Lorentz factor distribution of blazars from the optical Fundamental Plane of black hole activity

Saikia, Payaswini; Körding, Elmar; Falcke, H.

doi:10.1093/mnras/stw1321

Cited by 18 publications

(21 citation statements)

References 40 publications

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“…3 for γ peak = γ EC peak , and considering ν Syn peak and ν IC peak from Table 1. and in agreement with estimates from radio variability and brightness temperature (confirming early measurements made by Jorstad et al (2005)). Also, Saikia et al (2016) introduced a new independent method based on the optical fundamental plane of black hole activity 5 to estimate the Γ distribution, showing a valid range from 1 to 40, with N (Γ) ∝ Γ −2.1±0.4 , or an even more restrictive range with Γ between 15 and 30 (Nalewajko et al 2014), as deduced from a study of γ-ray flares, with a multifrequency approach and testing EC scenarios. There are two different setups that are important to consider, and that are related to the photon-frequency (ν) associated with the external photon field.…”

Section: Assuming a Dominant Ec Scenariomentioning

confidence: 99%

“…A&A 616, A63 2018Also, Saikia et al (2016) introduced a new independent method based on the optical fundamental plane of black hole activity 5 to estimate the Γ distribution, showing a valid range from 1 to 40, with N (Γ) ∝ Γ −2.1 ± 0.4 , or an even more restrictive range with Γ between 15 and 30 (Nalewajko et al 2014), as deduced from a study of γ-ray flares, with a multifrequency approach and testing EC scenarios.…”

Section: Assuming a Dominant Ec Scenariomentioning

confidence: 99%

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Theγ-ray emitting region in low synchrotron peak blazars

Arsioli

Chang

2018

A&A

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Aims. From the early days in γ-ray astronomy, locating the origin of GeV emission within the core of an active galactic nucleus (AGN) persisted as an open question; the problem is to discern between near- and far-site scenarios with respect to the distance from the super massive central engine. We investigate this question under the light of a complete sample of low synchrotron peak (LSP) blazars which is fully characterized along many decades in the electromagnetic spectrum, from radio up to tens of GeV. We consider the high-energy emission from bright radio blazars and test for synchrotron self-Compton (SSC) and external Compton (EC) scenarios in the framework of localizing the γ-ray emission sites. Given that the inverse Compton (IC) process under the EC regime is driven by the abundance of external seed photons, these photons could be mainly ultraviolet (UV) to X-rays coming from the accretion disk region and the broad-line region (BLR), therefore close to the jet launch base; or infrared (IR) seed photons from the dust torus and molecular cloud spine-sheath, therefore far from jet launch base. We investigate both scenarios, and try to reveal the physics behind the production of γ-ray radiation in AGNs which is crucial in order to locate the production site. Methods. Based on a complete sample of 104 radio-selected LSP blazars, with 37 GHz flux density higher than 1 Jy, we study broadband population properties associated with the nonthermal jet emission process, and test the capability of SSC and EC scenarios to explain the overall spectral energy distribution (SED) features. We use SEDs well characterized from radio to γ rays, considering all currently available data. The enhanced available information from recent works allows us to refine the study of Syn to IC peak correlations, which points to a particular γ-ray emission site. Results. We show that SSC alone is not enough to account for the observed SEDs. Our analysis favors an EC scenario under the Thomson scattering regime, with a dominant IR external photon field. Therefore, the far-site (i.e., far from the jet launch) is probably the most reasonable scenario to account for the population properties of bright LSP blazars in cases modeled with a pure leptonic component. We calculate the photon energy density associated with the external field at the jet comoving frame to be U′ext = 1.69 × 10−2 erg cm−3, finding good agreement to other correlated works.

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Section: Assuming a Dominant Ec Scenariomentioning

confidence: 99%

Section: Assuming a Dominant Ec Scenariomentioning

confidence: 99%

Theγ-ray emitting region in low synchrotron peak blazars

Arsioli

Chang

2018

A&A

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“…A power-law distribution of Lorentz factors for AGNs can be assumed, ( ) G~G -N a , where population synthesis studies show that a value of a between 1.5 and 1.75 provides a good match between a synthetic and observed distribution of apparent velocities (Lister & Marscher 1997;Marscher 2006b). Recent work indicates a value of =  a 2.1 0.4 for blazars (Saikia et al 2016). Many observations indicate that GRBs are produced by ultra-relativistic outflows with  G 100.…”

Section: Introductionmentioning

confidence: 99%

Low-Γ Jets From Compact Stellar Mergers: Candidate Electromagnetic Counterparts to Gravitational Wave Sources

Lamb

Kobayashi

2016

ApJ

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Short gamma-ray bursts (GRBs) are believed to be produced by relativistic jets from mergers of neutron stars (NSs) or NSs and black-holes (BHs). If the Lorentz-factorsΓof jets from compact stellar mergers follow a similar power-law distribution to those observed for other high-energy astrophysical phenomena (e.g., blazars, active galactic nuclei), the population of jets should be dominated by low-Γ outflows. These jets will not produce prompt gamma-rays, but jet energy will be released as X-ray/optical/radio transients when they collide with the ambient medium. Using Monte Carlo simulations, we study the properties of such transients. Approximately 78% of merger jets <300 Mpc result in failed GRBs if the jet Γ follows a power-law distribution of index −1.75. X-ray/ optical transients from failed GRBs will have broad distributions of their characteristics: light-curves peak -t 0.1 10 p days after a merger; flux peaks for X-ray   , for well localized sources on the sky. X-ray/optical transients are followed by radio transients with peak times narrowly clustered aroundt 10 p days, and peak flux of ∼10-100 mJy at 10 GHz and ∼0.1 mJy at 150 MHz. By considering the all-sky rate of short GRBs within the LIGO/Virgo range, the rate of on-axis orphan afterglows from failed GRBs should be 2.6(26) per year for NS-NS (NS-BH) mergers, respectively. Since merger jets from gravitational-wave (GW) trigger events tend to be directed to us, a significant fraction of GW events could be associated with the on-axis orphan afterglow.

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“…Given these solutions, if acceleration were to take place at a mildly relativistic recollimation shock, this would lead to an initial bulk Lorentz factor of the jet of Γ j<|s ≈ 10 3 for 1ES 0229+200, while for 1ES 1101−232, it would result in Γ j<|s ≈ 500. Such large jet Lorentz factors are problematic given that the usually assumed values for less extreme blazars, based on observations with very-long-baseline interferometry (VLBI) and on models of relativistic jets, are of the order of a few to a few tens (Pushkarev et al 2009;Saikia et al 2016).…”

Section: Scenario Ii: Co-acceleration On Mildly Relativistic Shocksmentioning

confidence: 99%

Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars

Zech

Lemoine

2021

A&A

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Aims. The multi-wavelength emission from a newly identified population of ‘extreme-TeV’ blazars, with Compton peak frequencies around 1 TeV, is difficult to interpret with standard one-zone emission models. Large values of the minimum electron Lorentz factor and quite low magnetisation values seem to be required. Methods. We propose a scenario where protons and electrons are co-accelerated on internal or recollimation shocks inside the relativistic jet. In this situation, energy is transferred from the protons to the electrons in the shock transition layer, leading naturally to a high minimum Lorentz factor for the latter. A low magnetisation favours the acceleration of particles in relativistic shocks. Results. The shock co-acceleration scenario provides additional constraints on the set of parameters of a standard one-zone lepto-hadronic emission model, reducing its degeneracy. Values of the magnetic field strength of a few mG and minimum electron Lorentz factors of 103 to 104, required to provide a satisfactory description of the observed spectral energy distributions of extreme blazars, result here from first principles. While acceleration on a single standing shock is sufficient to reproduce the emission of most of the extreme-TeV sources we have examined, re-acceleration on a second shock appears needed for those objects with the hardest γ-ray spectra. Emission from the accelerated proton population, with the same number density as the electrons but in a lower range of Lorentz factors, is strongly suppressed. Satisfactory self-consistent representations were found for the most prominent representatives of this new blazar class.

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Lorentz factor distribution of blazars from the optical Fundamental Plane of black hole activity

Cited by 18 publications

References 40 publications

Theγ-ray emitting region in low synchrotron peak blazars

Theγ-ray emitting region in low synchrotron peak blazars

Low-Γ Jets From Compact Stellar Mergers: Candidate Electromagnetic Counterparts to Gravitational Wave Sources

Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars

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