- ID:
- ivo://CDS.VizieR/J/AJ/138/332
- Title:
- LEDA CMD/tip of the red giant branch
- Short Name:
- J/AJ/138/332
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The color-magnitude diagrams/tip of the red giant branch (CMDs/TRGB) section of the Extragalactic Distance Database contains a compilation of observations of nearby galaxies from the Hubble Space Telescope. Approximately 250 (and increasing) galaxies in the Local Volume have CMDs and the stellar photometry tables used to produce them available through the Web. Various stellar populations that make up a galaxy are visible in the CMDs, but our primary purpose for collecting and analyzing these galaxy images is to measure the TRGB in each. We can estimate the distance to a galaxy by using stars at the TRGB as standard candles. In this paper, we describe the process of constructing the CMDs and make the results available to the public.
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- ID:
- ivo://CDS.VizieR/VII/242
- Title:
- LEDA galaxies with DENIS measurements catalog
- Short Name:
- VII/242
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of near-infrared properties of LEDA galaxies, using the full resolution images from the DENIS survey. The fluxes are integrated in eight homothetic ellipses defined by their proper axis ratio, position angle and major axis (up to twice the blue diameter at the isophote 25mag/arcsec^2^) extracted from the LEDA database. From the curves of growth in I, J and K_ms_ photometric bands, we estimated different apparent magnitudes and diameters ("total", "Kron" and "isophotal"). Isophotal parameters refer to the limiting surface brightnesses : 22.5(Imag)/arcsec^2^, 21.0(Jmag)/arcsec^2^ and 20.0(K_ms_mag)/arcsec^2^ for the three photometric bands, respectively. The result is a catalog of 753 153 objects (among which there are 508 224 galaxies, 34 449 probable galaxies and 210 480 galaxies to be confirmed). The catalog gives about (the figures vary, depending on the considered magnitude or diameter) : 668 000 I-band magnitudes, 576 000 J-band magnitudes, 357 000 K_ms_-band magnitudes and 452 000 I-band diameters, 299 000 J-band diameters, 114 000 K_ms_-band diameters. The typical standard deviations for I, J and K_ms_ magnitudes are 0.14, 0.15 and 0.25, respectively, for magnitudes limited at I=16, J=15 and K_ms_=14. The contamination by superimposed objects probably remains the major source of problems and could require future improvement. The completeness limits in magnitude are about : 15.5, 14.5 and 13 in I, J and K_ms_, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/23
- Title:
- LEGUS galaxies1 observations
- Short Name:
- J/ApJS/235/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Legacy ExtraGalactic UV Survey (LEGUS) is a multiwavelength Cycle 21 Treasury program on the Hubble Space Telescope. It studied 50 nearby star-forming galaxies in 5 bands from the near-UV to the I-band, combining new Wide Field Camera 3 observations with archival Advanced Camera for Surveys data. LEGUS was designed to investigate how star formation occurs and develops on both small and large scales, and how it relates to the galactic environments. In this paper we present the photometric catalogs for all the apparently single stars identified in the 50 LEGUS galaxies. We present optical and near-UV color-magnitude diagrams for all the galaxies. For each galaxy we derived the distance from the tip of the red giant branch. We then used the NUV color-magnitude diagrams to identify stars more massive than 14M_{sun}_, and compared their number with the number of massive stars expected from the GALEX FUV luminosity. Our analysis shows that the fraction of massive stars forming in star clusters and stellar associations is about constant with the star formation rate. This lack of a relation suggests that the timescale for evaporation of unbound structures is comparable or longer than 10Myr. At low star formation rates this translates to an excess of mass in clustered environments as compared to model predictions of cluster evolution, suggesting that a significant fraction of stars form in unbound systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/154
- Title:
- LEGUS & Ha-LEGUS obs. of NGC4449 star clusters
- Short Name:
- J/ApJ/889/154
- Date:
- 17 Jan 2022 11:55:48
- Publisher:
- CDS
- Description:
- We present a new catalog and results for the cluster system of the starburst galaxy NGC 4449, based on multiband imaging observations taken as part of the LEGUS and H_{alpha}_-LEGUS surveys. We improve the spectral energy fitting method used to estimate cluster ages, and find that the results, particularly for older clusters, are in better agreement with those from spectroscopy. The inclusion of H{alpha} measurements, the role of stochasticity for low-mass clusters, the assumptions about reddening, and the choices of SSP model and metallicity all have important impacts on the age dating of clusters. A comparison with ages derived from stellar color-magnitude diagrams for partially resolved clusters shows reasonable agreement, but large scatter in some cases. The fraction of light found in clusters relative to the total light (i.e., T_L_) in the U, B, and V filters in 25 different ~kiloparsec-size regions throughout NGC 4449 correlates with both the specific region luminosity, R_L_, and the dominant age of the underlying stellar population in each region. The observed cluster age distribution is found to decline over time as dN/d{tau}{propto}{tau}^{gamma}^, with {gamma}=-0.85+/-0.15, independent of cluster mass, and is consistent with strong, early cluster disruption. The mass functions of the clusters can be described by a power law with dN/dM{propto}M^{beta}^ and {beta}=-1.86+/-0.2, independent of cluster age. The mass and age distributions are quite resilient to differences in age-dating methods. There is tentative evidence for a factor of 2-3 enhancement in both the star and cluster formation rate ~100-300Myr ago, indicating that cluster formation tracks star formation generally. The enhancement is probably associated with an earlier interaction event.
- ID:
- ivo://CDS.VizieR/J/MNRAS/406/1318
- Title:
- Lensed-arc statistics of galaxy clusters
- Short Name:
- J/MNRAS/406/1318
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The statistics of strongly lensed arcs in samples of galaxy clusters provide information on cluster structure that is complementary to that from individual clusters. However, samples of clusters that have been analysed to date have been either small, heterogeneous or observed with limited angular resolution. We measure the lensed-arc statistics of 97 clusters imaged at high angular resolution with the Hubble Space Telescope, identifying lensed arcs using two automated arc-detection algorithms. The sample includes similar numbers of X-ray-selected [MAssive Cluster Survey (MACS)] and optically selected [Red-Sequence Cluster Survey (RCS)] clusters, and spans cluster redshifts in the range 0.2<z<1. We compile a catalogue of 42 arcs in the X-ray-selected subsample and seven arcs in the optical subsample. All but five of these arcs are reported here for the first time.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A118
- Title:
- Lensed QSOs light curves & spectral monitoring
- Short Name:
- J/A+A/616/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the framework of the Gravitational LENses and DArk MAtter (GLENDAMA) project, we present a database of nine gravitationally lensed quasars (GLQs) that have two or four images brighter than r=20mag and are located in the northern hemisphere. This new database consists of a rich variety of follow-up observations included in the GLENDAMA global archive, which is publicly available online and contains 6557 processed astronomical frames of the nine lens systems over the period 1999-2016. In addition to the GLQs, our archive also incorporates binary quasars, accretion-dominated radio-loud quasars, and other objects, where about 50% of the non-GLQs were observed as part of a campaign to identify GLQ candidates. Most observations of GLQs correspond to an ongoing long-term macro-programme with 2-10m telescopes at the Roque de los Muchachos Observatory, and these data provide information on the distribution of dark matter at all scales. We outline some previous results from the database, and we additionally obtain new results for several GLQs that update the potential of the tool for astrophysical studies.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A104
- Title:
- Lensed QSO UM673/Q0142-100 VRi light curves
- Short Name:
- J/A+A/551/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present four years of photometric observations of the doubly imaged quasar UM673, carried out in three filters (VRi) with the Danish 1.54m telescope at the La Silla Observatory. We studied the variations in flux and in color index of each lensed component as a function of time, and we obtained an independent estimation of the magnitude of the faint lens galaxy, showing that its contribution cannot be neglected.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A121
- Title:
- 2 lensed quasars light curves
- Short Name:
- J/A+A/553/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Within the framework of the COSMOGRAIL collaboration we present 7- and 8.5-year-long light curves and time-delay estimates for two gravitationally lensed quasars: SDSS J1206+4332 and HS 2209+1914. We monitored these doubly lensed quasars in the R-band using four telescopes: the Mercator, Maidanak, Himalayan Chandra, and Euler Telescopes, together spanning a period of 7 to 8.5 observing seasons from mid-2004 to mid-2011. The photometry of the quasar images was obtained through simultaneous deconvolution of these data. The time delays were determined from these resulting light curves using four very different techniques: a dispersion method, a spline fit, a regression difference technique, and a numerical model fit. This minimizes the bias that might be introduced by the use of a single method.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/76
- Title:
- Lensed z~6-8 galaxies behind CLASH clusters
- Short Name:
- J/ApJ/792/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We utilize 16 band Hubble Space Telescope (HST) observations of 18 lensing clusters obtained as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) Multi-Cycle Treasury program to search for z ~ 6-8 galaxies. We report the discovery of 204, 45, and 13 Lyman-break galaxy candidates at z ~ 6, z ~ 7, and z ~ 8, respectively, identified from purely photometric redshift selections. This large sample, representing nearly an order of magnitude increase in the number of magnified star-forming galaxies at z ~ 6-8 presented to date, is unique in that we have observations in four WFC3/UVIS UV, seven ACS/WFC optical, and all five WFC3/IR broadband filters, which enable very accurate photometric redshift selections. We construct detailed lensing models for 17 of the 18 clusters to estimate object magnifications and to identify two new multiply lensed z >~ 6 candidates. The median magnifications over the 17 clusters are 4, 4, and 5 for the z ~ 6, z ~ 7, and z ~ 8 samples, respectively, over an average area of 4.5 arcmin^2^ per cluster. We compare our observed number counts with expectations based on convolving "blank" field UV luminosity functions through our cluster lens models and find rough agreement down to ~27 mag, where we begin to suffer significant incompleteness. In all three redshift bins, we find a higher number density at brighter observed magnitudes than the field predictions, empirically demonstrating for the first time the enhanced efficiency of lensing clusters over field surveys. Our number counts also are in general agreement with the lensed expectations from the cluster models, especially at z ~ 6, where we have the best statistics.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1678
- Title:
- LensPerfect A1689 analysis
- Short Name:
- J/ApJ/723/1678
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a strong lensing (SL) mass model of A1689 which resolves substructures an estimated 25kpc across within the central ~400kpc diameter. We achieve this resolution by perfectly reproducing the observed (strongly lensed) input positions of 168 multiple images of 55 knots residing within 135 images of 42 galaxies. Our model makes no assumptions about light tracing mass, yet we reproduce the brightest visible structures with some slight deviations. A1689 remains one of the strongest known lenses on the sky, with an Einstein radius of R_E_=47.0+/-1.2" (143^+3^_-4_kpc) for a lensed source at z_s_=2. We find that a single Navarro-Frenk-White (NFW) or Sersic profile yields a good fit simultaneously (with only slight tension) to both our SL mass model and published weak lensing (WL) measurements at larger radius (out to the virial radius). Our SL model prefers slightly higher concentrations than previous SL models, bringing our SL+WL constraints in line with other recent derivations. Our results support those of previous studies which find A1689 has either an anomalously large concentration or significant extra mass along the line of sight (perhaps in part due to triaxiality).
