- ID:
- ivo://CDS.VizieR/J/ApJ/894/78
- Title:
- Strong gravitational lenses from DECaLS
- Short Name:
- J/ApJ/894/78
- Date:
- 03 Dec 2021 00:50:48
- Publisher:
- CDS
- Description:
- We perform a semi-automated search for strong gravitational lensing systems in the 9000 deg2 Dark Energy Camera Legacy Survey (DECaLS), part of the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys. The combination of the depth and breadth of these surveys are unparalleled at this time, making them particularly suitable for discovering new strong gravitational lensing systems. We adopt the deep residual neural network architecture developed by Lanusse+ (2018MNRAS.473.3895L) for the purpose of finding strong lenses in photometric surveys. We compile a training sample that consists of known lensing systems in the Legacy Surveys and the Dark Energy Survey as well as non-lenses in the footprint of DECaLS. In this paper we show the results of applying our trained neural network to the cutout images centered on galaxies typed as ellipticals in DECaLS. The images that receive the highest scores (probabilities) are visually inspected and ranked. Here we present 335 candidate strong lensing systems, identified for the first time.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/631/A91
- Title:
- 2 strongly lensed galaxies MUSE & ALMA datacubes
- Short Name:
- J/A+A/631/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the molecular and ionized gas kinematics of two strongly lensed galaxies at z~1 that lie on the main sequence at this redshift, based on observations from ALMA and MUSE, respectively. We derive the CO and [OII] rotation curves and dispersion profiles of these two galaxies. We find a difference between the observed molecular and ionized gas rotation curves for one of the two galaxies, the Cosmic Snake, for which we obtain a spatial resolution of few hundred parsecs along the major axis. The rotation curve of the molecular gas is steeper than the rotation curve of the ionized gas. In the second galaxy, A521, the molecular and ionized gas rotation curves are consistent, but the spatial resolution is only of few kpc on the major axis. Using simulations, we investigate the effect of the thickness of the gas disk and effective radius on the observed rotation curves and find that a more extended and thicker disk smooths the curve. We also find that the presence of a strongly inclined (>70{deg}) thick disk (>1kpc) can smooth the rotation curve because it degrades the spatial resolution along the line of sight. By building a model using a stellar disk and two gas disks, we reproduce the rotation curves of the Cosmic Snake with a molecular gas disk that is more massive and more radially and vertically concentrated than the ionized gas disk. Finally, we also obtain an intrinsic velocity dispersion in the Cosmic Snake of 18.5+/-7km/s and 19.5+/-6km/s for the molecular and ionized gas, respectively, which is consistent with a molecular disk with a smaller and thinner disk. For A521, the intrinsic velocity dispersion values are 11+/-8km/s and 54+/-11km/s, with a higher value for the ionized gas. This could indicate that the ionized gas disk is thicker and more turbulent in this galaxy. These results highlight the diversity of the kinematics of galaxies at z~1 and the different spatial distribution of the molecular and ionized gas disks. It suggests the presence of thick ionized gas disks at this epoch and that the formation of the molecular gas is limited to the midplane and center of the galaxy in some objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/787/24
- Title:
- Structural parameters of true edge-on galaxies
- Short Name:
- J/ApJ/787/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of true edge-on disk galaxies automatically selected from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS, Cat. II/294). A visual inspection of the g, r, and i images of about 15000 galaxies allowed us to split the initial sample of edge-on galaxy candidates into 4768 (31.8% of the initial sample) genuine edge-on galaxies, 8350 (55.7%) non-edge-on galaxies, and 1865 (12.5%) edge-on galaxies not suitable for simple automatic analysis because these objects either show signs of interaction and warps, or nearby bright stars project on it. We added more candidate galaxies from RFGC, EFIGI, RC3, and Galaxy Zoo catalogs found in the SDSS footprints. Our final sample consists of 5747 genuine edge-on galaxies. We estimate the structural parameters of the stellar disks (the stellar disk thickness, radial scale length, and central surface brightness) in the galaxies by analyzing photometric profiles in each of the g, r, and i images. We also perform simplified three-dimensional modeling of the light distribution in the stellar disks of edge-on galaxies from our sample. Our large sample is intended to be used for studying scaling relations in the stellar disks and bulges and for estimating parameters of the thick disks in different types of galaxies via the image stacking. In this paper, we present the sample selection procedure and general description of the sample.
- ID:
- ivo://CDS.VizieR/J/AJ/129/682
- Title:
- Structural properties of S+S galaxies
- Short Name:
- J/AJ/129/682
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a structural analysis of nearby galaxies in spiral-spiral pairs in optical BVRI bands and compare them with the structures of isolated spiral galaxies and galaxies in ongoing mergers. We use these comparisons to determine how galaxy structure changes during galaxy interactions and mergers. We analyze light concentration (C), asymmetry (A), and clumpiness (S) parameters, and use the projections of CAS parameter space to compare these samples.
- ID:
- ivo://CDS.VizieR/J/AJ/136/773
- Title:
- Structure of classical bulges and pseudobulges
- Short Name:
- J/AJ/136/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we study the properties of pseudobulges (bulges that appear similar to disk galaxies) and classical bulges (bulges which appear similar to E-type galaxies) in bulge-disk decompositions. We show that the distribution of bulge Sersic indices, n_b_, is bimodal, and this bimodality correlates with the morphology of the bulge. Pseudobulges have n_b_~<2 and classical bulges have n_b_>~2 with little to no overlap. Also, pseudobulges do not follow the correlations of Sersic index with structural parameters or the photometric projections of the fundamental plane in the same way that classical bulges and elliptical galaxies do. We find that pseudobulges are systematically flatter than classical bulges and thus more disk-like in both their morphology and shape.
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/1131
- Title:
- Structures in the GA region
- Short Name:
- J/MNRAS/369/1131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To further our understanding of the Great Attractor (GA), we have undertaken a redshift survey using the 2dF on the AAT. Clusters and filaments in the GA region were targeted with 25 separate pointings resulting in approximately 2600 new redshifts. Targets included poorly studied X-ray clusters from the CIZA catalogue as well as the Cen-Crux and PKS 1343-601 clusters, both of which lie close to the classic GA centre. For nine clusters in the region, we report velocity distributions as well as virial and projected mass estimates. The virial mass of CIZA J1324.75736, now identified as a separate structure from the Cen-Crux cluster, is found to be ~3x10^14^M_{sun}_ in good agreement with the X-ray inferred mass. In the PKS 1343-601 field, five redshifts are measured of which four are new. An analysis of redshifts from this survey, in combination with those from the literature, reveals the dominant structure in the GA region to be a large filament, which appears to extend from Abell S0639 (l=281{deg}, b=+11{deg}) to (l~5{deg}, b~-50{deg}), encompassing the Cen-Crux, CIZA J1324.75736, Norma and Pavo II clusters. Behind the Norma Cluster at cz~15000km/s, the masses of four rich clusters are calculated. These clusters (Triangulum-Australis, Ara, CIZA J1514.64558 and CIZA J1410.44246) may contribute to a continued large- scale flow beyond the GA. The results of these observations will be incorporated into a subsequent analysis of the GA flow.
- ID:
- ivo://CDS.VizieR/J/ApJ/659/1176
- Title:
- Study of bars in 180 spiral galaxies
- Short Name:
- J/ApJ/659/1176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Critical insights on galaxy evolution stem from the study of bars. With the advent of HST surveys that trace bars in the rest-frame optical out to z~1, it is critical to provide a reference baseline for bars at z~0 in the optical band. We present results on bars at z~0 in the optical and NIR based on 180 spirals from OSUBSGS (Eskridge et al., 2002, Cat. J/ApJS/143/73).
- ID:
- ivo://CDS.VizieR/J/other/ChA+A/34.367
- Title:
- Study of PGC-54-like galaxies
- Short Name:
- J/other/ChA+A/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the improved Peng's method, we have made the image processing and spiral arm fitting of the newly released spiral galactic images of Sloan Digital Sky Survey (SDSS), and obtained the equivalent thicknesses of galactic disks, as well as the tangential angles of spiral arms of 73 spiral galaxies. These physical quantities are very important for future studies on the properties of spiral galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/11
- Title:
- Subaru-UDGs in the Coma cluster
- Short Name:
- J/ApJS/225/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of ultra-diffuse galaxies (UDGs) in the Coma cluster. UDGs are a subset of low surface brightness (SB) galaxies with very large effective radii defined by van Dokkum et al. (2015ApJ...798L..45V). We surveyed the Subaru data archive for deep Suprime-Cam/Subaru R-band images, and used data covering the 1.7x2.7{deg} region of the Coma cluster. The data are ~1 magnitude deeper than the data of van Dokkum et al. in limiting SB. This paper explains the details of our sample selection procedure. This UDG catalog includes positions, magnitudes, effective radii, mean and central SBs, and colors (when available). Comparisons with previous galaxy catalogs in the literature are performed, and we show that the current catalog is the largest for UDGs. We also discuss that most of the UDGs are members of the Coma cluster, and the major axis of the UDGs tends to align toward the cluster center (radial alignment).
- ID:
- ivo://CDS.VizieR/J/A+A/579/A115
- Title:
- SUDARE-VOICE variability-selection of AGN
- Short Name:
- J/A+A/579/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the most peculiar characteristics of active galactic nuclei (AGNs) is their variability over all wavelengths. This property has been used in the past to select AGN samples and is foreseen to be one of the detection techniques applied in future multi-epoch surveys, complementing photometric and spectroscopic methods. In this paper, we aim to construct and characterise an AGN sample using a multi-epoch dataset in the r band from the SUDARE-VOICE survey. Our work makes use of the VST monitoring programme of an area surrounding the Chandra Deep Field South to select variable sources. We use data spanning a six-month period over an area of 2 square degrees, to identify AGN based on their photometric variability. The selected sample includes 175 AGN candidates with magnitude r<23mag. We distinguish different classes of variable sources through their lightcurves, as well as X-ray, spectroscopic, SED, optical, and IR information overlapping with our survey. We find that 12% of the sample (21/175) is represented by supernovae (SN). Of the remaining sources, 4% (6/154) are stars, while 66% (102/154) are likely AGNs based on the available diagnostics. We estimate an upper limit to the contamination of the variability selected AGN sample =~34%, but we point out that restricting the analysis to the sources with available multi-wavelength ancillary information, the purity of our sample is close to 80% (102 AGN out of 128 non-SN sources with multi-wavelength diagnostics). Our work thus confirms the efficiency of the variability selection method, in agreement with our previous work on the COSMOS field. In addition we show that the variability approach is roughly consistent with the infrared selection.