- ID:
- ivo://CDS.VizieR/J/A+A/437/883
- Title:
- K20 survey: spectroscopic catalogue
- Short Name:
- J/A+A/437/883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K20 survey is a near infrared-selected, deep (Ks<20) redshift survey targeting galaxies in two independent regions of the sky, the Chandra Deep Field South and the field around the quasar 0055-2659, for a total area of 52arcmin^2^. The total Ks-selected sample includes 545 objects. Low-resolution (R~300-600) optical spectra for 525 of them have been obtained with the FORS1/FORS2 spectrographs at the ESO/VLT, providing 501 spectroscopic identifications (including 12 type-1 AGN and 45 stars); consequently, we were able to measure redshifts and identify stars in 96% of the observed objects, whereas the spectroscopic completeness with respect to the total photometrically selected sample is 92% (501/545). The K20 survey is therefore the most complete spectroscopic survey of a near infrared-selected sample to date. The K20 survey contains 444 spectroscopically identified galaxies, covering a redshift range of 0.05<z<2.73, with a mean redshift <z>=0.75; excluding the 32 "low-quality" redshifts does not significantly change these values.
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- ID:
- ivo://CDS.VizieR/J/ApJS/234/5
- Title:
- LaCoSSPAr in the Southern Galactic Cap. I.
- Short Name:
- J/ApJS/234/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic redshift catalog from the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap (SGC), which is designed to observe all sources (Galactic and extragalactic) by using repeating observations with a limiting magnitude of r=18.1mag in two 20deg^2^ fields. The project is mainly focusing on the completeness of LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source selection methods, and the basic performance parameters of the LAMOST telescope. In both fields, more than 95% of galaxies have been observed. A post-processing has been applied to the LAMOST 1D spectrum to remove the majority of remaining sky background residuals. More than 10000 spectra have been visually inspected to measure the redshift by using combinations of different emission/absorption features with an uncertainty of {sigma}_z_/(1+z)<0.001. In total, 1528 redshifts (623 absorption and 905 emission line galaxies) in Field A and 1570 redshifts (569 absorption and 1001 emission line galaxies) in Field B have been measured. The results show that it is possible to derive redshift from low S/N galaxies with our post-processing and visual inspection. Our analysis also indicates that up to one-fourth of the input targets for a typical extragalactic spectroscopic survey might be unreliable. The multi-wavelength data analysis shows that the majority of mid-infrared-detected absorption (91.3%) and emission line galaxies (93.3%) can be well separated by an empirical criterion of W2-W3=2.4. Meanwhile, a fainter sequence paralleled to the main population of galaxies has been witnessed both in Mr/W2-W3 and M*/W2-W3 diagrams, which could be the population of luminous dwarf galaxies but contaminated by the edge-on/highly inclined galaxies (~30%).
- ID:
- ivo://CDS.VizieR/J/ApJ/744/110
- Title:
- LAE galaxies between 2.1=<z<=3.1
- Short Name:
- J/ApJ/744/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of a new, wide-field survey for z=3.1 Ly{alpha} emitters (LAEs) in the Extended Chandra Deep Field South (ECDF-S). By using a nearly top-hat 5010{AA} filter and complementary broadband photometry from the MUSYC survey, we identify a complete sample of 141 objects with monochromatic fluxes brighter than 2.4x10^-17^erg/cm^2^/s and observers-frame equivalent widths (EWs) greater than ~80{AA} (i.e., 20{AA} in the rest frame of Ly{alpha}). The bright end of this data set is dominated by X-ray sources and foreground objects with Galaxy Evolution Explorer detections, but when these interlopers are removed, we are still left with a sample of 130 LAE candidates, 39 of which have spectroscopic confirmations. This sample overlaps the set of objects found in an earlier ECDF-S survey, but due to our filter's redder bandpass, it also includes 68 previously uncataloged sources. We confirm earlier measurements of the z=3.1 LAE emission-line luminosity function and show that an apparent anticorrelation between EW and continuum brightness is likely due to the effect of correlated errors in our heteroskedastic data set. Finally, we compare the properties of z=3.1 LAEs to LAEs found at z=2.1. We show that in the ~1Gyr after z~3, the LAE luminosity function evolved significantly, with L* fading by ~0.4mag, the number density of sources with L>1.5x10^42^erg/s declining by ~50%, and the EW scale length contracting from 70^+7^_-5_{AA} to 50^+9^_-6_{AA}. When combined with literature results, our observations demonstrate that over the redshift range z~0 to z~4, LAEs contain less than ~10% of the star formation rate density of the universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/95
- Title:
- LAE galaxies in the ECDF-S at z~2.1 and z~3.1
- Short Name:
- J/ApJ/753/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a rest-frame ultraviolet morphological analysis of 108 z~2.1 Ly{alpha} emitters (LAEs) in the Extended Chandra Deep Field South and compare it to a similar sample of 171 LAEs at z~3.1. Using Hubble Space Telescope images from the Galaxy Evolution from Morphology and SEDs survey, Great Observatories Origins Deep Survey, and Hubble Ultradeep Field, we measure size and photometric component distributions, where photometric components are defined as distinct clumps of UV-continuum emission. At both redshifts, >80% of LAEs have observed half-light radii <2kpc, but the median half-light radius rises from 0.95+/-0.04kpc at z=3.1 to 1.41+/-0.14kpc at z=2.1. A similar evolution is seen in the sizes of individual rest-UV components, but there is no evidence for evolution in the number of multi-component systems. In the z=2.1 sample, we see clear correlations between the size of an LAE and other physical properties derived from its spectral energy distribution (SED). LAEs are found to be larger for galaxies with higher stellar mass, star formation rate, and dust obscuration, but there is no evidence for a trend between equivalent width and half-light radius at either redshift. The presence of these correlations suggests that a wide range of objects are being selected by LAE surveys at z~2, including a significant fraction of objects for which a massive and moderately extended population of old stars underlies the young starburst giving rise to the Ly{alpha} emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/762
- Title:
- LAEs at z~4.5 in the LALA Cetus field
- Short Name:
- J/ApJ/706/762
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large sample of Ly{alpha}-emitting galaxies (LAEs) spectroscopically confirmed at redshift z~4.5, based on Inamori-Magellan Areal Camera and Spectrograph spectroscopic observations of candidate z~4.5 Ly{alpha}-emitting galaxies in the large area Lyman alpha (LALA) narrowband imaging survey Cetus field. We identify 110 of them as z~4.5 Ly{alpha} emitters based on single-line detections with no continuum emission blueward of the line. Six foreground galaxies are identified, either based on multiple lines or blueward continuum emission. The Ly{alpha} confirmation rate varies from <50% to 76% for candidates selected in different narrowband filters at slightly different redshifts. The sample includes many objects with equivalent widths (EWs)>~200{AA}. These large EW candidates are spectroscopically confirmed at the same rate as candidates with more modest EWs.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/136
- Title:
- LAEs between 0.19<z<1.25 with GALEX grism
- Short Name:
- J/ApJ/738/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy of two samples of Galaxy Evolution Explorer grism selected Ly{alpha} emitters (LAEs): one at z=0.195-0.44 and the other at z=0.65-1.25. We have also observed a comparison sample of galaxies in the same redshift intervals with the same UV magnitude distributions but with no detected Ly{alpha}. We use the optical spectroscopy to eliminate active galactic nuclei and to obtain the optical emission-line properties of the samples. We compare the luminosities of the LAEs in the two redshift intervals and show that there is dramatic evolution in the maximum Ly{alpha} luminosity over z=0-1. Focusing on the z=0.195-0.44 samples alone, we show that there are tightly defined relations between all of the galaxy parameters and the rest-frame equivalent width (EW) of H{alpha}. The higher EW(H{alpha}) sources all have lower metallicities, bluer colors, smaller sizes, and less extinction, consistent with their being in the early stages of the galaxy formation process.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/L1
- Title:
- LAEs discovered with ultra-deep MUSE sp. in UDF
- Short Name:
- J/ApJ/865/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using an ultra-deep blind survey with the MUSE integral field spectrograph on the European Southern Observatory Very Large Telescope, we obtain spectroscopic redshifts to a depth never before explored: galaxies with observed magnitudes m_AB_>~30-32. Specifically, we detect objects via Ly{alpha} emission at 2.9<z<6.7 without individual continuum counterparts in areas covered by the deepest optical/near-infrared imaging taken by the Hubble Space Telescope, the Hubble Ultra Deep Field. In total, we find 102 such objects in 9 square arcminutes at these redshifts. Detailed stacking analyses confirm the Ly{alpha} emission as well as the 1216 {AA} breaks and faint ultraviolet continua (M_UV_~-15). This makes them the faintest spectroscopically confirmed objects at these redshifts, similar to the sources believed to reionize the universe. A simple model for the expected fraction of detected/undetected Ly{alpha} emitters as a function of luminosity is consistent with these objects being the high-equivalent width tail of the normal Ly{alpha}-emitter population at these redshifts.
- ID:
- ivo://CDS.VizieR/J/AJ/145/159
- Title:
- LAMOST. II. ugriz photometry of 526 new quasars
- Short Name:
- J/AJ/145/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new quasars discovered in the vicinity of the Andromeda and Triangulum galaxies with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, also named the Guoshoujing Telescope, during the 2010 and 2011 observational seasons. Quasar candidates are selected based on the available Sloan Digital Sky Survey, Kitt Peak National Observatory 4m telescope, Xuyi Schmidt Telescope Photometric Survey optical, and Wide-field Infrared Survey Explorer near-infrared photometric data. We present 509 new quasars discovered in a stripe of ~135deg^2^ from M31 to M33 along the Giant Stellar Stream in the 2011 pilot survey data sets, and also 17 new quasars discovered in an area of ~100 deg^2^ that covers the central region and the southeastern halo of M31 in the 2010 commissioning data sets. These 526 new quasars have i magnitudes ranging from 15.5 to 20.0, redshifts from 0.1 to 3.2. They represent a significant increase of the number of identified quasars in the vicinity of M31 and M33. There are now 26, 62, and 139 known quasars in this region of the sky with i magnitudes brighter than 17.0, 17.5, and 18.0, respectively, of which 5, 20, and 75 are newly discovered. These bright quasars provide an invaluable collection with which to probe the kinematics and chemistry of the interstellar/intergalactic medium in the Local Group of galaxies. A total of 93 quasars are now known with locations within 2.5{deg} of M31, of which 73 are newly discovered. Tens of quasars are now known to be located behind the Giant Stellar Stream, and hundreds are behind the extended halo and its associated substructures of M31. The much enlarged sample of known quasars in the vicinity of M31 and M33 can potentially be utilized to construct a perfect astrometric reference frame to measure the minute proper motions (PMs) of M31 and M33, along with the PMs of substructures associated with the Local Group of galaxies. Those PMs are some of the most fundamental properties of the Local Group.
- ID:
- ivo://CDS.VizieR/J/AJ/155/189
- Title:
- LAMOST Quasar Survey: quasar properties from DR2&3
- Short Name:
- J/AJ/155/189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second installment for the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Quasar Survey, which includes quasars observed from 2013 September to 2015 June. There are 9024 confirmed quasars in DR2 and 10911 in DR3. After cross-match with the Sloan Digital Sky Survey (SDSS) quasar catalogs and NED, 12126 quasars are discovered independently. Among them, 2225 quasars were released by SDSS DR12 QSO catalog in 2014 after we finalized the survey candidates. 1801 sources were identified by SDSS DR14 as QSOs. The remaining 8100 quasars are considered as newly founded, and among them, 6887 quasars can be given reliable emission line measurements and the estimated black hole masses. Quasars found in LAMOST are mostly located at low-to-moderate redshifts, with a mean value of 1.5. The highest redshift observed in DR2 and DR3 is 5. We applied emission line measurements to H{alpha}, H{beta}, Mg II, and C IV. We deduced the monochromatic continuum luminosities using photometry data, and estimated the virial black hole masses for the newly discovered quasars. Results are compiled into a quasar catalog, which will be available online.
- ID:
- ivo://CDS.VizieR/J/AJ/151/24
- Title:
- LAMOST quasar survey: quasar properties from the DR1
- Short Name:
- J/AJ/151/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present preliminary results of the quasar survey in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) first data release (DR1), which includes the pilot survey and the first year of the regular survey. There are 3921 quasars reliably identified, among which 1180 are new quasars discovered in the survey. These quasars are at low to median redshifts, with a highest z of 4.83. We compile emission line measurements around the H{alpha}, H{beta}, Mg II, and C IV regions for the new quasars. The continuum luminosities are inferred from SDSS photometric data with model fitting, as the spectra in DR1 are non-flux-calibrated. We also compile the virial black hole mass estimates, with flags indicating the selection methods, and broad absorption line quasars. The catalog and spectra for these quasars are also available. Of the 3921 quasars, 28% are independently selected with optical-infrared colors, indicating that the method is quite promising for the completeness of the quasar survey. LAMOST DR1 and the ongoing quasar survey will provide valuable data for studies of quasars.