The gamma-ray blazar quest: new optical spectra, state of art and future perspectives

Massaro, F.; Crespo, Nuria Álvarez; D’Abrusco, R.; Landoni, M.; Masetti, N.; Ricci, F.; Milisavljevic, Dan; Paggi, A.; Chavushyan, V.; Jiménez‐Bailón, E.; Patiño-Álvarez, V.; Strader, Jay; Chomiuk, Laura; Franca, F. La; Smith, H. A.; Tosti, G.

doi:10.1007/s10509-016-2926-6

Cited by 45 publications

(19 citation statements)

References 86 publications

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“…but characterised by the typical properties of blazars (e.g., two humped SED or flat radio spectrum). However, several optical spectroscopic investigations such as, Massaro et al (2016)…”

Section: Lac Catalogue: a Subset Of The 4fglmentioning

confidence: 99%

Radio spectral properties of cores and extended regions in blazars in the MHz regime

d’Antonio

Giroletti

Giovannini

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Low-frequency radio surveys allow in-depth studies and new analyses of classes of sources previously known and characterised only in other bands. In recent years, low radio frequency observations of blazars have been available thanks to new surveys, such as the GaLactic and Extragalactic All-sky MWA Survey (GLEAM). We search for gamma-ray blazars in a low frequency (ν < 240 MHz) survey, to characterise the spectral properties of the spatial components. We cross-correlate GLEAM with the fourth catalogue of active galactic nuclei (4LAC) detected by the Fermi satellite. This improves over previous works using a low frequency catalogue that is wider, deeper, with a better spectral coverage and the latest and most sensitive gamma-ray source list.In comparison to the previous study based on the commissioning survey, the detection rate increased from 35% to 70%. We include Australia Telescope 20 GHz (AT20G) Survey data to extract high-frequency high-angular resolution information on the radio cores of blazars. We find low radio frequency counterparts for 1274 out of 1827 blazars in the 72-231 MHz range. Blazars have flat spectrum at ∼ 100 MHz regime, with a mean spectral index α = −0.44 ± 0.01 (assuming S ν ∝ ν α ). Low synchrotron peaked objects have a flatter spectrum than high synchrotron peaked objects. Low frequency radio and gamma-ray emission show a significant but scattered correlation. The ratio between lobe and core radio emission in gamma-ray blazars is smaller than previously estimated.

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“…but characterised by the typical properties of blazars (e.g., two humped SED or flat radio spectrum). However, several optical spectroscopic investigations such as, Massaro et al (2016)…”

Section: Lac Catalogue: a Subset Of The 4fglmentioning

confidence: 99%

Radio spectral properties of cores and extended regions in blazars in the MHz regime

d’Antonio

Giroletti

Giovannini

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Only 1 source is classified as an FSRQ in the 4FGL catalog (The Fermi-LAT collaboration 2019). There are 24, 2, 11, 10, 12, and 15 sources that have been identified as the BL Lac-type by Massaro et al (2016) using spectroscopic observations, respectively. After cross-matching these results (3FHL, M16, D19, M19, M18, P17, A16, and 4FGL), 74 sources are obtained (also see Table 4 and Table 3).…”

Section: Comparison With Literature Resultsmentioning

confidence: 99%

An Empirical “High-confidence” Candidate Zone for Fermi BL Lacertae Objects

Kang

Zhu

Feng

et al. 2020

ApJ

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In the third catalog of active galactic nuclei detected by the F ermi Large Area Telescope Clean (3LAC) sample, there are 402 blazars candidates of uncertain type (BCU). The proposed analysis will help to evaluate the potential optical classification flat spectrum radio quasars (FSRQs) versus BL Lacertae (BL Lacs) objects of BCUs, which can help to understand which is the most elusive class of blazar hidden in the Fermi sample. By studying the 3LAC sample, we found some critical values of γ-ray photon spectral index (Γ ph ), variability index (VI) and radio flux (F R ) of the sources separate known FSRQs and BL Lac objects. We further utilize those values to defined an empirical "highconfidence" candidate zone that can be used to classify the BCUs. Within such a zone (Γ ph < 2.187, logF R < 2.258 and logVI < 1.702), we found that 120 BCUs can be classified BL Lac candidates with a higher degree of confidence (with a misjudged rate < 1%). Our results suggest that an empirical "high confidence" diagnosis is possible to distinguish the BL Lacs from the Fermi observations based on only on the direct observational data of Γ ph , VI and F R .

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“…Based on the strong non-thermal spectra, produced by sources with powerful relativistic jets, [26,27,28] identified a sequence of infra-red colors from the Wide-field Infrared Survey Explorer (WISE) that specifically characterizes blazars, especially in the case of strong γ-ray emission. The execution of spectroscopic campaigns, such as the SDSS [29,30], or the targeted optical spectroscopic investigations led by [31,32,33,34] on the basis of the proposed counterparts to high energy sources, mostly confirmed the blazar nature of several candidates, providing, in some cases, additional information of the source redshifts and intrinsic powers. Combining the first 4 years of monitoring with the Fermi/LAT telescope with spectroscopic follow-ups, the resulting distribution of known AGNs, emitting γ-ray radiation, turned out to appear as it is illustrated in Fig.…”

Section: Multiple-wavelength Investigations and Optical Follow-upsmentioning

confidence: 99%

Relativistic plasmas in AGN jets

et al. 2017

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Abstract. Relativistic jets of plasma are a key ingredient of many types of Active Galactic Nuclei (AGN). Today we know that AGNs are powered by the accretion of inter stellar material into the gravitational field of a Super Massive Black Hole and that this process can release as much power as a whole galaxy, like the Milky Way, from a region that is comparable to the Solar System in size. Depending on the properties of the central energy source, a large fraction of this power can be involved in the acceleration of magnetized plasmas at relativistic speeds, to form large scale jets. The presence of jets affects the spectrum of AGNs through the emission of synchrotron radiation and Inverse Compton scattering of low energy photons, thus leading to a prominent non-thermal spectrum, some times extending from radio frequencies all the way up to γ-ray energies. Here we review some characteristic processes of radiation emission in AGN jets, which lead to the emission of photons in the radio, optical, X-ray and γ-ray bands, and we present the results of a spectroscopic campaign of optical counterparts. We discuss our observations and their connection with γ-ray properties in a scenario that traces the role of relativistic jets in different classes of AGNs, detected both in the local as well as in the remote Universe.PACS. 52.25.Os Emission, absorption and scattering of electromagnetic radiation -52.27.Ny Relativistic plasmas -98.54.Cm Active and peculiar galaxies and related systems (including BL Lacertae objects, blazars, Seyfert galaxies, Markarian galaxies, and active galactic nuclei) -98.70.Rz γ-ray sources; γ-ray bursts

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The gamma-ray blazar quest: new optical spectra, state of art and future perspectives

Cited by 45 publications

References 86 publications

Radio spectral properties of cores and extended regions in blazars in the MHz regime

Radio spectral properties of cores and extended regions in blazars in the MHz regime

An Empirical “High-confidence” Candidate Zone for Fermi BL Lacertae Objects

Relativistic plasmas in AGN jets

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