9 research outputs found
Radiation and Polarization Signatures of 3D Multi-zone Time-dependent Hadronic Blazar Model
We present a newly developed time-dependent three-dimensional multi-zone
hadronic blazar emission model. By coupling a Fokker-Planck based
lepto-hadronic particle evolution code 3DHad with a polarization-dependent
radiation transfer code, 3DPol, we are able to study the time-dependent
radiation and polarization signatures of a hadronic blazar model for the first
time. Our current code is limited to parameter regimes in which the hadronic
-ray output is dominated by proton synchrotron emission, neglecting
pion production. Our results demonstrate that the time-dependent flux and
polarization signatures are generally dominated by the relation between the
synchrotron cooling and the light crossing time scale, which is largely
independent of the exact model parameters. We find that unlike the low-energy
polarization signatures, which can vary rapidly in time, the high-energy
polarization signatures appear stable. As a result, future high-energy
polarimeters may be able to distinguish such signatures from the lower and more
rapidly variable polarization signatures expected in leptonic models.Comment: Accepted for Publication in The Astrophysical Journa
Violent Hard X-ray Variability of Mrk 421 Observed by NuSTAR in 2013 April
The well studied blazar Markarian 421 (Mrk 421, =0.031) was the subject of
an intensive multi-wavelength campaign when it flared in 2013 April. The
recorded X-ray and very high energy (VHE, E100 GeV) -ray fluxes are
the highest ever measured from this object. At the peak of the activity, it was
monitored by the hard X-ray focusing telescope {\it Nuclear Spectroscopic
Telescope Array} ({\it NuSTAR}) and {\it Swift} X-Ray Telescope (XRT). In this
work, we present a detailed variability analysis of {\it NuSTAR} and {\it
Swift}-XRT observations of Mrk 421 during this flaring episode. We obtained the
shortest flux doubling time of 14.015.03 minutes, which is the shortest
hard X-ray (379 keV) variability ever recorded from Mrk 421 and is on the
order of the light crossing time of the black hole's event horizon. A pattern
of extremely fast variability events superposed on slowly varying flares is
found in most of the {\it NuSTAR} observations. We suggest that these peculiar
variability patterns may be explained by magnetic energy dissipation and
reconnection in a fast moving compact emission region within the jet. Based on
the fast variability, we derive a lower limit on the magnetic field strength of
~G, where is the
Doppler factor in units of 10, and is the characteristic X-ray
synchrotron frequency in units of ~Hz.Comment: 23 pages, 5 figures, 2 tables, to appear in the Astrophysical Journa
A hard gamma-ray flare from 3C 279 in 2013 December
The blazar 3C 279 exhibited twin γ-ray flares of similar intensity in 2013 December and 2014 April. In this work, we present a detailed multi-wavelength analysis of the 2013 December flaring event. Multi-frequency observations reveal the uncorrelated variability patterns with X-ray and optical–UV fluxes peaking after the γ-ray maximum. The broadband spectral energy distribution (SED) at the peak of the γ-ray activity shows a rising γ-ray spectrum but a declining optical–UV flux. This observation along with the detection of uncorrelated variability behavior rules out the one-zone leptonic emission scenario. We, therefore, adopt two independent methodologies to explain the SED: a time-dependent lepto-hadronic modeling and a two-zone leptonic radiative modeling approach. In the lepto-hadronic modeling, a distribution of electrons and protons subjected to a randomly orientated magnetic field produces synchrotron radiation. Electron synchrotron is used to explain the IR to UV emission while proton synchrotron emission is used to explain the high-energy γ-ray emission. A combination of both electron synchrotron self-Compton emission and proton synchrotron emission is used to explain the X-ray spectral break seen during the later stage of the flare. In the two-zone modeling, we assume a large emission region emitting primarily in IR to X-rays and γ-rays to come primarily from a fast-moving compact emission region. We conclude by noting that within a span of four months, 3C 279 has shown the dominance of a variety of radiative processes over each other and this reflects the complexity involved in understanding the physical properties of blazar jets in general
The Violent Hard X-Ray Variability of Mrk 421 Observed by NuSTAR in 2013 April
The well-studied blazar Markarian 421 (Mrk 421, z = 0.031) was the subject of an intensive multi-wavelength campaign when it flared in 2013 April. The recorded X-ray and very high-energy (E > 100 GeV) γ-ray fluxes are the highest ever measured from this object. At the peak of the activity, it was monitored by the hard X-ray focusing telescope Nuclear Spectroscopic Telescope Array (NuSTAR) and the Swift X-Ray Telescope (XRT). In this work, we present a detailed variability analysis of NuSTAR and Swift-XRT observations of Mrk 421 during this flaring episode. We obtained the shortest flux doubling time of 14.01 ± 5.03 minutes, which is the shortest hard X-ray (3-79 keV) variability ever recorded from Mrk 421, and is on the order of the light-crossing time of the black hole's event horizon. A pattern of extremely fast variability events superposed on slowly varying flares is found in most of the NuSTAR observations. We suggest that these peculiar variability patterns may be explained by magnetic energy dissipation and reconnection in a fast-moving compact emission region within the jet. Based on the fast variability, we derive a lower limit on the magnetic field strength of B ≥ 0.73{δ }_1^(-2/3) {ν }_(19)^(1/3) G, where δ_1 is the Doppler factor in units of 10, and ν_(19) is the characteristic X-ray synchrotron frequency in units of 10^(19) Hz
RADIATION AND POLARIZATION SIGNATURES OF THE 3D MULTIZONE TIME-DEPENDENT HADRONIC BLAZAR MODEL
The dynamics in the spot, futures, and call options with basis asymmetries: an intraday analysis in a generalized multivariate GARCH-M MSKST framework
Stock, Futures, Options, GARCH, Distribution, Basis, Asymmetric volatility, C32, C50, G15,