- ID:
- ivo://nasa.heasarc/bmwchancat
- Title:
- Brera Multi-scale Wavelet Chandra Source Catalog
- Short Name:
- BMWCHANCAT
- Date:
- 14 Feb 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the BMW-Chandra source catalog drawn from essentially all Chandra ACIS-I pointed observations with an exposure time in excess of 10 ks that were public as of March 2003 (136 observations). Using the wavelet detection algorithm developed by Lazzati et al. (1999ApJ...524..414) and Campana et al. (1999ApJ...524..423C), which can characterize both point-like and extended sources, the authors identified 21325 sources. Among them, 16758 are serendipitous, i.e. not associated with the targets of the pointings, and do not require a non-automated analysis. This makes this catalog the largest compilation of Chandra sources as of the date of publication of this catalog (August 2008). The 0.5 - 10 keV absorption corrected fluxes of these sources range from ~3 x 10<sup>-16</sup> to 9 x 10<sup>-12</sup> erg/cm<sup>2</sup>/s with a median of 7 x 10<sup>-15</sup> erg/cm<sup>2</sup>/s. The catalog consists of count rates and relative errors in three energy bands (total, 0.5 - 7 keV; soft, 0.5 - 2 keV; and hard, 2 - 7 keV), and source positions relative to the highest signal-to-noise detection among the three bands. The wavelet algorithm also provides an estimate of the extension of the source. The authors include information drawn from the headers of the original files, as well, and extracted source counts in four additional energy bands, SB1 (0.5 - 1 keV), SB2 (1 - 2 keV), HB1 (2 - 4 keV), and HB2 (4 - 7 keV). They computed the sky coverage for the full catalog and for a subset at high Galactic latitude (|b| > 20 degrees). The complete catalog provides a sky coverage in the soft band (0.5 - 2 keV, S/N = 3) of ~8 deg<sup>2</sup> at a limiting flux of 10<sup>-13</sup> erg/cm<sup>2</sup>/s, and ~2 deg<sup>2</sup> at a limiting flux of ~10<sup>-15</sup> erg/cm<sup>2</sup>/s. The total numbers of matches with the FIRST, IRASPSC, 2MASS, and GSC2 catalogs obtained after a closest-distance selection are 13, 87, 6700, and 4485, respectively. This table was created by the HEASARC in September 2008 based on the CDS table J/A+A/488/1221 file catalog.dat. The catalog version is BMC 1.0.1F. All sources in this version of the catalog were from observations in POINTING and TIMED ACIS read modes. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/bmwhricat
- Title:
- Brera Multi-scale Wavelet ROSAT HRI Source Catalog
- Short Name:
- BMW-HRI
- Date:
- 14 Feb 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Brera Multi-scale Wavelet ROSAT High Resolution Imager Source Catalog (BMW-HRI) is derived from all ROSAT HRI pointed observations with exposure time longer than 100 seconds available in the ROSAT public archives. The data were analyzed automatically using a wavelet detection algorithm suited to the detection and characterization of both point-like and extended sources. This algorithm is able to detect and disentangle sources in very crowded fields and/or in presence of extended or bright sources. Images have been also visually inspected after the analysis to ensure verification. The final catalog, derived from 4,303 observations, consists of 29,089 sources detected with a detection probability of greater or equal 4.2 sigma. For each source, the primary catalog entries provide name, position, count rate, flux and extension along with the relative errors. In addition, results of cross-correlations with existing catalogs at different wavelengths (FIRST, IRAS, 2MASS, and GSC2) are also reported. As an external check, the authors compared their catalog with the previously available ROSHRICAT catalog (both in its short and long versions) and were able to recover, for the short version, ~90% of the entries. The sky coverage of the entire HRI data set was computed by means of simulations. The complete BMW-HRI catalog provides a sky coverage of 732 square degrees down to a limiting flux of ~1x10<sup>-12</sup> erg/s/cm<sup>2</sup> and of 10 square degrees down to ~1x10<sup>-14</sup> erg/s/cm<sup>2</sup>. The authors were able to compute the cosmological log(N)-log(S) distribution down to a flux of about 1.2x10<sup>-14</sup> erg/s/cm<sup>2</sup>. This catalog was ingested by the HEASARC in March 2003, based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/IX/34">CDS Catalog IX/34</a> file catalog.dat.gz. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJS/147/29
- Title:
- BRHalpha data of blue compact dwarf galaxies
- Short Name:
- J/ApJS/147/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B, R, and H{alpha} images for a total of 114 nearby galaxies (v_helio_<4000km/s) that, with exception of nine objects, are classified as blue compact dwarfs (BCDs). BR integrated magnitudes, H{alpha} fluxes and H{alpha} equivalent widths for all the objects in the sample are presented.
2014. Bright Ages Survey. II.
- ID:
- ivo://CDS.VizieR/J/ApJ/648/250
- Title:
- Bright Ages Survey. II.
- Short Name:
- J/ApJ/648/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Bright Ages Survey is a K-band-selected redshift survey over six separate fields with UBVRIzJHK imaging covering a total of 75.6arcmin^2^ and reaching K=20-20.5. Two fields have deep HST imaging, while all are centered on possible overdensities in the range. Here we report photometric redshifts and spectroscopy for this sample, which has been described in Paper I (Colbert et al., 2006ApJ...638..603C).
- ID:
- ivo://CDS.VizieR/J/A+A/544/A34
- Title:
- Bright AGN VLBI imaging study at 2 and 8GHz
- Short Name:
- J/A+A/544/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate statistical and individual astrophysical properties of active galactic nuclei (AGNs), such as parsec-scale flux density, core dominance, angular and linear sizes, maximum observed brightness temperatures of VLBI core components, spectral index distributions for core and jet components, and evolution of brightness temperature along the jets. Furthermore, we statistically compare core flux densities and brightness temperature as well as jet spectral indices of {gamma}-ray bright and weak sources. We used 19 very long baseline interferometry (VLBI) observing sessions carried out simultaneously at 2.3GHz and 8.6GHz with the participation of 10 Very Long Baseline Array (VLBA) stations and up to 10 additional geodetic telescopes. The observations span the period 1998-2003. We present here single-epoch results from high-resolution radio observations of 370 AGNs. Our VLBI images at 2.3GHz and 8.6GHz as well as Gaussian models are presented and analyzed. At least one-fourth of the cores are completely unresolved on the longest baselines of the global VLBI observations. The VLBI core components are partially opaque with the median value of spectral index of alpha_core_~0.3, while the jet features are usually optically thin alpha_jet_~-0.7. The spectral index typically decreases along the jet ridge line owing to the spectral aging, with a median value of -0.05mas^-1^. Brightness temperatures are found to be affected by Doppler boosting and reach up to ~10^13^K with a median of ~2.5x10^11^K at both frequencies. The brightness temperature gradients along the jets typically follow a power law T_b_~r^-2.2^ at both frequencies. We find that 147 sources (40%) positionally associated with gamma-ray detections from the Fermi LAT Second Source Catalog have higher core flux densities and brightness temperatures, and are characterized by the less steep radio spectrum of the optically thin jet emission.
2016. Bright Be shell stars
- ID:
- ivo://CDS.VizieR/J/A+A/459/137
- Title:
- Bright Be shell stars
- Short Name:
- J/A+A/459/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Echelle observations are presented and discussed for 23 of the 27 known "normal" shell stars brighter than about 6.5mag. In addition to those typical cases, three stars with known transitions between emission & shell and pure emission line appearance, and three rapidly rotating B stars without records of line emission (Bn stars) are added to the sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/137
- Title:
- Bright blazars variability brightness temp.
- Short Name:
- J/ApJ/866/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Relativistic effects dominate the emission of blazar jets complicating our understanding of their intrinsic properties. Although many methods have been proposed to account for them, the variability Doppler factor method has been shown to describe the blazar populations best. We use a Bayesian hierarchical code called Magnetron to model the light curves of 973 sources observed by the Owens Valley Radio Observatory's 40-m telescope as a series of flares with an exponential rise and decay, and estimate their variability brightness temperature. Our analysis allows us to place the most stringent constraints on the equipartition brightness temperature i.e., the maximum achieved intrinsic brightness temperature in beamed sources which we found to be <T_{eq}>=2.78x10^11^K+/-26%. Using our findings we estimated the variability Doppler factor for the largest sample of blazars increasing the number of available estimates in the literature by almost an order of magnitude. Our results clearly show that {gamma}-ray loud sources have faster and higher amplitude flares than {gamma}-ray quiet sources. As a consequence they show higher variability brightness temperatures and thus are more relativistically beamed, with all of the above suggesting a strong connection between the radio flaring properties of the jet and {gamma}-ray emission.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A1
- Title:
- Bright B-type variables in Scorpius
- Short Name:
- J/A+A/557/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first two of a total of six nano-satellites that will constitute the BRITE-Constellation space photometry mission have recently been launched successfully. In preparation for this project, we carried out time-resolved colour photometry in a field that is an excellent candidate for BRITE measurements from space. We acquired 117h of Stromgren uvy data during 19 nights. Our targets comprised the {beta} Cephei stars {kappa} and {lambda} Sco, the eclipsing binary {mu}^1^ Sco, and the variable super/hypergiant {zeta}^1^ Sco. For {kappa} Sco, a photometric mode identification in combination with results from the spectroscopic literature suggests a dominant (l,m)=(1,-1) {beta} Cephei-type pulsation mode of the primary star. The longer period of the star may be a rotational variation or a g-mode pulsation. For {lambda} Sco, we recover the known dominant {beta} Cephei pulsation, a longer-period variation, and observed part of an eclipse. Lack of ultraviolet data precludes mode identification for this star. We noticed that the spectroscopic orbital ephemeris of the closer pair in this triple system is inconsistent with eclipse timings and propose a refined value for the orbital period of the closer pair of 5.95189+/-0.00003d. We also argue that the components of the {lambda} Sco system are some 30% more massive than previously thought. The binary light curve solution of {mu}^1^ Sco requires inclusion of the irradiation effect to explain the u light curve, and the system could show additional low amplitude variations on top of the orbital light changes. {zeta}^1^ Sco shows long-term variability on a time scale of at least two weeks that we prefer to interpret in terms of a variable wind or strange mode pulsations.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A69
- Title:
- Bright C_2_H emission in Lupus disks
- Short Name:
- J/A+A/631/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent ALMA surveys in different star-forming regions have shown that CO emission in protoplanetary disks is much fainter than expected. Accordingly, CO-based gas masses and gas/dust ratios are orders of magnitude lower than previously thought. This may be explained either as fast gas dispersal, or as chemical evolution and locking up of volatiles in larger bodies leading to the low observed CO fluxes. The latter processes lead to enhanced C/O ratios in the gas, which may be reflected in enhanced abundances of carbon-bearing molecules like C_2_H. The goal of this work is to employ C_2_H observations to understand whether low CO fluxes are caused by volatile depletion, or by fast gas dissipation. We present ALMA Cycle 4 C_2_H (N=3-2, J=7/2-5/2, F=4-3 and F=3-2) observations of a subsample of nine sources in the Lupus star-forming region. The integrated C_2_H emission is determined and compared to previous CO isotopologue observations and physical-chemical model predictions. Seven out of nine disks are detected in C_2_H, whose line emission is almost as bright as ^{13}CO. All detections are significantly brighter than the typical sensitivity of the observations, hinting at a bimodal distribution of the C_2_H line intensities. This conclusion is strengthened when our observations are compared with additional C_2_H observations of other disks. When compared with physical-chemical models run with DALI, the observed C_2_H fluxes can be reproduced only if some level of volatile carbon and oxygen depletion is allowed and [C]/[O]>1 in the gas. Models with reduced gas/dust ratios near unity fail instead to reproduce the observed C_2_H line luminosity. A steeper than linear correlation between C_2_H and CN emission line is found for the Lupus disks. This is linked to the fact that C_2_H emission lines are affected more strongly by [C]/[O] variations than CN lines. Ring-like structures are detected both in C_2_H and in continuum emission but, as for CN, they do not seem to be connected. Sz 71 shows ring shaped emission in both C_2_H and CN with the location of the peak intensity coinciding, within our 30 au resolution. Our new ALMA C_2_H observations favour volatile carbon and oxygen depletion rather than fast gas dispersal to explain the faint CO observations for most of the disks. This result has implications for disk-evolution and planet-formation theories, as disk gas masses may be larger than expected if CO is considered to be the main carbon carrier in the gas phase.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/47
- Title:
- Brightest cluster galaxies bright in 22um (W4BCGs)
- Short Name:
- J/ApJ/853/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Brightest cluster galaxies (BCGs) are believed to have assembled most of their stars early in time and therefore should be passively evolving at low redshifts and appear "red-and-dead." However, there have been reports that a minority of low-redshift BCGs still have ongoing star formation rates (SFRs) of a few to even ~100M_{sun}_/yr. Such BCGs are found in "cool-core" ("CC") clusters, and their star formation is thought to be fueled by "cooling flow." To further investigate the implications of low-redshift, star-forming BCGs, we perform a systematic search using the 22{mu}m data ("W4" band) from the Wide-field Infrared Survey Explorer (WISE) on the GMBCG catalog, which contains 55424 BCGs at 0.1<~z<~0.55 identified in the Sloan Digital Sky Survey (SDSS). Our sample consists of 389 BCGs that are bright in W4 ("W4BCGs"), most being brighter than 5mJy. While some (<~20%) might host active galactic nuclei, most W4BCGs should owe their strong mid-IR emissions to dust-enshrouded star formation. Their median total IR luminosity (L_IR_) is 5x10^11^L_{sun}_ (SFR~50M_{sun}_/yr), and 27% of the whole sample has L_IR_>10^12^L_{sun}_ (SFR>100M_{sun}_/yr). Using 10 W4BCGs that have Chandra X-ray data, we show that 7 of them are possibly in CC clusters. However, in most cases (five out of seven) the mass deposition rate cannot account for the observed SFR. This casts doubt on the idea that cooling flows are the cause of the star formation in non-quiescent BCGs.
