- ID:
- ivo://CDS.VizieR/J/ApJ/749/65
- Title:
- H-ATLAS search for strongly lensed galaxies
- Short Name:
- J/ApJ/749/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While the selection of strongly lensed galaxies (SLGs) with 500{mu}m flux density S_500_>100mJy has proven to be rather straightforward, for many applications it is important to analyze samples larger than the ones obtained when confining ourselves to such a bright limit. Moreover, only by probing to fainter flux densities is it possible to exploit strong lensing to investigate the bulk of the high-z star-forming galaxy population. We describe HALOS (the Herschel-ATLAS Lensed Objects Selection), a method for efficiently selecting fainter candidate SLGs, reaching a surface density of =~1.5-2/deg^2^, i.e., a factor of about 4-6 higher than that at the 100mJy flux limit. HALOS will allow the selection of up to ~1000 candidate SLGs (with amplifications {mu}>~2) over the full H-ATLAS survey area. Applying HALOS to the H-ATLAS Science Demonstration Phase field (=~14.4deg^2^) we find 31 candidate SLGs, whose candidate lenses are identified in the VIKING near-infrared catalog. Using the available information on candidate sources and candidate lenses we tentatively estimate a =~72% purity of the sample. As expected, the purity decreases with decreasing flux density of the sources and with increasing angular separation between candidate sources and lenses. The redshift distribution of the candidate lensed sources is close to that reported for most previous surveys for lensed galaxies, while that of candidate lenses extends to redshifts substantially higher than found in the other surveys. The counts of candidate SLGs are also in good agreement with model predictions. Even though a key ingredient of the method is the deep near-infrared VIKING photometry, we show that H-ATLAS data alone allow the selection of a similarly deep sample of candidate SLGs with an efficiency close to 50%; a slightly lower surface density (=~ 1.45/deg2) can be reached with a ~70% efficiency.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/847/136
- Title:
- H{beta} to N2 line fluxes of nearby galaxies
- Short Name:
- J/ApJ/847/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present calibrations for star formation rate (SFR) indicators in the ultraviolet, mid-infrared, and radio-continuum bands, including one of the first direct calibrations of 150MHz as an SFR indicator. Our calibrations utilize 66 nearby star-forming galaxies with Balmer-decrement-corrected H{alpha} luminosities, which span five orders of magnitude in SFR and have absolute magnitudes of -24<M_r_{<}-12. Most of our photometry and spectrophotometry are measured from the same region of each galaxy, and our spectrophotometry has been validated with SDSS photometry, so our random and systematic errors are small relative to the intrinsic scatter seen in SFR indicator calibrations. We find that the Wide-field Infrared Space Explorer W4 (22.8{mu}m), Spitzer 24{mu}m, and 1.4GHz bands have tight correlations with the Balmer-decrement-corrected H{alpha} luminosity, with a scatter of only 0.2dex. Our calibrations are comparable to those from the prior literature for L* galaxies, but for dwarf galaxies, our calibrations can give SFRs that are far greater than those derived from most previous literature.
- ID:
- ivo://CDS.VizieR/J/ApJS/236/30
- Title:
- Herschel-ATLAS (H-ATLAS) DR2
- Short Name:
- J/ApJS/236/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) is a survey of 660deg^2^ with the PACS and SPIRE cameras in five photometric bands: 100, 160, 250, 350, and 500{mu}m. This is the second of three papers describing the data release for the large fields at the south and north Galactic poles (NGP and SGP). In this paper we describe the catalogs of far-infrared and submillimeter sources for the NGP and SGP, which cover 177.1deg^2^ and 303.4deg^2^, respectively. The catalogs contain 118980 sources for the NGP field and 193527 sources for the SGP field detected at more than 4{sigma} significance in any of the 250, 350, or 500{mu}m bands. The source detection is based on the 250{mu}m map, and we present photometry in all five bands for each source, including aperture photometry for sources known to be extended. The rms positional accuracy for the faintest sources is about 2.4" in both RA and DEC. We present a statistical analysis of the catalogs and discuss the practical issues-completeness, reliability, flux boosting, accuracy of positions, accuracy of flux measurements-necessary to use the catalogs for astronomical projects.
- ID:
- ivo://CDS.VizieR/J/AJ/143/128
- Title:
- High-metallicity M giant candidates from SDSS
- Short Name:
- J/AJ/143/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tidal stripping and three-body interactions with the central supermassive black hole may eject stars from the Milky Way. These stars would comprise a set of "intragroup" stars (IGS) that trace the past history of interactions in our galactic neighborhood. Using the Sloan Digital Sky Survey (SDSS) DR7 (Cat. II/294, superseded by Cat. V/139), we identify candidate solar-metallicity red giant intragroup stars using color cuts that are designed to exclude nearby M and L dwarfs. We present 677 intragroup candidates that are selected between 300kpc and 2Mpc, and are either the reddest intragroup candidates (M7-M10) or are L dwarfs at larger distances than previously detected.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A46
- Title:
- High redshift cosmic web with quasar systems
- Short Name:
- J/A+A/568/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the formation, evolution, and present-day properties of the cosmic web we need to study it at low and high redshifts. We trace the cosmic web at redshifts 1.0<z<1.8 using the quasar (QSO) data from in the SDSS DR7 QSO catalogue. We apply a friend-of-friend (FoF) algorithm to the quasar and random catalogues to determine systems at a series of linking length, and analyse richness and sizes of these systems. At the linking lengths l<=30Mpc/h, the number of quasar systems is larger than the number of systems detected in random catalogues, and the systems themselves have smaller diameters than random systems. The diameters of quasar systems are comparable to the sizes of poor galaxy superclusters in the local Universe. The richest quasar systems have four members. The mean space density of quasar systems is close to the mean space density of local rich superclusters. At intermediate linking lengths (40<=l<=70Mpc/h), the richness and length of quasar systems are similar to those derived from random catalogues. Quasar system diameters are similar to the sizes of rich superclusters and supercluster chains in the local Universe. The percolating system, which penetrate the whole sample volume appears in a quasar sample at a smaller linking length than in random samples (85Mpc/h). At the linking length 70Mpc/h, the richest systems of quasars have diameters exceeding 500Mpc. Quasar luminosities in systems are not correlated with the system richness. Quasar system catalogues in our web pages and at the Strasbourg Astronomical Data Center (CDS) serve as a database for searching for superclusters of galaxies and for tracing the cosmic web at high redshifts.
- ID:
- ivo://CDS.VizieR/J/ApJ/675/49
- Title:
- High-redshift QSOs in the SWIRE survey
- Short Name:
- J/ApJ/675/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a simple optical/infrared (IR) photometric selection of high-redshift QSOs that identifies a Lyman break in the optical photometry and requires a red IR color to distinguish QSOs from common interlopers. The search yields 100 z~3 (U-dropout) QSO candidates with 19<r'<22 over 11.7deg^2^ in the ELAIS-N1 (EN1) and ELAIS-N2 (EN2) fields of the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy Survey. The z~3 selection is reliable, with spectroscopic follow-up of 10 candidates confirming that they are all QSOs at 2.83<z<3.44. We find that our z~4 (g'-dropout) sample suffers from both unreliability and incompleteness but present seven previously unidentified QSOs at 3.50<z<3.89.
- ID:
- ivo://CDS.VizieR/J/AJ/139/315
- Title:
- HI-selected galaxies in SDSS. Optical data
- Short Name:
- J/AJ/139/315
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the optical data for 195 HI-selected galaxies that fall within both the Sloan Digital Sky Survey (SDSS) and the Parkes Equatorial Survey (ES). The photometric quantities have been independently recomputed for our sample using a new photometric pipeline optimized for large galaxies, thus correcting for SDSS's limited reliability for automatic photometry of angularly large or low surface brightness (LSB) galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A127
- Title:
- Homogeneous sample of 34000 M7-M9.5 dwarfs
- Short Name:
- J/A+A/623/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The space density of late M dwarfs, sub-types M7 to M9.5, is not well determined. We have applied the photo-type method of Skrzypek et al. to iz photometry from SDSS and YJHK photometry from UKIDSS, over an effective area of 3070deg^2^, to produce a new, bright J(Vega)<17.5, homogeneous sample of 33665 M7 to M9.5 dwarfs. The typical S/N of each source summed over the 6 bands is >100. Classifications are provided to the nearest half spectral sub-type. Through comparison with the classifications in the BUD spectroscopic sample of Schmidt et al. (2010, Cat. J/AJ/139/1808), the typing is shown to be accurately calibrated to the BUD classifications, with a precision better than 0.5 sub-types rms, i.e. is as precise as good spectroscopic classification. Sources with large chisq>20 include several catalogued late-type subdwarfs. The new sample of late M dwarfs is highly complete, but there is a bias in the classification of rare peculiar blue or red objects. For example L subdwarfs are misclassified towards earlier types by approximately two spectral sub-types. We estimate that this bias affects only ~1% of sources. Therefore the sample is well suited for measuring the luminosity function, as well as investigating the softening towards the Galactic plane of the exponential variation of density with height.
- ID:
- ivo://CDS.VizieR/J/ApJ/685/235
- Title:
- Host and companion galaxies in the SDSS
- Short Name:
- J/ApJ/685/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the number of companions per galaxy (N_c_) as a function of r-band absolute magnitude for both the Sloan Digital Sky Survey (DR5) and the Croton and coworkers semianalytic catalog, 2006MNRAS.365...11C, applied to the Millennium Run simulation (Springel et al., 2005Natur.435..629S). For close pairs with projected separations of 5-20kpc/h, velocity differences less than 500km/s, and luminosity ratios between 1:2 and 2:1, we find good agreement between the observations and simulations, with N_c_ consistently close to 0.02 over the range -22<M_r_<-18. For larger pair separations, N_c_(M_r_) instead becomes increasingly steep toward the faint end, implying that luminosity-dependent clustering plays an important role on small scales. Using the simulations to assess and correct for projection effects, we infer that the real-space N_c_(M_r_) for close pairs peaks at about M^*^ and declines by at least a factor of 2 as M_r_ becomes fainter. Conversely, by measuring the number density of close companions, we estimate that at least 90% of all major mergers occur between galaxies which are fainter than L^*^. Finally, measurements of the luminosity density of close companions indicate that L^*^ galaxies likely dominate in terms of the overall importance of major mergers in the evolution of galaxy populations at low redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/830/13
- Title:
- Host-galaxy NUV-NIR data of 32 superluminous SNe
- Short Name:
- J/ApJ/830/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013 and derive measurements of their luminosities, star formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe (SLSNe I) are found almost exclusively in low-mass (M_*_<2x10^9^M_{sun}_) and metal-poor (12+log_10_[O/H]<8.4) galaxies. We compare the mass and metallicity distributions of our sample to nearby galaxy catalogs in detail and conclude that the rate of SLSNe I as a fraction of all SNe is heavily suppressed in galaxies with metallicities >~0.5Z_{sun}_. Extremely low metallicities are not required and indeed provide no further increase in the relative SLSN rate. Several SLSN I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star formation histories. Type II (hydrogen-rich) SLSNe (SLSNe II) are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is an SLSN I in a massive, luminous infrared galaxy at redshift z=0.29, while PTF 10tpz is an SLSN II located in the nucleus of an early-type host at z=0.04.
