We present the properties of the first 250 {mu}m blind sample of nearby galaxies (15<D<46Mpc) containing 42 objects from the Herschel Astrophysical Terahertz Large Area Survey. Herschel's sensitivity probes the faint end of the dust luminosity function for the first time, spanning a range of stellar mass (7.4<M*<11.3log10M_{sun}_), star formation activity (-11.8<SSFR<-8.9log10yr^-1^), gas fraction (3-96 per cent), and colour (0.6<FUV-K_S_<7.0mag). The median cold dust temperature is 14.6K, colder than in the Herschel Reference Survey (18.5K) and Planck Early Release Compact Source Catalogue (17.7K). The mean dust-to-stellar mass ratio in our sample is higher than these surveys by factors of 3.7 and 1.8, with a dust mass volume density of (3.7+/-0.7)x10^5^M_{sun}_/Mpc^3^. Counter-intuitively, we find that the more dust rich a galaxy, the lower its UV attenuation. Over half of our dust-selected sample are very blue in FUV-K_S_ colour, with irregular and/or highly flocculent morphology; these galaxies account for only 6 per cent of the sample's stellar mass but contain over 35 per cent of the dust mass. They are the most actively star-forming galaxies in the sample, with the highest gas fractions and lowest UV attenuation. They also appear to be in an early stage of converting their gas into stars, providing valuable insights into the chemical evolution of young galaxies.
We present a sample of 80 candidate strongly lensed galaxies with flux density above 100mJy at 500{mu}m extracted from the Herschel Astrophysical Terahertz Large Area Survey, over an area of 600deg^2^. Available imaging and spectroscopic data allow us to confirm the strong lensing in 20 cases and to reject it in one case. For other eight objects, the lensing scenario is strongly supported by the presence of two sources along the same line of sight with distinct photometric redshifts. The remaining objects await more follow-up observations to confirm their nature. The lenses and the background sources have median redshifts z_L_=0.6 and z_S_=2.5, respectively, and are observed out to z_L_=1.2 and z_S_=4.2. We measure the number counts of candidate lensed galaxies at 500{mu}m and compare them with theoretical predictions, finding a good agreement for a maximum magnification of the background sources in the range 10-20. These values are consistent with the magnification factors derived from the lens modelling of individual systems. The catalogue presented here provides sub-mm bright targets for follow-up observations aimed at exploiting gravitational lensing, to study with unprecedented details the morphological and dynamical properties of dusty star-forming regions in z>=1.5 galaxies.
We present Low-Frequency Array (LOFAR) High-Band Array observations of the Herschel-ATLAS North Galactic Pole survey area. The survey we have carried out, consisting of four pointings covering around 142deg^2^ of sky in the frequency range 126-173MHz, does not provide uniform noise coverage but otherwise is representative of the quality of data to be expected in the planned LOFAR wide-area surveys, and has been reduced using recently developed 'facet calibration' methods at a resolution approaching the full resolution of the data sets (~10x6 arcsec) and an rms off-source noise that ranges from 100{mu}Jy beam^-1^ in the centre of the best fields to around 2mJy/beam at the furthest extent of our imaging. We describe the imaging, cataloguing and source identification processes, and present some initial science results based on a 5{sigma} source catalogue. These include (i) an initial look at the radio/far-infrared correlation at 150 MHz, showing that many Herschel sources are not yet detected by LOFAR; (ii) number counts at 150MHz, including, for the first time, observational constraints on the numbers of star-forming galaxies; (iii) the 150-MHz luminosity functions for active and star-forming galaxies, which agree well with determinations at higher frequencies at low redshift, and show strong redshift evolution of the star-forming population; and (iv) some discussion of the implications of our observations for studies of radio galaxy life cycles.
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.
We report the results of an extensive spectroscopic survey of galaxies in the roughly 160 arcmin^2^ ACS-GOODS region surrounding the Hubble Deep Field North (HDF-N). We have identified 892 galaxies or stars with z<24, R<24.5, or B<25 in the region. The spectra were obtained with either the DEIMOS or LRIS spectrographs on the Keck 10m telescopes. The results are compared with photometric redshift estimates and with redshifts from the literature, as well as with the redshifts of a parallel effort led by a group at Keck. Our sample, when combined with the literature data, provides identifications for 1324 sources. We use our results to determine the redshift distributions with magnitude, to analyze the rest-frame color distributions with redshift and spectral type, and to investigate the dependence of the X-ray galaxy properties on the local galaxy density in the redshift interval z=0-1.5. We find the rather surprising result that the galaxy X-ray properties are not strongly dependent on the local galaxy density for galaxies in the same luminosity range.
We investigate the scaling relations of bulge and disk structural parameters for a sample of 108 disk galaxies. Structural parameters of individual galaxies are obtained from two-dimensional bulge/disk decomposition of their H-band surface brightness distributions. Bulges are modelled with a generalized exponential (Sersic) with variable integer shape index n.
The paper presents results of an H-band imaging survey of spiral galaxies in the Perseus-Pisces supercluster area. The derived global photometric parameters of the sample galaxies (magnitudes, diameters, etc.) are collected in Table 3.
H-band spectroscopic analysis of 25 bright M31 GCs
Short Name:
J/ApJ/829/116
Date:
21 Oct 2021
Publisher:
CDS
Description:
Chemical abundances are presented for 25 M31 globular clusters (GCs), based on moderately high resolution (R=22500) H-band integrated light (IL) spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Infrared (IR) spectra offer lines from new elements, lines of different strengths, and lines at higher excitation potentials compared to the optical. Integrated abundances of C, N, and O are derived from CO, CN, and OH molecular features, while Fe, Na, Mg, Al, Si, K, Ca, and Ti abundances are derived from atomic features. These abundances are compared to previous results from the optical, demonstrating the validity and value of IR IL analyses. The CNO abundances are consistent with typical tip of the red giant branch stellar abundances but are systematically offset from optical Lick index abundances. With a few exceptions, the other abundances agree between the optical and the IR within the 1{sigma} uncertainties. The first integrated K abundances are also presented and demonstrate that K tracks the {alpha} elements. The combination of IR and optical abundances allows better determinations of GC properties and enables probes of the multiple populations in extragalactic GCs. In particular, the integrated effects of the Na/O anticorrelation can be directly examined for the first time.
We compare the H{beta} line strengths of 1.90<z<2.35 star-forming galaxies observed with the near-IR grism of the Hubble Space Telescope with ground-based measurements of Ly{alpha} from the HETDEX Pilot Survey and narrow-band imaging. By examining the line ratios of 73 galaxies, we show that most star-forming systems at this epoch have a Ly{alpha} escape fraction below ~6%.
We present the first results from a high sampling rate, multimonth reverberation mapping campaign undertaken primarily at MDM Observatory with supporting observations from telescopes around the world. The primary goal of this campaign was to obtain either new or improved H{beta} reverberation lag measurements for several relatively low luminosity active galactic nuclei (AGNs). We feature results for NGC 4051 here because, until now, this object has been a significant outlier from AGN scaling relationships, e.g., it was previously a ~2-3{sigma} outlier on the relationship between the broad-line region (BLR) radius and the optical continuum luminosity - the R_BLR_-L relationship. Our new measurements of the lag time between variations in the continuum and H{beta} emission line made from spectroscopic monitoring of NGC 4051 lead to a measured BLR radius of R_BLR_=1.87^+0.54^_-0.50_ light days and black hole mass of M_BH_=(1.73^+0.55^_-0.52_)x10^6^M_{sun}_. We also present a preliminary look at velocity-resolved H{beta} light curves and time delay measurements, although we are unable to reconstruct an unambiguous velocity-resolved reverberation signal.