- 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).
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/788/55
- Title:
- HST/WFC3 SNR discoveries in M83 (NGC5236)
- Short Name:
- J/ApJ/788/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical/NIR imaging survey of the face-on spiral galaxy M83, using data from the Hubble Space Telescope Wide Field Camera 3 (WFC3). Seven fields are used to cover a large fraction of the inner disk, with observations in nine broadband and narrowband filters. In conjunction with a deep Chandra survey and other new radio and optical ground-based work, these data enable a broad range of science projects to be pursued. We provide an overview of the WFC3 data and processing and then delve into one topic, the population of young supernova remnants (SNRs). We used a search method targeted toward soft X-ray sources to identify 26 new SNRs. Many compact emission nebulae detected in [FeII]1.644{mu}m align with known remnants and this diagnostic has also been used to identify many new remnants, some of which are hard to find with optical images. We include 37 previously identified SNRs that the data reveal to be <0.5" in angular size and thus are difficult to characterize from ground-based data. The emission line ratios seen in most of these objects are consistent with shocks in dense interstellar material rather than showing evidence of ejecta. We suggest that the overall high elemental abundances in combination with high interstellar medium pressures in M83 are responsible for this result.
- ID:
- ivo://CDS.VizieR/J/PASP/119/7
- Title:
- HST WFPC2 star clusters in M31
- Short Name:
- J/PASP/119/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a followup to the automated cluster search carried out by Williams & Hodge (2001ApJ...548..190W), we have examined 39 Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) pointings to locate and study a comprehensive collection of disk clusters. The Williams technique was effective in finding young clusters, but not intermediate-age or old clusters. Our searches have shown that M31 has large numbers of these intermediate and older open clusters, most of them undetected by both the Williams survey and other ground-based searches. We present a catalog of 343 clusters detected on the WFPC2 images. Extrapolation from our data indicates that the entire disk of M31 contains approximately 80000 star clusters. We have carried out integrated multicolor photometry of these clusters to ascertain their properties and to compare their properties with cluster systems of other galaxies. We show the cluster luminosity function, the color-magnitude diagram, the formation function, and the size distribution. Cluster densities and colors show trends with disk position. An age distribution is derived and, although the ages are very uncertain for the fainter clusters, there is evidence for cluster dynamical destruction at about the same rate as in our Galaxy.
- ID:
- ivo://CDS.VizieR/J/PASP/120/1
- Title:
- HST WFPC2 star clusters in M31. II.
- Short Name:
- J/PASP/120/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports on a survey of star clusters in M31 based on archival images from the Hubble Space Telescope. Paper I reported results from images obtained with the Wide Field Planetary Camera 2 (WFPC2) and this paper reports results from the Advanced Camera for Surveys (ACS). The ACS survey has yielded a total of 339 star clusters, 52 of which mostly globular clusters were found to have been catalogued previously. As for the previous survey, the luminosity function of the clusters drops steeply for absolute magnitudes fainter than M_V_=-3; the implied cluster mass function has a turnover for masses less than a few hundred solar masses. The color-integrated magnitude diagram of clusters shows three significant features: (1) a group of very red, luminous objects: the globular clusters, (2) a wide range in color for the fainter clusters, representing a considerable range in age and reddening, and (3) a maximum density of clusters centered approximately at V=21, B-V=0.30, V-I=0.50, where there are intermediate-age, intermediate-mass clusters with ages close to 500 million years and masses of about 2000 solar masses. We give a brief qualitative interpretation of the distribution of clusters in the CMDs in terms of their formation and destruction rates.
- ID:
- ivo://CDS.VizieR/J/PASP/122/745
- Title:
- HST WFPC2 star clusters in M31. III.
- Short Name:
- J/PASP/122/745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes the results of a Hubble Space Telescope (HST) WFPC2 search for star clusters in active star-formation regions of M31. Nine of the clusters were previously cataloged and 77 are new. Our 23 fields cover key areas of the galaxy's recent star-formation activity. We provide a catalog of positions and integrated magnitudes in four colors, taken with the 336W, 439W, 555W, and 814W filters of the HST.
- ID:
- ivo://CDS.VizieR/J/AJ/138/770
- Title:
- HST/WFPC survey of M31 bright young clusters
- Short Name:
- J/AJ/138/770
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the properties of 89 low-mass star clusters located in the vicinity of luminous young clusters ("blue globulars") in the disk of M31. Eighty-two of the clusters are newly detected. We have determined their integrated magnitudes and colors, based on a series of Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 exposures in blue and red (HST filters F450W and F814W).
- ID:
- ivo://CDS.VizieR/J/AJ/116/2081
- Title:
- Hubble Deep Field catalog of color-based redshift
- Short Name:
- J/AJ/116/2081
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive simple empirical color-redshift relations for z<~4 galaxies in the Hubble Deep Field (HDF) using a linear function of three photometric colors (U-B, B-V, V-I). The dispersion between the estimated redshifts and the spectroscopically observed ones is small for relations derived in several separate color regimes; the dispersions range from {sigma}_z_~=0.03 to 0.1 for z<~2 galaxies, and from {sigma}_z_~=0.14 to 0.25 for z>~2 galaxies. We apply the color-redshift relations to the HDF photometric catalog and obtain estimated redshifts that are consistent with those derived from spectral template fitting methods. The advantage of these color-redshift relations is that they are simple and easy to use and do not depend on the assumption of any particular spectral templates; they provide model independent redshift estimates for z<~4 galaxies using only multiband photometry, and they apply to about 90% of all galaxies. We provide a color-based estimated redshift catalog of HDF galaxies to z<~4. We use the estimated redshifts to investigate the redshift distribution of galaxies in the HDF; we find peaks in the redshift distribution that suggest large-scale clustering of galaxies to at least z~1 and that are consistent with those identified in spectroscopic probes of the HDF.
- ID:
- ivo://CDS.VizieR/J/AJ/117/17
- Title:
- Hubble Deep Field near-IR obs.
- Short Name:
- J/AJ/117/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents data obtained during the NICMOS Guaranteed Time Observations of a portion of the Hubble Deep Field. The data are in a catalog format similar to the publication of the original WFPC2 Hubble Deep Field program (Williams et al., 1996, Cat. <J/AJ/112/1335>). The catalog contains 342 objects in a 49.1"x48.4" subfield of the total observed field, 235 of which are considered coincident with objects in the WFPC2 catalog. The 3{sigma} signal-to-noise ratio level is at an aperture AB magnitude of approximately 28.8 at 1.6{mu}m. The catalog sources, listed in order of right ascension, are selected to satisfy a limiting signal-to-noise ratio criterion of greater than or equal to 2.5. This introduces a few false detections into the catalog, and users should take careful note of the completeness and reliability levels for the catalog discussed in sections 9 and 10. The catalog also contains a test parameter indicating the results of half-catalog tests and the degree of coincidence with the original WFPC2 catalog.
- ID:
- ivo://CDS.VizieR/J/AJ/112/1335
- Title:
- Hubble Deep Field observations
- Short Name:
- J/AJ/112/1335
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Deep Field (HDF) is a Director's Discretionary program on HST in Cycle 5 to image an undistinguished field at high Galactic latitude in four passbands as deeply as reasonably possible. These images provide the most detailed view to date of distant field galaxies and are likely to be important for a wide range of studies in galaxy evolution and cosmology. In order to optimize observing in the time available, a field in the northern continuous viewing zone was selected and images were taken for ten consecutive days, or approximately 150 orbits. Shorter 1-2 orbit images were obtained of the fields immediately adjacent to the primary HDF in order to facilitate spectroscopic follow-up by ground- based telescopes. The observations were made from 1995 December 18-30, and both raw and reduced data have been put in the public domain as a community service. We present a summary of the criteria for selecting the field, the rationale behind the filter selection and observing times in each band, and the strategies for planning the observations to maximize the exposure time while avoiding Earth-scattered light. Data reduction procedures are outlined, and images of the combined frames in each band are presented. Objects detected in these images are listed in a catalog with their basic photometric parameters.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/583
- Title:
- Hubble Deep Field surface photometry
- Short Name:
- J/A+AS/129/583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detailed surface photometry of a sample of early-type galaxies in the Hubble Deep Field is presented as part of a long-term project aimed to settle strong observational constraints to the theories modelling the evolution of elliptical galaxies from the early stages. The sample has been extracted, in the V_606_ band, from the database provided by the ESO-STECF-HDF Group (Couch, 1996, <http://ecf.hq.eso.org>). The selection criteria involve the total magnitude, the number of pixels detected above the background level and an automatic star/galaxy classifier. Moreover, form visual inspection of the frames, we excluded the galaxies showing unambiguous late-type morphology. The analysis of the luminosity and geometrical profiles, carried out on the 162 candidates obeying our selection criteria, resulted in a list of 99 'bona fide' early-type galaxies, for which accurate total magnitudes and effective radii were computed on the basis of the equivalent luminosity profiles. The comparison with the magnitudes given by Williams et al. (1996, Cat. <J/AJ/112/1335>) indicates that the automated photometry tends to underestimate the total luminosity of the ellipticals. The luminosity profiles of most of galaxies in our sample follow fairly well the de~Vaucouleurs law ('Normal' profiles). However, a relevant fraction of galaxies, even following the r^1/4^ law in the main body light distribution, exhibit in the inner region a flattening of the luminosity profile not attributable to the PSF (`Flat' profiles) or, in some cases, a complex (multi-nucleus) structure (`Merger' profiles). A statistically significant correlation is found between the shapes of the luminosity profiles and the ellipticity distribution. In particular, the average ellipticity of galaxies belonging to the `Flat' and `Merger' classes is significantly higher than that of the `Normal' galaxies. Finally, even taken into account the relevant uncertainty of the outer position angle profiles, the amount of isophotal twisting of HDF ellipticals turns out to be significantly larger with respect to that of the local samples.
