., <~30mas or 160-240pc. As a second size probe, we rotate and stack 26 faint high-magnification sources along the major shear axis. Less elongation is found even for objects with an intrinsic half-light radius of 10mas. Together, these results indicate that extremely faint z~2-8 galaxies have near point-source profiles (half-light radii <30mas and perhaps 5-10mas). These results suggest smaller completeness corrections and hence shallower faint-end slopes for the z~2-8 LFs than derived in some recent studies (by {Delta}{alpha}>~0.1-0.3).
- ID:
- ivo://CDS.VizieR/J/ApJ/548/127
- Title:
- Hubble Deep Field-South region
- Short Name:
- J/ApJ/548/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the galaxy-galaxy angular correlations as a function of photometric redshift in a deep, wide galaxy survey centered on the Hubble Deep Field-South (HDF-S). Images were obtained with the Big Throughput Camera on the Blanco 4-m telescope at CTIO, of 1/2 square degree in broadband uBVRI, reaching ~24mag. Approximately 40,000 galaxies are detected in the survey. We determine photometric redshifts using galaxy template fitting to the photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/532/A104
- Title:
- Hubble flow around Fornax cluster of galaxies
- Short Name:
- J/A+A/532/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work aims to provide a new mass estimate for the Fornax cluster and the Fornax-Eridanus complex, avoiding methods like the virial or fits of the X-ray emission profile, which assume that the system is in equilibrium. This is probably not the case for Fornax, because it is still in process of formation. Our mass estimate is based on determination of the zero-velocity surface, which, in the context of the spherical infall model, permits an evaluation of the total mass inside such a surface. The zero-velocity surface radius R0 was estimated either by a running median procedure or by fitting the data to the velocity field expected from the spherical model, including effects of the cosmological constant. The velocity field in a region within 20Mpc of the Fornax center was mapped using a list of 109 galaxies whose distances have an average accuracy of 0.31mag in their distance modulus. Our analysis indicates that the mass of the Fornax cluster itself is [0.40-3.32]x10^14^M_{sun}_ inside a radius of [2.62-5.18]Mpc while the mass inside [3.88-5.60]Mpc, corresponding to the Fornax-Eridanus complex, is [1.30-3.93]x10^14^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/486/697
- Title:
- Hydra I Cluster Catalogue (HCC)
- Short Name:
- J/A+A/486/697
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the properties of the early-type dwarf galaxy population in the Hydra I cluster. We investigate the galaxy luminosity function, the colour-magnitude relation, and the magnitude-surface brightness relation down to M_V_=-10mag. Deep VLT/FORS1 images in V and I bands were examined. We identify cluster members by radial velocity measurements and select other cluster galaxy candidates by their morphology. The candidates' total magnitudes and central surface brightnesses were derived from the analysis of their surface brightness profiles.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A92
- Title:
- HydraI galaxy cluster dwarf catalog (HCDC)
- Short Name:
- J/A+A/659/A92
- Date:
- 10 Mar 2022 07:25:32
- Publisher:
- CDS
- Description:
- Due to their relatively low stellar mass content and diffuse nature, the evolution of dwarf galaxies can be strongly affected by their environment. Analyzing the properties of the dwarf galaxies over a wide range of luminosities, sizes, morphological types, and environments, we can obtain insights about their evolution. At ~50Mpc, the Hydra I cluster of galaxies is among the closest cluster in the z=~0 Universe, and an ideal environment to study dwarf galaxy properties in a cluster environment. We exploit deep imaging data of the Hydra I cluster to construct a new photometric catalog of dwarf galaxies in the cluster core, which is then used to derive properties of the Hydra I cluster dwarf galaxy population as well as to compare it with other clusters. Moreover, we investigate the dependency of dwarf galaxy properties on their surrounding environment. The new wide-field g- and r-band images of the Hydra I cluster obtained with the OmegaCAM camera on the VLT Survey Telescope (VST) in the context of the VST Early-type GAlaxy Survey (VEGAS) were used to study the dwarf galaxy population in the Hydra I cluster core down to r-band magnitude Mr=-11.5mag. We used an automatic detection tool to identify dwarf galaxies from a ~1deg^2^ field centered on the Hydra I core, covering almost half of the cluster virial radius. The photometric pipeline was used to estimate the principal photometric parameters for all targets. Scaling relations and visual inspection were used to assess the cluster membership and construct a new dwarf galaxy catalog. Finally, based on the new catalog, we studied the structural (Sersic index n, effective radius Re, and axis ratio) and photometric (colors and surface brightness) properties of the dwarf galaxies, also investigating how they vary as a function of clustercentric distance. The new Hydra I dwarf catalog contains 317 galaxies with a luminosity between -18.5<Mr<-11.5mag, a semi-major axis larger than ~200pc (a=0.84"), of which 202 are new detections, and previously unknown dwarf galaxies in the Hydra I central region. We estimate that our detection efficiency reaches 50% at the limiting magnitude Mr=-11.5mag, and at the mean effective surface brightness <{mu}_e,r_=26.5mag/arcsec^2^. We present the standard scaling relations for dwarf galaxies, which are color-magnitude, size-luminosity, and Sersic n-magnitude relations, and compare them with other nearby clusters. We find that there are no observational differences for dwarfs scaling relations in clusters of different sizes. We study the spatial distribution of galaxies, finding evidence for the presence of substructures within half the virial radius. We also find that mid- and high-luminosity dwarfs (Mr<-14.5mag) become, on average, redder toward the cluster center, and that they have a mild increase in Re with increasing clustercentric distance, similar to what is observed for the Fornax cluster. No clear clustercentric trends are reported for surface brightness and Sersic index. Considering galaxies in the same magnitude bins, we find that for high and mid-luminosity dwarfs (Mr<-13.5mag), the g-r color is redder for the brighter surface brightness and higher Sersic n index objects. This finding is consistent with the effects of harassment and/or partial gas stripping.
539. IC 3476 Halpha image
- ID:
- ivo://CDS.VizieR/J/A+A/646/A139
- Title:
- IC 3476 Halpha image
- Short Name:
- J/A+A/646/A139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the IB(s)m galaxy IC 3476 observed in the context of the Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE), a blind narrow-band H{alpha}+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT. The deep narrow-band image reveals a very pertubed ionised gas distribution that is characterised by a prominent banana-shaped structure in the front of the galaxy formed of giant HII regions crossing the stellar disc. Star-forming structures, at ~8kpc from the edges of the stellar disc, are also detected in a deep far-ultraviolet ASTROSAT/UVIT image. This particular morphology indicates that the galaxy is undergoing an almost edge-on ram pressure stripping event. The same H{alpha}+[NII] image also shows that the star formation activity is totally quenched in the leading edge of the disc, where the gas has been removed during the interaction with the surrounding medium. The spectral energy distribution fitting analysis of the multi-frequency data indicates that this quenching episode is very recent (~50Myr), and roughly corresponds to an increase of the star formation activity by a factor of ~161% in the inner regions with respect to that expected for secular evolution. The analysis of these data, whose angular resolution enables the study of the induced effects of the perturbation down to the scale of individual HII regions (r_eq_~=40pc), also suggests that the increase of star formation activity is due to the compression of the gas along the stellar disc of the galaxy, which is able to increase its mean electron density and boost the star formation process producing bright HII regions with luminosities up to L(H{alpha})~=10^38^erg/s. The combined analysis of the VESTIGE data with deep IFU spectroscopy gathered with MUSE and with high spectral resolution Fabry Perot data also indicates that the hydrodynamic interaction has deeply perturbed the velocity field of the ionised gas component while leaving that of the stellar disc unaffected. The comparison of the data with tuned high-resolution hydrodynamic simulations accounting for the different gas phases (atomic, molecular, ionised) consistently indicates that the perturbing event is very recent (50-150Myr), once again confirming that ram pressure stripping is a violent phenomenon that is able to perturb the evolution of galaxies in rich environments on short timescales.
- ID:
- ivo://CDS.VizieR/J/ApJS/182/12
- Title:
- ICM entropy profiles (ACCEPT)
- Short Name:
- J/ApJS/182/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial entropy profiles of the intracluster medium (ICM) for a collection of 239 clusters taken from the Chandra X-ray Observatory's Data Archive. We find that most ICM entropy profiles are well fitted by a model which is a power law at large radii and approaches a constant value at small radii: K(r)=K_0_+K_100_(r/100kpc)^{alpha}^, where K_0_ quantifies the typical excess of core entropy above the best-fitting power law found at larger radii. For completeness, we include previously unpublished optical spectroscopy of H{alpha} and [NII] emission lines discussed in Cavagnolo et al. (2008ApJ...683L.107C). All data and results associated with this work are publicly available via the project Web site (ACCEPT: Archive of Chandra Cluster Entropy Profile Tables).
