6 research outputs found
Determination of chaotic behaviour in time series generated by charged particle motion around magnetized Schwarzschild black holes
We study behaviour of ionized region of a Keplerian disk orbiting a
Schwarzschild black hole immersed in an asymptotically uniform magnetic field.
In dependence on the magnetic parameter , and inclination angle
of the disk plane with respect to the magnetic field direction, the
charged particles of the ionized disk can enter three regimes: a) regular
oscillatory motion, b) destruction due to capture by the magnetized black hole,
c) chaotic regime of the motion. In order to study transition between the
regular and chaotic type of the charged particle motion, we generate time
series of the solution of equations of motion under various conditions, and
study them by non-linear (box counting, correlation dimension, Lyapunov
exponent, recurrence analysis, machine learning) methods of chaos
determination. We demonstrate that the machine learning method appears to be
the most efficient in determining the chaotic region of the space.
We show that the chaotic character of the ionized particle motion increases
with the inclination angle. For the inclination angles whole
the ionized internal part of the Keplerian disk is captured by the black hole.Comment: 21 pages, 9 figure
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Averaged recurrence quantification analysis: Method omitting the recurrence threshold choice
Recurrence quantification analysis (RQA) is a well established method of nonlinear data analysis. In this work, we present a new strategy for an almost parameter-free RQA. The approach finally omits the choice of the threshold parameter by calculating the RQA measures for a range of thresholds (in fact recurrence rates). Specifically, we test the ability of the RQA measure determinism, to sort data with respect to their signal to noise ratios. We consider a periodic signal, simple chaotic logistic equation, and Lorenz system in the tested data set with different and even very small signal-to-noise ratios of lengths 10 2, 10 3, 10 4, and 10 5. To make the calculations possible, a new effective algorithm was developed for streamlining of the numerical operations on graphics processing unit (GPU)
A ring accelerator? Unusual jet dynamics in the IceCube candidate PKS 1502+106
On 2019/07/30.86853 UT, IceCube detected a high-energy astrophysical neutrino
candidate. The Flat Spectrum Radio Quasar PKS 1502+106 is located within the 50
percent uncertainty region of the event. Our analysis of 15 GHz Very Long
Baseline Array (VLBA) and astrometric 8 GHz VLBA data, in a time span prior and
after the IceCube event, reveals evidence for a radio ring structure which
develops with time. Several arc-structures evolve perpendicular to the jet
ridge line. We find evidence for precession of a curved jet based on kinematic
modelling and a periodicity analysis. An outflowing broad line region (BLR)
based on the C IV line emission (Sloan Digital Sky Survey, SDSS) is found. We
attribute the atypical ring to an interaction of the precessing jet with the
outflowing material. We discuss our findings in the context of a spine-sheath
scenario where the ring reveals the sheath and its interaction with the
surroundings (narrow line region, NLR, clouds). We find that the radio emission
is correlated with the -ray emission, with radio lagging the
-rays. Based on the -ray variability timescale, we constrain
the -ray emission zone to the BLR (30-200 ) and within the
jet launching region. We discuss that the outflowing BLR provides the external
radiation field for -ray production via external Compton scattering.
The neutrino is most likely produced by proton-proton interaction in the blazar
zone (beyond the BLR), enabled by episodic encounters of the jet with dense
clouds, i.e. some molecular cloud in the NLR.Comment: 35 pages, 33 figures, 3 tables; accepted by the MNRAS Main Journa
Constraining X-Ray Variability of the Blazar 3C 273 Using XMM-Newton Observations over Two Decades
Blazars exhibit relentless variability across diverse spatial and temporal frequencies. The study of long- and short-term variability properties observed in the X-ray band provides insights into the inner workings of the central engine. In this work, we present timing and spectral analyses of the blazar 3C 273 using the X-ray observations from the XMM-Newton telescope covering the period from 2000 to 2020. The methods of timing analyses include estimation of fractional variability, long- and short-term flux distribution, rms–flux relation, and power spectral density analysis. The spectral analysis include estimating a model-independent flux hardness ratio and fitting the observations with multiplicative and additive spectral models such as power law , log-parabola , broken power law , and blackbody . The blackbody represents the thermal emission from the accretion disk, while the other models represent the possible energy distributions of the particles emitting synchrotron radiation in the jet. During the past two decades, the source flux changed by a factor of three, with a considerable fractional variability of 27%. However, the intraday variation was found to be moderate. Flux distributions of the individual observations were consistent with a normal or log-normal distribution, while the overall flux distribution including all observations appears to be rather multimodal and of a complex shape. The spectral analyses indicate that a log-parabola added to a blackbody gives the best fit for most of the observations. The results indicate a complex scenario in which the variability can be attributed to the intricate interaction between the disk/corona system and the jet