- ID:
- ivo://CDS.VizieR/J/other/Sci/348.418
- Title:
- Isolated compact elliptical galaxies
- Short Name:
- J/other/Sci/348.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compact elliptical galaxies form a rare class of stellar system (~30 presently known) characterized by high stellar densities and small sizes and often harboring metal-rich stars. They were thought to form through tidal stripping of massive progenitors, until two isolated objects were discovered where massive galaxies performing the stripping could not be identified. By mining astronomical survey data, we have now found 195 compact elliptical galaxies in all types of environment. They all share similar dynamical and stellar population properties. Dynamical analysis for nonisolated galaxies demonstrates the feasibility of their ejection from host clusters and groups by three-body encounters, which is in agreement with numerical simulations. Hence, isolated compact elliptical and isolated quiescent dwarf galaxies are tidally stripped systems that ran away from their hosts.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/777/42
- Title:
- Kinematic and HI data for the NFGS
- Short Name:
- J/ApJ/777/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We relate transitions in galaxy structure and gas content to refueling, here defined to include both the external gas accretion and the internal gas processing needed to renew reservoirs for star formation. We analyze two z=0 data sets: a high-quality ~200 galaxy sample (the Nearby Field Galaxy Survey, data release herein) and a volume-limited ~3000 galaxy sample with reprocessed archival data. Both reach down to baryonic masses ~10^9^M_{sun}_ and span void-to-cluster environments. Two mass-dependent transitions are evident: (1) below the "gas-richness threshold" scale (V~125km/s), gas-dominated quasi-bulgeless Sd-Im galaxies become numerically dominant; while (2) above the "bimodality" scale (V~200km/s), gas-starved E/S0s become the norm. Notwithstanding these transitions, galaxy mass (or V as its proxy) is a poor predictor of gas-to-stellar mass ratio M_gas_/M_*_. Instead, M_gas_/M_*_ correlates well with the ratio of a galaxy's stellar mass formed in the last Gyr to its preexisting stellar mass, such that the two ratios have numerically similar values. This striking correspondence between past-averaged star formation and current gas richness implies routine refueling of star-forming galaxies on Gyr timescales. We argue that this refueling underlies the tight M_gas_/M_*_ versus color correlations often used to measure "photometric gas fractions." Furthermore, the threshold and bimodality scale transitions reflect mass-dependent demographic shifts between three refueling regimes--accretion-dominated, processing-dominated, and quenched. In this picture, gas-dominated dwarfs are explained not by inefficient star formation but by overwhelming gas accretion, which fuels stellar mass doubling in <~1Gyr. Moreover, moderately gas-rich bulged disks such as the Milky Way are transitional, becoming abundant only in the narrow range between the threshold and bimodality scales.
- ID:
- ivo://CDS.VizieR/II/106
- Title:
- Kiso Ultraviolet Catalog (KUV)
- Short Name:
- II/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a list of 1186 ultraviolet-excess objects found during two surveys with the Kiso Schmidt telescope of the Tokyo Astronomical Observatory. The UGR three-image method was used to detect the objects catalogued, which range in blue magnitude from about 10.0 to 18.5. The table contains equatorial positions to an accuracy of about 0.5 seconds of arc (equinox and equator B1950.0, epoch of observation), magnitudes (green of the "three-image [UGR] method"), color indices (as estimated from the enhancement of the U image relative to the G), object codes (white dwarf, QSO, diffuse object, etc.), and alternate designations (in addition to a KUV coordinate designation).
- ID:
- ivo://CDS.VizieR/J/ApJS/234/5
- Title:
- LaCoSSPAr in the Southern Galactic Cap. I.
- Short Name:
- J/ApJS/234/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic redshift catalog from the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap (SGC), which is designed to observe all sources (Galactic and extragalactic) by using repeating observations with a limiting magnitude of r=18.1mag in two 20deg^2^ fields. The project is mainly focusing on the completeness of LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source selection methods, and the basic performance parameters of the LAMOST telescope. In both fields, more than 95% of galaxies have been observed. A post-processing has been applied to the LAMOST 1D spectrum to remove the majority of remaining sky background residuals. More than 10000 spectra have been visually inspected to measure the redshift by using combinations of different emission/absorption features with an uncertainty of {sigma}_z_/(1+z)<0.001. In total, 1528 redshifts (623 absorption and 905 emission line galaxies) in Field A and 1570 redshifts (569 absorption and 1001 emission line galaxies) in Field B have been measured. The results show that it is possible to derive redshift from low S/N galaxies with our post-processing and visual inspection. Our analysis also indicates that up to one-fourth of the input targets for a typical extragalactic spectroscopic survey might be unreliable. The multi-wavelength data analysis shows that the majority of mid-infrared-detected absorption (91.3%) and emission line galaxies (93.3%) can be well separated by an empirical criterion of W2-W3=2.4. Meanwhile, a fainter sequence paralleled to the main population of galaxies has been witnessed both in Mr/W2-W3 and M*/W2-W3 diagrams, which could be the population of luminous dwarf galaxies but contaminated by the edge-on/highly inclined galaxies (~30%).
- ID:
- ivo://CDS.VizieR/J/ApJ/860/100
- Title:
- LCs of 26 hydrogen-poor superluminous SNe
- Short Name:
- J/ApJ/860/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the light-curve properties of a sample of 26 spectroscopically confirmed hydrogen-poor superluminous supernovae (SLSNe-I) in the Palomar Transient Factory survey. These events are brighter than SNe Ib/c and SNe Ic-BL, on average, by about 4 and 2mag, respectively. The peak absolute magnitudes of SLSNe-I in rest-frame g band span -22<~M_g_<~-20mag, and these peaks are not powered by radioactive ^56^Ni, unless strong asymmetries are at play. The rise timescales are longer for SLSNe than for normal SNe Ib/c, by roughly 10 days, for events with similar decay times. Thus, SLSNe-I can be considered as a separate population based on photometric properties. After peak, SLSNe-I decay with a wide range of slopes, with no obvious gap between rapidly declining and slowly declining events. The latter events show more irregularities (bumps) in the light curves at all times. At late times, the SLSN-I light curves slow down and cluster around the ^56^Co radioactive decay rate. Powering the late-time light curves with radioactive decay would require between 1 and 10M_{sun}_ of Ni masses. Alternatively, a simple magnetar model can reasonably fit the majority of SLSNe-I light curves, with four exceptions, and can mimic the radioactive decay of ^56^Co, up to ~400days from explosion. The resulting spin values do not correlate with the host-galaxy metallicities. Finally, the analysis of our sample cannot strengthen the case for using SLSNe-I for cosmology.
- ID:
- ivo://CDS.VizieR/J/ApJ/901/61
- Title:
- LCs of 4 superluminous SNe from the ZTF survey
- Short Name:
- J/ApJ/901/61
- Date:
- 17 Feb 2022 13:56:34
- Publisher:
- CDS
- Description:
- We present photometry and spectroscopy of four hydrogen-poor luminous supernovae discovered during the 2-month long science commissioning and early operations of the Zwicky Transient Facility (ZTF) survey. Three of these objects, SN 2018bym (ZTF18aapgrxo), SN 2018avk (ZTF18aaisyyp), and SN 2018bgv (ZTF18aavrmcg), resemble typical SLSN-I spectroscopically, while SN 2018don (ZTF18aajqcue) may be an object similar to SN 2007bi experiencing considerable host galaxy reddening, or an intrinsically long-lived, luminous, and red SN Ic. We analyze the light curves, spectra, and host galaxy properties of these four objects and put them in context of the population of SLSN-I. SN 2018bgv stands out as the fastest-rising SLSN-I observed to date, with a rest-frame g-band rise time of just 10 days from explosion to peak-if it is powered by magnetar spin-down, the implied ejecta mass is only ~1M_{sun}_. SN 2018don also displays unusual properties-in addition to its red colors and comparatively massive host galaxy, the light curve undergoes some of the strongest light-curve undulations postpeak seen in an SLSN-I, which we speculate may be due to interaction with circumstellar material. We discuss the promises and challenges of finding SLSNe in large-scale surveys like ZTF given the observed diversity in the population.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/23
- Title:
- LEGUS galaxies1 observations
- Short Name:
- J/ApJS/235/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Legacy ExtraGalactic UV Survey (LEGUS) is a multiwavelength Cycle 21 Treasury program on the Hubble Space Telescope. It studied 50 nearby star-forming galaxies in 5 bands from the near-UV to the I-band, combining new Wide Field Camera 3 observations with archival Advanced Camera for Surveys data. LEGUS was designed to investigate how star formation occurs and develops on both small and large scales, and how it relates to the galactic environments. In this paper we present the photometric catalogs for all the apparently single stars identified in the 50 LEGUS galaxies. We present optical and near-UV color-magnitude diagrams for all the galaxies. For each galaxy we derived the distance from the tip of the red giant branch. We then used the NUV color-magnitude diagrams to identify stars more massive than 14M_{sun}_, and compared their number with the number of massive stars expected from the GALEX FUV luminosity. Our analysis shows that the fraction of massive stars forming in star clusters and stellar associations is about constant with the star formation rate. This lack of a relation suggests that the timescale for evaporation of unbound structures is comparable or longer than 10Myr. At low star formation rates this translates to an excess of mass in clustered environments as compared to model predictions of cluster evolution, suggesting that a significant fraction of stars form in unbound systems.
- ID:
- ivo://CDS.VizieR/J/AJ/151/136
- Title:
- LITTLE THINGS dwarf irregular galaxies FUV regions
- Short Name:
- J/AJ/151/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine FUV images of the LITTLE THINGS sample of nearby dwarf irregular (dIrr) and Blue Compact Dwarf galaxies to identify distinct young regions in their far outer disks. We use these data, obtained with the Galaxy Evolution Explorer satellite, to determine the furthest radius at which in situ star formation can currently be identified. The FUV knots are found at distances from the center of the galaxies of 1-8 disk scale lengths and have ages of =<20 Myr and masses of 20 M_{sun}_ to 1x10^5^ M_{sun}_. The presence of young clusters and OB associations in the outer disks of dwarf galaxies shows that dIrrs do have star formation taking place there in spite of the extreme nature of the environment. Most regions are found where the H I surface density is ~1 M_{sun}_/pc^2^, though both the H I and dispersed old stars go out much further. This limiting density suggests a cutoff in the ability to form distinct OB associations and perhaps even stars. We compare the star formation rates in the FUV regions to the average rates expected at their radii and beyond from the observed gas, using the conventional correlation for gas-rich regions. The localized rates are typically 10% of the expected average rates for the outer disks. Either star formation in dIrrs at surface densities <1 M_{sun}_/pc^2^ occurs without forming distinct associations, or the Kennicutt-Schmidt relation over-predicts the rate beyond this point. In the latter case, the stellar disks in the far-outer parts of dIrrs result from scattering of stars from the inner disk.
- ID:
- ivo://CDS.VizieR/J/AJ/117/206
- Title:
- LMC far-ultraviolet imaging
- Short Name:
- J/AJ/117/206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the deepest pure UV observations with the highest angular resolution ever performed, a set of 12 exposures with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 and F160BW filter obtained in parallel observing mode, which covers ~12arcmin^2^ in the Large Magellanic Cloud (LMC), north of the bar, and in the "general field" regime of the LMC. The 341 independent measurements of 198 objects represent an accumulated exposure of >=2x10^4^s and reveal stars as faint as m_UV_~=22mag. The observations show that about two-thirds of the UV emission from the LMC is emitted by our HST-detected UV stars in the field, that is, not in clusters or associations. We identified optical counterparts in the Royal Observatory Edinburgh/Naval Research Laboratory photometric catalog for about one-third of the objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/31
- Title:
- Local Star Formation effects on type Ia SNe
- Short Name:
- J/ApJ/812/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies found a correlation with ~3{sigma} significance between the local star formation measured by GALEX in SN Ia host galaxies and the distances or dispersions derived from these SNe. We search for these effects by using data from recent cosmological analyses to greatly increase the SN Ia sample; we include 179 GALEX-imaged SN Ia hosts with distances from the Joint Light-curve Analysis (JLA) and Pan-STARRS SN Ia cosmology samples and 157 GALEX-imaged SN Ia hosts with distances from the Riess et al. (2011, J/ApJ/730/119) H_0_ measurement. We find little evidence that SNe Ia in locally star-forming environments are fainter after light curve correction than SNe Ia in locally passive environments. We find a difference of 0.000+/-0.018 (stat+sys) mag for SNe fit with SALT2 and 0.029+/-0.027 (stat+sys) mag for SNe fit with MLCS2k2 (R_V_=2.5), which suggests that proposed changes to recent measurements of H_0_ and w are not significant and numerically smaller than the parameter measurement uncertainties. We measure systematic uncertainties of ~0.01-0.02mag by performing several plausible variants of our analysis. We find the greatly reduced significance of these distance modulus differences compared to Rigault et al. (2013A&A...560A..66R) results from two improvements with fairly equal effects, our larger sample size and the use of the JLA and Riess et al. sample selection criteria. Without these improvements, we recover the results of Rigault et al. We find that both populations have similar dispersions in distance than found by Rigault et al. and Kelly et al. (2015Sci...347.1459K), with slightly smaller dispersions for locally passive (log({Sigma}_SFR_)<-2.9dex) SNe Ia fit with MLCS, the opposite of the effect seen by Rigault et al. and Kelly et al. We caution that measuring the local environments of SNe Ia in the future may require a higher resolution instrument than GALEX and that SN Ia sample selection has a significant effect on local star formation biases.
