- ID:
- ivo://nasa.heasarc/cgrabs
- Title:
- Candidate Gamma-Ray Blazar Survey Source Catalog
- Short Name:
- CGRABS
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors have constructed a uniform all-sky survey of bright blazars, selected primarily by their flat radio spectra, that is designed to provide a large catalog of likely gamma-ray active galactic nuclei (AGNs). The defined sample, the Candidate Gamma-Ray Blazar Survey (CGRaBS) source catalog, has 1625 targets with radio and X-ray properties similar to those of the EGRET blazars, spread uniformly across the |b| > 10 degrees sky. They also report progress toward optical characterization of the sample; of objects with known red magnitude R < 23, 85% have been classified and 81% have measured redshifts. One goal of this program is to focus attention on the most interesting (e.g., high-redshift, high-luminosity, etc.) sources for intensive multi-wavelength study during the observations by the Large Area Telescope (LAT) on the Gamma-Ray Large-Area Space Telescope (GLAST) satellite observatory. This table was created by the HEASARC in April 2008 based on an electronic version of Table 2 of the reference paper obtained from the electronic ApJS web site. This is a service provided by NASA HEASARC .
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/750/140
- Title:
- Candidate globular clusters in NGC 1316
- Short Name:
- J/ApJ/750/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study mass functions of globular clusters derived from Hubble Space Telescope/Advanced Camera for Surveys images of the early-type merger remnant galaxy NGC 1316, which hosts a significant population of metal-rich globular clusters of intermediate age (~3Gyr). For the old, metal-poor ("blue") clusters, the peak mass of the mass function M_p_ increases with internal half-mass density {rho}_h_ as M_p_{prop.to}{rho}_h_^0.44^, whereas it stays approximately constant with galactocentric distance R_gal_. The mass functions of these clusters are consistent with a simple scenario in which they formed with a Schechter initial mass function and evolved subsequently by internal two-body relaxation. For the intermediate-age population of metal-rich ("red") clusters, the faint end of the previously reported power-law luminosity function of the clusters with R_gal_>9kpc is due to many of those clusters having radii larger than the theoretical maximum value imposed by the tidal field of NGC 1316 at their R_gal_. This renders disruption by two-body relaxation ineffective. Only a few such diffuse clusters are found in the inner regions of NGC 1316. Completeness tests indicate that this is a physical effect. Using comparisons with star clusters in other galaxies and cluster disruption calculations using published models, we hypothesize that most red clusters in the low-{rho}_h_ tail of the initial distribution have already been destroyed in the inner regions of NGC 1316 by tidal shocking, and that several remaining low-{rho}_h_ clusters will evolve dynamically to become similar to "faint fuzzies" that exist in several lenticular galaxies. Finally, we discuss the nature of diffuse red clusters in early-type galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/429
- Title:
- Candidate globular clusters in NGC 5170
- Short Name:
- J/MNRAS/403/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here, we present Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging, in the B and I bands, of the edge-on Sb/Sc galaxy NGC 5170. Excluding the central disc region, we detect 142 objects with colours and sizes typical of globular clusters (GCs). Our main result is the discovery of a "blue tilt" (a mass-metallicity relation), at the 3{sigma} level, in the metal-poor GC subpopulation of this Milky Way like galaxy.
- ID:
- ivo://CDS.VizieR/J/other/Sci/292.698
- Title:
- Candidate halo dark matter
- Short Name:
- J/other/Sci/292.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Milky Way galaxy contains a large, spherical component which is believed to harbor a substantial amount of unseen matter. Recent observations indirectly suggest that as much as half of this "dark matter" may be in the form of old, very cool white dwarfs, the remnants of an ancient population of stars as old as the galaxy itself. We conducted a survey to find faint, cool white dwarfs with large space velocities, indicative of their membership in the galaxy's spherical halo component. The survey reveals a substantial, directly observed population of old white dwarfs, too faint to be seen in previous surveys. This newly discovered population accounts for at least 2 percent of the halo dark matter. It provides a natural explanation for the indirect observations, and represents a direct detection of galactic halo dark matter.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/158
- Title:
- Candidate halo wide binaries
- Short Name:
- J/ApJ/790/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an improved catalog of halo wide binaries compiled from an extensive literature search. Most of our binaries stem from the common proper motion binary catalogs by Allen et al. (2000, J/A+A/356/529) and Chaname & Gould (2004ApJ...601..289C), but we have also included binaries from the lists of Ryan (1992AJ....104.1144R) and Zapatero-Osorio & Martin (2004, J/A+A/419/167). All binaries were carefully checked and their distances and systemic radial velocities are included when available. Probable membership to the halo population was tested by means of reduced proper motion diagrams for 251 candidate halo binaries. After eliminating obvious disk binaries, we ended up with 211 probable halo binaries, 150 of which have radial velocities available. We compute galactic orbits for these 150 binaries and calculate the time they spend within the galactic disk. Considering the full sample of 251 candidate halo binaries as well as several subsamples, we find that the distribution of angular separations (or expected major semiaxes) follows a power law f(a) ~ a.^-1^ (Oepik's relation) up to different limits. For the 50 most disk-like binaries, those that spend their entire lives within z = +/-500 pc, this limit is found to be 19,000 AU (0.09 pc), while for the 50 most halo-like binaries, those that spend on average only 18% of their lives within z = +/-500 pc, the limit is 63,000 AU (0.31 pc). In a companion paper, we employ this catalog to establish limits on the masses of the halo massive perturbers (massive compact halo objects).
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/163
- Title:
- Candidate Halpha sources in GBS
- Short Name:
- J/MNRAS/466/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of candidate Halpha emission and absorption line sources and blue objects in the Galactic Bulge Survey (GBS) region. We use a point source catalogue of the GBS fields (two strips of (lxb)=(6{deg}x1{deg}) centred at b=1.5{deg} above and below the Galactic centre), covering the magnitude range 16>=r'>=22.5. We utilize (r'-i', r'-Halpha) colour-colour diagrams to select Halpha emission and absorption line candidates, and also identify blue objects (compared to field stars) using the r'-i' colour index. We identify 1337 Halpha emission line candidates and 336 Halpha absorption line candidates. These catalogues likely contain a plethora of sources, ranging from active (binary) stars, early-type emission line objects, cataclysmic variables (CVs) and low-mass X-ray binaries (LMXBs) to background active galactic nuclei (AGN). The 389 blue objects we identify are likely systems containing a compact object, such as CVs, planetary nebulae and LMXBs. Hot subluminous dwarfs (sdO/B stars) are also expected to be found as blue outliers. Crossmatching our outliers with the GBS X-ray catalogue yields sixteen sources, including seven (magnetic) CVs and one qLMXB candidate among the emission line candidates, and one background AGN for the absorption line candidates. One of the blue outliers is a high state AM CVn system. Spectroscopic observations combined with the multi-wavelength coverage of this area, including X-ray, ultraviolet and (time-resolved) optical and infrared observations, can be used to further constrain the nature of individual sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/3336
- Title:
- Candidate high-z protoclusters among PCS
- Short Name:
- J/MNRAS/476/3336
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By determining the nature of all the Planck compact sources within 808.4deg^2^ of large Herschel surveys, we have identified 27 candidate protoclusters of dusty star-forming galaxies (DSFGs) that are at least 3{sigma} overdense in either 250, 350, or 500um sources. We find roughly half of all the Planck compact sources are resolved by Herschel into multiple discrete objects, with the other half remaining unresolved by Herschel. We find a significant difference between versions of the Planck catalogues, with earlier releases hosting a larger fraction of candidate protoclusters and Galactic cirrus than later releases, which we ascribe to a difference in the filters used in the creation of the three catalogues. We find a surface density of DSFG candidate protoclusters of (3.3+/-0.7)x10^-2^sources/deg^2^, in good agreement with previous similar studies. We find that a Planck colour selection of S_857_/S_545_<2 works well to select candidate protoclusters, but can miss protoclusters at z<2. The Herschel colours of individual candidate protocluster members indicate our candidate protoclusters all likely all lie at z>1. Our candidate protoclusters are a factor of 5 times brighter at 353GHz than expected from simulations, even in the most conservative estimates. Further observations are needed to confirm whether these candidate protoclusters are physical clusters, multiple protoclusters along the line of sight, or chance alignments of unassociated sources.
- ID:
- ivo://CDS.VizieR/J/AJ/153/157
- Title:
- Candidate ICRF flat-spectrum radio sources. III.
- Short Name:
- J/AJ/153/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ~160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58m European Southern Observatory New Technology Telescope, and the two 8.2m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.
- ID:
- ivo://CDS.VizieR/J/AJ/149/78
- Title:
- Candidate IR variables from SAGE-SMC survey
- Short Name:
- J/AJ/149/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our study on the infrared variability of point sources in the Small Magellanic Cloud (SMC). We use the data from the Spitzer Space Telescope Legacy Program "Surveying the Agents of Galaxy Evolution in the Tidally Stripped, Low Metallicity Small Magellanic Cloud" (SAGE-SMC) and the "Spitzer Survey of the Small Magellanic Cloud" (S^3^MC) survey, over three different epochs, separated by several months to 3 years. Variability in the thermal infrared is identified using a combination of Spitzer's InfraRed Array Camera 3.6, 4.5, 5.8, and 8.0{mu}m bands, and the Multiband Imaging Photometer for Spitzer 24{mu}m band. An error-weighted flux difference between each pair of three epochs ("variability index") is used to assess the variability of each source. A visual source inspection is used to validate the photometry and image quality. Out of ~2 million sources in the SAGE-SMC catalog, 814 meet our variability criteria. We matched the list of variable star candidates to the catalogs of SMC sources classified with other methods, available in the literature. Carbon-rich Asymptotic Giant Branch (AGB) stars make up the majority (61%) of our variable sources, with about a third of all of our sources being classified as extreme AGB stars. We find a small, but significant population of oxygen-rich (O-rich) AGB (8.6%), Red Supergiant (2.8%), and Red Giant Branch (<1%) stars. Other matches to the literature include Cepheid variable stars (8.6%), early type stars (2.8%), Young-stellar objects (5.8%), and background galaxies (1.2%). We found a candidate OH maser star, SSTISAGE1C J005212.88-730852.8, which is a variable O-rich AGB star, and would be the first OH/IR star in the SMC, if confirmed. We measured the infrared variability of a rare RV Tau variable (a post-AGB star) that has recently left the AGB phase. 59 variable stars from our list remain unclassified.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/772
- Title:
- Candidate LAEs at z=5.7 and z=6.6
- Short Name:
- J/MNRAS/472/772
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic follow-up of candidate luminous Ly{alpha} emitters (LAEs) at z=5.7-6.6 in the SA22 field with VLT/X-SHOOTER. We confirm two new luminous LAEs at z=5.676 (SR6) and z=6.532 (VR7), and also present HST follow-up of both sources. These sources have luminosities L_Ly {alpha}_~=3x10^43^erg/s, very high rest-frame equivalent widths of EW_0_>=200{AA} and narrow Ly{alpha} lines (200-340km/s). VR7 is the most UV-luminous LAE at z>6.5, with M_1500_=-22.5, even brighter in the UV than CR7. Besides Ly{alpha}, we do not detect any other rest-frame UV lines in the spectra of SR6 and VR7, and argue that rest-frame UV lines are easier to observe in bright galaxies with low Ly{alpha} equivalent widths. We confirm that Ly{alpha} line widths increase with Ly{alpha} luminosity at z=5.7, while there are indications that Ly{alpha} lines of faint LAEs become broader at z=6.6, potentially due to reionization. We find a large spread of up to 3 dex in UV luminosity for >L* LAEs, but find that the Ly{alpha} luminosity of the brightest LAEs is strongly related to UV luminosity at z=6.6. Under basic assumptions, we find that several LAEs at z~=6-7 have Ly{alpha} escape fractions >=100 per cent, indicating bursty star formation histories, alternative Ly{alpha} production mechanisms, or dust attenuating Ly{alpha} emission differently than UV emission. Finally, we present a method to compute {xi}_ion_, the production efficiency of ionizing photons, and find that LAEs at z~=6-7 have high values of log_10_({xi}_ion_/Hz/erg)~=25.51+/-0.09 that may alleviate the need for high Lyman-Continuum escape fractions required for reionization.
