- ID:
- ivo://CDS.VizieR/J/MNRAS/412/727
- Title:
- SDSS red gal. automated morph. classification
- Short Name:
- J/MNRAS/412/727
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the last decade, the advent of enormous galaxy surveys has motivated the development of automated morphological classification schemes to deal with large data volumes. Existing automated schemes can successfully distinguish between early- and late-type galaxies and identify merger candidates, but are inadequate for studying detailed morphologies of red sequence galaxies. To fill this need, we present a new automated classification scheme that focuses on making finer distinctions between early types roughly corresponding to Hubble types E, S0 and Sa. We visually classify a sample of 984 non-star-forming Sloan Digital Sky Survey galaxies with apparent sizes >14-arcsec. We then develop an automated method to closely reproduce the visual classifications, which both provides a check on the visual results and makes it possible to extend morphological analysis to much larger samples. We visually classify the galaxies into three bulge classes (BC) by the shape of the light profile in the outer regions: discs have sharp edges and bulges do not, while some galaxies are intermediate. We separately identify galaxies with features: spiral arms, bars, clumps, rings and dust.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/850/140
- Title:
- SDSS spectral analysis of IR-bright DOGs
- Short Name:
- J/ApJ/850/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the ionized gas properties of infrared (IR)-bright dust-obscured galaxies (DOGs) that show an extreme optical/IR color, (i-[22])_AB_>7.0, selected with the Sloan Digital Sky Survey (SDSS) and Wide-field Infrared Survey Explorer (WISE). For 36 IR-bright DOGs that show [OIII]{lambda}5007 emission in the SDSS spectra, we performed a detailed spectral analysis to investigate their ionized gas properties. In particular, we measured the velocity offset (the velocity with respect to the systemic velocity measured from the stellar absorption lines) and the velocity dispersion of the [OIII] line. We found that the derived velocity offset and dispersion of most IR-bright DOGs are larger than those of Seyfert 2 galaxies (Sy2s) at z<0.3, meaning that the IR-bright DOGs show relatively strong outflows compared to Sy2s. This can be explained by the difference in IR luminosity contributed from active galactic nuclei, L_IR_ (AGN), because we found that (i) L_IR_ (AGN) correlates with the velocity offset and dispersion of [OIII] and (ii) our IR-bright DOG sample has larger L_IR_ (AGN) than Sy2s. Nevertheless, the fact that about 75% IR- bright DOGs have a large (>300km/s) velocity dispersion, which is a larger fraction compared to other AGN populations, suggests that IR-bright DOGs are good laboratories to investigate AGN feedback. The velocity offset and dispersion of [OIII] and [NeIII]{lambda}3869 are larger than those of [OII]{lambda}3727, which indicates that the highly ionized gas tends to show stronger outflows.
- ID:
- ivo://CDS.VizieR/J/ApJ/758/1
- Title:
- SDSS-Spitzer AGN properties
- Short Name:
- J/ApJ/758/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from the Sloan Digital Sky Survey (SDSS) and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic contributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [Ne II] 12.8{mu}m emission line is well correlated with the star formation rate measured from the SDSS spectra, and this holds for the star-forming, composite, and AGN-dominated systems. AGNs show a clear excess of [Ne III] 15.6{mu}m emission relative to star-forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including the mid-IR spectral slope, the ratio of the [Ne V] 14.3{mu}m to [Ne II] 12.8{mu}m fluxes, the equivalent widths of the 7.7{mu}m, 11.3{mu}m, and 17{mu}m polycyclic aromatic hydrocarbon (PAH) features, and the optical "D" parameter which measures the distance at which a source lies from the locus of star-forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN dominance. We find that the PAH 11.3{mu}m feature is significantly suppressed in the most AGN-dominated systems.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A71
- Title:
- 209276 SDSS star-forming galaxies aperture-free
- Short Name:
- J/A+A/599/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Large area surveys with a high number of galaxies observed have undoubtedly marked a milestone in the understanding of several properties of galaxies, such as star-formation history, morphology, and metallicity. However, in many cases, these surveys provide fluxes from fixed small apertures (e.g. fibre), which cover a scant fraction of the galaxy, compelling us to use aperture corrections to study the global properties of galaxies. In this work, we derive the current total star formation rate (SFR) of Sloan Digital Sky Survey (SDSS) star-forming galaxies, using an empirically based aperture correction of the measured H{alpha} flux for the first time, thus minimising the uncertainties associated with reduced apertures. All the H{alpha} fluxes have been extinction-corrected using the H{alpha}/H{beta} ratio free from aperture effects. The total SFR for ~210000 SDSS star-forming galaxies has been derived applying pure empirical H{alpha} and H{alpha}/H{beta} aperture corrections based on the Calar Alto Legacy Integral Field Area (CALIFA) survey. We find that, on average, the aperture-corrected SFR is ~0.65dex higher than the SDSS fibre-based SFR. The relation between the SFR and stellar mass for SDSS star-forming galaxies (SFR-M*) has been obtained, together with its dependence on extinction and H{alpha} equivalent width. We compare our results with those obtained in previous works and examine the behaviour of the derived SFR in six redshift bins, over the redshift range 0.005<=z<=0.22. The SFR-M* sequence derived here is in agreement with selected observational studies based on integral field spectroscopy of individual galaxies as well as with the predictions of recent theoretical models of disc galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A33
- Title:
- SDSS star-forming galaxies multi-wavelength study
- Short Name:
- J/A+A/561/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied a large sample of ~14000 dwarf star-forming galaxies with strong emission lines. These low-metallicity galaxies with oxygen abundances of 12+logO/H~7.4-8.5 are selected from the Sloan Digital Sky Survey (SDSS) and distributed in the redshift range of z~0-0.6. We modelled spectral energy distributions (SED) of all galaxies, which were based on the SDSS spectra in the visible range of 0.38{mu}m-0.92{mu}m and included both the stellar and ionised gas emission. These SEDs were extrapolated to the UV and mid-infrared ranges to cover the wavelength range of 0.1{mu}m-22{mu}m. The SDSS spectroscopic data were supplemented by photometric data from the GALEX, SDSS, 2MASS, WISE, IRAS, and NVSS all-sky surveys. Using these data, we derived global characteristics of the galaxies, such as their element abundances, luminosities, and stellar masses.
- ID:
- ivo://CDS.VizieR/J/ApJS/145/245
- Title:
- SDSS stars in Draco dwarf spheroidal galaxy
- Short Name:
- J/ApJS/145/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sloan Digital Sky Survey (SDSS, Stoughton et al., 2002AJ....123..485S) has scanned the entire region containing the Draco dwarf spheroidal galaxy to 23mag in g*. We present a catalog of stars found in a 453 arcmin^2^, elliptical region centered on the Draco dwarf spheroidal galaxy. Objects in the catalog are matched with five previously published catalogs. The catalog contains SDSS photometry for 5634 individual objects, and also the photometry from matches to any of the other catalogs. A comparison of the photometry between catalogs allows us to identify 142 candidate variable objects. One hundred and twelve of the suspected variables have colors consistent with RR Lyrae variables.
- ID:
- ivo://CDS.VizieR/J/ApJS/153/429
- Title:
- SDSS strong emission line HII galaxies
- Short Name:
- J/ApJS/153/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first edition of the SDSS HII galaxies with Oxygen abundances Catalog (SHOC), which is a listing of strong emission-line galaxies (ELGs) from the Sloan Digital Sky Survey (SDSS, see http://www.sdss.org). We present 612 SDSS emission-line galaxies (624 separate SDSS targets in total), for which the oxygen abundances 12+log(O/H) have rms uncertainties <=0.20dex. The subsample of 263 ELGs (272 separate SDSS targets) have an uncertainty <=0.10dex, while 459 ELGs (470 separate SDSS targets) have an uncertainty <=0.15dex. The catalog includes the main parameters of all selected ELGs, the intensities and equivalent widths of hydrogen and oxygen emission lines, as well as oxygen abundances with their uncertainties. The information on the presence of Wolf-Rayet blue and/or red bumps in 109 galaxies is also included. With the use of combined g, r, i SDSS images we performed visual morphological classification of all SHOC galaxies. Four hundred sixty-one galaxies (75%) are classified as confident or probable blue compact galaxies (BCG/BCG?), 78 as irregular ones, 20 as low surface brightness galaxies (LSBG), 10 as obviously interacting, and 43 as spiral galaxies. In creating the catalog, 30 narrow-line active galactic nuclei and 69 LINERs were also identified; these are also presented apart of the main catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A155
- Title:
- SDSS surface photometry of M31
- Short Name:
- J/A+A/526/A155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The objective of this work is to obtain an extinction-corrected distribution of optical surface brightness and colour indices of the large nearby galaxy M31 using homogeneous observational data and a model for intrinsic extinction. We process the Sloan Digital Sky Survey (SDSS) images in ugriz passbands and construct corresponding mosaic images, taking special care of subtracting the varying sky background. We apply the galactic model developed in Tempel et al. (2010A&A...509A..91T) and far-infrared imaging to correct the photometry for intrinsic dust effects. We obtain observed and dust-corrected distributions of the surface brightness of M31 and a map of line-of-sight extinctions inside the galaxy. Our extinction model suggests that either M31 is intrinsically non-symmetric along the minor axis or the dust properties differ from those of the Milky Way. Assuming the latter case, we present the surface brightness distributions and integral photometry for the Sloan filters as well as the standard UBVRI system.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/82
- Title:
- SDSS, WISE and HI data of local spiral galaxies
- Short Name:
- J/ApJ/884/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The emerging light from a galaxy is under the influence of its own interstellar medium, as well as its spatial orientation. Considering a sample of 2239 local spiral galaxies in optical (Sloan Digital Sky Survey u, g, r, i, and z) and infrared bands (WISE W1, W1), we study the dependency of the global intrinsic attenuation in spiral galaxies on their morphologies, sizes, and spatial inclinations. Reddening is minimal at the extremes of low mass and gas depletion and maximal in galaxies that are relatively massive and metal-rich and still retain substantial gas reserves. A principal component constructed from observables that monitor galaxy mass, relative H i content to old stars, and infrared surface brightness is strongly correlated with the amplitude of obscuration. We determine both a parametric model for dust obscuration and a nonparametric model based on the Gaussian process formalism. An average dust attenuation curve is derived for wavelengths between 0.36 and 4.5{mu}m.
- ID:
- ivo://CDS.VizieR/J/ApJ/782/45
- Title:
- SEAMBHs. I. Mrk 142, Mrk 335, and IRAS F12397+3333
- Short Name:
- J/ApJ/782/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report first results from a large project to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). Such objects may be different from other AGNs in being powered by slim accretion disks and showing saturated accretion luminosities, but both are not yet fully understood. The results are part of a large reverberation mapping (RM) campaign using the 2.4m Shangri-La telescope at the Yunnan Observatory in China. The goals are to investigate the gas distribution near the BH and the properties of the central accretion disks, to measure BH mass and Eddington ratios, and to test the feasibility of using such objects as a new type of cosmological candles. The paper presents results for three objects, Mrk 335, Mrk 142, and IRAS F12397+3333, with H{beta} time lags relative to the 5100{AA} continuum of 10.6_-2.9_^+1.7^, 6.4_-2.2_^+0.8^ and 11.4_-1.9_^+2.9^ days, respectively. The corresponding BH masses are (8.3_-3.2_^+2.6^)x10^6^M_{sun}_, (3.4_-1.2_^+0.5^)x10^6^M_{sun}_, and (7.5_-4.1_^+4.3^x10^6^M_{sun}_, and the lower limits on the Eddington ratios are 0.6, 2.3, and 4.6 for the minimal radiative efficiency of 0.038. Mrk 142 and IRAS F12397+333 (extinction corrected) clearly deviate from the currently known relation between H{beta} lag and continuum luminosity. The three Eddington ratios are beyond the values expected in thin accretion disks and two of them are the largest measured so far among objects with RM-based BH masses. We briefly discuss implications for slim disks, BH growth, and cosmology.
