- ID:
- ivo://CDS.VizieR/J/ApJS/175/29
- Title:
- Spectroscopy of QSO pairs
- Short Name:
- J/ApJS/175/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ly{alpha} forest has opened a new redshift regime for cosmological investigation. At z>2 it provides a unique probe of cosmic geometry and an independent constraint on dark energy that is not subject to standard candle or ruler assumptions. In Paper I of this series on using the Ly{alpha} forest observed in pairs of QSOs for a new application of the Alcock-Paczynski test, we present and discuss the results of a campaign to obtain moderate-resolution spectroscopy (FWHM~2.5{AA}) of the Ly{alpha} forest in pairs of QSOs with small redshift differences ({Delta}z<0.25, z>2.2) and arcminute separations ({Theta}<5'). This data set, composed of seven individual QSOs, 35 pairs, and one triplet, is also well suited for future investigations of the coherence of Ly{alpha} absorbers on ~1Mpc transverse scales and the transverse proximity effect. We note seven revisions for previously published QSO identifications and/or redshifts.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/678/635
- Title:
- Spectroscopy of quasar binary candidates
- Short Name:
- J/ApJ/678/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopy of binary quasar candidates, with component separations of 3"<={Delta}{theta}<6", selected from SDSS DR4 using kernel density estimation (KDE). Of our 27 new quasar pair observations, 10 are binary quasars, which doubles the number of known g<21 binaries with 3"<={Delta}{theta}<6" separations. Several of our observed binaries are wide-separation lens candidates that merit additional higher resolution spectroscopy, as well as deep imaging to search for lensing galaxies. Our candidates are initially selected by UV excess (u-g<1), but are otherwise selected irrespective of the relative colors of the quasar pair, and we thus use them to suggest optimal color similarity and photometric redshift approaches for targeting binary quasars or projected quasar pairs. We find that a third or more of all binary quasars have quite dissimilar components on the basis of a typical color similarity criterion ({chi}^2^_color_<~20). From a sample that is complete on proper scales of 23.7h^-1^kpc<R_prop_<29.9h^-1^kpc, we determine the projected quasar correlation function.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/23
- Title:
- Spectroscopy of 88 z<0.7 SDSS QSOs
- Short Name:
- J/ApJS/201/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a systematic search for subparsec supermassive black hole (BH) binaries among z<~0.7 Sloan Digital Sky Survey quasars. These are predicted by models of supermassive BH and host galaxy coevolution, therefore their census and population properties constitute an important test of these models. In our working hypothesis, one of the two BHs accretes at a much higher rate than the other and carries with it the only broad emission line region of the system, making the system analogous to a single-lined spectroscopic binary star. Accordingly, we used spectroscopic principal component analysis to search for broad H{beta} emission lines that are displaced from the quasar rest frame by |{Delta}{nu}|>~1000km/s. This method also yields candidates for rapidly recoiling BHs. Of the 88 candidates, several were previously reported in the literature. We found a correlation between the peak offset and skewness of the broad H{beta} profiles, suggesting a common physical explanation for these profiles. We carried out follow-up spectroscopic observations of 68 objects to search for changes in the peak velocities of the H{beta} lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/1
- Title:
- SpIES: the Spitzer IRAC Equatorial Survey
- Short Name:
- J/ApJS/225/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the first data release from the Spitzer-IRAC Equatorial Survey (SpIES); a large-area survey of ~115deg^2^ in the Equatorial SDSS Stripe 82 field using Spitzer during its "warm" mission phase. SpIES was designed to probe sufficient volume to perform measurements of quasar clustering and the luminosity function at z>=3 to test various models for "feedback" from active galactic nuclei (AGNs). Additionally, the wide range of available multi-wavelength, multi-epoch ancillary data enables SpIES to identify both high-redshift (z>=5) quasars as well as obscured quasars missed by optical surveys. SpIES achieves 5{sigma} depths of 6.13uJy (21.93 AB magnitude) and 5.75uJy (22.0 AB magnitude) at 3.6 and 4.5um, respectively --depths significantly fainter than the Wide-field Infrared Survey Explorer (WISE). We show that the SpIES survey recovers a much larger fraction of spectroscopically confirmed quasars (~98%) in Stripe 82 than are recovered by WISE (~55%). This depth is especially powerful at high-redshift (z>=3.5), where SpIES recovers 94% of confirmed quasars, whereas WISE only recovers 25%. Here we define the SpIES survey parameters and describe the image processing, source extraction, and catalog production methods used to analyze the SpIES data. In addition to this survey paper, we release 234 images created by the SpIES team and three detection catalogs: a 3.6um only detection catalog containing ~6.1 million sources, a 4.5um only detection catalog containing ~6.5 million sources, and a dual-band detection catalog containing ~5.4 million sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/119
- Title:
- Spitzer/IRAC variability survey of Bootes field
- Short Name:
- J/ApJ/817/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Decadal IRAC Bootes Survey is a mid-IR variability survey of the ~9deg^2^ of the NDWFS Bootes Field and extends the time baseline of its predecessor, the Spitzer Deep, Wide-Field Survey (SDWFS), from 4 to 10 years. The Spitzer Space Telescope visited the field five times between 2004 and 2014 at 3.6 and 4.5{mu}m. We provide the difference image analysis photometry for a half a million mostly extragalactic sources. In mid-IR color-color plane, sources with quasar colors constitute the largest variability class (75%), 16% of the variable objects have stellar colors and the remaining 9% have the colors of galaxies. Adding the fifth epoch doubles the number of variable active galactic nuclei (AGNs) for the same false positive rates as in SDWFS, or increases the number of sources by 20% while decreasing the false positive rates by factors of 2-3 for the same variability amplitude. We quantify the ensemble mid-IR variability of ~1500 spectroscopically confirmed AGNs using single power-law structure functions (SFs), which we find to be steeper (index {gamma}~0.45) than in the optical ({gamma}~0.3), leading to much lower amplitudes at short time-lags. This provides evidence for large emission regions, smoothing out any fast UV/optical variations, as the origin of infrared quasar variability. The mid-IR AGN SF slope {gamma} seems to be uncorrelated with both the luminosity and rest-frame wavelength, while the amplitude shows an anti-correlation with the luminosity and a correlation with the rest-frame wavelength.
- ID:
- ivo://CDS.VizieR/J/MNRAS/414/500
- Title:
- Spitzer/IRS ATLAS project source
- Short Name:
- J/MNRAS/414/500
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a panoramic atlas of Spitzer/Infrared Spectrograph (IRS) spectra of extragalactic sources collected from the recent literature, with value-added measurements of their spectral features obtained in a homogeneous and concise manner. The atlas covers the full spectrum of the extragalactic Universe and includes star-forming galaxies, obscured and unobscured active galaxies, luminous and ultra-luminous infrared galaxies, and hybrid objects. Measured features such as the polycyclic aromatic hydrocarbons, the strength of the silicates in emission or absorption around 9.7um, rest-frame monochromatic luminosities or colours, combined with measurements derived from spectral decomposition are used to establish diagnostics that allow for classification of sources, based on their infrared properties alone. Average templates of the various classes are also derived. The full atlas with the value-added measurements and ancillary archival data are publicly available at http://www.denebola.org/atlas, with full references to the original data.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/79
- Title:
- Spitzer observations of radio-loud AGNs (CARLA)
- Short Name:
- J/ApJ/769/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first results from the Clusters Around Radio-Loud AGN program, a Cycle 7 and 8 Spitzer Space Telescope snapshot program to investigate the environments of a large sample of obscured and unobscured luminous radio-loud active galactic nuclei (AGNs) at 1.2<z<3.2. These data, obtained for 387 fields, reach 3.6 and 4.5{mu}m depths of [3.6]_AB_=22.6 and [4.5]_AB_=22.9 at the 95% completeness level, which is two to three times fainter than L* in this redshift range. By using the color cut [3.6]-[4.5]>-0.1 (AB), which efficiently selects high-redshift (z>1.3) galaxies of all types, we identify galaxy cluster member candidates in the fields of the radio-loud AGN. The local density of these Infrared Array Camera (IRAC)-selected sources is compared to the density of similarly selected sources in blank fields. We find that 92% of the radio-loud AGN reside in environments richer than average. The majority (55%) of the radio-loud AGN fields are found to be overdense at a>=2{sigma} level; 10% are overdense at a>=5{sigma} level. A clear rise in surface density of IRAC-selected sources toward the position of the radio-loud AGN strongly supports an association of the majority of the IRAC-selected sources with the radio-loud AGN. Our results provide solid statistical evidence that radio-loud AGN are likely beacons for finding high-redshift galaxy (proto-)clusters. We investigate how environment depends on AGN type (unobscured radio-loud quasars versus obscured radio galaxies), radio luminosity and redshift, finding no correlation with either AGN type or radio luminosity. We find a decrease in density with redshift, consistent with galaxy evolution for this uniform, flux-limited survey. These results are consistent with expectations from the orientation-driven AGN unification model, at least for the high radio luminosity regimes considered in this sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/182/628
- Title:
- Spitzer quasar and ULIRG evolution study
- Short Name:
- J/ApJS/182/628
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results from a comprehensive study of 74 ultraluminous infrared galaxies (ULIRGs) and 34 Palomar-Green (PG) quasars within z~0.3 observed with the Spitzer Infrared Spectrograph (IRS). The contribution of nuclear activity to the bolometric luminosity in these systems is quantified using six independent methods that span a range in wavelength and give consistent results within ~+/-10%-15% on average. This agreement suggests that deeply buried active galactic nuclei (AGNs) invisible to Spitzer IRS but bright in the far-infrared are not common in this sample. The average derived AGN contribution in ULIRGs is ~35%-40%, ranging from ~15%-35% among "cool" (f_25_/f_60_<=0.2) optically classified HII-like and LINER ULIRGs to ~50 and ~75% among warm Seyfert 2 and Seyfert 1 ULIRGs, respectively. This number exceeds ~80% in PG QSOs.
- ID:
- ivo://CDS.VizieR/J/A+A/375/661
- Title:
- Stability of VLBI reference frame
- Short Name:
- J/A+A/375/661
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The file table 2 gives the results of various tests and noise measurements performed on time serie of extragalactic radio source coordinates. Systematic and random behaviours in time serie of individual determinations of cooordinates for 283 sources over 1987-1999 are investigated. The random variability of the source coordinates is characterized by the {chi}^2^ test (Bevington, 1969, p.187) and the "goodness of fit (gof)" (Bevington, 1969, p.188). The Allan variance method (Allan, 1966, Proc. IEEE, vol. 54, 221) is used to investigate spectral characteristics of the time series. The source structure index (Fey & Charlot, 1997ApJS..111...95F, 2000, Cat. <J/ApJS/128/17>) qualifies the level of position disturbance expected at the date of the map (1 for the less disturbed, 4 for the most disturbed). The estimation of "linear rates" in the coordinates is a qualifier of the systematic parts of the source instability. This table contains the 283 best observed sources and is divided in three parts, with the left hand side giving general information and counts, the middle part giving statistics in the source local frame, and the right hand side giving statistics in the equatorial frame.
- ID:
- ivo://CDS.VizieR/J/AZh/87/739
- Title:
- Steep and ultra-steep spectra RC sources
- Short Name:
- J/AZh/87/739
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of spectroscopy of 71 objects with steep and ultra-steep spectra (alpha<-0.9, S{prop.to}nu^alpha^) from the "Big Trio" (RATAN-600-VLA-BTA) project, performed with the "Scorpio" spectrograph on the 6-m telescope of the Special Astrophysical Observatory (Russian Academy of Sciences). Redshifts were determined for these objects. We also present several other parameters of the sources, such as their R magnitudes, maximum radio sizes in seconds of arc, flux densities at 500, 1425, and 3940MHz, radio luminosities at 500 and 3940MHz, and morphology. Of the total number of radio galaxies studied, four have redshifts 1<=z<2, three have 2<=z<3, one has 3<=z<4, and one has z=4.51. Thirteen sources have redshifts 0.7<z<1 and 15 have 0.2<z<0.7. Of all the quasars studied, five have redshifts 0.7<z<1, seven have 1<=z<2, four have 2<=z<3, and one has z=3.57. We did not detect any spectral lines for 17 objects.
