- ID:
- ivo://CDS.VizieR/J/ApJS/183/214
- Title:
- Arecibo Legacy Fast Alfa Survey (ALFALFA) VIII.
- Short Name:
- J/ApJS/183/214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a fourth catalog of HI sources from the Arecibo Legacy Fast ALFA (ALFALFA) Survey. We report 541 detections over 136deg^2^, within the region of the sky having 22h<RA<03h and 24<DE<26{deg}. This complements a previous catalog in the region 26<DE<28{deg}. We present here the detections falling into three classes: (1) extragalactic sources with signal-to-noise ratio (S/N)>6.5, where the reliability of the catalog is better than 95%; (2) extragalactic sources 5.0<S/N<6.5 and a previously measured optical redshift that corroborates our detection; or (3) High Velocity Clouds (HVCs), or subcomponents of such clouds, in the periphery of the Milky Way. Of the 541 objects presented here, 90 are associated with HVCs, while the remaining 451 are identified as extragalactic objects. Optical counterparts have been matched with all but one of the extragalactic objects.
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- ID:
- ivo://CDS.VizieR/J/AJ/138/338
- Title:
- Arecibo Legacy Fast ALFA Survey. IX.
- Short Name:
- J/AJ/138/338
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalog of HI sources extracted from the ongoing Arecibo Legacy Fast ALFA (ALFALFA) extragalactic HI line survey, found within the sky region bounded by 9:36<RA<11:36 and +08<DE<+12. The HI catalog presented here for this 118deg^2^ region is combined with the ones derived from surrounding regions also covered by the ALFALFA survey to examine the large-scale structure in the complex Leo region. Because of the combination of wide sky coverage and superior sensitivity, spatial and spectral resolution, the ALFALFA HI catalog of the Leo region improves significantly on the numbers of low HI mass sources as compared with those found in previous HI surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/136/713
- Title:
- Arecibo legacy fast ALFA survey. VI.
- Short Name:
- J/AJ/136/713
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third installment of HI sources extracted from the Arecibo Legacy Fast ALFA extragalactic survey. This data set continues the work of the Virgo ALFALFA catalog. The catalogs and spectra published here consist of data obtained during the 2005 and 2006 observing sessions of the survey. The catalog consists of 578 HI detections within the range 11h36m<RA(J2000)<13h52m and +08{deg}<DE(J2000)<+12{deg}, and cz_{sun}_<18000km/s. The catalog entries are matched with optical counterparts where possible through the examination of digitized optical images. The catalog detections can be classified into three categories: (a) detections of high reliability with a signal-to-noise ratio (S/N)>6.5; (b) high-velocity clouds in the Milky Way or its periphery; and (c) signals of lower S/N which coincide spatially with an optical object and known redshift. 75% of the sources are newly published HI detections. Of particular note is a complex of HI clouds projected between M87 and M49 that do not coincide with any optical counterparts. Candidate objects without optical counterparts are few. Position corrections for telescope pointing errors are applied to the data set by comparing the ALFALFA continuum centroid with those cataloged in the NRAO VLA Sky Survey (NVSS, Cat. VIII/65). The uncorrected positional accuracy averages 27"(21" median) for all sources with S/N>6.5 and is of order ~21"(16" median) for signals with S/N>12. Uncertainties in distances toward the Virgo cluster can affect the calculated HI mass distribution.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/129
- Title:
- A redshift catalog of the galaxy cluster A2029
- Short Name:
- J/ApJ/871/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the structure of galaxy cluster A2029 and its surroundings based on intensive spectroscopy along with X-ray and weak lensing observations. The redshift survey includes 4376 galaxies (1215 spectroscopic cluster members) within 40' of the cluster center; the redshifts are included here. Two subsystems, A2033 and a southern infalling group (SIG), appear in the infall region based on the spectroscopy, as well as on the weak lensing and X-ray maps. The complete redshift survey of A2029 also identifies at least 12 foreground and background systems (10 are extended X-ray sources) in the A2029 field; we include a census of their properties. The X-ray luminosities (L_X_)-velocity dispersions ({sigma}_cl_) scaling relations for A2029, A2033, SIG, and the foreground/background systems are consistent with the known cluster scaling relations. The combined spectroscopy, weak lensing, and X-ray observations provide a robust measure of the masses of A2029, A2033, and SIG. The total mass of the infalling groups (A2033 and SIG) is ~60% of the M200 of the primary cluster, A2029. Simple dynamical considerations suggest that A2029 will accrete these subsystems in the next few Gyr. In agreement with simulations and other clusters observed in a similar redshift range, the total mass in the A2029 infall region is comparable to the A2029 M200 and will mostly be accreted in the long-term future.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/88
- Title:
- A redshift survey of the central region of A2199
- Short Name:
- J/ApJ/842/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from an extensive spectroscopic survey of the central region of the nearby galaxy cluster Abell 2199 (A2199) at z=0.03. By combining 775 new redshifts from the MMT/Hectospec observations with the data in the literature, we construct a large sample of 1624 galaxies with measured redshifts at R<30', which results in high spectroscopic completeness at r_petro,0_<20.5 (77%). We use these data to study the kinematics and clustering of galaxies, focusing on the comparison with those of the intracluster medium (ICM) from Suzaku X-ray observations. We identify 406 member galaxies of A2199 at R<30' using the caustic technique. The velocity dispersion profile of cluster members appears smoothly connected to the stellar velocity dispersion profile of the cD galaxy. The luminosity function is well fitted with a Schechter function at M_r_< -15. The radial velocities of cluster galaxies generally agree well with those of the ICM, but there are some regions where the velocity difference between the two is about a few hundred kilometers per second. The cluster galaxies show a hint of global rotation at R<5' with v_rot_=300-600km/s, but the ICM in the same region does not show such rotation. We apply a friends-of-friends algorithm to the cluster galaxy sample at R<60' and identify 32 group candidates, and examine the spatial correlation between the galaxy groups and X-ray emission. This extensive survey in the central region of A2199 provides an important basis for future studies of interplay among the galaxies, the ICM, and the dark matter in the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/777/64
- Title:
- A search for double-peaked AGNs in AGES
- Short Name:
- J/ApJ/777/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dual supermassive black holes (SMBHs) with kiloparsec-scale separations in merger-remnant galaxies are informative tracers of galaxy evolution, but the avenue for identifying them in large numbers for such studies is not yet clear. One promising approach is to target spectroscopic signatures of systems where both SMBHs are fueled as dual active galactic nuclei (AGNs), or where one SMBH is fueled as an offset AGN. Dual AGNs may produce double-peaked narrow AGN emission lines, while offset AGNs may produce single-peaked narrow AGN emission lines with line-of-sight velocity offsets relative to the host galaxy. We search for such dual and offset systems among 173 Type 2 AGNs at z<0.37 in the AGN and Galaxy Evolution Survey (AGES), and we find two double-peaked AGNs and five offset AGN candidates. When we compare these results to a similar search of the DEEP2 Galaxy Redshift Survey and match the two samples in color, absolute magnitude, and minimum velocity offset, we find that the fraction of AGNs that are dual SMBH candidates increases from z=0.25 to z=0.7 by a factor of ~6 (from 2/70 to 16/91, or 2.9_-1.9_^+3.6^% to 18_-5_^+5^%). This may be associated with the rise in the galaxy merger fraction over the same cosmic time. As further evidence for a link with galaxy mergers, the AGES offset and dual AGN candidates are tentatively ~3 times more likely than the overall AGN population to reside in a host galaxy that has a companion galaxy (from 16/173 to 2/7, or 9_-2_^+3^% to 29_-19_^+26^%). Follow-up observations of the seven offset and dual AGN candidates in AGES will definitively distinguish velocity offsets produced by dual SMBHs from those produced by narrow-line region kinematics, and will help sharpen our observational approach to detecting dual SMBHs.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2540
- Title:
- Asiago-ESO/RASS QSO survey. I.
- Short Name:
- J/AJ/119/2540
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the first results of a survey for bright quasars (V<14.5 and R<15.4) covering the northern hemisphere at Galactic latitudes |b|>30{deg}. The photometric database is derived from the Guide Star and USNO catalogs. Quasars are identified on the basis of their X-ray emission measured in the ROSAT All-Sky Survey. The surface density of quasars brighter than 15.5mag turns out to be (10+/-2)x10^-3^deg^-2^, about 3 times higher than that estimated by the Palomar-Green (PG) survey. The quasar optical luminosity function (LF) at 0.04<z<=0.3 is computed and shown to be consistent with a luminosity-dependent luminosity evolution of the type derived by La Franca & Cristiani (1997AJ....113.1517L) in the range 0.3<z<=2.2. The predictions of semianalytical models of hierarchical structure formation agree remarkably well with the present observations.
- ID:
- ivo://CDS.VizieR/J/AJ/124/2955
- Title:
- Asiago-ESO/RASS QSO survey. II.
- Short Name:
- J/AJ/124/2955
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper of a series describing the Asiago-ESO/RASS QSO survey, a project aimed at the construction of an all-sky, statistically well defined sample of very bright QSOs (BJ<=15). Such a survey is required to remove the present uncertainties about the properties of the local QSO population and constitutes an homogeneous database for detailed evolutionary studies of active galactic nuclei (AGNs). We present here the complete southern sample, which comprises 243 bright (12.60<=BJ<=15.13) QSO candidates at high galactic latitudes (|b_gal_|>=30{deg}). The area covered by the survey is 5660deg^2^. Spectroscopy for the 137 still unidentified objects has been obtained. The total number of AGNs turns out to be 11163 of which are new identifications. The properties of the selection are discussed. The completeness and the success rate for this survey at the final stage are 63% and 46%, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/192
- Title:
- A spectroscopic census of A2029 members
- Short Name:
- J/ApJ/872/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A rich spectroscopic census of members of the local massive cluster A2029 includes 1215 members of A2029 and its two infalling groups, A2033 and the Southern Infalling Group. The two infalling groups are identified in spectroscopic, X-ray, and weak-lensing maps. We identify active galactic nuclei (AGNs), star-forming galaxies, E+A galaxies, and quiescent galaxies based on the spectroscopy. The fractions of AGN and post-starburst E+A galaxies in A2029 are similar to those of other clusters. We derive the stellar mass (M_*_)-metallicity relation of A2029 based on 227 star-forming members; A2029 members within 10^9^M_{sun}_<M_*_<10^9.5^M_{sun}_ are more metal-rich than Sloan Digital Sky Survey galaxies within the same mass range. We utilize the spectroscopic index D_n_4000, a strong age indicator, to trace past and future evolution of the A2029 system. The median D_n_4000 of the members decreases as the projected clustercentric distance increases for all three subsystems. The D_n_4000-M_*_ relations of the members in A2029 and its two infalling groups differ significantly, indicating the importance of stochastic effects for understanding the evolution of cluster galaxy populations.
- ID:
- ivo://CDS.VizieR/J/ApJ/705/68
- Title:
- A Spitzer ultradeep survey (SUUSS)
- Short Name:
- J/ApJ/705/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out an unbiased, spectroscopic survey using the low-resolution module of the infrared spectrograph (IRS) onboard Spitzer targeting two 2.6 square arcminute regions in the GOODS-North field. The IRS was used in a spectral mapping mode with 5hr of effective integration time per pixel. One region was covered between 14 and 21um and the other between 20 and 35um. We extracted spectra for 45 sources. About 84% of the sources have reported detections by GOODS at 24um, with a median f_{nu}_(24um)~100uJy. All but one source are detected in all four IRAC bands, 3.6 to 8um. We use a new cross-correlation technique to measure redshifts and estimate IRS spectral types; this was successful for ~60% of the spectra. Fourteen sources show significant polycyclic aromatic hydrocarbon emission, four mostly SiO absorption, eight present mixed spectral signatures (low PAH and/or SiO) and two show a single line in emission. For the remaining 17, no spectral features were detected. Redshifts range from z~0.2 to z~2.2, with a median of 1. IR luminosities are roughly estimated from 24um flux densities, and have median values of 2.2x10^11^L_{sun}_ and 7.5x10^11^L_{sun}_ at z~1 and z~2, respectively. This sample has fewer active galactic nuclei than previous faint samples observed with the IRS, which we attribute to the fainter luminosities reached here.
