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CBATPICAGN: Help

CBATPICAGN - CGRO BATSE-observed Piccinotti sample of active galactic nuclei


Overview

Compton Gamma-Ray Observatory (CGRO) BATSE Earth-occultation data have been used by Malizia et al. (1999, ApJ, 519, 637) to search for emission in the 20-100 keV band from all sources in the Piccinotti sample (Piccinotti et al. 1982, ApJ, 253, 485: the HEASARC A2PIC database), which represents the only complete 20-10 keV survey to date of the extragalactic sky down to a limiting flux of 3.1 x 10-11 ergs cm-2 s-1. Nearly 4 years of observations have been analyzed to reach a 5 sigma confidence level of about 7.8 x 10-11 ergs cm-2 s-1 in the band considered. Of the 36 sources in the sample, 14 have been detected above the 5 sigma confidence level, while marginal detection (3<= sigma <= 5) can be claimed for 13 sources; for nine objects, 2 sigma upper limits are reported. A comparison of BATSE results with data at higher energies is used to estimate the robustness of the data analysis: while the detection level of each source is reliable, the flux measurement may be overestimated in some sources by as much as 35%, probably because of incomplete data cleaning. Comparison of BATSE fluxes with X-ray fluxes obtained in the 2-10 keV range and averaged over years indicates that a canonical power law of photon index 1.7 gives a good description of the broadband spectra of bright active galactic nuclei (AGNs) and that spectral breaks preferentially occur above 100 keV.

Catalog Bibcode

1999ApJ...519..637M

References

BATSE Observations of the Piccinotti Sample of Active Galactic Nuclei, Malizia A., Bassani L., Zhang S.N., Dean A.J., Paciesas W.S., Palumbo G.G.C., <Astrophysical Journal, 519, 637-641, 1999 July 10>

Provenance

This HEASARC database was created in October 1999 based primarily on Table 1 of Malizia et al. (1999), together with the positions and HEAO-1 designations taken from the original Piccinotti Catalog (Piccinotti et al. 1982, ApJ, 253, 485: the HEASARC A2PIC database).

Parameters

Name
A frequently used designation for the object.

Type
Optical classification of the object, e.g., Seyfert 1, BL Lac. etc; notice that SB stands for starburst galaxy.

Heao1_Name
The HEAO-1 designation for the object (not in Malizia et al. 1999, in general, but taken by the HEASARC from the original Piccinotti Catalog (Piccinotti et al. 1982, ApJ, 253, 485: the HEASARC A2PIC database).

RA
The right ascension of the object (not in Malizia et al. 1999, but taken by the HEASARC from the original Piccinotti Catalog (Piccinotti et al. 1982, ApJ, 253, 485: the HEASARC A2PIC database).

Dec
The declination of the object (not in Malizia et al. 1999, but taken by the HEASARC from the original Piccinotti Catalog (Piccinotti et al. 1982, ApJ, 253, 485: the HEASARC A2PIC database).

LII
The galactic longitude of the object (not in Malizia et al. 1999, but taken by the HEASARC from the original Piccinotti Catalog (Piccinotti et al. 1982, ApJ, 253, 485: the HEASARC A2PIC database).

BII
The galactic latitude of the object (not in Malizia et al. 1999, but taken by the HEASARC from the original Piccinotti Catalog (Piccinotti et al. 1982, ApJ, 253, 485: the HEASARC A2PIC database).

Flux_Mean
The mean 2-10 keV flux in units of erg cm-2 s-1, as estimated by the authors based on data values in the literature.

Vr
The observed flux variability in the 2-10 keV band, as estimated by the authors based on data values in the literature. .

Flux_Batse
The weighted mean 20-100 keV flux as measured by BATSE, calculated over nearly 4 years of observations. Fluxes in the 20-100 keV energy band were obtained by folding a single power law of photon index 1.75 for Seyfert galaxies, 3C 273, and M82, and 2.25 for BL Lac objects, with the BATSE instrumental response function. Although these mean estimates depend on the choice of photon index, the differences in fluxes are of the order of 10-20% around the values quoted here for changes in the power law of +/-0.25. If this flux_batse parameter is left blank, this indicates that the source was not detected by BATSE: the 2 sigma upper limit to the BATSE flux is given in the parameter flux_batse_error in such cases.

Flux_Batse_Error
The error in the weighted mean 20-100 keV flux as measured by BATSE for BATSE detections, or the 2 sigma upper limit to the BATSE flux for nondetections.

N_Batse
The statistical significance of the BATSE detection, i.e, number of sigma.

Flux_Ratio
The weighted mean value of the BATSE/OSSE flux ratios in the 20-100 keV energy band for cases when there are contemporaneous BATSE and OSSE data. Notice that the weighted mean value of this parameter for the full sample is 1.36 +/- 0.03 confirming previous reports of a BATSE/OSSE normalization discrepancy, and further indicating that, in the particular case of extragalactic sources, the BATSE flux can be systematically higher than the OSSE flux by as much as 35%.

Flux_Ratio_Error
The error in the weighted mean value of the BATSE/OSSE flux ratios.

Osse_Coverage
For contemporaneous BATSE and OSSE observations: the first number indicates the number of viewing periods examined by the authors, while the second number indicates the total number of observation days analyzed over those periods.

Class
The browse classification, created by the HEASARC based on the optical classification given in the type parameter.


Contact Person

Questions regarding the CBATPICAGN database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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