- ID:
- ivo://CDS.VizieR/J/MNRAS/476/4725
- Title:
- SC4K catalogue of candidate LAEs
- Short Name:
- J/MNRAS/476/4725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and explore deep narrow- and medium-band data obtained with the Subaru and the Isaac Newton Telescopes in the ~2deg^2^ COSMOS field. We use these data as an extremely wide, low-resolution (R~20-80) Integral Field Unit survey to slice through the COSMOS field and obtain a large sample of ~4000 Ly{alpha} emitters (LAEs) from z~2 to 6 in 16 redshift slices (SC4K). We present new Ly {alpha} luminosity functions (LFs) covering a comoving volume of ~10^8^Mpc^3^. SC4K extensively complements ultradeep surveys, jointly covering over 4dex in Ly{alpha} luminosity and revealing a global (2.5<z<6) synergy LF with {alpha}=-1.93^+0.12^_-0.12_, log_10_{Phi}^*^_Ly{alpha}_=-3.45^+0.22^_-0.29_Mpc^-3^, and log_10_L^*^_Ly{alpha}_=42.93^+0.15^_-0.11_erg/s. The Schechter component of the Ly{alpha} LF reveals a factor ~5 rise in L^*^_Ly{alpha}_ and a ~7 x decline in {Phi}^*^_Ly{alpha}_ from z~2 to 6. The data reveal an extra power-law (or Schechter) component above L_Ly{alpha}_~=10^43.3^erg/s at z~2.2-3.5 and we show that it is partially driven by X-ray and radio active galactic nucleus (AGN), as their Ly{alpha} LF resembles the excess. The power-law component vanishes and/or is below our detection limits above z>3.5, likely linked with the evolution of the AGN population. The Ly {alpha} luminosity density rises by a factor ~2 from z~2 to 3 but is then found to be roughly constant (1.1^+0.2^_-0.2_x10^40^erg/s/Mpc^3^) to z~6, despite the ~0.7 dex drop in ultraviolet (UV) luminosity density. The Ly{alpha}/UV luminosity density ratio rises from 4+/-1 per cent to 30+/-6 per cent from z~2.2 to 6. Our results imply a rise of a factor of ~=2 in the global ionization efficiency ({xi}_ion_) and a factor ~=4+/-1 in the Ly{alpha} escape fraction from z~2 to 6, hinting for evolution in both the typical burstiness/stellar populations and even more so in the typical interstellar medium conditions allowing Ly{alpha} photons to escape.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/819/154
- Title:
- SDSS-DR7 QSOs with X-ray and UV luminosities
- Short Name:
- J/ApJ/819/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observed relation between the soft X-ray and the optical-ultraviolet emission in active galactic nuclei (AGNs) is nonlinear and it is usually parametrized as a dependence between the logarithm of the monochromatic luminosity at 2500{AA} and at 2keV. Previous investigations have found that the dispersion of this relation is rather high (~0.35-0.4 in log units), which may be caused by measurement uncertainties, variability, and intrinsic dispersion due to differences in the AGN physical properties (e.g., different accretion modes). We show that, once optically selected quasars with homogeneous SED and X-ray detection are selected, and dust reddened and/or gas obscured objects are not included, the measured dispersion drops to significantly lower values (i.e., ~0.21-0.24dex). We show that the residual dispersion is due to some extent to variability, and to remaining measurement uncertainties. Therefore, the real physical intrinsic dispersion should be <0.21dex. Such a tight relation, valid over four decades in luminosity, must be the manifestation of an intrinsic (and universal) physical relation between the disk, emitting the primary radiation, and the hot electron corona emitting X-rays.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A184
- Title:
- SDSS J151349.52+035211.28 Xshooter spectra
- Short Name:
- J/A+A/618/A184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection and detailed analysis of a diffuse molecular cloud at z_abs_=2.4636 towards the quasar SDSS J151349.52+035211.28 (hereafter J1513+0352) (zem~=2.68) observed with the X-shooter spectrograph at the Very Large Telescope. We measure very high column densities of atomic and molecular hydrogen, with logN(HI,H_2_)~=21.8,21.3. This is the highest H_2_ column density ever measured in an intervening damped Lyman-{alpha}system but we do not detect CO, implying log N(CO)/N(H_2_)<-7.8, which could be due to a low metallicity of the cloud. From the metal absorption lines, we derive the metallicity to be Z~=0.15Z_{sun}_ and determine the amount of dust by measuring the induced extinction of the background quasar light, AV~=0.4. We simultaneously detect Ly{alpha} emission at the same redshift, with a centroid located at a most probable impact parameter of only {rho}~=1.4kpc. We argue that the line of sight is therefore likely passing through the interstellar medium of a galaxy, as opposed to the circumgalactic medium. The relation between the surface density of gas and that of star formation seems to follow the global empirical relation derived in the nearby Universe although our constraints on the star formation rate and on the galaxy extent remain too loose to be conclusive. We study the transition from atomic to molecular hydrogen using a theoretical description based on the microphysics of molecular hydrogen.We use the derived chemical properties of the cloud and physical conditions (Tk~=90K and n~=250cm^-3^) derived through the excitation of H_2_ rotational levels and neutral carbon fine structure transitions to constrain the fundamental parameters that govern this transition. By comparing the theoretical and observed HI column densities, we are able to bring an independent constraint on the incident UV flux, which we find to be in agreement with that estimated from the observed star formation rate.
- ID:
- ivo://CDS.VizieR/J/AJ/139/1212
- Title:
- SDSS photometry of interacting galaxies
- Short Name:
- J/AJ/139/1212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Galaxy Evolution Explorer (GALEX) ultraviolet telescope to study stellar populations and star formation morphology in a well-defined sample of 42 nearby optically selected pre-merger interacting galaxy pairs. Galaxy interactions were likely far more common in the early universe than in the present; thus our study provides a nearby well-resolved comparison sample for high-redshift studies. We have combined the GALEX near-ultraviolet (NUV) and far-ultraviolet images with broadband optical maps from the Sloan Digitized Sky Survey to investigate the ages and extinctions of the tidal features and the disks.
245. SDSS-ROSAT AGN data
- ID:
- ivo://CDS.VizieR/J/AJ/130/387
- Title:
- SDSS-ROSAT AGN data
- Short Name:
- J/AJ/130/387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 228 optically selected active galactic nuclei (AGNs) in the 0.01-6.3 redshift range with a high fraction of X-ray detections (81%-86%), we study the relation between rest-frame UV and soft X-ray emission and its evolution with cosmic time. The majority of the AGNs in our sample (155 objects) have been selected from the Sloan Digital Sky Survey (SDSS) in an unbiased way, rendering the sample results representative of all SDSS AGNs.
- ID:
- ivo://CDS.VizieR/IX/35
- Title:
- Second EUVE Catalogues
- Short Name:
- IX/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Extreme Ultraviolet Explorer satellite was launched on June 7, 1992 from Cape Canaveral, Florida on a Delta II rocket. The payload contains three EUV scanning telescopes equipped with imaging detectors as well as a Deep Survey Spectrometer instrument which divides the light from a fourth telescope between an imaging detector and three EUV spectrometers. The wavelength range is 10-60nm, corresponding to an energy range of 20-120eV, in the 4 bands: 10nm : Lexan/Boron, 58-174{AA}, 89{AA}peak DS: Lexan/Boron, 67-178{AA}, 91{AA}peak (Deep Survey) 20nm : Al/Ti/C, 156-234{AA}, 171{AA}peak DS: Al/C, 157-364{AA}, 171{AA}peak (Deep Survey) 40nm : Ti/Sb/Ti/Al, 368-590{AA}, 405{AA}peak 60nm : Sn/SiO, 519-742{AA}, 555{AA}peak More details about the EUVE performances may be found in the paper by Sirk et al. (1997ApJS..110..347S) The EUVE Source Catalog published in 1996 paper is made of three source tables, plus a list of associations for each table: - survey.dat lists the 514 objects detected during the all-sky survey. - deepsurv.dat lists the 35 sources detected by the deep survey of half the ecliptic plane; three deep survey objects are also detected in the all-sky survey. - detect.dat lists 188 sources that have been detected in other ways, principally by deep exposures with the scanner telescopes as part of the Right Angle Program through 24 December 1994 (later RAP detections are reported in the 1999 paper) The corresponding association tables are idsurvey, iddeepsu.dat and iddetect.dat respectively, in which one EUVE source may by associated to 0, one or more counterparts. In nearly all cases the associated objects lie within 1arcmin of the actual source position. The all-sky catalog of faint EUV sources published in 1997 lists the faint sources detected jointly by EUVE and ROSAT WFC. The 1999 paper lists the detections made from the observations since the first EUVE RAP catalog (1994 January) and covers 17% of the sky.
- ID:
- ivo://CDS.VizieR/J/AJ/136/259
- Title:
- Second GALEX UV variability catalog (GUVV-2)
- Short Name:
- J/AJ/136/259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second Galaxy Evolution Explorer (GALEX) Ultraviolet Variability (GUVV-2) Catalog, which contains information on 410 newly discovered time-variable sources gained through simultaneous near UV (NUV 1750-2750{AA}) and far-UV (FUV 1350-1750{AA}) photometric observations. Source variability was determined by comparing the NUV and/or FUV fluxes derived from orbital exposures recorded during a series of multiple observational visits to 169 GALEX fields on the sky.
- ID:
- ivo://CDS.VizieR/J/ApJS/206/4
- Title:
- SED and bolometric corrections for luminous QSOs
- Short Name:
- J/ApJS/206/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the mid-infrared (mid-IR) through ultraviolet (UV) spectral energy distributions (SEDs) of 119652 luminous broad-lined quasars with 0.064<z<5.46 using mid-IR data from Spitzer and WISE, near-infrared data from the Two Micron All Sky Survey and UKIDSS, optical data from the Sloan Digital Sky Survey, and UV data from the Galaxy Evolution Explorer. The mean SED requires a bolometric correction (relative to 2500{AA}) of BC_2500{AA}_=2.75+/-0.40 using the integrated light from 1um-2keV, and we further explore the range of bolometric corrections exhibited by individual objects. In addition, we investigate the dependence of the mean SED on various parameters, particularly the UV luminosity for quasars with 0.5<~z<~3 and the properties of the UV emission lines for quasars with z>~1.6; the latter is a possible indicator of the strength of the accretion disk wind, which is expected to be SED-dependent.
- ID:
- ivo://CDS.VizieR/J/ApJ/684/136
- Title:
- SEDs of ELAIS-S1 mid-IR sources
- Short Name:
- J/ApJ/684/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the broadband SEDs of the largest available highly complete (72%) spectroscopic sample of MIR-selected galaxies and AGNs at intermediate redshift. The sample contains 203 extragalactic sources from the 15um ELAIS-SWIRE survey, all with measured spectroscopic redshift. Most of these sources have full multiwavelength coverage from the FUV (GALEX) to the FIR (Spitzer) and lie in the redshift range 0.1<z<1.3. This large sample allows us for the first time to characterize the spectral properties of sources responsible for the strong evolution observed in the MIR. Based on SED-fitting, we have classified the MIR sources, identifying AGN signatures in about 50% of them. This fraction is significantly higher than that derived from optical spectroscopy (~29%) and is due in particular to the identification of AGN activity in objects spectroscopically classified as galaxies (the spectroscopic classification may be somewhat unreliable because of host galaxy dilution in the optical). It is likely that in most of our objects, the AGN is either obscured or low luminosity, and thus dominates the energetic output only in the MIR, showing up just in the range where the host galaxy SED has a minimum. The fraction of AGNs strongly depends on flux density, with that derived through the SED-fitting about 20% at S_15um_~0.5-1mJy and gradually increasing to 100% at S_15um_>10mJy, while that obtained from optical spectroscopy is never >30%, even at higher flux densities.
- ID:
- ivo://CDS.VizieR/J/ApJ/701/1398
- Title:
- SFR for starburst galaxies
- Short Name:
- J/ApJ/701/1398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comparison of star formation rates (SFR) determined from mid-infrared 7.7um polycyclic aromatic hydrocarbon (PAH) luminosity [SFR(PAH)], from 1.4GHz radio luminosity [SFR(radio)], and from far-ultraviolet luminosity [SFR(UV)] for a sample of 287 starburst galaxies with z<0.5 having Spitzer IRS observations.
