- ID:
- ivo://CDS.VizieR/J/MNRAS/478/3740
- Title:
- High-z LAEs and LBGs in SHARDS survey
- Short Name:
- J/MNRAS/478/3740
- Date:
- 11 Mar 2022 14:56:32
- Publisher:
- CDS
- Description:
- We have undertaken a comprehensive search for both Lyman alpha emitters (LAEs) and Lyman break galaxies (LBGs) in the Survey for High-z Absorption Red and Dead Sources (SHARDS) Survey of the Great Observatories Origins Deep Survey North field. SHARDS is a deep imaging survey, made with the 10.4m Gran Telescopio Canarias, employing 25 medium band filters in the range from 500 to 941nm. This is the first time that both LAEs and LBGs are surveyed simultaneously in a systematic way in a large field. We draw a sample of 1558 sources; 528 of them are LAEs. Most of the sources (1434) show rest-frame UV continua. A minority of them (124) are pure LAEs with virtually no continuum detected in SHARDS. We study these sources from z~3.35 up to z~6.8, well into the epoch of reionization. Note that surveys done with just one or two narrow band filters lack the possibility to spot the rest-frame UV continuum present in most of our LAEs. We derive redshifts, star formation rates, Ly{alpha} equivalent widths, and luminosity functions (LFs). Grouping within our sample is also studied, finding 92 pairs or small groups of galaxies at the same redshift separated by less than 60 comoving kpc. In addition, we relate 87 and 55 UV-selected objects with two known overdensities at z=4.05 and z=5.198, respectively. Finally, we show that surveys made with broad-band filters are prone to introduce many unwanted sources (~20 per cent interlopers), which means that previous studies may be overestimating the calculated LFs, specially at the faint end.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/244/16
- Title:
- HLF photometric catalog in GOODS-S v2.0
- Short Name:
- J/ApJS/244/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This manuscript describes the public release of the Hubble Legacy Fields (HLF) project photometric catalog for the extended GOODS-South region from the Hubble Space Telescope (HST) archival program AR-13252. The analysis is based on the version 2.0 HLF data release that now includes all ultraviolet (UV) imaging, combining three major UV surveys. The HLF data combines over a decade worth of 7475 exposures taken in 2635 orbits totaling 6.3Ms with the HST Advanced Camera for Surveys Wide Field Channel (ACS/WFC) and the Wide Field Camera 3 (WFC3) UVIS/IR Channels in the greater GOODS-S extragalactic field, covering all major observational efforts (e.g., GOODS, GEMS, CANDELS, ERS, UVUDF, and many other programs; see Illingworth+ arXiv:1606.00841). The HLF GOODS-S catalogs include photometry in 13 bandpasses from the UV (WFC3/UVIS F225W, F275W, and F336W filters), optical (ACS/WFC F435W, F606W, F775W, F814W and F850LP filters), to near-infrared (WFC3/IR F098M, F105W, F125W, F140W and F160W filters). Such a data set makes it possible to construct the spectral energy distributions (SEDs) of objects over a wide wavelength range from high-resolution mosaics that are largely contiguous. Here, we describe a photometric analysis of 186474 objects in the HST imaging at wavelengths 0.2-1.6{mu}m. We detect objects from an ultra-deep image combining the PSF-homogenized and noise-equalized F850LP, F125W, F140W, and F160W images, including Gaia astrometric corrections. SEDs were determined by carefully taking the effects of the point-spread function in each observation into account.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/2770
- Title:
- Hot white dwarfs in GALEX-DR5
- Short Name:
- J/MNRAS/411/2770
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present comprehensive catalogues of hot star candidates in the Milky Way (MW), selected from Galaxy Evolution Explorer (GALEX) far-UV (FUV; 1344-1786{AA}) and near-UV (NUV; 1771-2831{AA}) imaging. The FUV and NUV photometry allows us to extract the hottest stellar objects, in particular hot white dwarfs (WD), which are elusive at other wavelengths because of their high temperatures and faint optical luminosities. We generated catalogues of UV sources from two GALEX's surveys: All-Sky Imaging Survey (AIS; depth AB magnitude ~19.9/20.8 in FUV/NUV) and Medium-depth Imaging Survey (MIS; depth ~22.6/22.7mag). The two catalogues (from GALEX fifth data release) contain 65.3/12.6 million (AIS/MIS) unique UV sources with errorNUV<= 0.5 mag, over 21 435/1579deg^2^. We also constructed subcatalogues of the UV sources with matched optical photometry from Sloan Digital Sky Survey (SDSS; seventh data release): these contain 0.6/0.9 million (AIS/MIS) sources with errors <=0.3mag in both FUV and NUV, excluding sources with multiple optical counterparts, over an area of 7325/1103 deg2. All catalogues are available online. We then selected 28 319 (AIS)/9028 (MIS) matched sources with FUV-NUV<-0.13; this colour cut corresponds to stellar Teff hotter than ~18 000K (the exact value varying with gravity). An additional colour cut of NUV-r>0.1 isolates binaries with largely differing Teffs, and some intruding quasi-stellar objects (QSOs; more numerous at faint magnitudes). Available spectroscopy for a subsample indicates that hot-star candidates with NUV-r<0.1 (mostly 'single' hot stars) have negligible contamination by non-stellar objects. We discuss the distribution of sources in the catalogues, and the effects of error and colour cuts on the samples. The density of hot-star candidates increases from high to low Galactic latitudes, but drops on the MW plane due to dust extinction. Our hot-star counts at all latitudes are better matched by MW models computed with an initial-final mass relation (IFMR) that favours lower final masses. The model analysis indicates that the brightest sample is likely composed of WDs located in the thin disc, at typical distances between 0.15 and 1kpc, while the fainter sample comprises also a fraction of thick disc and halo stars. Proper motion distributions, available only for the bright sample (NUV<18mag), are consistent with the kinematics of a thin-disc population.
- ID:
- ivo://CDS.VizieR/J/AJ/132/378
- Title:
- HST and UV photometry of NGC 6822
- Short Name:
- J/AJ/132/378
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope WFPC2 and STIS imaging of the low-metallicity galaxy NGC 6822, performed as part of a study of the young stellar populations in the galaxies of the Local Group. Eleven WFPC2 pointings, with some overlap, cover two regions extending over 19 and 13arcmin^2^, respectively, off the galaxy center. The filters used are F170W, F255W, F336W, F439W, and F555W. One 25x25 field observed with the STIS FUV- and NUV-MAMA includes Hodge's OB 8 association and the HII region Hubble V, contained in field 1 of Bianchi et al. (2001, Cat. <J/AJ/121/2020>); this previous study provides additional WFPC2 four-band photometry. We derive the physical parameters of the stars in the fields and the extinction by comparing the photometry to grids of model magnitudes.
- ID:
- ivo://CDS.VizieR/J/ApJS/248/31
- Title:
- HST & Chandra obs. of elliptical galaxies
- Short Name:
- J/ApJS/248/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate X-ray binary (XRB) luminosity function (XLF) scaling relations for Chandra-detected populations of low-mass XRBs (LMXBs) within the footprints of 24 early-type galaxies. Our sample includes Chandra and Hubble Space Telescope observed galaxies at D<~25Mpc that have estimates of the globular cluster (GC) specific frequency (S_N_) reported in the literature. As such, we are able to directly classify X-ray-detected sources as being coincident with unrelated background/foreground objects, GCs, or sources that are within the fields of the galaxy targets. We model the GC and field LMXB population XLFs for all galaxies separately and then construct global models characterizing how the LMXB XLFs vary with galaxy stellar mass and S_N_. We find that our field LMXB XLF models require a component that scales with S_N_ and has a shape consistent with that found for the GC LMXB XLF. We take this to indicate that GCs are "seeding" the galactic field LMXB population, through the ejection of GC LMXBs and/or the diffusion of the GCs in the galactic fields themselves. However, we also find that an important LMXB XLF component is required for all galaxies that scales with stellar mass, implying that a substantial population of LMXBs are formed "in situ," which dominates the LMXB population emission for galaxies with S_N_<~2. For the first time, we provide a framework quantifying how directly associated GC LMXBs, GC-seeded LMXBs, and in situ LMXBs contribute to LMXB XLFs in the broader early-type galaxy population.
- ID:
- ivo://CDS.VizieR/J/ApJ/804/79
- Title:
- HST/COS observations of QSOs within 600kpc of M31
- Short Name:
- J/ApJ/804/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We demonstrate the presence of an extended and massive circumgalactic medium (CGM) around Messier 31 using archival HST Cosmic Origins Spectrograph ultraviolet spectroscopy of 18 QSOs projected within two virial radii of M31 (R_vir_=300kpc). We detect absorption from SiIII at -300<~V_LSR_<~-150km/s toward all three sightlines at R<~0.2R_vir_, 3 of 4 sightlines at 0.8<~R/R_vir_<~1.1, and possibly 1 of 11 at 1.1<R/R_vir_<~1.8. We present several arguments that the gas at these velocities observed in these directions originates from the M31 CGM rather than the Local Group or Milky Way CGM or Magellanic Stream. We show that the dwarf galaxies located in the CGM of M31 have very similar velocities over similar projected distances from M31. We find a non-trivial relationship only at these velocities between the column densities (N) of all the ions and R, whereby N decreases with increasing R. At R<0.8R_vir_, the covering fraction is close to unity for Si III and C IV (f_c_~60%-97% at the 90% confidence level), but drops to f_c_<~10%-20% at R>~R_vir_. We show that the M31 CGM gas is bound, multiphase, predominantly ionized, and is more highly ionized gas at larger R. We estimate using Si II, Si III, and Si IV, a CGM metal mass of >~2x10^6^M_{sun}_ and gas mass of >~3x10^9^(Z_{sun}_/Z)M_{sun}_ within 0.2R_vir_, and possibly a factor of ~10 larger within R_vir_, implying substantial metal and gas masses in the CGM of M31.
- ID:
- ivo://CDS.VizieR/J/ApJ/823/49
- Title:
- HST/COS observations of 7 white dwarfs
- Short Name:
- J/ApJ/823/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The search for transiting habitable exoplanets has broadened to include several types of stars that are smaller than the Sun in an attempt to increase the observed transit depth and hence the atmospheric signal of the planet. Of all spectral types, white dwarfs (WDs) are the most favorable for this type of investigation. The fraction of WDs that possess close-in rocky planets is unknown, but several large angle stellar surveys have the photometric precision and cadence to discover at least one if they are common. Ultraviolet observations of WDs may allow for detection of molecular oxygen or ozone in the atmosphere of a terrestrial planet. We use archival Hubble Space Telescope data from the Cosmic Origins Spectrograph to search for transiting rocky planets around UV-bright WDs. In the process, we discovered unusual variability in the pulsating WD GD 133, which shows slow sinusoidal variations in the UV. While we detect no planets around our small sample of targets, we do place stringent limits on the possibility of transiting planets, down to sub-lunar radii. We also point out that non-transiting small planets in thermal equilibrium are detectable around hotter WDs through infrared excesses, and identify two candidates.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/15
- Title:
- HST/COS obs. of QSO outflows in 500-1050{AA}. VII.
- Short Name:
- J/ApJS/249/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From Hubble Space Telescope/Cosmic Origins Spectrograph spectra of five quasars, 16 outflows are detected. For 11 outflows, we are able to constrain their distances to the central source (R) and their energetics. In instances of multiple electron number density determinations (used in the calculation of R) for the same outflow, the values are consistent within errors. For the 11 outflows, eight have measurements for R (between 10 and 1000pc), one has a lower limit, another has an upper limit, and the last has a range in R. There are two outflows that have enough kinetic luminosity to be major contributors to active galactic nucleus feedback. The outflowing mass is found primarily in a very high-ionization phase, which is probed using troughs from, e.g., Ne VIII, Na IX, Mg X, and Si XII. Such ions connect the physical conditions of these ultraviolet outflows to the X-ray warm absorber outflows seen in nearby Seyfert galaxies. The ion Cl VII and several new transitions from Ne V have been detected for the first time.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/35
- Title:
- HST/COS spectra of QSOs with SiIV data
- Short Name:
- J/ApJ/871/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Every quasar (quasi-stellar object; QSO) spectrum contains absorption-line signatures from the interstellar medium, disk-halo interface, and circumgalactic medium (CGM) of the Milky Way (MW). We analyze Hubble Space Telescope/Cosmic Origins Spectrograph (COS) spectra of 132 QSOs to study the significance and origin of SiIV absorption at |v_LSR_|<=100km/s in the Galactic halo. The gas in the north predominantly falls in at -50<~v_LSR_<~0km/s, whereas in the south, no such pattern is observed. The SiIV column density has an average and a standard deviation of <N_SiIV_>=(3.8+/-1.4)x10^13^cm^-2^. At |b|>~30{deg}, N_SiIV_ does not significantly correlate with b, which cannot be explained by a commonly adopted flat-slab geometry. We propose a two-component model to reconstruct the N_SiIV_-b distribution: a plane-parallel component N_DH_^{perp}^ to account for the MW's disk-halo interface and a global component N_G_ to reproduce the weak dependence on b. We find N_DH_^{perp}^=1.3_-0.7_^+4.7^x10^12^cm^-2^ and N_G_=3.4+/-0.3)x10^13^cm^-2^ on the basis of Bayesian analyses and block bootstrapping. The global component is most likely to have a Galactic origin, although its exact location is uncertain. If it were associated with the MW's CGM, we would find M_gas,all_>~ 4.7x10^9^M_{sun}_(C_f_/1)(R/75kpc)^2^(f_SiIV_/0.3)^-1^(Z/0.3Z_{sun}_)^-1^ for the cool gas at all velocities in the Galactic halo. Our analyses show that there is likely a considerable amount of gas at |v_LSR_|<=100km/s hidden in the MW's CGM.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/6
- Title:
- HST -COS & -STIS absorption-line spectroscopy. II.
- Short Name:
- J/ApJS/230/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present basic data and modeling for a survey of the cool, photoionized circumgalactic medium (CGM) of low-redshift galaxies using far-UV QSO absorption-line probes. This survey consists of "targeted" and "serendipitous" CGM subsamples, originally described in Stocke+ (Paper I, 2013ApJ...763..148S). The targeted subsample probes low-luminosity, late-type galaxies at z<0.02 with small impact parameters (<{rho}>=71kpc), and the serendipitous subsample probes higher luminosity galaxies at z<~0.2 with larger impact parameters (<{rho}>=222kpc). Hubble Space Telescope and FUSE UV spectroscopy of the absorbers and basic data for the associated galaxies, derived from ground-based imaging and spectroscopy, are presented. We find broad agreement with the COS-Halos results, but our sample shows no evidence for changing ionization parameter or hydrogen density with distance from the CGM host galaxy, probably because the COS-Halos survey probes the CGM at smaller impact parameters. We find at least two passive galaxies with HI and metal-line absorption, confirming the intriguing COS-Halos result that galaxies sometimes have cool gas halos despite no on-going star formation. Using a new methodology for fitting HI absorption complexes, we confirm the CGM cool gas mass of Paper I, but this value is significantly smaller than that found by the COS-Halos survey. We trace much of this difference to the specific values of the low-z metagalactic ionization rate assumed. After accounting for this difference, a best-value for the CGM cool gas mass is found by combining the results of both surveys to obtain log(M/M_{sun}_)=10.5+/-0.3, or ~30% of the total baryon reservoir of an L>=L^*^, star-forming galaxy.
