- ID:
- ivo://CDS.VizieR/J/ApJS/224/33
- Title:
- CLASH-VLT: the FF cluster MACS J0416.1-2403
- Short Name:
- J/ApJS/224/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VIMOS-Very Large Telescope (VLT) spectroscopy of the Frontier Fields (FF) cluster MACS J0416.1-2403 (z=0.397). Taken as part of the CLASH-VLT survey, the large spectroscopic campaign provided more than 4000 reliable redshifts over ~600arcmin^2^, including ~800 cluster member galaxies. The unprecedented sample of cluster members at this redshift allows us to perform a highly detailed dynamical and structural analysis of the cluster out to ~2.2r_200_ (~4Mpc). Our analysis of substructures reveals a complex system composed of a main massive cluster (M_200_~0.9x10^15^M_{sun}_ and {sigma}_V,r200_~1000km/s) presenting two major features: (i) a bimodal velocity distribution, showing two central peaks separated by {Delta}V_rf_~1100km/s with comparable galaxy content and velocity dispersion, and (ii) a projected elongation of the main substructures along the NE-SW direction, with a prominent sub-clump ~600kpc SW of the center and an isolated BCG approximately halfway between the center and the SW clump. We also detect a low-mass structure at z~0.390, ~10' south of the cluster center, projected at ~3Mpc, with a relative line-of-sight velocity of {Delta}V_rf_~-1700km/s. The cluster mass profile that we obtain through our dynamical analysis deviates significantly from the "universal" NFW, being best fit by a Softened Isothermal Sphere model instead. The mass profile measured from the galaxy dynamics is found to be in relatively good agreement with those obtained from strong and weak lensing, as well as with that from the X-rays, despite the clearly unrelaxed nature of the cluster. Our results reveal an overall complex dynamical state of this massive cluster and support the hypothesis that the two main subclusters are being observed in a pre-collisional phase, in agreement with recent findings from radio and deep X-ray data. In this article, we also release the entire redshift catalog of 4386 sources in the field of this cluster, which includes 60 identified Chandra X-ray sources and 105 JVLA radio sources.
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- ID:
- ivo://CDS.VizieR/J/A+A/631/A37
- Title:
- Classical Cepheids consistent radial velocities
- Short Name:
- J/A+A/631/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate radial velocities (vrad) of Cepheids are mandatory within the context of Cepheid distance measurements using the Baade-Wesselink technique. The most common vrad derivation method consists in cross-correlating the observed stellar spectra with a binary template and measuring a velocity on the resulting mean profile. Nevertheless, for Cepheids and other pulsating stars, the spectral lines selected within the template as well as the way of fitting the cross-correlation function (CCF) have a direct and significant impact on the measured vrad. Our first aim is to detail the steps to compute consistent CCFs and vrad of Cepheids. Next, this study aims at characterising the impact of Cepheid spectral properties and vrad computation methods on the resulting line profiles and vrad time series. We collected more than 3900 high-resolution spectra from seven different spectrographs of 64 Classical Milky Way (MW) Cepheids. These spectra were normalised and standardised using a single custom-made process on pre-defined wavelength ranges.We built six tailored correlation templates selecting unblended spectral lines of different depths based on a synthetic Cepheid spectrum, on three different wavelength ranges from 3900 to 8000{AA}. Each observed spectrum was cross-correlated with these templates to build the corresponding CCFs, adopted as the proxy for the spectrum mean line profile. We derived a set of line profile observables as well as three different vrad measurements from each CCF and two custom proxies for the CCF quality and amount of signal. This study presents a large catalogue of consistent Cepheid CCFs and vrad time series. It confirms that each step of the process has a significant impact on the deduced vrad: the wavelength, the template line depth and width, and the vrad computation method. The way towards more robust Cepheid vrad time series seems to go through steps that minimise the asymmetry of the line profile and its impact on the vrad. Centroid or first-moment vrad, that exhibit slightly smaller amplitudes but significantly smaller scatter than Gaussian or biGaussian vrad, should therefore be favoured. Stronger or deeper spectral lines also tend to be less asymmetric and lead to more robust vrad than weaker lines.
- ID:
- ivo://CDS.VizieR/J/A+A/378/116
- Title:
- Classification and vsini of Vega-type and PMS stars
- Short Name:
- J/A+A/378/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1.dat contains the log of the spectroscopic observations of the stars in the EXPORT sample taken with the Isaac Newton Telescope during the 1998 International Time Campaigns at the Canary Islands' Observatories. File table2.dat contains the log of the spectroscopic observations of the stars in the EXPORT sample taken with the William Herschel Telescope during the 1998 International Time Campaigns at the Canary Islands' Observatories. File table6.dat contains the results of the spectral classification and the projected rotational velocities for the stars in the EXPORT sample with comparisons with results from previous work.
- ID:
- ivo://CDS.VizieR/J/ApJS/152/201
- Title:
- Classification of 2000 bright IRAS sources
- Short Name:
- J/ApJS/152/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An artificial neural network (ANN) scheme has been employed that uses a supervised back-propagation algorithm to classify 2000 bright sources from the Calgary database of Infrared Astronomical Satellite (IRAS) spectra in the region 8-23{mu}m. The database has been classified into 17 predefined classes based on the spectral morphology. We have been able to classify over 80% of the sources correctly in the first instance. The speed and robustness of the scheme will allow us to classify the whole of the Low Resolution Spectrometer database, containing more than 50,000 sources, in the near future.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/1873
- Title:
- Classification of LAMOST DR4 galaxies
- Short Name:
- J/MNRAS/474/1873
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the classification and composite spectra of galaxies in the fourth data release (DR4) of the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST). We select 40182 spectra of galaxies from LAMOST DR4, which have photometric information but no spectroscopic observations in the Sloan Digital Sky Survey (SDSS). These newly observed spectra are recalibrated and classified into six classes - passive, H{alpha}-weak, star-forming, composite, LINER and Seyfert - using the line intensity (H{beta}, [OIII] 5007, H{alpha} and [NII] 6585). We also study the correlation between spectral class and morphological type through three parameters: concentration index, (u-r) colour and D4000n index. We calculate composite spectra of high signal-to-noise ratio (S/N) for six spectral classes and, using these composites, we pick out some features that can differentiate the classes effectively, including H{beta}, Fe5015, H{gamma}A, HK and the Mg2 band. In addition, we compare our composite spectra with the SDSS ones and analyse their differences. A galaxy catalogue of 40182 newly observed spectra (36601 targets) and the composite spectra of the six classes are available online (http://sciwiki.lamost.org/downloads/wll).
- ID:
- ivo://CDS.VizieR/J/A+A/403/659
- Title:
- Classification of WR planetary nebulae
- Short Name:
- J/A+A/403/659
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse 42 emission-line nuclei of Planetary Nebulae (PNe), in the framework of a large spectrophotometric survey of [WC] nuclei of PNe conducted since 1994, using low/medium resolution spectra obtained at ESO and at OHP. We construct a grid of selected line-intensities (normalized to C IV-5806{AA}=100) ordered by decreasing ionisation potential going from 871 to 24eV. In this grid, the stars appear to belong clearly to prominent O (hot [WO1-4] types) or C (cooler [WC4-11] types) line-sequences, in agreement with the classification of massive WR stars applied to Central Stars of Planetary Nebulae (CSPNe) by Crowther et al. (1998MNRAS.296..367C, CMB98). We propose 20 selected line ratios and the FWHM of CIV and CIII lines as classification diagnostics, which agree well with the 7 line ratios and the FWHM proposed by CMB98.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/4416
- Title:
- Classifying galaxy spectra at 0.5<z<1
- Short Name:
- J/MNRAS/478/4416
- Date:
- 10 Dec 2021 13:08:01
- Publisher:
- CDS
- Description:
- The spectrum of a galaxy contains information about its physical properties. Classifying spectra using templates helps to elucidate the nature of a galaxy's energy sources. In this paper, we investigate the use of self-organizing maps in classifying galaxy spectra against templates. We trained semi-supervised self-organizing map networks using a set of templates covering the wavelength range from far ultraviolet to near-infrared. The trained networks were used to classify the spectra of a sample of 142 galaxies with 0.5<z<1 and the results compared to classifications performed using K-means clustering, a supervised neural network, and chi-squared minimization. Spectra corresponding to quiescent galaxies were more likely to be classified similarly by all methods while starburst spectra showed more variability. Compared to classification using chi-squared minimization or the supervised neural network, the galaxies classed together by the self-organizing map had more similar spectra. The class ordering provided by the 1D self-organizing maps corresponds to an ordering in physical properties, a potentially important feature for the exploration of large data sets.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A104
- Title:
- Cl 1103.7-1245 at z=0.96: spectroscopic catalog
- Short Name:
- J/A+A/544/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new spectroscopic observations in a field containing the highest redshift cluster of the ESO Distant Cluster Survey (EDisCS). We measure galaxy redshifts and determine the velocity dispersions of the galaxy structures located in this field. Together with the main cluster Cl 1103.7-1245 (z=0.9580; {sigma}_clus_=522+/-111km/s) we find a secondary structure at z=0.9830, Cl 1103.7-1245c. We then characterize the galaxy properties in both systems. These new spectroscopic observations for Cl 1103.7-1245 complement the previous analysis of Milvang-Jensen et al. (2008, Cat. J/A+A/482/419), whose observations targetted z=0.70.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/171
- Title:
- CLEAR. II. SFRs of quiescent galaxies
- Short Name:
- J/ApJ/898/171
- Date:
- 16 Mar 2022 00:57:30
- Publisher:
- CDS
- Description:
- The origin of the correlations between mass, morphology, quenched fraction, and formation history in galaxies is difficult to define, primarily due to the uncertainties in galaxy star formation histories (SFHs). SFHs are better constrained for higher redshift galaxies, observed closer to their formation and quenching epochs. Here we use "nonparametric" SFHs and a nested sampling method to derive constraints on the formation and quenching timescales of quiescent galaxies at 0.7<z<2.5. We model deep HST grism spectroscopy and photometry from the CLEAR (CANDELS Ly{alpha} Emission at Reionization) survey. The galaxy formation redshifts, z50 (defined as the point where they had formed 50% of their stellar mass) range from z_50_~2 (shortly prior to the observed epoch) up to z_50_~5-8. We find that early formation redshifts are correlated with high stellar-mass surface densities, log{Sigma}_1_/(M_{sun}_kpc^-2^)>10.25, where {Sigma}_1_ is the stellar mass within 1pkpc (proper kpc). Quiescent galaxies with the highest stellar-mass surface density, log{Sigma}_1_/(M_{sun}_kpc^-2^)>10.25, show a minimum formation redshift: all such objects in our sample have z_50_>2.9. Quiescent galaxies with lower surface density, log{Sigma}_1_/(M_{sun}_kpc^-2^)=9.5-10.25, show a range of formation epochs (z_50_~1.5-8), implying these galaxies experienced a range of formation and assembly histories. We argue that the surface density threshold log{Sigma}_1_/(M_{sun}_kpc^-2^)>10.25 uniquely identifies galaxies that formed in the first few Gyr after the big bang, and we discuss the implications this has for galaxy formation models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/3443
- Title:
- Cl0939+4713 H{alpha} z~0.4 star-forming galaxies
- Short Name:
- J/MNRAS/458/3443
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cluster star-forming galaxies are found to have an excess of far-infrared emission relative to H{alpha}, when compared to those in the field, which could be caused by intense active galactic nuclei (AGN) activity, dust and/or declining star formation histories. Here we present spectroscopic observations of H{alpha} emitters in the Cl 0939+4713 (Abell 851) super-cluster at z=0.41, using AF2+ WYFFOS on the William Herschel Telescope. We measure [OII], H{beta}, [OIII], H{alpha} and [NII] for a sample of 119 H{alpha} emitters in and around the cluster. We find that 17+/-5 per cent of the H{alpha} emitters are AGN, irrespective of environment. For star-forming galaxies, we obtain Balmer decrements, metallicities and ionization parameters with different methods, individually and by stacking. We find a strong mass-metallicity relation at all environments, with no significant dependence on environment. The ionization parameter declines with increasing stellar mass for low-mass galaxies. H{alpha} emitters residing in intermediate environments show the highest ionization parameters (along with high [OIII]/H{alpha} and high [OIII]/[OII] line ratios, typically twice as large as in the highest and lowest densities), which decline with increasing environmental density. Dust extinction (A_H{alpha}_) correlates strongly with stellar mass, but also with environmental density. Star-forming galaxies in the densest environments are found to be significantly dustier (A_H{alpha}_~=1.5-1.6) than those residing in the lowest density environments (A_H{alpha}_~=0.6), deviating significantly from what would be predicted given their stellar masses.
