- ID:
- ivo://CDS.VizieR/J/ApJ/671/323
- Title:
- Spitzer Spectra of a 10mJy galaxy sample
- Short Name:
- J/ApJ/671/323
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete flux-limited sample of 50 galaxies is presented having f{nu}(24um)>10mJy, chosen from a survey with MIPS on Spitzer of 8.2deg^2^ in the NOAO Deep Wide-Field Survey (NDWFS) region in Bootes. Spectra obtained with the low-resolution modules of IRS on Spitzer are described for 36 galaxies in this sample; 25 show strong PAH emission features characteristic of starbursts, and 11 show silicate absorption or emission, emission lines, or featureless spectra characteristic of AGNs. Infrared or optical spectral classifications are available for 48 of the entire sample of 50; 33 galaxies are classified as starbursts and 15 as AGNs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/224/38
- Title:
- SPOGS. I. SDSS Shocked POststarburst Galaxy cand.
- Short Name:
- J/ApJS/224/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are many mechanisms by which galaxies can transform from blue, star-forming spirals, to red, quiescent early-type galaxies, but our current census of them does not form a complete picture. Recent observations of nearby case studies have identified a population of galaxies that quench "quietly". Traditional poststarburst searches seem to catch galaxies only after they have quenched and transformed, and thus miss any objects with additional ionization mechanisms exciting the remaining gas. The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify transforming galaxies, in which the nebular lines are excited via shocks instead of through star formation processes. Utilizing the Oh-Sarzi-Schawinski-Yi (OSSY, 2011ApJS..195...13O) measurements on the Sloan Digital Sky Survey Data Release 7 catalog, we applied Balmer absorption and shock boundary criteria to identify 1067 SPOG candidates (SPOGs*) within z=0.2. SPOGs* represent 0.2% of the OSSY sample galaxies that exceed the continuum signal-to-noise cut (and 0.7% of the emission line galaxy sample). SPOGs* colors suggest that they are in an earlier phase of transition than OSSY galaxies that meet an "E+A" selection. SPOGs* have a 13% 1.4GHz detection rate from the Faint Images of the Radio Sky at Twenty Centimeters Survey, higher than most other subsamples, and comparable only to low-ionization nuclear emission line region hosts, suggestive of the presence of active galactic nuclei (AGNs). SPOGs* also have stronger Na i D absorption than predicted from the stellar population, suggestive of cool gas being driven out in galactic winds. It appears that SPOGs* represent an earlier phase in galaxy transformation than traditionally selected poststarburst galaxies, and that a large proportion of SPOGs* also have properties consistent with disruption of their interstellar media, a key component to galaxy transformation. It is likely that many of the known pathways to transformation undergo a SPOG phase. Studying this sample of SPOGs* further, including their morphologies, AGN properties, and environments, has the potential for us to build a more complete picture of the initial conditions that can lead to a galaxy evolving.
- ID:
- ivo://CDS.VizieR/J/ApJ/837/88
- Title:
- SPT-GMOS spectroscopy of gal. in massive clusters
- Short Name:
- J/ApJ/837/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The velocity distribution of galaxies in clusters is not universal; rather, galaxies are segregated according to their spectral type and relative luminosity. We examine the velocity distributions of different populations of galaxies within 89 Sunyaev Zel'dovich (SZ) selected galaxy clusters spanning 0.28<z<1.08. Our sample is primarily draw from the SPT-GMOS spectroscopic survey, supplemented by additional published spectroscopy, resulting in a final spectroscopic sample of 4148 galaxy spectra -- 2868 cluster members. The velocity dispersion of star-forming cluster galaxies is 17+/-4% greater than that of passive cluster galaxies, and the velocity dispersion of bright (m<m^*^-0.5) cluster galaxies is 11+/-4% lower than the velocity dispersion of our total member population. We find good agreement with simulations regarding the shape of the relationship between the measured velocity dispersion and the fraction of passive versus star-forming galaxies used to measure it, but we find a small offset between this relationship as measured in data and simulations, which suggests that our dispersions are systematically low by as much as 3% relative to simulations. We argue that this offset could be interpreted as a measurement of the effective velocity bias that describes the ratio of our observed velocity dispersions and the intrinsic velocity dispersion of dark matter particles in a published simulation result. Measuring velocity bias in this way suggests that large spectroscopic surveys can improve dispersion-based mass-observable scaling relations for cosmology even in the face of velocity biases, by quantifying and ultimately calibrating them out.
- ID:
- ivo://CDS.VizieR/J/AJ/160/130
- Title:
- SpT & NIR color excess of Solar-type stars
- Short Name:
- J/AJ/160/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although solar-analog stars have been studied extensively over the past few decades, most of these studies have focused on visible wavelengths, especially those identifying solar-analog stars to be used as calibration tools for observations. As a result, there is a dearth of well-characterized solar analogs for observations in the near-infrared, a wavelength range important for studying solar system objects. We present 184 stars selected based on solar-like spectral type and V-J and V-K colors whose spectra we have observed in the 0.8-4.2{mu}m range for calibrating our asteroid observations. Each star has been classified into one of three ranks based on spectral resemblance to vetted solar analogs. Of our set of 184 stars, we report 145 as reliable solar-analog stars, 21 as solar analogs usable after spectral corrections with low-order polynomial fitting, and 18 as unsuitable for use as calibration standards owing to spectral shape, variability, or features at low to medium resolution. We conclude that all but five of our candidates are reliable solar analogs in the longer wavelength range from 2.5 to 4.2{mu}m. The average colors of the stars classified as reliable or usable solar analogs are V-J=1.148, V-H=1.418, and V-K= 1.491, with the entire set being distributed fairly uniformly in R.A. across the sky between -27{deg} and +67{deg} in decl.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A167
- Title:
- SPT-S J041839-4751.8 APEX spectra
- Short Name:
- J/A+A/631/A167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of six far-infrared fine structure lines in the z=4.225 lensed dusty star-forming galaxy SPT 0418-47 (SPT-S J041839-4751.8) to probe the physical conditions of its inter stellar medium (ISM). In particular, we report Atacama Pathfinder EXperiment (APEX) detections of the [OI] 145um and [OIII] 88um lines and Atacama Compact Array (ACA) detections of the [NII] 122 and 205um lines. The [OI] 145um/[CII] 158um line ratio is ~5x higher compared to the average of local galaxies. We interpret this as evidence that the ISM is dominated by photo-dissociation regions with high gas densities. The line ratios, and in particular those of [OIII] 88um and [NII] 122um imply that the ISM in SPT 0418-47 is already chemically enriched to nearly solar metallicity. While the strong gravitational amplification was required to detect these lines with APEX, larger samples can be observed with the Atacama Large Millimeter/submillimeter Array (ALMA), and should allow observers to determine if the dense, solar metallicity ISM is common among these highly star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/45
- Title:
- SPT-SZ survey galaxy clusters optical spectroscopy
- Short Name:
- J/ApJ/792/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy of galaxies in clusters detected through the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). We report our own measurements of 61 spectroscopic cluster redshifts, and 48 velocity dispersions each calculated with more than 15 member galaxies. This catalog also includes 19 dispersions of SPT-observed clusters previously reported in the literature. The majority of the clusters in this paper are SPT-discovered; of these, most have been previously reported in other SPT cluster catalogs, and five are reported here as SPT discoveries for the first time. By performing a resampling analysis of galaxy velocities, we find that unbiased velocity dispersions can be obtained from a relatively small number of member galaxies (<~ 30), but with increased systematic scatter. We use this analysis to determine statistical confidence intervals that include the effect of membership selection. We fit scaling relations between the observed cluster velocity dispersions and mass estimates from SZ and X-ray observables. In both cases, the results are consistent with the scaling relation between velocity dispersion and mass expected from dark-matter simulations. We measure a ~30% log-normal scatter in dispersion at fixed mass, and a ~10% offset in the normalization of the dispersion-mass relation when compared to the expectation from simulations, which is within the expected level of systematic uncertainty.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A109
- Title:
- Ssynthetic spectra of supernovae models
- Short Name:
- J/A+A/621/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational surveys are now able to detect an increasing number of transients, such as core-collapse supernovae (SN) and powerful non-terminal outbursts (SN impostors). Dedicated spectroscopic facilities can follow up these events shortly after detection. Here we investigate the properties of these explosions at early times.We use the radiative transfer code CMFGEN to build an extensive library of spectra simulating the interaction of supernovae and their progenitor's winds/circumstellar medium (CSM).We consider a range of progenitor mass-loss rates (dM/dt=5x10^-4^ to 10^-2^ M_{sun}/yr), abundances (solar, CNO-processed, and He-rich), and SN luminosities (L=1.9x10^8^ to 2.5x10^10^L_{sun}_). The models simulate events ~=1-day after explosion, and we assume a fixed location of the shock front as R_in_=8.6x10^13^cm. We show that the large range of massive star properties at the pre-SN stage causes a diversity of early-time interacting SN and impostors. We identify three main classes of early-time spectra consisting of relatively high-ionisation (e.g. HeII and OVI), medium-ionisation (e.g. CIII and NIII), and low-ionisation lines (e.g. HeI and FeII/III). They are regulated by L and the CSM density. Given a progenitor wind velocity v_inf_, our models also place a lower limit of dM/dt>~5x10^-4^(v_inf_=150km/s)M_{sun}_/yr for detection of CSM interaction signatures in observed spectra. Early-time SN spectra should provide clear constraints on progenitors by measuring H, He, and CNO abundances if the progenitors come from single stars. The connections are less clear considering the effects of binary evolution. Nevertheless, our models provide a clear path for linking the final stages of massive stars to their post-explosion spectra at early times, and guiding future observational follow-up of transients with facilities such as the Zwicky Transient Facility.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/140
- Title:
- Stacked spectra of SDSS star forming galaxies
- Short Name:
- J/ApJ/765/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of ~200000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [OIII]{lambda}4363 and [OII]{lambda}{lambda}7320,7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M_*_/M_{sun}_)=7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H{prop.to}M_*_^1/2^) until it turns over at log(M_*_/M_{sun}_)=8.9 and asymptotes to 12+log(O/H)=8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1445
- Title:
- Standard calibration stars infrared spectra
- Short Name:
- J/AJ/132/1445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared spectra with increased spectral resolution and accuracy of the absolute infrared spectral flux have been created for a subset of stellar standards created by Cohen and his collaborators in previous papers in this series. Moderate-resolution ({lambda}/{Delta}{lambda}~400) spectroscopy obtained on infrared standard stars by the Short Wavelength Spectrometer on the Infrared Space Observatory was combined with high-quality photometry tied to our recent absolute calibration from the Midcourse Space Experiment. Thus, 1-35 micron spectra were created for 33 stars, 9 of which are Cohen et al. secondary standards and another 20 of which are tertiary standards for which Cohen adopted spectral templates. The wavelength spacing is given by (0.0001/1 micron)*lambda^2, which provides for 10,000 samples over the 1-35 micron spectral range
- ID:
- ivo://CDS.VizieR/J/AJ/133/2825
- Title:
- Star beyond the NLTT catalog
- Short Name:
- J/AJ/133/2825
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have combined near-infrared data from the Two Micron All Sky Survey with ancillary optical data to identify previously unrecognized proper-motion stars that have colors and magnitudes consistent with nearby M dwarfs. We present follow-up observations of 392 stars from that sample, including ~200 stars discussed here for the first time. Our distance estimates, based primarily on spectroscopic parallaxes, place 123 stars within 20pc of the Sun. One hundred and seventy-six stars exhibit H{alpha} emission, and 82 stars have plausible X-ray counterparts from ROSAT observations.
