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941. Emission-line galaxies from HST PEARS survey
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.
942. Emission-line galaxies from PEARS. II.
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.
943. Emission-line galaxies from SDSS DR7
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.
944. Emission-line galaxies from SDSS. I.
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.
945. Emission-line galaxies from the FIGS survey
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.
946. Emission-line galaxies nearby voids.
ID:
ivo://CDS.VizieR/J/A+AS/116/43
Title:
Emission-line galaxies nearby voids.
Short Name:
J/A+AS/116/43
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the observational results of our search for emission-line galaxies (ELG) towards nearby voids. In order to find ELG, we started a survey using the IIIa-J objective prism plates from the Hamburg QSO Survey. The plates are digitized and an automatic procedure was applied to select the candidates. Digitized direct plates were used to determine coordinates and to reject overlaps between spectra. The accuracy of the coordinates is +/-2". A total area of 1248deg^2^ was scanned, distributed in four different regions. All the selected objects were observed with follow-up spectroscopy. We have obtained a final sample of 203 objects, of which 196 are emission-line galaxies, four are galaxies with absorption lines and three are QSOs. Almost half of our objects are newly discovered ones and three quarters of the given redshifts are new. Our sample contains mainly high ionization galaxies and is less sensitive in the detection of low-ionization objects. The apparent magnitudes, as derived from the objective prism plates, range between 15.0<=B<=19.5. The sample is dominated by nearby galaxies, with a peak in the redshift distribution at cz=4500 km/s.
947. Emission-line objects from ALFALFA H{alpha} survey
ID:
ivo://CDS.VizieR/J/AJ/143/145
Title:
Emission-line objects from ALFALFA H{alpha} survey
Short Name:
J/AJ/143/145
Date:
21 Oct 2021
Publisher:
CDS
Description:
During a wide-field narrowband H{alpha} imaging survey, we noted the presence of numerous isolated emission-line point sources in the data. These objects could represent ultra-low-luminosity galaxies at low-redshift (detection via H{alpha}), isolated extragalactic HII regions associated with the galaxy targeted by the original observation, or background galaxies or QSOs where strong emission lines (most often [OIII]{lambda}5007) redshift into our narrowband filter. We have carried out a systematic search for these "H{alpha} dots" in over 200 15x15arcmin fields. To date we have cataloged 61 candidate emission-line sources in roughly 11.7deg^2^. The sample has a median R magnitude of 19.5, and detects objects as faint as R=22.6. Follow-up spectroscopy reveals that ~85% of the candidates are bona fide emission-line objects, with roughly 60% of the real sources being lower-redshift objects (detection via H{alpha}) and 40% being higher-redshift objects detected via [OIII] emission or some other emission line. Here we present the results of our initial survey and follow-up spectroscopy. We use our sample to study the properties (including star-formation rates and metal abundances) of low-luminosity star-forming galaxies in the nearby universe and of low-metallicity star-forming galaxies at z~0.33.
948. Emission-line properties of Seyfert 2 nuclei
ID:
ivo://CDS.VizieR/J/MNRAS/366/480
Title:
Emission-line properties of Seyfert 2 nuclei
Short Name:
J/MNRAS/366/480
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the third paper of a series devoted to the study of the global properties of Joguet's sample (2001A&A...380...19J) of 79 nearby galaxies observable from the southern hemisphere, of which 65 are Seyfert 2 galaxies. We use the population synthesis models of Paper II (Cid Fernandes et al., 2004MNRAS.355..273C) to derive 'pure' emission-line spectra for the Seyfert 2 galaxies in the sample, and thus explore the statistical properties of the nuclear nebular components and their relation to the stellar populations.
949. Emission lines of radio-loud AGN
ID:
ivo://CDS.VizieR/J/ApJ/599/886
Title:
Emission lines of radio-loud AGN
Short Name:
J/ApJ/599/886
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the completion of a survey of radio-loud active galactic nuclei (AGNs) begun in an earlier paper (Eracleous & Halpern, 1994ApJS...90....1E) with the main goal of finding and studying broad, double-peaked Balmer lines. We present H{alpha} spectra of 13 more broad-lined objects, including three with double-peaked H{alpha} profiles. The final sample includes 106 radio-loud AGNs. In our final census 20% of objects have H{alpha} lines with double peaks or twin shoulders (the "double-peaked emitters"), and of these 60% (the disklike emitters) can be fitted quite well with a model attributing the emission to a circular, relativistic, Keplerian disk. In four objects where broad H{beta} and Mg II lines have been observed, we compare the profiles with models of photoionized accretion disks and find them to be in reasonable agreement.
950. Emission-line spectroscopy in NGC 891
ID:
ivo://CDS.VizieR/J/ApJ/832/118
Title:
Emission-line spectroscopy in NGC 891
Short Name:
J/ApJ/832/118
Date:
21 Oct 2021
Publisher:
CDS
Description:
The observed scale heights of extraplanar diffuse ionized gas (eDIG) layers exceed their thermal scale heights by a factor of a few in the Milky Way and other nearby edge-on disk galaxies. Here, we test a dynamical equilibrium model of the eDIG layer in NGC 891, where we ask whether the thermal, turbulent, magnetic field, and cosmic-ray pressure gradients are sufficient to support the layer. In optical emission-line spectroscopy from the SparsePak integral field unit on the WIYN 3.5m telescope, the H{alpha} emission in position-velocity space suggests that the eDIG is found in a ring between galactocentric radii of R_min_<=R<=8kpc, where R_min_>=2kpc. We find that the thermal ({sigma}_th_=11km/s) and turbulent ({sigma}_turb_=25km/s) velocity dispersions are insufficient to satisfy the hydrostatic equilibrium equation given an exponential electron scale height of h_z_=1.0kpc. Using a literature analysis of radio continuum observations from the CHANG-ES survey, we demonstrate that the magnetic field and cosmic-ray pressure gradients are sufficient to stably support the gas at R>=8kpc if the cosmic rays are sufficiently coupled to the system ({gamma}_cr_=1.45). Thus, a stable dynamical equilibrium model is viable only if the eDIG is found in a thin ring around R=8kpc, and nonequilibrium models such as a galactic fountain flow are of interest for further study.