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3631. SWIRE ELAIS-S1 IR-peak galaxy IR fluxes
ID:
ivo://CDS.VizieR/J/A+A/476/151
Title:
SWIRE ELAIS-S1 IR-peak galaxy IR fluxes
Short Name:
J/A+A/476/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
Main data on the IR-peakers sample in the SWIRE ELAIS-S1 field. For each IR-peak galaxy, we report R band magnitude (AB units, from the ESIS survey, Berta et al., 2006A&A...451..881B), Spitzer SWIRE fluxes (Lonsdale et al., 2003PASP..115..897L, 2004ApJS..154...54L), photometric redshift (based on Hyper-z fit, Bolzonella et al., 2000A&A...363..476B), the stellar mass and its minimal-maximal range. The stellar mass estimate is based on mixed stellar population (MSP) synthesis (Berta et al., 2004A&A...418..913B). The minimal and maximal stellar masses are obtained by exploring the SFH-extinction parameter space with the Adaptive Simulated Annealing algorithm (Ingber et al., 2001, http://www.ingber.com/asa01_lecture.pdf). See the paper associated to these data for more details.
3632. SWIRE Photometric Redshift Catalogue
ID:
ivo://CDS.VizieR/II/290
Title:
SWIRE Photometric Redshift Catalogue
Short Name:
II/290
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the SWIRE Photometric Redshift Catalogue 1025119 redshifts of unprecedented reliability and of accuracy comparable with or better than previous work. Our methodology is based on fixed galaxy and quasi-stellar object templates applied to data at 0.36-4.5um, and on a set of four infrared emission templates fitted to infrared excess data at 3.6-170um. The galaxy templates are initially empirical, but are given greater physical validity by fitting star formation histories to them, which also allows us to estimate stellar masses.
3633. SX Phe stars in Fornax. II.
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.
3634. Synchroton peak for blazars and radio galaxies
ID:
ivo://CDS.VizieR/J/ApJ/740/98
Title:
Synchroton peak for blazars and radio galaxies
Short Name:
J/ApJ/740/98
Date:
21 Oct 2021
Publisher:
CDS
Description:
We revisit the concept of a blazar sequence that relates the synchrotron peak frequency ({nu}_peak_) in blazars with synchrotron peak luminosity (L_peak_, in {nu}L_{nu}_) using a large sample of radio-loud active galactic nuclei. We present observational evidence that the blazar sequence is formed from two populations in the synchrotron {nu}_peak_-L_peak_ plane, each forming an upper edge to an envelope of progressively misaligned blazars, and connecting to an adjacent group of radio galaxies having jets viewed at much larger angles to the line of sight. When binned by jet kinetic power (L_kin_; as measured through a scaling relationship with extended radio power), we find that radio core dominance decreases with decreasing synchrotron L_peak_, revealing that sources in the envelope are generally more misaligned. We find population-based evidence of velocity gradients in jets at low kinetic powers (~10^42^-10^44.5^erg/s), corresponding to Fanaroff-Riley (FR) I radio galaxies and most BL Lac objects. These low jet power "weak-jet" sources, thought to exhibit radiatively inefficient accretion, are distinguished from the population of non-decelerating, low synchrotron-peaking (LSP) blazars and FR II radio galaxies ("strong" jets) which are thought to exhibit radiatively efficient accretion. The two-population interpretation explains the apparent contradiction of the existence of highly core-dominated, low-power blazars at both low and high synchrotron peak frequencies, and further implies that most intermediate synchrotron peak sources are not intermediate in intrinsic jet power between LSP and high synchrotron-peaking (HSP) sources, but are more misaligned versions of HSP sources with similar jet powers.
3635. Synthetic absorption in star forming regions
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.
3636. Synthetic galaxy spectra
ID:
ivo://CDS.VizieR/J/A+A/538/A38
Title:
Synthetic galaxy spectra
Short Name:
J/A+A/538/A38
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an optimized library of synthetic galaxy spectra that are to be used for the Gaia satellite observations of unresolved galaxies. These galaxy spectral templates are useful for the optimal performance of the unresolved galaxy classifier (UGC) software. The UGC will assign spectral classes to the observed unresolved galaxies by Gaia (classification) and estimate some of their intrinsic astrophysical parameters, which were used to create the synthetic library (parametrization). We present the new optimized synthetic library of galaxy spectra and the classification and parametrization results using the Gaia-simulated version of this library. To optimize our synthetic library, we applied the principal component analysis (PCA) method to our synthetic spectra and studied the influence of the star-formation rate parameters on the spectra, and how these agree with some typical characteristics of the galaxy spectral types. We used support vector machines (SVM) to classify and parametrize the optimal simulated spectra. The library of synthetic galaxy spectra was optimized. In this new set of synthetic spectra, overlaps in spectral energy distributions and colors are highly suppressed, while the results of UGC classification are improved.
3637. Synthetic supernova extinction curves
ID:
ivo://CDS.VizieR/J/MNRAS/412/1070
Title:
Synthetic supernova extinction curves
Short Name:
J/MNRAS/412/1070
Date:
21 Oct 2021
Publisher:
CDS
Description:
We apply the supernova (SN) extinction curves to reproduce the observed properties of SST J1604+4304 which is a young infrared (IR) galaxy at z~1. The SN extinction curves used in this work were obtained from models of unmixed ejecta of Type II supernovae for the Salpeter initial mass function with a mass range from 8 to 30M_{sun}_ or 8 to 40M_{sun}_. The effect of dust distributions on the attenuation of starlight is investigated by performing the {chi}^2^ fitting method against various dust distributions. These are the commonly used uniform dust screen, the clumpy dust screen and the internal dust geometry. We add to these geometries three scattering properties, namely, no scattering, isotropic scattering and forward-only scattering. Judging from the {chi}^2^ values, we find that the uniform screen models with any scattering property provide good approximations to the real dust geometry.
3638. Systematic search for M31 novae from Schmidt plates
ID:
ivo://CDS.VizieR/J/A+A/477/67
Title:
Systematic search for M31 novae from Schmidt plates
Short Name:
J/A+A/477/67
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper reports on the detection of optical novae in our neighbour galaxy M 31 based on digitized historical Tautenburg Schmidt plates. The accurate positions of the detected novae lead to a much larger database when searching for recurrent novae in M 31. We conducted a systematic search for novae on 306 digitized Tautenburg Schmidt plates covering a time span of 36 years from 1960 to 1996. From the database of both ~3x10^5^ light curves and >~10^6^ detections on only one plate per colour band, nova candidates were efficiently selected by automated algorithms and subsequently individually inspected by eye. We report the detection of 84 nova candidates.
3639. Tadpole galaxies in the Hubble UDF
ID:
ivo://CDS.VizieR/J/ApJ/639/724
Title:
Tadpole galaxies in the Hubble UDF
Short Name:
J/ApJ/639/724
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the Hubble Ultra Deep Field (HUDF, Cat. <II/258>) an abundance of galaxies is seen with a knot at one end plus an extended tail, resembling a tadpole. These "tadpole galaxies" appear dynamically unrelaxed - presumably in an early merging stage - where tidal interactions likely created the distorted knot-plus-tail morphology. Here we systematically select tadpole galaxies from the HUDF and study their properties as a function of their photometric redshifts.
3640. Taffy system CO(1-0) datacube
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.