文章基本信息

标题：A complete sample of LSP blazars fully described in γ-rays
其他标题：Newγ-ray detections and associations withFermi-LAT
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作者：B. Arsioli ; G. Polenta
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：616
DOI：10.1051/0004-6361/201832786
语种：English
出版社：EDP Sciences
摘要：Context.We study theγ-ray and broadband spectral energy distribution (SED) properties of a complete sample of 104 bright, radio-selected low-synchrotron peaked (LSP) blazars, which have well-characterized SEDs from radio to X-rays. Most of the sources have already been detected in theγ-ray band byFermi-LAT, however almost 20% of these blazars have no counterpart in any of theFermicatalogs published so far.Aims.Using theFermiScience Tools, we look forγ-ray emission for those objects not yet reported in anyFermi-LAT catalog, finding new detections and associations. We then study the multifrequency SED for all sources in our sample, fitting their synchrotron (Syn) and inverse Compton (IC) components. A complete sample of LSP blazars with a full description inγ-ray is unique. We use this sample to derive the distribution of the Compton dominance (CD) along with population properties such as Syn and IC peak power, and frequency distributions.Methods.We performed a binned likelihood analysis in the 0.3–500 GeV energy band withFermi-LAT Pass 8 data, integrating over 7.5 yr of observations. We studiedγ-ray light curves and test statistic (TS) maps to validate new detections and associations, thereby building a better picture of the high-energy activity in radio-selected LSP blazars. We fit the IC component for the new detections using all data at our disposal from X-rays to GeVγ-rays, enhancing the amount of information available to study the Syn to IC peak-power correlations.Results.We deliver a unique characterization inγ-rays for a complete sample of LSP blazars. We show that three previously unidentified 3FGL sources can be associated with blazars when using improvedγ-ray positions obtained from TS maps. Six previously unreportedγ-ray sources are detected at TS > 20 level, while another three show TS values between 10–20. We evaluate two cases in which source confusion is likely present. In four cases there is no significantγ-ray signature when integrating over 7.5 yr. Short-lived flares at ~1 month scale, however, have been detected in these sources. Finally, we measure the log(CD) for the sample, which has a Gaussian-like distribution with median log(CD) ≈ 0.1, implying that on average the peak-power for the Syn and IC components in LSP blazars is similar.
关键词：Key wordsengamma rays: galaxiesgalaxies: active