Long-term optical spectroscopic variations in blazar 3C 454.3

Aims. Characterisation of the long-term variations in the broad line region in a luminous blazar, where Comptonisation of broad-line emission within a relativistic jet is the standard scenario for production of γ-ray emission that dominates the spectral energy distribution. Methods. We analysed ten years of optical spectroscopic data from the Steward Observatory for the blazar 3C 454.3, as well as γ-ray data from the Fermi Large Area Telescope (LAT). The optical spectra are dominated by a highly variable non-thermal synchrotron continuum with a prominent Mg II broad emission line. The line flux was obtained by spectral decomposition including significant contribution from the Fe II pseudo-continuum. Three methods were used to characterise variations in the line flux: (1) stacking of the continuum-subtracted spectra, (2) subtracting the running mean light curves calculated for different timescales, and (3) evaluating potential time delays via the discrete correlation function (DCF). Results. Despite very large variations in the γ-ray and optical continua, the line flux changes only moderately (<0.1 dex). The data suggest that the line flux responds to a dramatic change in the blazar activity from a very high state in 2010 to a deep low state in 2012. Two interpretations are possible: either the line flux is anti-correlated with the continuum or the increase in the line luminosity is delayed by ∼600 days. If this time delay results from the reverberation of poorly constrained accretion disc emission in both the broad-line region (BLR) and the synchrotron emitting blazar zone within a relativistic jet, we would obtain natural estimates for the BLR radius RBLR, MgII ≳ 0.28 pc and for the supermassive black hole mass MSMBH ∼ 8.5 × 108 M⊙. We did not identify additional examples of short-term “flares” of the line flux, in addition to the previously reported case observed in 2010.

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

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/21/12/305 ◽

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.

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Radiation from the impact of broad-line region clouds onto AGN accretion disks

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037639 ◽

2020 ◽

Vol 636 ◽

pp. A92

Author(s):

A. L. Müller ◽

G. E. Romero

Keyword(s):

Accretion Disk ◽

Spectral Energy Distribution ◽

Strong Shock ◽

Shock Acceleration ◽

Spectral Energy ◽

Broad Line ◽

Broad Line Region ◽

Line Region ◽

The Impact ◽

Relativistic Particles

Context. Active galactic nuclei are supermassive black holes surrounded by an accretion disk, two populations of clouds, bipolar jets, and a dusty torus. The clouds move in Keplerian orbits at high velocities. In particular, the broad-line region (BLR) clouds have velocities ranging from 1000 to 10 000 km s−1. Given the extreme proximity of these clouds to the supermassive black hole, frequent collisions with the accretion disk should occur. Aims. The impact of BLR clouds onto the accretion disk can produce strong shock waves where particles might be accelerated. The goal of this work is to investigate the production of relativistic particles, and the associated non-thermal radiation in these events. In particular, we apply the model we develop to the Seyfert galaxy NGC 1068. Methods. We analyze the efficiency of diffusive shock acceleration in the shock of colliding clouds of the BLR with the accretion disk. We calculate the spectral energy distribution of photons generated by the relativistic particles and estimate the number of simultaneous impacts needed to explain the gamma radiation observed by Fermi in Seyfert galaxies. Results. We find that is possible to understand the measured gamma emission in terms of the interaction of clouds with the disk if the hard X-ray emission of the source is at least obscured between 20% and 40%. The total number of clouds contained in the BLR region might be between 3 × 108 and 6 × 108, which are values in good agreement with the observational evidence. The maximum energy achieved by the protons (∼PeV) in this context allows the production of neutrinos in the observing range of IceCube.

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Feii strength in NLS1s – dependence on the viewing angle and FWHM(Hβ)

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003269 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 332-334

Author(s):

Swayamtrupta Panda ◽

Paola Marziani ◽

Bożena Czerny

Keyword(s):

Main Sequence ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Broad Line ◽

Viewing Angle ◽

Black Hole Mass ◽

Broad Line Region ◽

Line Region ◽

Disk Plane ◽

Cloud Density

AbstractWe address the effect of orientation of the accretion disk plane and the geometry of the broad line region (BLR) in the context of understanding the distribution of quasars along their Main Sequence. We utilize the photoionization code CLOUDY to model the BLR, incorporating the ‘un-constant’ virial factor. We show the preliminary results of the analysis to highlight the co-dependence of the Eigenvector 1 parameter, RFeII on the broad HβFWHM (i.e. the line dispersion) and the inclination angle (θ), assuming fixed values for the Eddington ratio (Lbol/ LEdd), black hole mass (MBH), spectral energy distribution (SED) shape, cloud density (nH) and composition.†

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Modeling the spectral energy distribution of 3C 454.3 in a “flat” broad-line region scenario

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psu067 ◽

2014 ◽

Vol 66 (5) ◽

Cited By ~ 3

Author(s):

Maichang Lei ◽

Jiancheng Wang

Keyword(s):

Energy Distribution ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Broad Line ◽

Broad Line Region ◽

Line Region

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The Infrared, Optical and Ultraviolet Properties of Active Nuclei

Symposium - International Astronomical Union ◽

10.1017/s0074180900077743 ◽

1984 ◽

Vol 110 ◽

pp. 73-83

Author(s):

Marie-Helene Ulrich

Keyword(s):

Energy Distribution ◽

Temporal Variations ◽

Optical Polarization ◽

Broad Line ◽

Continuum Spectrum ◽

Broad Line Region ◽

Line Region ◽

The Continuum

We review the important properties of active nuclei, in particular (i) the optical polarization and its relation to the jets found by VLBI (ii) the energy distribution and the temporal variations of the continuum spectrum and (iii) the distribution of the matter in the broad line region.

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Investigations of Broad Line Region Structure and Kinematics Using Variability

Symposium - International Astronomical Union ◽

10.1017/s0074180900140458 ◽

1989 ◽

Vol 134 ◽

pp. 93-95

Author(s):

C. Martin Gaskell ◽

Anuradha P. Koratkar ◽

Linda S. Sparke

Keyword(s):

Time Series ◽

Cross Correlation ◽

Sampling Interval ◽

Broad Line ◽

Line Flux ◽

Line Region ◽

Cross Correlations ◽

The Mean ◽

The Cross ◽

The Continuum

Gaskell and Sparke (1986) showed that one can determine the sizes of BLRs more accurately that the mean sampling interval by cross-correlating the continuum flux time series with a line flux time series. The position of the peak in the cross-correlation function (CCF) and its shape give an indication of the BLR size. The technique is explained in detail in Gaskell and Peterson (1987). The widely propagated misunderstanding is that the method involves simply interpolating both time series and cross-correlating them (in which case the CCF is dominated by the cross-correlations of “made-up” data). Actually the method involves cross correlating the observed points in one time series (continuum, say) with the linear interpolations of the other series (line flux). The line flux time series must always be smoother than the continuum time series it is derived from. We have usually employed the method with the interpolation done both ways round and averaged them (to reduce errors due to the interpolation) and we can intercompare the two results (to investigate errors).

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Peculiar emission line spectra of core extremely red BOSS quasars at z∼2–3: orientation and/or evolution?

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937086 ◽

2020 ◽

Vol 634 ◽

pp. A116 ◽

Cited By ~ 2

Author(s):

M. Villar Martín ◽

M. Perna ◽

A. Humphrey ◽

N. Castro Rodríguez ◽

L. Binette ◽

...

Keyword(s):

Emission Line ◽

Near Infrared ◽

Outer Part ◽

Line Emission ◽

Optical Emission ◽

Broad Line ◽

Broad Line Region ◽

Line Region ◽

Evolutionary Phase

Context. Core extremely red quasars (core ERQ) have been proposed to represent an intermediate evolutionary phase in which a heavily obscured quasar blows out the circumnuclear interstellar medium with very energetic outflows before it becomes an optical quasar. Aims. We investigate whether the properties of core ERQ fit the AGN orientation-based unification scenario. Methods. We revised the general UV and optical emission line properties of core ERQ in the context of the orientation-based scenario. We used diagnostic diagrams based on UV emission line ratios and UV-to-optical line kinematic information to compare the physical and kinematic gas properties of core ERQ with those of other luminous narrow- and broad-line AGN. In particular, we provide a revised comparison of the [OIII] kinematics in 21 core ERQ (20 from Perrotta et al. 2019, MNRAS, 488, 4126 and SDSS J171420.38+414815.7, based on GTC EMIR near-infrared spectroscopy) with other samples of quasars with matching luminosity with the aim of evaluating whether core ERQ host the most extreme [OIII] outflows. Results. The UV line ratios suggest that the physical properties (e.g., density and metallicity) of the ionised gas in core ERQ are similar to those observed in the broad-line region of blue nitrogen-loud quasars. The [OIII] outflow velocities of core ERQ are on average consistent with those of very luminous blue type 1 quasars, although extreme outflows are much more frequent in core ERQ. These similarities can be explained in the context of the AGN unification model under the assumption that core ERQ are viewed with an intermediate orientation between type 2 (edge-on) and type 1 (face-on) quasars. Conclusions. We propose that core ERQ are very luminous but otherwise normal quasars viewed at an intermediate orientation. This orientation allows a direct view of the outer part of the large broad-line region from which core ERQ UV line emission originates; the extreme [OIII] outflow velocities are instead a consequence of the very high luminosity of core ERQ.

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Broad Line Variations in NGC 5548

Symposium - International Astronomical Union ◽

10.1017/s0074180900140549 ◽

1989 ◽

Vol 134 ◽

pp. 114-115

Author(s):

Edward I. Rosenblatt ◽

Matthew A. Malkan

Keyword(s):

Monitoring Program ◽

Seyfert Galaxies ◽

Active Galaxies ◽

Broad Line ◽

Line Flux ◽

Continuum Source ◽

Line Region ◽

Profile Changes ◽

Ngc 5548 ◽

The Continuum

Since broad line variations can, in principle, constrain the structure and kinematics of the broad line region in active galaxies we have conducted a monitoring program of 20 Seyfert galaxies over a 5 year period in order to study broad line flux and profile changes. Included in our sample is the Seyfert 1.5 galaxy NGC 5548. Fifteen observations were taken from 1979 to 1984 mainly with the 60″ Palomar telescope and a SIT vidicon spectrograph. Measurements show (Fig. 1) that both the Hβ and Hγ line flux varied by 200% and the continuum varied by 300%. Furthermore, these changes were positively correlated as one would expect from photoionization by a central continuum source.

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