- ID:
- ivo://CDS.VizieR/J/AJ/119/241
- Title:
- South Galactic cap MCT blue objects
- Short Name:
- J/AJ/119/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results for the south Galactic cap region of the Montreal-Cambridge-Tololo survey of blue subluminous stars are presented. This region overlaps the 840 deg^2^ region studied almost three decades ago by Slettebak & Brundage (1971AJ.....76..338S). We present a list of equatorial coordinates, photographic photometry, and spectroscopic identifications, as well as finding charts, for 188 blue objects [(U-B)_pg_<=-0.6] brighter than B_pg_=16.5 in this area. Completeness of the survey and comparisons with other similar efforts are discussed.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/884/L31
- Title:
- Spectra & HST obs. of gal. in 1ES1553+113 field
- Short Name:
- J/ApJ/884/L31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relationship between galaxies and the state/chemical enrichment of the warm-hot intergalactic medium (WHIM) expected to dominate the baryon budget at low-z provides sensitive constraints on structure formation and galaxy evolution models. We present a deep redshift survey in the field of 1ES1553+113, a blazar with a unique combination of ultraviolet (UV)+X-ray spectra for surveys of the circumgalactic/intergalactic medium (CGM/IGM). Nicastro+ (2018Natur.558..406N) reported the detection of two OVII WHIM absorbers at z=0.4339 and 0.3551 in its spectrum, suggesting that the WHIM is metal rich and sufficient to close the missing baryons problem. Our survey indicates that the blazar is a member of a z=0.433 group and that the higher-z OVII candidate arises from its intragroup medium. The resulting bias precludes its use in baryon censuses. The z=0.3551 candidate occurs in an isolated environment 630kpc from the nearest galaxy (with stellar mass logM_*_/M_{sun}_~9.7), which we show is unexpected for the WHIM. Finally, we characterize the galactic environments of broad HI Ly{alpha} absorbers (Doppler widths of b=40-80km/s; T<~4x10^5^K) that provide metallicity-independent WHIM probes. On average, broad Ly{alpha} absorbers are ~2x closer to the nearest luminous (L>0.25L*) galaxy (700kpc) than narrow (b<30km/s; T<~4x10^5^K) ones (1300kpc) but ~2x further than OVI absorbers (350kpc). These observations suggest that gravitational collapse heats portions of the IGM to form the WHIM, but with feedback that does not enrich the IGM far beyond galaxy/group halos to levels currently observable in UV/X-ray metal lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/668/839
- Title:
- Spectrophotometric redshifts for 1308 HUDF galaxies
- Short Name:
- J/ApJ/668/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of spectrophotometric redshifts for 1308 galaxies from the Grism ACS Program for Extragalactic Science (GRAPES) observations with the Hubble Space Telescope. These low-resolution spectra between 6000{AA} and 9500{AA} are supplemented with U, J, H, and Ks data from various facilities, resulting in redshifts computed with ~40 spectral bins per galaxy. For 75 galaxies in the range 0.5<z<1.5 with spectroscopic redshifts, the standard deviation in the fractional error in 1+z is 0.037. With this catalog, we compute the B-band luminosity function in this redshift range from 72 galaxies. Due to the depth of the GRAPES survey, we are able to accurately constrain the faint-end slope by going to MB~-18mag at z=1.0+/-0.2, nearly 2mag fainter than previous studies. The faint-end slope is alpha=-1.32+/-0.07. When compared to numerous published values at various redshifts, we find strong evidence for a steepening of the faint-end slope with redshift, which is expected in the hierarchical formation scenario of galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/157
- Title:
- Spectrophotometric redshifts of GOODS galaxies
- Short Name:
- J/ApJ/883/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the accuracy of 4000{AA}/Balmer-break based redshifts by combining Hubble Space Telescope (HST) grism data with photometry. The grism spectra are from the Probing Evolution And Reionization Spectroscopically survey with HST using the G800L grism on the Advanced Camera for Surveys. The photometric data come from a compilation by the 3D-HST collaboration of imaging from multiple surveys (notably, the Cosmic Assembly Near-infrared Deep Extragalactic Survey (CANDELS) and 3D-HST). We show evidence that spectrophotometric redshifts (SPZs) typically improve the accuracy of photometric redshifts by ~17%-60%. Our SPZ method is a template-fitting-based routine that accounts for correlated data between neighboring points within grism spectra via the covariance matrix formalism and also accounts for galaxy morphology along the dispersion direction. We show that the robustness of the SPZ is directly related to the fidelity of the D4000 measurement. We also estimate the accuracy of continuum-based redshifts, i.e., for galaxies that do not contain strong emission lines, based on the grism data alone ({sigma}_{Delta}z/(1+z)_^NMAD^<~0.06). Given that future space-based observatories like Wide Field InfraRed Survey Telescope and Euclid will spend a significant fraction of time on slitless spectroscopic observations, we estimate number densities for objects with |{Delta}z/(1+z_s_)|<=0.02. We predict ~700-4400 galaxies degree^-2^ for galaxies with D4000>1.1 and |{Delta}z/(1+z_s_)|<=0.02 to a limiting depth of i_AB_=24mag. This is especially important in the absence of an accompanying rich photometric data set like the existing one for the CANDELS fields, where redshift accuracy from future surveys will rely only on the presence of a feature like the 4000{AA}/Balmer breaks or the presence of emission lines within the grism spectra.
- ID:
- ivo://CDS.VizieR/J/ApJ/695/1591
- Title:
- Spectrophotometry in PEARS fields
- Short Name:
- J/ApJ/695/1591
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep ACS slitless grism observations and identification of stellar sources are presented within the Great Observatories Origins Deep Survey North and South fields which were obtained in the Probing Evolution And Reionization Spectroscopically (PEARS) program. It is demonstrated that even low-resolution spectra can be a very powerful means of identifying stars in the field, especially low-mass stars with stellar types M0 and later. The PEARS fields lay within the larger GOODS fields, and we used new, deeper images to further refine the selection of stars in the PEARS field, down to a magnitude of z_850_=25 using a newly developed stellarity parameter. The total number of stars with reliable spectroscopic and morphological identification was 95 and 108 in the north and south fields, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJS/126/331
- Title:
- Spectrophotometry of nearby field galaxies
- Short Name:
- J/ApJS/126/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained integrated and nuclear spectra as well as U, B, R surface photometry for a representative sample of 196 nearby galaxies. These galaxies span the entire Hubble sequence in morphological type, as well as a wide range of luminosities (M_B_=-14 to -22). Here we present the spectrophotometry for these galaxies. The selection of the sample and the U, B, R surface photometry is described in a companion paper (J/ApJS/126/271).
- ID:
- ivo://CDS.VizieR/J/ApJS/250/26
- Title:
- Spectroscopic follow-up of the QUBRICS quasars
- Short Name:
- J/ApJS/250/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the spectroscopic follow-up of the QUasars as BRIght beacons for Cosmology in the Southern Hemisphere (QUBRICS; Calderone+ 2019, J/ApJ/887/268) survey. The selection method is based on a machine-learning approach applied to photometric catalogs, covering an area of ~12400deg^2^ in the Southern Hemisphere. The spectroscopic observations started in 2018 and identified 55 new, high-redshift (z>=2.5), bright (i<=18) quasi-stellar objects (QSOs), with the catalog published in late 2019. Here we report the current status of the survey, bringing the total number of bright QSOs at z>=2.5 identified by QUBRICS to 224. The success rate of the QUBRICS selection method, in its most recent training, is estimated to be 68%. The predominant contaminant turns out to be lower-z QSOs at z<2.5. This survey provides a unique sample of bright QSOs at high z available for a number of cosmological investigations. In particular, carrying out the redshift drift measurements (Sandage Test) in the Southern Hemisphere, using the High Resolution Spectrograph at the 39m Extremely Large Telescope appears to be possible with less than 2500hr of observations spread over 30 targets in 25yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/647/303
- Title:
- Spectroscopic survey of hypervelocity stars
- Short Name:
- J/ApJ/647/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss our targeted search for hypervelocity stars (HVSs), stars traveling with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Our survey, now half-complete, has successfully identified a total of four probable HVSs plus a number of other unusual objects. Here we report the two most recently discovered HVSs: SDSS J110557.45+093439.5 and possibly SDSS J113312.12+010824, traveling with Galactic rest-frame velocities at least +508+/-12 and 418+/-10km/s, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/741/98
- Title:
- Spectroscopy of galaxy clusters to find LCBGs
- Short Name:
- J/ApJ/741/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the DEIMOS spectrograph on the Keck II Telescope to obtain spectra of galaxies in the fields of five distant, rich galaxy clusters over the redshift range 0.5<z<0.9 in a search for luminous compact blue galaxies (LCBGs). Unlike traditional studies of galaxy clusters, we preferentially targeted blue cluster members identified via multi-band photometric pre-selection based on imaging data from the WIYN telescope. Of the 1288 sources that we targeted, we determined secure spectroscopic redshifts for 848 sources, yielding a total success rate of 66%. Our redshift measurements are in good agreement with those previously reported in the literature, except for 11 targets which we believe were previously in error. Within our sample, we confirm the presence of 53 LCBGs in the five galaxy clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/140
- Title:
- Spectroscopy of Herschel-SPIRE galaxies
- Short Name:
- J/ApJ/761/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck spectroscopic observations and redshifts for a sample of 767 Herschel-SPIRE selected galaxies (HSGs) at 250, 350, and 500{mu}m, taken with the Keck I Low Resolution Imaging Spectrometer and the Keck II DEep Imaging Multi-Object Spectrograph. The redshift distribution of these SPIRE sources from the Herschel Multitiered Extragalactic Survey (HerMES) peaks at z=0.85, with 731 sources at z<2 and a tail of sources out to z~5. We measure more significant disagreement between photometric and spectroscopic redshifts (<{Delta}z/(1+z_spec_)>=0.29) than is seen in non-infrared selected samples, likely due to enhanced star formation rates and dust obscuration in infrared-selected galaxies. The infrared data are used to directly measure integrated infrared luminosities and dust temperatures independent of radio or 24{mu}m flux densities. By probing the dust spectral energy distribution (SED) at its peak, we estimate that the vast majority (72%-83%) of z<2 Herschel-selected galaxies would drop out of traditional submillimeter surveys at 0.85-1mm. This work significantly increased the number of spectroscopically confirmed infrared-luminous galaxies at z{Gt}0 and demonstrates the growing importance of dusty starbursts for galaxy evolution studies and the build-up of stellar mass throughout cosmic time.