Emission-line Galaxy Candidates Research Articles

The Star Formation Across Cosmic Time (SFACT) Survey. I. Survey Description and Early Results from a New Narrowband Emission-line Galaxy Survey

We introduce the Star Formation Across Cosmic Time (SFACT) survey. SFACT is a new narrowband survey for emission-line galaxies (ELGs) and QSOs being carried out using the wide-field imager on the WIYN 3.5 m telescope. Because of the superior depth and excellent image quality afforded by WIYN, we routinely detect ELGs to r = 25.0. Our survey observations are made using three custom narrowband filters centered on 6590 Å, 6950 Å, and 7460 Å. Due to the sensitivity of the survey, we are able to simultaneously detect sources via a number of different emission lines over a wide range of redshifts. The principal lines detected in SFACT are Hα (redshifts up to 0.144), [O iii]λ5007 (redshifts up to 0.500), and [O ii]λ3727 (redshifts up to 1.015). In this paper, we detail the properties of the survey as well as present initial results obtained by analyzing our three pilot-study fields. These fields have yielded a total of 533 ELG candidates in an area of 1.50 deg2 (surface density of 355 ELGs deg−2). Follow-up spectra for a subset of the ELG candidates are also presented. One of the key attributes of the SFACT survey is that the ELGs are detected in discrete redshift windows that will allow us to robustly quantify the properties of the star-forming and active galactic nucleus populations as a function of redshift to z = 1 and beyond. The planned acquisition of additional narrowband filters will allow us to expand our survey to substantially higher redshifts.

A Catalog of Emission-line Galaxies from the Faint Infrared Grism Survey: Studying Environmental Influence on Star Formation

Abstract 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 Hα λ6563, [O iii] λλ4959, 5007, and [O ii] λ3727 emission lines, for ELGs down to AB(F105W) >28 and >10−17 erg cm−2 s−1 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 [O iii] 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 Hα emitters and for 0.8 < z < 1.3 [O iii] emitters. We find similar rates of close-pair interaction between ELGs and non-ELGs. For galaxy surface densities Σ ≤ 30 Mpc−2, we find no consistent effect of environment on star formation.

The MUSE Hubble Ultra Deep Field Survey

We present the MUSE Hubble Ultra Deep Survey, a mosaic of nine MUSE fields covering 90% of the entire HUDF region with a 10-h deep exposure time, plus a deeper 31-h exposure in a single 1.15 arcmin2 field. The improved observing strategy and advanced data reduction results in datacubes with sub-arcsecond spatial resolution (0.̋65 at 7000 Å) and accurate astrometry (0.̋07 rms). We compare the broadband photometric properties of the datacubes to HST photometry, finding a good agreement in zeropoint up to mAB = 28 but with an increasing scatter for faint objects. We have investigated the noise properties and developed an empirical way to account for the impact of the correlation introduced by the 3D drizzle interpolation. The achieved 3σ emission line detection limit for a point source is 1.5 and 3.1 × 10-19 erg s-1 cm-2 for the single ultra-deep datacube and the mosaic, respectively. We extracted 6288 sources using an optimal extraction scheme that takes the published HST source locations as prior. In parallel, we performed a blind search of emission line galaxies using an original method based on advanced test statistics and filter matching. The blind search results in 1251 emission line galaxy candidates in the mosaic and 306 in the ultradeep datacube, including 72 sources without HST counterparts (mAB > 31). In addition 88 sources missed in the HST catalog but with clear HST counterparts were identified. This data set is the deepest spectroscopic survey ever performed. In just over 100 h of integration time, it provides nearly an order of magnitude more spectroscopic redshifts compared to the data that has been accumulated on the UDF over the past decade. The depth and high quality of these datacubes enables new and detailed studies of the physical properties of the galaxy population and their environments over a large redshift range.

Spectroscopy of KISS Emission-Line Galaxy Candidates. IV. KPNO and WIYN Observations

Spectroscopic observations for 614 emission-line galaxy (ELG) candidates from the KPNO International Spectroscopic Survey (KISS) have been obtained using the KPNO 2.1 m telescope and the WIYN 3.5 m telescope. KISS is a wide-field objective-prism survey for extragalactic emission-line objects that has cataloged over 2400 ELG candidates to date. Spectroscopic follow-up observations are being carried out at several telescopes to study the characteristics of the survey objects. We present the following data derived from the KPNO spectra: redshifts, reddening estimates, line equivalent widths, Hα line fluxes, and emission-line ratios. The galaxies have been classified based on their emission-line characteristics. The procedure for selecting the ELG candidates in KISS is found to be very reliable: the follow-up observations verify the presence of emission lines in 93% of the sample presented here. A comparison of objective-prism survey data—redshifts, Hα line fluxes, and equivalent widths—to the long-slit measurements shows good overall agreement.

The KPNO International Spectroscopic Survey. V. Hα-selected Survey List 3

The KPNO International Spectroscopic Survey (KISS) is an objective-prism survey designed to detect extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors and is the first purely digital objective-prism survey for emission-line galaxies (ELGs). Here we present the third list of ELG candidates selected from our red spectral data, which cover the wavelength range 6400–7200 A. In most cases, the detected emission line is Hα. The current survey list covers the region of the NOAO Deep Wide Field Survey (NDWFS). This survey covers two fields; the first is 3° × 3° and located at R.A. = 14h30m, δ = 34°30' (B1950.0), and the second is 23 × 40 and centered at R.A. = 2h7m30s, δ = -4°44'. A total area of 19.65 deg2 is covered by the KISS data. A total of 261 candidate emission-line objects have been selected for inclusion in the survey list (13.3 deg-2). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift, emission-line flux, and line equivalent width based on measurements of the digital objective-prism spectra. The properties of the KISS ELGs are examined using the available observational data. When combined with the wealth of multiwavelength data already available for the NDWFS fields, the current list of KISS ELGs should provide a valuable tool for studying star formation and nuclear activity in galaxies in the local universe.

Spectroscopy of KISS Emission-Line Galaxy Candidates. III. A Second Set of MDM Observations

Spectroscopic observations for 315 emission-line galaxy (ELG) candidates from the KPNO International Spectroscopic Survey (KISS) have been obtained using the MDM Observatory 2.4 m telescope on Kitt Peak. KISS is a wide-field objective-prism survey for extragalactic emission-line objects that has cataloged over 2200 ELG candidates to date. Spectroscopic follow-up observations are being carried out to study the characteristics of the survey objects. The observational data presented here include redshifts, reddening estimates, line equivalent widths, H? line fluxes, and emission-line ratios. The galaxies have been classified based on their emission-line characteristics. The procedure for selecting the ELG candidates in KISS is found to be very reliable: 93% of the candidates in this sample are verified to have emission lines. A comparison of objective-prism survey data?redshifts, H? line fluxes, and equivalent widths?to the long-slit measurements shows good overall agreement.

Tunable-Filter Imaging of Quasar Fields atz ~ 1. II. The Star-forming Galaxy Environments of Radio-loud Quasars

We have scanned the fields of six radio-loud quasars using the Taurus Tunable Filter to detect redshifted [O II] λ3727 line–emitting galaxies at redshifts 0.8 < z < 1.3. Forty-seven new emission-line galaxy (ELG) candidates are found. This number corresponds to an average space density about 100 times of that found locally and, at L([O ]) < 1042 ergs s-1 cm-2, is 2–5 times greater than the field ELG density at similar redshifts, implying that radio-loud quasars inhabit sites of above average star formation activity. The implied star formation rates are consistent with surveys of field galaxies at z ~ 1. However, the variation in candidate density between fields is large and indicative of a range of environments, from the field to rich clusters. The ELG candidates also cluster—both spatially and in terms of velocity—about the radio sources. In fields known to contain rich galaxy clusters, the ELGs lie at the edges and outside the concentrated cores of red, evolved galaxies, consistent with the morphology-density relation seen in low-redshift clusters. This work, combined with other studies, suggests that the ELG environments of powerful active galactic nuclei look very much the same from moderate to high redshifts, i.e., 0.8 < z < 4.

Spectroscopy of KISS Emission-Line Galaxy Candidates. II. Hobby-Eberly Telescope Observations

The KPNO International Spectroscopic Survey (KISS) is an ongoing wide-field objective-prism survey for extragalactic emission-line objects. Over 2200 emission-line galaxy (ELG) candidates have been cataloged to date. To study the characteristics of the survey objects, spectroscopic follow-up observations are being carried out at several telescopes. Here we present the results of the spectroscopic observations for 258 KISS ELG candidates that have been obtained using the Marcario Low Resolution Spectrograph on the 9.2 m Hobby-Eberly Telescope (HET). We present the following data derived from the HET spectra: redshifts, reddening estimates, line equivalent widths, emission-line ratios, and galaxy activity types (e.g., AGN or star-forming). The long-slit redshifts are compared to those determined from the KISS objective-prism spectra and show good agreement. Earlier spectroscopic follow-up observations have typically verified the presence of emission lines for over 90% of the KISS ELG candidates. However, in the sample observed with the HET, only 78% of candidates are confirmed to be extragalactic emission-line sources. This is because the HET sample contains a large fraction of the faintest KISS objects, which typically have low spectral quality. A small number of objects at higher redshift (z ~ 0.3), detected by KISS from their [O III] emission rather than from Hα emission, are identified based on their spectra.

The KPNO International Spectroscopic Survey. IV. H-selected Survey List 2

The KPNO International Spectroscopic Survey (KISS) is an objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors and is the first purely digital objective-prism survey for emission-line galaxies. Here we present the second list of emission-line galaxy candidates selected from our red spectral data, which cover the wavelength range 6400 to 7200 A. In most cases, the detected emission line is Hα. The current survey list covers a 16-wide strip located at δ = 43°30' (B1950) and spans the right ascension range 11h55m to 16h15m. The survey strip runs through the center of the Bootes void and has enough depth to adequately sample the far side of the void. An area of 65.8 deg2 is covered. A total of 1029 candidate emission-line objects have been selected for inclusion in the survey list (15.6 deg-2). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift and emission-line flux and equivalent width based on measurements of the digital objective-prism spectra. The properties of the KISS emission-line galaxies are examined using the available observational data. Although the current survey covers only a modest fraction of the total volume of the Bootes void, we catalog at least 12 objects that appear to be located within the void. Only one of these objects has been recognized previously as a void galaxy.

The Distribution of Lyα‐Emitting Galaxies atz = 2.38

We present the detection of 34 emission-line galaxy candidates in a 80 × 80 × 60 comoving Mpc region surrounding the known z = 2.38 galaxy cluster J2143-4423. The space density of emitters is comparable to that found by Steidel et al. when targeting a cluster at redshift 3.09, which is a factor of 5.8 ± 2.5 greater than that found by field samples at similar redshifts. The distribution of these galaxy candidates contains several 5-10 Mpc scale voids. We compare our observations with mock catalogs derived from the VIRGO consortium ΛCDM n-body simulations. Fewer than 1% of the mock catalogs contain voids as large as we observe. Our observations thus tentatively suggest that the galaxy distribution at redshift 2.38 contains larger voids than predicted by current models. Three of the candidate galaxies and one previously discovered galaxy have the large luminosities and extended morphologies of Lyα blobs.

Spectroscopy of KISS Emission-Line Galaxy Candidates. I. MDM Observations

Spectroscopic observations for 351 emission-line galaxy candidates from the KPNO International Spectroscopic Survey (KISS) have been obtained using the MDM Observatory 2.4 m telescope on Kitt Peak. KISS is an ongoing wide-field objective-prism survey for extragalactic emission-line objects, which has cataloged over 2200 emission-line galaxy (ELG) candidates to date. Spectroscopic follow-up observations are being carried out to study the characteristics of the survey objects. The observational data presented here include redshifts, reddening estimates, line equivalent widths, Hα line fluxes, and emission-line ratios. The galaxies have been classified based on their emission-line characteristics. The procedure for selecting the ELG candidates in KISS is found to be very reliable: 95% of the candidates in this sample are verified to have emission lines. A comparison of objective-prism survey data—redshifts, Hα line fluxes, and equivalent widths—with the long-slit measurements shows good overall agreement.

Metal Abundances of KISS Galaxies. I. Coarse Metal Abundances and the Metallicity-Luminosity Relation

We derive metal abundance estimates for a large sample of starbursting emission-line galaxies (ELGs). Our sample is drawn from the KPNO International Spectroscopic Survey (KISS), which has discovered over 2000 ELG candidates to date. Follow-up optical spectra have been obtained for ∼900 of these objects. A three-step process is used to obtain metal abundances for these galaxies. We first calculate accurate nebular abundances for 12 galaxies whose spectra cover the full optical region from [O II] λλ3726, 3729 to beyond [S II] λλ6717, 6731 and include detection of [O III] λ4363. Using secondary metallicity indicators R23 and p3, we calculate metallicities for an additional 59 galaxies with spectra that cover a similar wavelength range but lack [O III] λ4363. The results are used to calibrate relations between metallicity and two readily observed emission-line ratios, which allow us to estimate coarse metallicities for 519 galaxies in total. The uncertainty in these latter abundance estimates is 0.16 dex. From the large, homogeneously observed sample of star-forming galaxies, we identify low-metallicity candidates for future study and investigate the metallicity-luminosity relation. We find a linear metallicity-luminosity relation of the form 12 + log(O/H) = 4.059 - 0.240MB, with an rms scatter of 0.252. This result implies that the slope of the metallicity-luminosity relation is steeper than when dwarf galaxies are considered alone and may be evidence that the relationship is not linear over the full luminosity range of the sample.

The KPNO International Spectroscopic Survey. III. [O [CSC]iii[/CSC]]-selected Survey List

The KPNO International Spectroscopic Survey (KISS) is an objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors, and it is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list of emission-line galaxy candidates selected from our blue spectral data, which cover the wavelength range 4800–5500 A. In most cases, the detected emission line is [O III] λ5007. The current survey list covers a 1°-wide strip located at δ = 29°30' (B1950.0) and spanning the right ascension range 8h30m to 17h0m. An area of 116.6 deg2 is covered. A total of 223 candidate emission-line objects have been selected for inclusion in the survey list (1.91 deg-2). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift, emission-line flux, and equivalent width based on measurements of the digital objective-prism spectra. The median apparent magnitude of the sample is B = 18.2, and galaxies with redshifts approaching z = 0.1 are detected. The properties of the KISS emission-line galaxies are examined using the available observational data and compared with previous surveys carried out with photographic plates, as well as with the Hα-selected portion of KISS.

The KPNO International Spectroscopic Survey. II. Hα-selected Survey List 1

The KPNO International Spectroscopic Survey (KISS) is a new objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors and is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list of emission-line galaxy candidates selected from our red spectral data, which cover the spectral range 6400 to 7200 A. In most cases, the detected emission line is Hα. The current survey list covers a 1°-wide strip located at δ = 29°30' (B1950.0) and spanning the right ascension range 12h15m to 17h0m. An area of 62.2 deg2 is covered. A total of 1128 candidate emission-line objects have been selected for inclusion in the survey list (18.1 deg-2). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift and emission-line flux and equivalent width based on measurements of the digital objective-prism spectra. The properties of the KISS emission-line galaxies are examined using the available observational data.

The KPNO International Spectroscopic Survey. I. Description of the Survey

The KPNO International Spectroscopic Survey (KISS) is a new objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys that were carried out with Schmidt telescopes using photographic plates with the advantages of modern CCD detectors. It is the first purely digital objective-prism survey, and extends previous photographic surveys to substantially fainter flux limits. In this, the first paper in the series, we give an overview of the survey technique, describe our data processing procedures, and present examples of the types of objects found by KISS. Our first H�-selected survey list detects objects at the rate of 18.1 per square degree, which is 181 times higher than the surface density of the Markarian survey. Since the sample is line-selected, there is an imposed redshift limit of z < � 0.095 due to the filter employed for the objective-prism observations. We evaluate the quality of the observed parameters derived from the survey data, which include accurate astrometry, photometry, redshifts, and line fluxes. Finally, we describe some of the many applications the KISS database will have for addressing specific questions in extragalactic astronomy. Subsequent papers in this series will present our survey lists of emission-line galaxy candidates. Subject headings: galaxies: emission-lines — galaxies: Seyfert — galaxies: starburst — surveys

Observations of a complete sample of H $_{\bf\alpha}$ emission-line galaxies. Long-slit spectroscopy of galaxies in UCM lists 1 and 2

Spectroscopic observations for the full sample of Her emission-line galaxy candidates (ELGs) from the Universidad Complutense de Madrid objective-prism survey Lists 1 and 2 have been obtained in order to investigate fully the properties of the survey constituents as well as the selection characteristics and completeness limits of the survey itself. The spectroscopic data include redshifts, line fluxes, equivalent widths, emission-line ratios, optical reddening estimates and synthesized color indexes. We find that 74% of the objects in this sample do exhibit emission Lines. We compare our observational data, with parameters given in the published survey lists in order to assess the usefulness of the latter. The different emission-line galaxies have been classified according to their spectra in several groups. Gray-scale images of the CCD spectra near the main emission lines, spatial profiles at the continuum and the Line for [OIII] λ5007 and Hα lines, as well as plots of the coadded spectra of selected galaxies are presented, and a number of peculiar objects are described.

AUTOMATIC SELECTION OF H-ALPHA EMISSION-LINE GALAXIES

ABSTRACT We have developed a procedure for the automatic selection of emission-line galaxies candidates from the digitization of objective prism plates. This procedure has been applied over two pair of direct and prism plates of the Universidad Complutense de Madrid (UCM) survey, digitized by the fast and high performance microdensitometer MAMA (Machine Automatique a Mesurer pour l'Astronomie) located at the Observatoire de Paris. The plates where obtained with the Schmidt Telescope at Calar Alto Observatory in Almeria (Spain). The instrumental setup used for the acquisition of the prism plates (IIIa-F emulsion and RG630 filter) allows to register the H-alpha +[NII] emission for galaxies up to z ≤ 0.045. Therefore the criteria developed for the automatic selection of ELGs candidates consist in identifying the H-alpha emission feature in the extracted monodimensional prism spectra. We have noted that there is not a nitid edge to distinguish between the spectra showing the H-alpha line in emission and the rest. Consequently we have studied the residual obtained after the estimation of the continuum and the variation of the slopes calculated over each spectrum in order to identify the line feature. The efficiency of this technique has been tested by comparing the results obtained applying the automatic procedure with those achieved after a careful visual search for the candidates, as performed up to date in the UCM and similar surveys. The results show us that the automatic procedure only ignore very extended and near saturated known galaxies with well resolved emitting regions located at the external regions. Spectroscopic observations of moderate dispersion for the whole set of candidates selected both automatic and visually show that the former has been able, not only to select the 100% of candidates with confirmed emission recognized also by visual means, but also, and what is more important, to identify a 29% more of confirmed ELGs, without lost of efficiency by the increase of spurious identifications. The digitization of the plates has allowed us to measure a set of accurate observational parameters as positions, magnitudes, sizes and redshifts that will permit to perform statistical analysis of this kind of objects before carrying out specific observations with larger telescopes. Since our plates have not sensitometric spots to calculate its characteristic curve, it has been necessary to obtain external calibrations by comparing with calibrated data offered by several catalogs. We have tested that the precision achieved using this method is mainly limited by the accuracy of the different catalog employed. The redshift of the candidates can be derived from the location of the H-alpha line on the prism spectra. Since they have no spectral features to refer the position of the Hα line, the positions of the objects in the direct plate and their transformations to the prism one have been used to provide a reference point which is dependent neither on magnitude, nor on color, nor spatial light distribution. A precision of 0.003 is reached when measuring redshifts by this method. Finally, the comparison of the candidate samples obtained from two plates of our survey covering the same area on the sky allows the study of the selection effects that affects the identification of the H-alpha line in photographic prism plates. The parameter EW X F of the emission H-alpha +[NII] can be used as a threshold that inform us about the unambiguous identification of the emission in the prism spectra, being 10-13 erg s-1 cm-2A the mean value of this parameter for the whole sample of the UCM survey. We have also developed an algorithm to simulate the expected objective-prism spectra for an object by using different instrumental setups. The simulation permits to investigate the different combinations of EW, fluxes and magnitude that allow the detection of the Hα line in the plates and will be used in the near future to predict the expected spectra by the substitution of the photographic emulsion with CCD detectors.

A new survey for low-luminosity emission-line galaxies

view Abstract Citations (25) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A New Survey for Low-Luminosity Emission-Line Galaxies Boroson, Todd A. ; Salzer, John J. ; Trotter, Adam Abstract A survey for low-luminosity emission-line galaxies is described in which deep CCD images have been obtained through five narrow-band ({DELTA}λ = 80 A) filters. The survey covers 0.7 square degrees to a depth corresponding to a monochromatic magnitude m_6600_ = 21.2 in the emission line plus continuum. The survey is sensitive to objects with strong Hα emission out to a redshift of z = 0.054, as well as higher redshift galaxies with [O III], Hβ, or [O II] emission. Two hundred ninety-three emission-line galaxy candidates were selected based on a (line plus continuum)/continuum ratio of 1.5 or greater. These candidates were observed spectroscopically with a multifiber spectrograph. Eleven low-redshift (z < 0.054) emission-line galaxies were confirmed with moderate to strong Hα emission and M_B_ in the range - 17.8 to - 12.9. Thirty-six additional objects are emission-line galaxies at higher redshift, including 11 in which only one emission line is seen. Nine of the low-redshift emission-line galaxies form an essentially complete sample, and two methods are explored to calculate the luminosity function. While the range of luminosity sampled is small enough that tradeoffs between slope and normalization of the luminosity function are possible, the combination of this survey with the study of Salzer allows fairly restrictive limits on these two quantities. The best-fit Schechter function to the combination of these two data sets has slope α = - 1.35 and normalization, logφ^*^ = -3.15 mag^-1^ Mpc^-3^. In heavy-element abundance, the objects found in this survey span the range defined by known dwarf emission-line galaxies, with the most metal- poor object having an O/H abundance about 0.09 of the solar value. Despite the fact that the survey technique employed is sensitive to the presence of ultra-low metal-abundance galaxies, no such objects were found. One group of higher redshift emission-line galaxies, those with [O III] λ5007 shifted into the Hα region, has relevance to the interpretation of faint blue galaxy counts. These objects are examples of the type of galaxy that has been proposed to account for the excess counts at B = 22 and fainter. We find that the number discovered in the survey is exactly that predicted by the local luminosity function, i.e., there is no evidence for strong evolution in the number density of these objects, in disagreement with that interpretation. Publication: The Astrophysical Journal Pub Date: August 1993 DOI: 10.1086/172940 Bibcode: 1993ApJ...412..524B Keywords: Emission Spectra; Galactic Radiation; Line Spectra; Mass To Light Ratios; Astronomical Photometry; Galactic Mass; Luminosity; Astrophysics; GALAXIES: LUMINOSITY FUNCTION; MASS FUNCTION; GALAXIES: PHOTOMETRY full text sources ADS | data products NED (47) SIMBAD (46)

New emission-line galaxies identified from an objective prism survey

As a part of an ongoing objective prism survey, 107 emission line galaxy candidates have been identified from three selected fields. We present a preliminary analysis of some of them based on spectroscopic observations with moderate spectral resolution and CCD images. From these data the nature of the observed objects is discussed. In almost all the cases the candidates emerge as star-burst nuclei. The four sample objects which have been also detected by IRAS follow the IR-Hα luminosity relationship observed in extragalacticHII regions.

Optical and Far-Infrared Properties of UM Survey Emission-Line Galaxies

For the University of Michigan (UM) survey, the Curtis Schmidt telescope at CTIO is used with Kodak IIIa-J plates and the 1.°8 objective prism to detect emission-line galaxies (ELGs) and quasars. Line emission is the primary selection criterion. The quasar sample has been investigated by Lewis, MacAlpine, and Weedman (1979) and by MacAlpine and Feldman (1982) while a study of the ELGs was begun by Lewis (1983). Here, we report on a more extensive analysis of the 172 ELG candidates in the UM Lists IV (MacAlpine and Lewis 1978) and V (MacAlpine and Williams 1981) areas.