- ID:
- ivo://CDS.VizieR/J/AJ/145/77
- Title:
- Imaging and spectroscopy in three galaxy clusters
- Short Name:
- J/AJ/145/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of stellar populations and evolutionary history of galaxies in three similarly rich galaxy clusters MS0451.6-0305 (z=0.54), RXJ0152.7-1357 (z=0.83), and RXJ1226.9+3332 (z=0.89). Our analysis is based on high signal-to-noise ground-based optical spectroscopy and Hubble Space Telescope imaging for a total of 17-34 members in each cluster. Using the dynamical masses together with the effective radii and the velocity dispersions, we find no indication of evolution of sizes or velocity dispersions with redshift at a given galaxy mass. We establish the Fundamental Plane (FP) and scaling relations between absorption line indices and velocity dispersions. We confirm that the FP is steeper at z~0.86 compared to the low-redshift FP, indicating that under the assumption of passive evolution the formation redshift, z_form_, depends on the galaxy velocity dispersion (or alternatively mass). At a velocity dispersion of {sigma}=125km/s (Mass=10^10.55^M_{sun}_) we find z_form_=1.24+/-0.05, while at {sigma}=225km/s (Mass=10^11.36^M_{sun}_) the formation redshift is z_form_=1.95^+0.3^_-0.2_, for a Salpeter initial mass function. The three clusters follow similar scaling relations between absorption line indices and velocity dispersions as those found for low-redshift galaxies. The zero point offsets for the Balmer lines depend on cluster redshifts. However, the offsets indicate a slower evolution, and therefore higher formation redshift, than the zero point differences found from the FP, if interpreting the data using a passive evolution model. Specifically, the strength of the higher order Balmer lines H{delta} and H{gamma} implies z_form_>2.8. The scaling relations for the metal indices in general show small and in some cases insignificant zero point offsets, favoring high formation redshifts for a passive evolution model.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/845/157
- Title:
- IMF in 3 low-redshift strong lenses from SNELLS
- Short Name:
- J/ApJ/845/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lensing masses, these ETGs were inferred to have a stellar initial mass function (IMF) consistent with that of the Milky Way, not the bottom-heavy IMF that has been reported as typical for high-{sigma} ETGs based on lensing, dynamical, and stellar population synthesis techniques. We use these unique systems to test the consistency of IMF estimates derived from different methods. We first estimate the stellar M*/L using lensing and stellar dynamics. We then fit high-quality optical spectra of the lenses using an updated version of the stellar population synthesis models developed by Conroy & van Dokkum. When examined individually, we find good agreement among these methods for one galaxy. The other two galaxies show 2-3{sigma} tension with lensing estimates, depending on the dark matter contribution, when considering IMFs that extend to 0.08M_{sun}_. Allowing a variable low-mass cutoff or a nonparametric form of the IMF reduces the tension among the IMF estimates to <2{sigma}. There is moderate evidence for a reduced number of low-mass stars in the SNELLS spectra, but no such evidence in a composite spectrum of matched-{sigma} ETGs drawn from the SDSS. Such variation in the form of the IMF at low stellar masses (m<~0.3M_{sun}_), if present, could reconcile lensing/dynamical and spectroscopic IMF estimates for the SNELLS lenses and account for their lighter M*/L relative to the mean matched-{sigma} ETG. We provide the spectra used in this study to facilitate future comparisons.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/167
- Title:
- Improved empirical models for Type Ia SNe
- Short Name:
- J/ApJ/869/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- SN Ia cosmology depends on the ability to fit and standardize observations of supernova magnitudes with an empirical model. We present here a series of new models of SN Ia spectral time series that capture a greater amount of supernova diversity than is possible with the models that are currently customary. These are entitled SuperNova Empirical MOdels (SNEMO; https://snfactory.lbl.gov/snemo). The models are constructed using spectrophotometric time series from 172 individual supernovae from the Nearby Supernova Factory, comprising more than 2000 spectra. Using the available observations, Gaussian processes are used to predict a full spectral time series for each supernova. A matrix is constructed from the spectral time series of all the supernovae, and Expectation Maximization Factor Analysis is used to calculate the principal components of the data. K-fold cross-validation then determines the selection of model parameters and accounts for color variation in the data. Based on this process, the final models are trained on supernovae that have been dereddened using the Fitzpatrick and Massa extinction relation. Three final models are presented here: SNEMO2, a two-component model for comparison with current Type Ia models; SNEMO7, a seven-component model chosen for standardizing supernova magnitudes, which results in a total dispersion of 0.100mag for a validation set of supernovae, of which 0.087mag is unexplained (a total dispersion of 0.113mag with an unexplained dispersion of 0.097mag is found for the total set of training and validation supernovae); and SNEMO15, a comprehensive 15-component model that maximizes the amount of spectral time-series behavior captured.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/154
- Title:
- Improved kinematic parallaxes for Sco-Cen members
- Short Name:
- J/ApJ/746/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the ages and star formation history of the F-type stars in the Upper Scorpius (US), Upper Centaurus-Lupus (UCL), and Lower Centaurus-Crux (LCC) subgroups of Scorpius-Centaurus (Sco-Cen), the nearest OB association. Our parent sample is the kinematically selected Hipparcos sample of de Zeeuw et al. (1999, Cat. J/AJ/117/354), restricted to the 138 F-type members. We have obtained classification-resolution optical spectra and have also determined the spectroscopic accretion disk fraction. With Hipparcos and 2MASS photometry, we estimate the reddening and extinction for each star and place the candidate members on a theoretical H-R diagram. For each subgroup we construct empirical isochrones and compare to published evolutionary tracks.
- ID:
- ivo://CDS.VizieR/J/ApJS/211/5
- Title:
- Improved line data for the Swan system ^12^C^13^C
- Short Name:
- J/ApJS/211/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the ^12^C^13^C isotopologue Swan d^3^{Pi}-a^3^{Pi} system 0-0, 0-1, 0-2, 1-0, 1-1, 1-2, 2-0, 2-1, and 2-2 vibrational bands. The line positions and energy levels were predicted through new analyses of published laboratory data for the ^12^C^13^C lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The ^12^C^13^C line data were combined with similar data for ^12^C_2_, reported in a companion paper (2013JQSRT.124...11B), and applied to produce synthetic spectra of carbon-rich metal-poor stars that have strong C_2_ Swan bands. The matches between synthesized and observed spectra were used to estimate band head positions for a few of the ^12^C^13^C vibrational bands and to verify that the new computed line data match observed spectra. The much weaker C_2_ lines of the bright red giant Arcturus were also synthesized in the band head regions.
- ID:
- ivo://CDS.VizieR/J/ApJS/152/251
- Title:
- Indo-US library of coude feed stellar spectra
- Short Name:
- J/ApJS/152/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained spectra for 1273 stars using the 0.9m coude feed telescope at Kitt Peak National Observatory. This telescope feeds the coude spectrograph of the 2.1m telescope. The spectra have been obtained with the No.5 camera of the coude spectrograph and a Loral 3Kx1K CCD. Two gratings have been used to provide spectral coverage from 3460 to 9464{AA}, at a resolution of ~1{AA} FWHM and at an original dispersion of 0.44{AA}/pix. For 885 stars we have complete spectra over the entire 3460 to 9464{AA} wavelength region (neglecting small gaps of less than 50{AA}), and partial spectral coverage for the remaining stars. The 1273 stars have been selected to provide broad coverage of the atmospheric parameters T_eff_, logg, and [Fe/H], as well as spectral type. The goal of the project is to provide a comprehensive library of stellar spectra for use in the automated classification of stellar and galaxy spectra and in galaxy population synthesis. In this paper we discuss the characteristics of the spectral library, viz., details of the observations, data reduction procedures, and selection of stars. We also present a few illustrations of the quality and information available in the spectra. The first version of the complete spectral library is now publicly available from the National Optical Astronomy Observatory (NOAO) via ftp and http, at http://www.noao.edu/cflib .
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/2288
- Title:
- Infall motions in massive star-forming regions
- Short Name:
- J/MNRAS/461/2288
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we aim to characterize high-mass clumps with infall motions. We selected 327 clumps from the Millimetre Astronomy Legacy Team 90-GHz survey, and identified 100 infall candidates. Combined with the results of He et al. (2015, Cat. J/MNRAS/450/1926), we obtained a sample of 732 high-mass clumps, including 231 massive infall candidates and 501 clumps where infall is not detected. Objects in our sample were classified as pre-stellar, proto-stellar, HII or photodissociation region (PDR). The detection rates of the infall candidates in the pre-stellar, proto-stellar, HII and PDR stages are 41.2 per cent, 36.6 per cent, 30.6 per cent and 12.7 per cent, respectively. The infall candidates have a higher H_2_ column density and volume density compared with the clumps where infall is not detected at every stage. For the infall candidates, the median values of the infall rates at the pre-stellar, proto-stellar, HII and PDR stages are 2.6 x 10^-3^, 7.0x10^-3^, 6.5x10^-3^ and 5.5x10^-3^M_{sun}_/yr, respectively. These values indicate that infall candidates at later evolutionary stages are still accumulating material efficiently. It is interesting to find that both infall candidates and clumps where infall is not detected show a clear trend of increasing mass from the pre-stellar to proto-stellar, and to the HII stages. The power indices of the clump mass function are 2.04+/-0.16 and 2.17+/-0.31 for the infall candidates and clumps where infall is not detected, respectively, which agree well with the power index of the stellar initial mass function (2.35) and the cold Planck cores (2.0).
- ID:
- ivo://CDS.VizieR/J/MNRAS/450/1926
- Title:
- Infall motions in massive star-forming regions
- Short Name:
- J/MNRAS/450/1926
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive star-forming regions with observed infall motions are good sites for studying the birth of massive stars. In this paper, 405 compact sources have been extracted from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) compact sources that also have been observed in the Millimetre Astronomy Legacy Team 90-GHz (MALT90) survey during years 1 and 2. These observations are complemented with Spitzer GLIMPSE/MIPSGAL mid-IR survey data to help classify the elected star-forming clumps into three evolutionary stages: pre-stellar, proto-stellar and UCHII regions. The results suggest that 0.05g/cm^2^ is a reliable empirical lower bound for the clump surface densities required for massive-star formation to occur. The optically thick HCO^+^(1-0) and HNC(1-0) lines, as well as the optically thin N_2_H^+^(1-0) line were used to search for infall motions towards these sources. By analysing the asymmetries of the optically thick HCO^+^(1-0) and HNC(1-0) lines and the mapping observations of HCO^+^(1-0), a total of 131 reliable infall candidates have been identified. The HCO^+^(1-0) line shows the highest occurrence of obvious asymmetric features, suggesting that it may be a better infall motion tracer than other lines such as HNC(1-0). The detection rates of infall candidates towards pre-stellar, proto-stellar and UCHII clumps are 0.3452, 0.3861 and 0.2152, respectively. The relatively high detection rate of infall candidates towards UCHII clumps indicates that many UCHII regions are still accreting matter. The peak column densities and masses of the infall candidates, in general, display an increasing trend with progressing evolutionary stages. However, the rough estimates of the mass infall rate show no obvious variation with evolutionary stage.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/131
- Title:
- Infrared absorbance of water H_2_O/H_2_O_2_ ice
- Short Name:
- J/ApJ/743/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H_2_O_2_), for the production of water (H_2_O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H_2_O_2_ ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H_2_O_2_ should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H_2_O_2_/H_2_O ice films between 2.5 and 200um, from 10 to 180K, containing 3%, 30%, and 97% H_2_O_2_ ice. Integrated absorbances for all the absorption features in low-temperature H_2_O_2_ ice have been derived from these spectra. For identifying H_2_O_2_ ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3um. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H_2_O ice absorption bands, no absorption features are found that can definitely be identified with H_2_O_2_ ice. In the absence of definite H_2_O_2_ features, the H_2_O_2_ abundance is constrained by its possible contribution to the weak absorption feature near 3.47um found on the long-wavelength wing of the 3um H_2_O ice band. This gives an average upper limit for H_2_O_2_, as a percentage of H_2_O, of 9%+/-4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.
- ID:
- ivo://CDS.VizieR/J/other/JAD/18.3
- Title:
- Infrared extinction spectra of aerosols
- Short Name:
- J/other/JAD/18.3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mid-infrared extinction spectra (500-6000cm^-1^) of a series of single-component aerosol particle ensembles representative of those found in a range of planetary and lunar atmospheres are presented. The aerosols were generated in the laboratory via condensation from the gas phase in a bath gas cooling cell, and the spectra recorded using a Fourier transform infrared spectrometer. This paper is the first in a series aimed towards building a spectral database for use in remote sensing of aerosols. The aerosol substances included here are methane, ethane, propane, butane, pentane, ethylene, acetylene, carbon dioxide, ammonia and sulfur dioxide.
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