scholarly journals Excluding possible sites of high-energy emission in 3C 84

2020 ◽  
Vol 500 (4) ◽  
pp. 4671-4677
Author(s):  
Lena Linhoff ◽  
Alexander Sandrock ◽  
Matthias Kadler ◽  
Dominik Elsässer ◽  
Wolfgang Rhode
Keyword(s):  
Black Hole ◽  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
Emission Region ◽  
Broad Line ◽  
Central Black Hole ◽  
Broad Line Region ◽  
Ring Geometry ◽  
Line Region

ABSTRACT The FR-I galaxy 3C 84, that is identified with the misaligned blazar NGC 1275, is well known as one of the very few radio galaxies emitting gamma-rays in the TeV range. Yet, the gamma-ray emission region cannot be pinpointed and the responsible mechanisms are still unclear. We calculate the optical absorption depth of high-energy photons in the broad-line region of 3C 84 depending on their energy and distance to the central black hole. Based on these calculations, a lower limit on the distance of the emission region from the central black hole can be derived. These lower limits are estimated for two broad-line region geometries (shell and ring) and two states of the source, the low state in 2016 October–December and a flare state in 2017 January. For the shell geometry, we can place the emission region outside the Ly α radius. For the ring geometry and the low flux activity, the minimal distance between the black hole, and the gamma-ray emission region is close to the Ly α radius. In the case of the flaring state (ring geometry), the results are not conclusive. Our results exclude the region near the central black hole as the origin of the gamma-rays detected by Fermi–LAT and Major Atmospheric Gamma-Ray Imaging Cherenkov. With these findings, we can constrain the theoretical models of acceleration mechanisms and compare the possible emission region to the source’s morphology resolved by radio images from the Very Long Baseline Array.

scholarly journals Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE γ-ray observations with H.E.S.S.

2019 ◽  
Vol 627 ◽  
pp. A159 ◽  
Author(s):  
◽  
H. Abdalla ◽  
R. Adam ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Black Hole ◽  
Lorentz Invariance ◽  
High Energy ◽  
Emission Region ◽  
Physical Parameters ◽  
Broad Line ◽  
Data Set ◽  
Broad Line Region ◽  
Link Type ◽  
Line Region

The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100 MeV <  E <  100 GeV) γ-ray band, which is continuously monitored with Fermi-LAT. During two periods of high activity in April 2014 and June 2015 target-of-opportunity observations were undertaken with the High Energy Stereoscopic System (H.E.S.S.) in the very-high-energy (VHE, E >  100 GeV) γ-ray domain. While the observation in 2014 provides an upper limit, the observation in 2015 results in a signal with 8.7σ significance above an energy threshold of 66 GeV. No VHE variability was detected during the 2015 observations. The VHE photon spectrum is soft and described by a power-law index of 4.2 ± 0.3. The H.E.S.S. data along with a detailed and contemporaneous multiwavelength data set provide constraints on the physical parameters of the emission region. The minimum distance of the emission region from the central black hole was estimated using two plausible geometries of the broad-line region and three potential intrinsic spectra. The emission region is confidently placed at r ≳ 1.7 × 1017 cm from the black hole, that is beyond the assumed distance of the broad-line region. Time-dependent leptonic and lepto-hadronic one-zone models were used to describe the evolution of the 2015 flare. Neither model can fully reproduce the observations, despite testing various parameter sets. Furthermore, the H.E.S.S. data were used to derive constraints on Lorentz invariance violation given the large redshift of 3C 279.

scholarly journals Millimetre Continuum Variations, VLBI Structure and Gamma-rays: Investigating Shocked Jet Physics

2002 ◽  
Vol 19 (1) ◽  
pp. 117-121 ◽  
Author(s):  
E. Valtaoja ◽  
T. Savolainen ◽  
K. Wiik ◽  
A. Lähteenmäki
Keyword(s):  
Flux Density ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Large Fraction ◽  
Jet Physics ◽  
Broad Line ◽  
Structural Variations ◽  
Broad Line Region ◽  
Line Region ◽  
Inverse Compton

AbstractWe compare the total flux density variations and the VLBI structural variations in a sample of 27 gamma-ray blazars. We find that all the radio variations are due to shocks; the flux of the underlying jet remains constant. A large fraction of the shocks grow and fade within the innermost 0.1 mas, appearing only as ‘core flares’. Comparisons with the EGRET data show that gamma-ray flares must come from the shocks, not from the jet. At the time of an EGRET flare, the shock is typically already over a parsec downstream from the radio core, beyond the accretion disk and/or the broad line region (BLR) photon fields. Thus, present models for gamma-ray production are inadequate, since they typically model the gamma-ray inverse Compton flux as coming from the jet, with significant disk or BLR external Compton components.

scholarly journals Prospects for γ-ray observations of narrow-line Seyfert 1 galaxies with the Cherenkov Telescope Array – II. γ–γ absorption in the broad-line region radiation fields

2020 ◽  
Vol 494 (1) ◽  
pp. 411-424 ◽  
Author(s):  
P Romano ◽  
M Böttcher ◽  
L Foschini ◽  
C Boisson ◽  
S Vercellone ◽  
...  
Keyword(s):  
High Energy ◽  
Emission Region ◽  
Broad Line ◽  
Narrow Line ◽  
Telescope Array ◽  
Cherenkov Telescope ◽  
Broad Line Region ◽  
Radiation Fields ◽  
Line Region ◽  
Γ Ray

ABSTRACT Gamma-ray emitting narrow-line Seyfert 1 (γ-NLS1) galaxies possibly harbour relatively low-mass black holes (106–108 M⊙) accreting close to the Eddington limit, and share many characteristics with their sibling sources, flat-spectrum radio quasars. Although they have been detected in the MeV–GeV band with Fermi–LAT, they have never been seen in the very high energy band with current imaging atmospheric Cherenkov telescopes (IACTs). Thus, they are key targets for the next-generation IACT, the Cherenkov Telescope Array (CTA). In a previous work we selected, by means of extensive simulations, the best candidates for a prospective CTA detection (SBS 0846+513, PMN J0948+0022, and PKS 1502+036) taking into account the effects of both the intrinsic absorption (approximated with a cut-off at 30 GeV), and the extragalactic background light on the propagation of γ-rays. In this work, we simulate the spectra of these three sources by adopting more realistic broad-line region (BLR) absorption models. In particular, we consider the detailed treatment of γ–γ absorption in the radiation fields of the BLR as a function of the location of the γ-ray emission region with parameters inferred from observational constraints. We find that, due to the energy range extent and its sensitivity, CTA is particularly well suited to locate the γ-ray emitting region in γ-NLS1. In particular CTA will be able not only to distinguish whether the γ-ray emitting region is located inside or outside the BLR, but also where inside the BLR it may be.

Estimating the Number of Broad-Line Region Clouds

1999 ◽  
Vol 194 ◽  
pp. 317-318
Author(s):  
M. Dietrich
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Filling Factor ◽  
Galactic Nuclei ◽  
Broad Line ◽  
Central Black Hole ◽  
Continuum Source ◽  
Broad Line Region ◽  
Line Region ◽  
Emission Line Spectrum

The observed emission-line spectrum of active galactic nuclei is consistent with cold dense gas photoionized by a central continuum source (cf. Ferland & Persson 1989). The estimate of the filling factor of the line-emitting region yields f˜10−6 only (cf. Osterbrock 1993) and motivated the picture of numerous clouds moving around a central black hole. Early estimates of the number of BLR clouds indicated a lower limit of 104 to 105 individual clouds (Capriotti et al. 1981; Atwood et al. 1982). Recently, Arav et al. (1998) estimated the number to be at least of the order of 107 discrete emitters. But the number and the nature of these clouds are still unknown.

scholarly journals The gravitational redshift in the broad line region of the active galactic nucleus Mrk 110

2006 ◽  
Vol 2 (S238) ◽  
pp. 369-370
Author(s):  
N. Gavrilović ◽  
L.Č Popović ◽  
W. Kollatschny
Keyword(s):  
Black Hole ◽  
Gravitational Field ◽  
Active Galactic Nucleus ◽  
Broad Line ◽  
Line Profiles ◽  
Central Black Hole ◽  
Broad Line Region ◽  
Line Region ◽  
Field Influence

AbstractWe used the long term spectroscopic observations of Mrk 110 (Hα and Hβ lines) to investigate the gravitational field influence on spectral line profiles. We found that effects of gravitational field can be measured and that the lines are more intense where the emission is originating close to the central black hole of Mrk 110.

Hadronuclear interpretation of the possible neutrino emission from PKS B1424-418, GB6 J1040+0617 and PKS 1502+106

2022 ◽  
Vol 21 (12) ◽  
pp. 305
Author(s):  
Ze-Rui Wang ◽  
Rui Xue
Keyword(s):  
Detection Rate ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Broad Line ◽  
Central Black Hole ◽  
Proton Proton ◽  
Broad Line Region ◽  
Neutrino Detection ◽  
Line Region ◽  
Jet Power

Abstract In addition to neutrino event IceCube-170922A which is observed to be associated with a γ-ray flare from blazar TXS 0506+056, there are also several neutrino events that may be associated with blazars. Among them, PKS B1424-418, GB6 J1040+0617 and PKS 1502+106 are low synchrotron peaked sources, which are usually believed to have the broad line region in the vicinity of the central black hole. They are considered as counterparts of IceCube event 35, IceCube-141209A and IceCube-190730A, respectively. By considering the proton-proton (pp) interactions between the dense gas clouds in the broad line region and the relativistic protons in the jet, we show that the pp model that is applied in this work can not only reproduce the multi-waveband spectral energy distribution but also suggest a considerable annual neutrino detection rate. We also discuss the emission from the photopion production and Bethe-Heitler pair production with a sub-Eddington jet power that is suggested in our model and find that it has little effect on the spectrum of total emission for all of three sources.

A Photoionization Method for Estimating Black Hole Masses in Quasars

2018 ◽  
Vol 14 (S342) ◽  
pp. 270-271
Author(s):  
C. Alenka Negrete ◽  
Deborah Dultzin ◽  
Paola Marziani ◽  
Jack W. Sulentic ◽  
M. L. Martínez-Aldama
Keyword(s):  
Black Hole ◽  
High Redshift ◽  
Broad Line ◽  
Reverberation Mapping ◽  
Physical Conditions ◽  
Broad Line Region ◽  
Supermassive Black Hole ◽  
Line Region ◽  
Black Hole Masses

AbstractWe present a method that uses photoionization codes (CLOUDY) to estimate the supermassive black hole masses (MBH) for quasars at low and high redshift. This method is based on the determination of the physical conditions of the broad line region (BLR) using observational diagnostic diagrams from line ratios in the UV. We also considered that the density and metallicity of the BLR in quasars at high z could be different from those at the nearby Universe. The computed black hole masses obtained using this method are in agreement with those derived from the method of reverberation mapping.

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