- ID:
- ivo://CDS.VizieR/J/other/AstBu/68.243
- Title:
- Star formation in isolated galaxies
- Short Name:
- J/other/AstBu/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the FUV fluxes measured with the GALEX to study the star formation properties of galaxies collected in the Local Orphan Galaxies catalog (LOG, 2011AstBu..66....1K). Among 517 LOG galaxies having radial velocities V_LG_<3500km/s and Galactic latitudes |b|>15{deg}, 428 objects have been detected in FUV. We briefly discuss some scaling relations between the specific star formation rate (SSFR) and stellar mass, HI-mass, morphology, and surface brightness of galaxies situated in extremely low density regions of the Local Supercluster. Our sample is populated with predominantly late-type, gas-rich objects with the median morphological type of Sdm. Only 5% of LOG galaxies are classified as early types: E, S0, S0/a, however, they systematically differ from normal E and S0 galaxies by lower luminosity and presence of gas and dust. We find that almost all galaxies in our sample have their SSFR below 0.4Gyr^-1^. This limit is also true even for a sample of 260 active star-burst Markarian galaxies situated in the same volume. The existence of such a quasi-Eddington limit for galaxies seems to be a key factor which characterizes the transformation of gas into stars at the current epoch.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/619/L95
- Title:
- Star formation in Stephan's Quintet
- Short Name:
- J/ApJ/619/L95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first Galaxy Evolution Explorer (GALEX) UV images of the well-known interacting group of galaxies, Stephan's Quintet (SQ). We detect widespread UV emission throughout the group. However, there is no consistent coincidence between UV structure and emission in the optical, H{alpha}, or HI. Excluding the foreground galaxy NGC 7320 (Sd), most of the UV emission is found in regions associated with the two spiral members of the group, NGC 7319 and NGC 7318b, and the intragroup medium starburst SQ-A. The extinction-corrected UV data are analyzed to investigate the overall star formation activity in SQ.
- ID:
- ivo://CDS.VizieR/J/ApJ/814/95
- Title:
- Star formation rate of 4<~z<~8 galaxies
- Short Name:
- J/ApJ/814/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent observations have shown that the characteristic luminosity of the rest-frame ultraviolet (UV) luminosity function does not significantly evolve at 4<z<7 and is approximately M_UV_^*^~21. We investigate this apparent non-evolution by examining a sample of 173 bright, M_UV_<-21 galaxies at z=4-7, analyzing their stellar populations and host halo masses. Including deep Spitzer/IRAC imaging to constrain the rest-frame optical light, we find that M_UV_^*^ galaxies at z=4-7 have similar stellar masses of log(M/M_{sun}_)=9.6-9.9 and are thus relatively massive for these high redshifts. However, bright galaxies at z=4-7 are less massive and have younger inferred ages than similarly bright galaxies at z=2-3, even though the two populations have similar star formation rates and levels of dust attenuation for a fixed dust-attenuation curve. Matching the abundances of these bright z=4-7 galaxies to halo mass functions from the Bolshoi {Lambda}CDM simulation implies that the typical halo masses in ~M_UV_^*^ galaxies decrease from log(M_h_/M_{sun}_)=11.9 at z=4 to log(M_h_/M_{sun}_)=11.4 at z=7. Thus, although we are studying galaxies at a similar stellar mass across multiple redshifts, these galaxies live in lower mass halos at higher redshift. The stellar baryon fraction in ~M_UV_^*^ galaxies in units of the cosmic mean {Omega}_b_/{Omega}_m_ rises from 5.1% at z=4 to 11.7% at z=7; this evolution is significant at the ~3{sigma} level. This rise does not agree with simple expectations of how galaxies grow, and implies that some effect, perhaps a diminishing efficiency of feedback, is allowing a higher fraction of available baryons to be converted into stars at high redshifts.
- ID:
- ivo://CDS.VizieR/J/AJ/138/1203
- Title:
- Star formation regions in nearby dwarf galaxies
- Short Name:
- J/AJ/138/1203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare star formation in the inner and outer disks of 11 dwarf irregular galaxies (dIm) within 3.6Mpc. The regions are identified on Galaxy Evolution Explorer near-UV images, and modeled with UV, optical, and near-IR colors to determine masses and ages. A few galaxies have made 10^5^-10^6^M_{sun}_ complexes in a starburst phase, while others have not formed clusters in the last 50Myr. The maximum region mass correlates with the number of regions as expected from the size-of-sample effect. We find no radial gradients in region masses and ages, even beyond the realm of H{alpha} emission, although there is an exponential decrease in the luminosity density and number density of the regions with radius. H{alpha} is apparently lacking in the outer parts only because nebular emission around massive stars is too faint to see. The outermost regions for the five galaxies with HI data formed at average gas surface densities of 1.9-5.9M_{sun}/pc^2^.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/86
- Title:
- Star-forming galaxies in ACO 2029
- Short Name:
- J/ApJ/773/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dense environments are known to quench star formation in galaxies, but it is still unknown what mechanism(s) are directly responsible. In this paper, we study the star formation of galaxies in A2029 and compare it to that of Coma, combining indicators at 24{mu}m, H{alpha}, and UV down to rates of 0.03M_{sun}_/yr. We show that A2029's star-forming galaxies follow the same mass-SFR relation as the field. The Coma cluster, on the other hand, has a population of galaxies with star formation rates (SFRs) significantly lower than the field mass-SFR relation, indicative of galaxies in the process of being quenched. Over half of these galaxies also host active galactic nuclei. Ram-pressure stripping and starvation/strangulation are the most likely mechanisms for suppressing the star formation in these galaxies, but we are unable to disentangle which is dominating. The differences we see between the two clusters' populations of star-forming galaxies may be related to their accretion histories, with A2029 having accreted its star-forming galaxies more recently than Coma. Additionally, many early-type galaxies in A2029 are detected at 24{mu}m and/or in the far-UV, but this emission is not directly related to star formation. Similar galaxies have probably been classified as star forming in previous studies of dense clusters, possibly obscuring some of the effects of the cluster environment on true star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1360
- Title:
- Star-forming knots in NGC 4194 center
- Short Name:
- J/AJ/127/1360
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report high-resolution ultraviolet and visible-wavelength imaging of the blue compact galaxy NGC 4194 (the Medusa) using the Hubble Space Telescope. A complete sample of 38 UV-bright knots is identified.
- ID:
- ivo://CDS.VizieR/J/A+A/521/A8
- Title:
- Star-forming regions in NGC 2903 bar
- Short Name:
- J/A+A/521/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nearby barred spiral NGC 2903 has an active starburst at its centre and HII regions distributed along its bar. We analyse the star-formation properties in the bar region of NGC 2903 and study its links to the typical bar morphological features. We combine space and ground-based data from the far-ultraviolet to the sub-millimeter spectral ranges to create a panchromatic view of the NGC 2903 bar. We produce two catalogues: one for the current star-formation regions, as traced by the H{alpha} compact emission, and a second for the ultraviolet (UV) emitting knots, containing positions and luminosities. From them, we obtain ultraviolet colours, star-formation rates, dust attenuation, and H{alpha} EWs, and analyse their spatial distribution. We estimate stellar cluster ages using stellar population synthesis models (Starburst99).
- ID:
- ivo://CDS.VizieR/III/53
- Title:
- Stars classified from S2/68 UV line features
- Short Name:
- III/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog provides the spectral classifications of 1900 stars from the papers listed in References. The classifications were made from spectra obtained by the S2/68 sky survey telescope experiment aboard the TD1 satellite.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/66
- Title:
- Stripe 82X survey multiwavelength catalog
- Short Name:
- J/ApJ/850/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiwavelength surveys covering large sky volumes are necessary to obtain an accurate census of rare objects such as high-luminosity and/or high-redshift active galactic nuclei (AGNs). Stripe 82X is a 31.3 X-ray survey with Chandra and XMM-Newton observations overlapping the legacy Sloan Digital Sky Survey Stripe 82 field, which has a rich investment of multiwavelength coverage from the ultraviolet to the radio. The wide-area nature of this survey presents new challenges for photometric redshifts for AGNs compared to previous work on narrow-deep fields because it probes different populations of objects that need to be identified and represented in the library of templates. Here we present an updated X-ray plus multiwavelength matched catalog, including Spitzer counterparts, and estimated photometric redshifts for 5961 (96% of a total of 6181) X-ray sources that have a normalized median absolute deviation, {sigma}_nmad_=0.06, and an outlier fraction, {eta}=13.7%. The populations found in this survey and the template libraries used for photometric redshifts provide important guiding principles for upcoming large-area surveys such as eROSITA and 3XMM (in X-ray) and the Large Synoptic Survey Telescope (optical).
- ID:
- ivo://CDS.VizieR/J/ApJS/247/12
- Title:
- Strong lens models for 37 clusters from SGAS
- Short Name:
- J/ApJS/247/12
- Date:
- 08 Mar 2022 13:45:09
- Publisher:
- CDS
- Description:
- We present strong gravitational lensing models for 37 galaxy clusters from the Sloan Digital Sky Survey Giant Arcs Survey (SGAS). We combine data from multi-band Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging, with ground-based imaging and spectroscopy from Magellan, Gemini, Apache Point Observatory, and the Multiple Mirror Telescope, in order to detect and spectroscopically confirm new multiply imaged lensed background sources behind the clusters. We report spectroscopic or photometric redshifts of sources in these fields, including cluster galaxies and background sources. Based on all available lensing evidence, we construct and present strong-lensing mass models for these galaxy clusters. The clusters span a redshift range of 0.176<z<0.66 with a median redshift of z=0.45, and sample a wide range of dynamical masses, 1.5<M_200_<35x10^14^M_{sun}_, as estimated from their velocity dispersions. As these clusters were selected as lenses primarily owing to a fortuitous alignment with background galaxies that results in giant arcs, they exhibit a wide range in Einstein radii, 1.3"<{theta}_E_<23.1" for a source at z=2, with a median {theta}_E_=10.8".
