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351. HST/COS observations of QSOs within 600kpc of M31
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.
352. HST/COS obs. of QSO outflows in 500-1050{AA}. VII.
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.
353. HST/COS spectra of QSOs with SiIV data
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.
354. HST -COS & -STIS absorption-line spectroscopy. II.
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.
355. HST FOS spectral atlas
ID:
ivo://CDS.VizieR/J/ApJS/140/143
Title:
HST FOS spectral atlas
Short Name:
J/ApJS/140/143
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyzed the absorption line spectra of all quasars observed with the high-resolution gratings of the Faint Object Spectrograph on board the Hubble Space Telescope. We examined 788 spectra for 334 quasars and present line lists and identifications of absorption lines in the spectra of 271 of them. Analysis of the statistics of the Ly{alpha} and metal absorption systems are presented in companion papers. The data and several analysis products are available on the authors' Web site, http://lithops.as.arizona.edu/~jill/QuasarSpectra .
356. HST observations of QSOs with medium spectra
ID:
ivo://CDS.VizieR/J/ApJ/818/113
Title:
HST observations of QSOs with medium spectra
Short Name:
J/ApJ/818/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the Hubble Space Telescope (HST) archive of ultraviolet (UV) quasar spectroscopy to conduct the first blind survey for damped Ly{alpha} absorbers (DLAs) at low redshift (z<1.6). Our statistical sample includes 463 quasars with spectral coverage spanning a total redshift path {Delta}z=123.3 or an absorption path {Delta}X=229.7. Within this survey path, we identify 4 DLAs defined as absorbers with HI column density N_HI_>=10^20.3^/cm2, which implies an incidence per absorption length lDLA(X)=0.017_-0.008_^+0.014^ at a median survey path redshift of z=0.623. While our estimate of l_DLA_(X) is lower than earlier estimates at z~0 from HI 21cm emission studies, the results are consistent within the measurement uncertainties. Our data set is too small to properly sample the N_HI_ frequency distribution function f(N_HI_,X), but the observed distribution agrees with previous estimates at z>2. Adopting the z>2 shape of f(N_HI_, X), we infer an HI mass density at z~0.6 of {rho}_HI_^DLA^=0.25_-0.12_^+0.20^. This is significantly lower than previous estimates from targeted DLA surveys with the HST, but consistent with results from low-z HI 21cm observations, and suggests that the neutral gas density of the universe has been decreasing over the past 10Gyr.
357. HST QSO Catalog
ID:
ivo://CDS.VizieR/J/ApJ/736/42
Title:
HST QSO Catalog
Short Name:
J/ApJ/736/42
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a survey for optically thick Lyman limit absorbers at z<2.6 using archival Hubble Space Telescope observations with the Faint Object Spectrograph and Space Telescope Imaging Spectrograph. We identify 206 Lyman limit systems (LLSs), increasing the number of cataloged LLSs at z<2.6 by a factor of ~10.
358. HST quasar absorption-line key project. VIII.
ID:
ivo://CDS.VizieR/J/PASP/106/646
Title:
HST quasar absorption-line key project. VIII.
Short Name:
J/PASP/106/646
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of CCD images (obtained at the Palomar 1.5m telescope) of more than 100 quasars; many of the objects have been or will be observed in the HST Key Project Quasar Absorption-Line Survey. The data set consists of B, g, and i photometry of 117 quasars and deeper g (limiting magnitude of ~22) images of 101 quasar fields. Positions accurate to ~1", measured with the Space Telescope Science Institute's Astrometric Support Program, are listed for all of the quasars in this study. Positions, magnitudes, and classifications of stars and galaxies located within ~100" of the quasars are given for all of the deep g data. The positions of the stars and galaxies relative to the quasar are accurate to ~0.5". The results presented here can be used to prepare spectroscopic programs designed to obtain redshifts of galaxies in the fields of these quasars.
359. HST Quasar Absorption Line Key Project. X.
ID:
ivo://CDS.VizieR/J/ApJS/97/1
Title:
HST Quasar Absorption Line Key Project. X.
Short Name:
J/ApJS/97/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
Sensitive H I 21cm emission line spectra have been measured for the directions to 143 quasars and AGNs chosen from the observing lists for the HST Quasar Absorption Line Key Project. Narrow-band and wide-band data were obtained with the NRAO 43m radio telescope for each object. The narrow-band data have a velocity resolution of 1km/s, extend from -220 to +170km/s, and are corrected for stray 21cm radiation. The wide-band data have a resolution of 4km/s and extend from -1000 to +1000km/s. The data are important for the interpretation of ultraviolet absorption lines near zero redshift in Key Project spectra. Twenty-two percent of the quasars lie behind Galactic high-velocity H I clouds with |VLSR|>100km/s whose presence can increase the equivalent width of interstellar absorption lines significantly. This paper contains the emission spectra and measures of the H I velocities and column densities along the sight line to each quasar. We discuss how the measurements can be used to estimate the visual and ultraviolet extinction toward each quasar and to predict the approximate strength of the strong ultraviolet resonance lines of neutral gas species in the HST Key Project spectra.
360. HST survey for Lyman limit systems. I.
ID:
ivo://CDS.VizieR/J/ApJS/195/16
Title:
HST survey for Lyman limit systems. I.
Short Name:
J/ApJS/195/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a set of 71 quasars observed in the near ultraviolet with the PR200L prism on the Advanced Camera for Surveys and the G280 grism on the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. The quasars were selected from the Sloan Digital Sky Survey data to search for intervening Lyman limit system (LLS) absorption. The sample was subjected to the constraints that the quasars have AB magnitude g'<18.5, quasar emission redshift 2.3<z_em_<2.6, and lack strong BAL or z~z_em_ absorption. The median emission redshift of the sample is {bar}z=2.403. The data were all processed using custom data reduction pipelines, and the one-dimensional spectra have sufficient signal-to-noise ratio and resolution to easily identify absorption from LLS over the redshift range 1.2<z<2.5. The WFC3 data presented here are the first non-calibration spectra from the G280 grism.