- ID:
- ivo://CDS.VizieR/J/A+A/620/A30
- Title:
- 12 embedded protostellar systems APEX spectra
- Short Name:
- J/A+A/620/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Simulations suggest that gas heating due to radiative feedback is a key factor in whether or not multiple protostellar systems will form. Chemistry is a good tracer of the physical structure of a protostellar system, since it depends on the temperature structure. We aim to study the relationship between envelope gas temperature and protostellar multiplicity. Single dish observations of various molecules that trace the cold, warm and UV-irradiated gas are used to probe the temperature structure of multiple and single protostellar systems on 7000 AU scales. Single, close binary, and wide multiples present similar current envelope gas temperatures, as estimated from H_2_CO and DCO^+^ line ratios. The temperature of the outflow cavity, traced by c-C_3_H_2_, on the other hand, shows a relation with bolometric luminosity and an anticorrelation with envelope mass. Although the envelope gas temperatures are similar for all objects surveyed, wide multiples tend to exhibit a more massive reservoir of cold gas compared to close binary and single protostars. Although the sample of protostellar systems is small, the results suggest that gas temperature may not have a strong impact on fragmentation. We propose that mass, and density, may instead be key factors in fragmentation.
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- ID:
- ivo://CDS.VizieR/J/ApJS/149/157
- Title:
- EMILI line-identification in IC 418 spectrum
- Short Name:
- J/ApJS/149/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The identification of spectral lines can be a tedious process requiring the interrogation of large spectroscopic databases, but it does lend itself to software algorithms that can determine the characteristics of candidate line identifications. We present here criteria used for the identification of lines and a logic developed for a line identification software package called EMILI, which uses the v2.04 Atomic Line List as the basic line database. EMILI considers all possible database transitions within the wavelength uncertainties for observed optical emission lines and computes an approximate intensity for each candidate line. It searches for other multiplet members that are expected to be seen with each candidate line, and rank-orders all of the tentative line identifications for each observed line based on a set of criteria. When applied to the spectra of the Orion Nebula and the planetary nebula IC 418, EMILI's recommended line IDs agree well with those of previous traditional manual line assignments. The existence of a semiautomated procedure should give impetus to the study of very high signal-to-noise spectra, enabling the identification of previously unidentified spectral lines to be handled with ease and consistency.
- ID:
- ivo://CDS.VizieR/J/MNRAS/365/454
- Title:
- Emission line analysis of HII galaxies
- Short Name:
- J/MNRAS/365/454
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical study of a very large sample of HII galaxies taken from the literature. We focus on the differences in several properties between galaxies that show the auroral line [OIII]{lambda}4363 and those that do not present this feature in their spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A30
- Title:
- Emission line flux densities for 12 YSOs
- Short Name:
- J/A+A/631/A30
- Date:
- 28 Oct 2021 07:35:47
- Publisher:
- CDS
- Description:
- Episodic accretion plays an important role in the evolution of young stars. Although it has been under investigation for a long time, the origin of such episodic accretion events is not yet understood. We investigate the dust and gas emission of a sample of young outbursting sources in the infrared to get a better understanding of their properties and circumstellar material, and we use the results in a further work to model the objects. We used Herschel data, from our PI program of 12 objects and complemented with archival observations to obtain the spectral energy distributions (SEDs) and spectra of our targets. We report here the main characteristics of our sample, focussing on the SED properties and on the gas emission lines detected in the PACS and SPIRE spectra. The SEDs of our sample show the diversity of the outbursting sources, with several targets showing strong emission in the far-infrared from the embedded objects. Most of our targets reside in a complex environment, which we discuss in detail. We detected several atomic and molecular lines, in particular rotational CO emission from several transitions from J=38-37 to J=4-3. We constructed rotational diagrams for the CO lines, and derived in three domains of assumed local thermodynamic equilibrium (LTE) temperatures and column densities, ranging mainly between 0-100K and 400-500K. We confirm correlation in our sample between intense CO J=16-15 emission and the column density of the warm domain of CO, N(warm). We notice a strong increase in luminosity of HH 381 IRS and a weaker increase for PP 13 S, which shows the beginning of an outburst.
- ID:
- ivo://CDS.VizieR/J/AJ/138/1022
- Title:
- Emission-line galaxies from HST PEARS survey
- Short Name:
- J/AJ/138/1022
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a search for emission-line galaxies (ELGs) in the southern fields of the Hubble Space Telescope Probing Evolution And Reionization Spectroscopically (PEARS) grism survey. The PEARS South Fields consist of five Advanced Camera for Surveys pointings (including the Hubble Ultra Deep Field) with the G800L grism for a total of 120 orbits, revealing thousands of faint object spectra in the GOODS-South region of the sky. ELGs are one subset of objects that are prevalent among the grism spectra. Using a two-dimensional detection and extraction procedure, we find 320 emission lines originating from 226 galaxy "knots" within 192 individual galaxies. Line identification results in 118 new grism-spectroscopic redshifts for galaxies in the GOODS-South Field. We measure emission-line fluxes using standard Gaussian fitting techniques. The star formation rates of the ELGs are presented, as well as a sample of distinct giant star-forming regions at z~0.1-0.5 across individual galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/772/48
- Title:
- Emission-line galaxies from PEARS. II.
- Short Name:
- J/ApJ/772/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitess grism spectroscopic data obtained with the Advanced Camera for Surveys on board Hubble Space Telescope. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random survey of galaxies, as well as the availability of a wide variety of ancillary observations complemented by the spectroscopic results. Using the PEARS data, we are able to identify star-forming galaxies (SFGs) within the redshift volume 0<z<1.5. Star-forming regions in the PEARS survey are pinpointed independently of the host galaxy. This method allows us to detect the presence of multiple emission-line regions (ELRs) within a single galaxy. We identified a total of 1162 H{alpha}, [OIII], and/or [OII] emission lines in the PEARS sample of 906 galaxies to a limiting flux of ~10^-18^erg/s/cm2. The ELRs have also been compared to the properties of the host galaxy, including morphology, luminosity, and mass. From this analysis, we find three key results: (1) the computed line luminosities show evidence of a flattening in the luminosity function with increasing redshift; (2) the star-forming systems show evidence of complex morphologies with star formation occurring predominantly within one effective (half-light) radius. However, the morphologies show no correlation with host stellar mass. (3) Also, the number density of SFGs with M_*_>=10^9^M_{sun}_ decreases by an order of magnitude at z<=0.5 relative to the number at 0.5<z<0.9, supporting the argument of galaxy downsizing.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/1043
- Title:
- Emission-line galaxies from SDSS DR7
- Short Name:
- J/MNRAS/421/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 2865 emission-line galaxies with strong nebular HeII{lambda}4686 emissions in the Sloan Digital Sky Survey Data Release 7 and use this sample to investigate the origin of this line in star-forming galaxies. We show that star-forming galaxies and galaxies dominated by an active galactic nucleus form clearly separated branches in the HeII{lambda}4686/H{beta} versus [NII]{lambda}6584/H{alpha} diagnostic diagram and derive an empirical classification scheme which separates the two classes. We also present an analysis of the physical properties of 189 star-forming galaxies with strong HeII{lambda}4686 emissions. These star-forming galaxies provide constraints on the hard ionizing continuum of massive stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/31
- Title:
- Emission-line galaxies from SDSS. I.
- Short Name:
- J/ApJS/201/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recently, much attention has been paid to double-peaked narrow emission-line (NEL) galaxies, some of which are suggested to be related to merging galaxies. We make a systematic search to build the largest sample of these sources from Data Release 7 of the Sloan Digital Sky Survey (SDSS). With reasonable criteria for fluxes, FWHMs of the emission lines, and separations of the peaks, we select 3030 double-peaked NEL galaxies. In light of the existence of broad Balmer lines and the locations of the two components of double-peaked NELs distinguished by the Kauffmann et al. (2003MNRAS.346.1055K) criteria in the Baldwin-Phillips-Terlevich diagram, we find that there are 81 Type I active galactic nuclei (AGNs), 837 double Type II AGNs (2-Type II), 708 galaxies with double star-forming components (2-SF), 400 with mixed star-forming and Type II AGN components (Type II + SF), and 1004 unknown-type objects. As a by-product, a sample of galaxies (12582) with asymmetric or top-flat profiles of emission lines is established. After visually inspecting the SDSS images of the two samples, we find 54 galaxies with dual cores.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/79
- Title:
- Emission-line galaxies from the FIGS survey
- Short Name:
- J/ApJ/888/79
- Date:
- 25 Oct 2021 10:14:43
- Publisher:
- CDS
- Description:
- We present a catalog of 208 0.3<z<2.1 emission-line galaxies (ELGs) selected from 1D slitless spectroscopy obtained using Hubble's WFC3 G102 grism, as part of the Faint Infrared Grism Survey. We identify ELG candidates by searching for significant peaks in all continuum-subtracted G102 spectra and, where possible, confirm candidates by identifying consistent emission lines in other available spectra or with published spectroscopic redshifts. We provide derived emission-line fluxes and errors, redshifts, and equivalent widths for H{alpha}{lambda}6563, [OIII]{lambda}{lambda}4959,5007, and [OII]{lambda}3727 emission lines, for ELGs down to AB(F105W)>28 and >10^-17^erg/cm^2^/s line flux. We use the resulting line catalog to investigate a possible relationship between line emission and a galaxy's environment. We use seventh-nearest-neighbor distances to investigate the typical surroundings of ELGs compared to non-ELGs, and we find that [OIII] emitters are preferentially found at intermediate galaxy densities near galaxy groups. We characterize these ELGs in terms of the galaxy specific star formation rate (SFR) versus stellar mass and find no significant influence of environment on that relation. We calculate SFRs and find no dependence of SFR on local galaxy surface density for 0.3<z<0.8 H{alpha} emitters and for 0.8<z<1.3 [OIII] emitters. We find similar rates of close-pair interaction between ELGs and non-ELGs. For galaxy surface densities {Sigma}<=30Mpc^-2^, we find no consistent effect of environment on star formation.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A30
- Title:
- Emission-line galaxies in ZwCl0024.0+1652
- Short Name:
- J/A+A/578/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cores of clusters at 0<~z<~1 are dominated by quiescent early-type galaxies, whereas the field is dominated by star-forming late-type galaxies. Clusters grow through the accretion of galaxies and groups from the surrounding field, which implies that galaxy properties, notably the star formation ability, are altered as they fall into overdense regions. The critical issues for understanding this evolution are how the truncation of star formation is connected to the morphological transformation and what physical mechanism is responsible for these changes. The GaLAxy Cluster Evolution Survey (GLACE) is conducting a thorough study of the variations in galaxy properties (star formation, AGN activity, and morphology) as a function of environment in a representative and well-studied sample of clusters. To address these questions, the GLACE survey is making a deep panoramic survey of emission line galaxies (ELG), mapping a set of optical lines ([OII], [OIII], H{beta} and H{alpha}/[NII] when possible) in several galaxy clusters at z~0.40, 0.63, and 0.86. Using the tunable filters (TF) of the OSIRIS instrument at the 10.4m GTC telescope, the GLACE survey applies the technique of TF tomography: for each line, a set of images are taken through the OSIRIS TF, each image tuned at a different wavelength (equally spaced), to cover a rest frame velocity range of several thousand km/s centred on the mean cluster redshift, and scanned for the full TF field of view of an 8arcmin diameter. Here we present the first results of the GLACE project, targeting the H{alpha}/[NII] lines in the intermediate-redshift cluster ZwCl0024.0+1652 at z=0.395. Two pointings have been performed that cover ~2*r_vir_.
