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- ID:
- ivo://CDS.VizieR/J/A+A/544/A81
- Title:
- Supernovae and their hosts in the SDSS DR8
- Short Name:
- J/A+A/544/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the creation of large and well-defined database that combines extensive new measurements and a literature search of 3876 supernovae (SNe) and their 3679 host galaxies located in the sky area covered by the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). This database should be much larger than previous ones, and should contain a homogenous set of global parameters of SN hosts, including morphological classifications and measures of nuclear activity. Identification of the host galaxy sample is 91% complete (with 3536 SNe in 3340 hosts), of which the SDSS names of ~1100 anonymous hosts are listed for the first time. The morphological classification is available for 2104 host galaxies, including 73 (56) hosts in interacting (merging) systems. The total sample of host galaxies collects heliocentric redshifts for 3317 (~90%) galaxies. The g-band magnitudes, D_25_, b/a, and PA are available for 2030 hosts of the morphologically classified sample of galaxies. Nuclear activity measures are provided for 1189 host galaxies. We analyze and discuss many selection effects and biases that can significantly affect any future analysis of our sample. The creation of this large database will help to better understand how the different types of SNe are correlated with the properties of the nuclei and global physical parameters of the host galaxies, and minimize possible selection effects and errors that often arise when data are selected from different sources and catalogues.
- ID:
- ivo://CDS.VizieR/J/ApJS/214/19
- Title:
- Suprime-Cam wide-field photometry of Leo A
- Short Name:
- J/ApJS/214/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have surveyed a complete extent of Leo A --an apparently isolated gas-rich low-mass dwarf irregular galaxy in the Local Group. The B, V, and I passband CCD images (typical seeing ~0.8") were obtained with the Subaru Telescope equipped with the Suprime-Cam mosaic camera. The wide-field (20'x24') photometry catalog of 38856 objects (V~16-26mag) is presented. This survey is also intended to serve as "a finding chart" for future imaging and spectroscopic observation programs of Leo A.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/73
- Title:
- Surface density profiles of GOODS-South galaxies
- Short Name:
- J/ApJ/763/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar mass surface density profiles of a mass-selected sample of 177 galaxies at 0.5<z<2.5, obtained using very deep Hubble Space Telescope optical and near-infrared data over the GOODS-South field, including recent CANDELS data. Accurate stellar mass surface density profiles have been measured for the first time for a complete sample of high-redshift galaxies more massive than 10^10.7^M_{sun}_. The key advantage of this study compared to previous work is that the surface brightness profiles are deconvolved for point-spread function smoothing, allowing accurate measurements of the structure of the galaxies. The surface brightness profiles account for contributions from complex galaxy structures such as rings and faint outer disks. Mass profiles are derived using radial rest-frame ug color profiles and a well-established empirical relation between these colors and the stellar mass-to-light ratio. We derive stellar half-mass radii from the mass profiles, and find that these are on average ~25% smaller than rest-frame g-band half-light radii. This average size difference of 25% is the same at all redshifts, and does not correlate with stellar mass, specific star formation rate, effective surface density, S\'ersic index, or galaxy size. Although on average the difference between half-mass size and half-light size is modest, for approximately 10% of massive galaxies this difference is more than a factor of two. These extreme galaxies are mostly extended, disk-like systems with large central bulges. These results are robust, but could be impacted if the central dust extinction becomes high. ALMA observations can be used to explore this possibility. These results provide added support for galaxy growth scenarios wherein massive galaxies at these epochs grow by accretion onto their outer regions.
- ID:
- ivo://CDS.VizieR/J/ApJS/156/345
- Title:
- Surface photometry of BCD galaxies
- Short Name:
- J/ApJS/156/345
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from an analysis of surface photometry of B, R, and H{alpha} images of a total of 114 nearby galaxies (v_helio_<4000km/s) drawn from the Palomar/Las Campanas Imaging Atlas of blue compact dwarf (BCD) galaxies. Surface brightness and color profiles for the complete sample have been obtained. We determine the exponential and Sersic profiles that best fit the surface brightness distribution of the underlying stellar population detected in these galaxies. We also compute the (B-R) color and total absolute magnitude of the underlying stellar population and compared them to the integrated properties of the galaxies in the sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/123
- Title:
- Swift optical & UV flux of four AGNs
- Short Name:
- J/ApJ/870/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Swift intensive accretion disk reverberation mapping of four AGN yielded light curves sampled ~200-350 times in 0.3-10keV X-ray and six UV/optical bands. Uniform reduction and cross-correlation analysis of these data sets yields three main results: (1) The X-ray/UV correlations are much weaker than those within the UV/optical, posing severe problems for the lamp-post reprocessing model in which variations in a central X-ray corona drive and power those in the surrounding accretion disk. (2) The UV/optical interband lags are generally consistent with {tau}{propto}{lambda}^4/3^ as predicted by the centrally illuminated thin accretion disk model. While the average interband lags are somewhat larger than predicted, these results alone are not inconsistent with the thin disk model given the large systematic uncertainties involved. (3) The one exception is the U band lags, which are on average a factor of ~2.2 larger than predicted from the surrounding band data and fits. This excess appears to be due to diffuse continuum emission from the broad-line region (BLR). The precise mixing of disk and BLR components cannot be determined from these data alone. The lags in different AGN appear to scale with mass or luminosity. We also find that there are systematic differences between the uncertainties derived by Just Another Vehicle for Estimating Lags In Nuclei (JAVELIN) versus more standard lag measurement techniques, with JAVELIN reporting smaller uncertainties by a factor of 2.5 on average. In order to be conservative only standard techniques were used in the analyses reported herein.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/1636
- Title:
- Swift/UVOT sources in NGC4321 (M100)
- Short Name:
- J/MNRAS/424/1636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the star-forming regions in the spiral galaxy NGC 4321 (M100). We take advantage of the spatial resolution (2.5-arcsec full width at half-maximum) of the Swift/Ultraviolet/Optical Telescope camera and the availability of three ultraviolet (UV) passbands in the region 1600<{lambda}<3000{AA}, in combination with optical and infrared (IR) imaging from Sloan Digital Sky Survey, KPNO/H{alpha} and Spitzer/IRAC, to obtain a catalogue of 787 star-forming regions out to three disc scalelengths. We use a large volume of star formation histories, combined with stellar population synthesis, to determine the properties of the young stellar component and its relationship with the spiral arms.
- ID:
- ivo://CDS.VizieR/J/ApJ/685/947
- Title:
- SX Phe stars in Fornax. II.
- Short Name:
- J/ApJ/685/947
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out an intensive survey of the northern region of the Fornax dwarf spheroidal galaxy with the aim of detecting the galaxy's short-period pulsating stars (P<0.25 days). Observations collected over three consecutive nights with the Wide Field Imager of the 2.2m MPI telescope at ESO allowed us to detect 85 high-amplitude (0.20-1.00mag in B light) variable stars with periods in the range from 0.046 to 0.126 days, similar to SX Phoenicis stars in Galactic metal-poor stellar populations. The plots of the observed periods vs. the B and V magnitudes show a dispersion largely exceeding the observational errors. To disentangle the matter, we separated the first-overtone from the fundamental-mode pulsators and tentatively identified a group of subluminous variables, about 0.35mag fainter than the others. Their nature as either metal-poor intermediate-age stars or stars formed by the merging of close binary systems is discussed. The rich sample of the Fornax variables also led us to reconstruct the period-luminosity relation for short-period pulsating stars. An excellent linear fit, M_V_=-1.83(+/-0.08)-3.65(+/-0.07)logP_F_, was obtained using 153 {delta} Scuti and SX Phoenicis stars in a number of different stellar systems.
- ID:
- ivo://CDS.VizieR/J/A+AS/111/57
- Title:
- Synthetic absorption in star forming regions
- Short Name:
- J/A+AS/111/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral evolutionary calculations have been employed in order to follow the behaviour of absorption lines in single-burst star forming regions. The model calculations are based on theoretical evolutionary tracks and model atmosphere stellar spectra at 5A resolution and they include the pre-main sequence phase. Three different metallicities have been considered; Z=0.001, 0.008 and 0.020, this range covers easily the one occupied by blue compact dwarf galaxies. This analysis focuses on the post-active burst phase and follows the evolution up to 15 million years after the episode of star formation has ceased, using an instantaneous burst of star formation. The absorption lines included are hydrogen, neutral and once ionized helium. Non-LTE absorption line profiles have been implemented to these lines, also at a 5A resolution. The equivalent widths and line profiles are studied as a function of lower and upper mass limits and slope of the mass function as well as the age. It is shown that the equivalent widths of the Balmer lines are increasing during the course of evolution, while the strength of the neutral and ionized helium lines decreases monotonically. Both the hydrogen and helium lines show high sensitivity to variations in the initial mass function (IMF). The Balmer line equivalent widths range from about 1.5 to 6.5A, depending on the IMF parameters used. As anticipated, these numbers are rather insensitive to the metallicity. Contrary to what has been claimed, the Balmer lines are prominent even if the lower mass limit is as high as 10M_{sun}_. It has been proposed that the weak hydrogen lines sometimes seen in starburst galaxies, often interpreted as evidence for a deficiency in low mass stars, could be due to the finite lifetimes of pre-main sequence stars. This analysis shows that it is very much dependent on the slope of the mass function. The equivalent width of the HeI-4471A line never exceeds 0.35A for any choice of the IMF parameters while the equivalent width of the HeII-4686A line reaches at the most 0.20A using the most top-heavy IMF. As expected, these numbers are only slightly dependent on the metallicity in the optical spectral region.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A138
- Title:
- Taffy system CO(1-0) datacube
- Short Name:
- J/A+A/647/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Taffy system (UGC 12914/15) consists of two massive spiral galaxies which had a head-on collision about 20Myr ago. New sensitive, high-resolution CO(1-0) observations of the Taffy system with the IRAM PdBI are presented. About 25% of the total interferometric CO luminosity stems from the bridge region. Assuming a Galactic N(H2)/ICO conversion factor for the galactic disks and a third of this value for the bridge gas, about 10% of the molecular gas mass is located in the bridge region. The giant HII region close to UGC 12915 is located at the northern edge of the high-surface brightness giant molecular cloud association (GMA), which has the highest velocity dispersion among the bridge GMAs. The bridge GMAs are clearly not virialized because of their high velocity dispersion. Three dynamical models are presented and while no single model reproduces all of the observed features, they are all present in at least one of the models. Most of the bridge gas detected in CO does not form stars. We suggest that turbulent adiabatic compression is responsible for the exceptionally high velocity dispersion of the molecular ISM and the suppression of star formation in the Taffy bridge. In this scenario the turbulent velocity dispersion of the largest eddies and turbulent substructures/clouds increase such that giant molecular clouds are no longer in global virial equilibrium. The increase of the virial parameter leads to a decrease of the star formation efficiency. Most of the low-surface density, CO-emitting gas will disperse without forming stars but some of the high-density gas will probably collapse and form dense star clusters, such as the luminous HII region close to UGC 12915. We suggest that globular clusters and super star clusters formed and still form through the gravitational collapse of gas previously compressed by turbulent adiabatic compression during galaxy interactions.