- ID:
- ivo://CDS.VizieR/J/other/NewA/58.61
- Title:
- SDSS DR9 galaxy clusters optical catalog
- Short Name:
- J/other/NewA/58.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new galaxy cluster catalog constructed from the Sloan Digital Sky Survey Data Release 9 (SDSS DR9) using an Adaptive Matched Filter (AMF) technique. Our catalog has 46479 galaxy clusters with richness {Lambda}_200_>20 in the redshift range 0.045<=z<0.641 in ~11500 deg^2^ of the sky. Angular position, richness, core and virial radii and redshift estimates for these clusters, as well as their error analysis, are provided as part of this catalog. In addition to the main version of the catalog, we also provide an extended version with a lower richness cut, containing 79368 clusters. This version, in addition to the clusters in the main catalog, also contains those clusters (with richness 10<{Lambda}_200_<20) which have a one-to-one match in the DR8 catalog developed by Wen et al (WHL). We obtain probabilities for cluster membership for each galaxy and implement several procedures for the identification and removal of false cluster detections. We cross-correlate the main AMF DR9 catalog with a number of cluster catalogs in different wavebands (Optical, X-ray). We compare our catalog with other SDSS-based ones such as the redMaPPer (Rykoff et al., 2014, Cat. J/ApJ/785/104, 26350 clusters) and the Wen et al. (WHL, 2012, Cat. J/ApJS/199/34) (132684 clusters) in the same area of the sky and in the overlapping redshift range. We match 97% of the richest Abell clusters (Richness group 3), the same as WHL, while redMaPPer matches ~90% of these clusters. Considering AMF DR9 richness bins, redMaPPer does not have one-to-one matches for 70% of our lowest richness clusters (20<{Lambda}_200_<40), while WHL matches 54% of these missed clusters (not present in redMaPPer). redMaPPer consistently does not possess one-to-one matches for ~20% AMF DR9 clusters with {Lambda}_200_>40, while WHL matches >=70% of these missed clusters on average. For comparisons with X-ray clusters, we match the AMF catalog with BAX, MCXC and a combined catalog from NORAS and REFLEX. We consistently obtain a greater number of one-to-one matches for X--ray clusters across higher luminosity bins (L_x_>6x10^44^erg/s) than redMaPPer while WHL matches the most clusters overall. For the most luminous clusters (L_x_>8), our catalog performs equivalently to WHL. This new catalog provides a wider sample than redMaPPer while retaining many fewer objects than WHL.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/220/3
- Title:
- SDSS-DR7 isolated galaxy morphologies
- Short Name:
- J/ApJS/220/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Isolated galaxies in low-density regions are significant in the sense that they are least affected by the hierarchical pattern of galaxy growth and interactions with perturbers, at least for the last few gigayears. To form a comprehensive picture of the star-formation history of isolated galaxies, we constructed a catalog of isolated galaxies and their comparison sample in relatively denser environments. The galaxies are drawn from the Sloan Digital Sky Survey Data Release 7 in the redshift range of 0.025<z<0.044. We performed a visual inspection and classified their morphology following the Hubble classification scheme. For the spectroscopic study, we make use of the catalog provided by Oh et al. (2011ApJS..195...13O). We confirm most of the earlier understanding on isolated galaxies. The most remarkable additional results are as follows. Isolated galaxies are dominantly late type with the morphology distribution (E:S0:S:Irr)=(9.9:11.3:77.6:1.2)%. The frequency of elliptical galaxies among isolated galaxies is only a third of that of the comparison sample. Most of the photometric and spectroscopic properties are surprisingly similar between the isolated and comparison samples. However, early-type isolated galaxies are less massive by 50% and younger (by H{beta}) by 20% than their counterparts in the comparison sample. This can be explained as a result of different merger and star-formation histories for differing environments in the hierarchical merger paradigm.
- ID:
- ivo://CDS.VizieR/J/AJ/135/785
- Title:
- SDSS-DR5 low-mass star spectroscopic sample
- Short Name:
- J/AJ/135/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic analysis of over 38000 low-mass stars from the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5). Analysis of this unprecedentedly large sample confirms the previously detected decrease in the fraction of magnetically active stars (as traced by H{alpha} emission) as a function of vertical distance from the Galactic Plane. The magnitude and slope of this effect varies as a function of spectral type. Using simple 1-D dynamical models, we demonstrate that the drop in activity fraction can be explained by thin disk dynamical heating and a rapid decrease in magnetic activity. The timescale for this rapid activity decrease changes according to the spectral type. By comparing our data to the simulations, we calibrate the age-activity relation at each M dwarf spectral type. We also present evidence for a possible decrease in the metallicity as a function of height above the Galactic Plane. In addition to our activity analysis, we provide line measurements, molecular band indices, colors, radial velocities, 3-D space motions and mean properties as a function of spectral type for the SDSS DR5 low-mass star sample.
3204. SDSS-DR5 quasar catalog
- ID:
- ivo://CDS.VizieR/VII/252
- Title:
- SDSS-DR5 quasar catalog
- Short Name:
- VII/252
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog, made from the SDSS Fifth Data Release, contains 77,429 objects; this is an increase of over 30,000 entries since the previous edition (Schneider et al., Cat. <VII/243>). The catalog consists of the objects in the SDSS Fifth Data Release that have luminosities larger than M_i_=-22.0 (in a cosmology with Ho=70km.s-1.Mpc-1, {Omega}_M_=0.3, and {Omega}_{Lambda}_=0.7), have at least one emission line with FWHM larger than 1000km.s-1 or have interesting or complex absorption features, are fainter than i~15.0, and have highly reliable redshifts. The area covered by the catalog is about 5740deg^2^. The quasar redshifts range from 0.08 to 5.41, with a median value of 1.48; the catalog includes 891 quasars at redshifts greater than 4, of which 36 are at redshifts greater than 5. Approximately half of the catalog quasars have i<19; nearly all have i<21. For each object the catalog presents positions accurate to better than 0.2" rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.03mag, and information on the morphology and selection method. The catalog also contains basic radio, near-infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3800-9200{AA} at a spectral resolution of about 2000; the spectra can be retrieved from the public database using the information provided in the catalog. The average SDSS colors of quasars as a function of redshift, derived from the catalog entries, are presented in tabular form. Approximately 96% of the objects in the catalog were discovered by the SDSS.
- ID:
- ivo://CDS.VizieR/J/ApJS/204/5
- Title:
- SDSS DR7 white dwarf catalog
- Short Name:
- J/ApJS/204/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of spectroscopically confirmed white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic catalog. We find 20407 white dwarf spectra, representing 19712 stars, and provide atmospheric model fits to 14120 DA and 1011 DB white dwarf spectra from 12843 and 923 stars, respectively. These numbers represent more than a factor of two increase in the total number of white dwarf stars from the previous SDSS white dwarf catalogs based on DR4 data. Our distribution of subtypes varies from previous catalogs due to our more conservative, manual classifications of each star in our catalog, supplementing our automatic fits. In particular, we find a large number of magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark broadening that would otherwise result in an overestimated logg if fit as a non-magnetic white dwarf. We calculate mean DA and DB masses for our clean, non-magnetic sample and find the DB mean mass is statistically larger than that for the DAs.
- ID:
- ivo://CDS.VizieR/J/AJ/125/1817
- Title:
- SDSS Early-Type Galaxies Catalog
- Short Name:
- J/AJ/125/1817
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of nearly 9000 early-type galaxies, in the redshift range 0.01<=z<=0.3, was selected from the Sloan Digital Sky Survey (SDSS) using morphological and spectral criteria. The paper describes how the sample was selected, presents examples of images and seeing-corrected fits to the observed surface brightness profiles, describes our method for estimating K-corrections, and shows that the SDSS spectra are of sufficiently high quality to measure velocity dispersions accurately. It also provides catalogs of the measured photometric and spectroscopic parameters. In related papers, these data are used to study how early-type galaxy observables, including luminosity, effective radius, surface brightness, color, and velocity dispersion, are correlated with one another.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/36
- Title:
- SDSS/FIRST dwarf galaxies with VLA high res. obs.
- Short Name:
- J/ApJ/888/36
- Date:
- 25 Oct 2021 10:17:58
- Publisher:
- CDS
- Description:
- We present a sample of nearby dwarf galaxies with radio-selected accreting massive black holes (BHs), the majority of which are non-nuclear. We observed 111 galaxies using sensitive, high-resolution observations from the Karl G. Jansky Very Large Array (VLA) in its most extended A-configuration at X band (~8-12GHz), yielding a typical angular resolution of ~0.25" and rms noise of ~15{mu}Jy. Our targets were selected by crossmatching galaxies with stellar masses M_*_<=3x10^9^M_{sun}_ and redshifts z<0.055 in the NASA-Sloan Atlas with the VLA Faint Images of the Radio Sky at Twenty centimeters Survey. With our new high-resolution VLA observations, we detect compact radio sources toward 39 galaxies and carefully evaluate possible origins for the radio emission, including thermal HII regions, supernova remnants, younger radio supernovae, background interlopers, and active galactic nuclei (AGNs) in the target galaxies. We find that 13 dwarf galaxies almost certainly host active massive BHs, despite the fact that only one object was previously identified as having optical signatures of an AGN. We also identify a candidate dual radio AGN in a more massive galaxy system. The majority of the radio-detected BHs are offset from the center of the host galaxies, with some systems showing signs of interactions/mergers. Our results indicate that massive BHs need not always live in the nuclei of dwarf galaxies, confirming predictions from simulations. Moreover, searches attempting to constrain BH seed formation using observations of dwarf galaxies need to account for such a population of "wandering" BHs.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A122
- Title:
- SDSS galaxies morphological classification
- Short Name:
- J/A+A/648/A122
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Machine learning methods are effective tools in astronomical tasks for classifying objects by their individual features. One of the promising utilities is related to the morphological classification of galaxies at different redshifts. We use the photometry-based approach for the SDSS data (1) to exploit five supervised machine learning techniques and define the most effective among them for the automated galaxy morphological classification; (2) to test the influence of photometry data on morphology classification; (3) to discuss problem points of supervised machine learning and labeling bias; and (4) to apply the best fitting machine learning methods for revealing the unknown morphological types of galaxies from the SDSS DR9 at z<0.1. We used different galaxy classification techniques: human labeling, multi-photometry diagrams, naive Bayes, logistic regression, support-vector machine, random forest, k-nearest neighbors. We present the results of a binary automated morphological classification of galaxies conducted by human labeling, multi-photometry, and five supervised machine learning methods. We applied it to the sample of galaxies from the SDSS DR9 with redshifts of 0.02<z<0.1 and absolute stellar magnitudes of -24mag<Mr<-19.4mag. For the analysis we used absolute magnitudes Mu, Mg, Mr, Mi, Mz; color indices Mu-Mr, Mg-Mi, Mu-Mg, Mr-Mz; and the inverse concentration index to the center R50/R90. We determined the ability of each method to predict the morphological type, and verified various dependencies of the method's accuracy on redshifts, human labeling, morphological shape, and overlap of different morphological types for galaxies with the same color indices. We find that the morphology based on the supervised machine learning methods trained over photometric parameters demonstrates significantly less bias than the morphology based on citizen-science classifiers. The support-vector machine and random forest methods with Scikit-learn software machine learning library in Python provide the highest accuracy for the binary galaxy morphological classification. Specifically, the success rate is 96.4% for support-vector machine (96.1% early E and 96.9% late L types) and 95.5% for random forest (96.7% early E and 92.8% late L types). Applying the support-vector machine for the sample of 316 031 galaxies from the SDSS DR9 at z<0.1 with unknown morphological types, we found 139659 E and 176372 L types among them.
3209. SDSS-GALEX QSO catalog
- ID:
- ivo://CDS.VizieR/J/AJ/140/1987
- Title:
- SDSS-GALEX QSO catalog
- Short Name:
- J/AJ/140/1987
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss a sample of ~60000 objects from the combined Sloan Digital Sky Survey-Galaxy Evolution Explorer (SDSS-GALEX) database with UV-optical colors that should isolate QSOs in the redshift range 0.5-1.5. We use SDSS spectra of a subsample of ~4500 to remove stellar and galaxy contaminants in the sample to a very high level, based on the 7-band photometry. We discuss the distributions of redshift, luminosity, and reddening of the 19100 QSOs (~96%) that we estimate to be present in the final sample of 19812 point sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/1274
- Title:
- SDSS-II SN Ia BVRI photometry
- Short Name:
- J/MNRAS/465/1274
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analysed multiband light curves of 328 intermediate-redshift (0.05<=z<0.24) Type Ia supernovae (SNe Ia) observed by the Sloan Digital Sky Survey-II Supernova Survey. The multiband light curves were parametrized by using the multiband stretch method, which can simply parametrize light-curve shapes and peak brightness without dust extinction models. We found that most of the SNe Ia that appeared in red host galaxies (u-r>2.5) do not have a broad light-curve width and the SNe Ia that appeared in blue host galaxies (u-r<2.0) have a variety of light-curve widths. The Kolmogorov-Smirnov test shows that the colour distribution of SNe Ia appearing in red/blue host galaxies is different (a significance level of 99.9 per cent). We also investigate the extinction law of host galaxy dust. As a result, we find that the value of Rv derived from SNe Ia with medium light-curve widths is consistent with the standard Galactic value, whereas the value of Rv derived from SNe Ia that appear in red host galaxies becomes significantly smaller. These results indicate that there may be two types of SNe Ia with different intrinsic colours, and that they are obscured by host galaxy dust with two different properties.
