Variability is a general property of accretion discs and their associated jets. We introduce a semi-analytic model for particle acceleration and radio jet/lobe evolution and explore the effect of Myr timescale jet variability on the particles accelerated by an AGN jet. Our work is motivated by the need for local powerful ultrahigh energy cosmic ray (UHECR) sources and evidence for variability in AGN and radio galaxies. Our main results are: i) UHECR and nonthermal radiative luminosities track the jet power but with a response set by the escape and cooling times, respectively; ii) jet variability produces structure in the electron, synchrotron and UHECR spectra that deviates from that produced for a constant jet power - in particular, spectral hardening features may be signatures of variability; iii) the cutoff in the integrated CR spectrum is stretched out due to the variation in jet power (and, consequently, maximum CR energy). The resulting spectrum is the convolution of the jet power distribution and the source term. We derive an approximate form for a log-normal distribution of powers; iv) we introduce the idea of $\sim 10$ GeV 'proxy electrons' that are cooling at the same rate that UHECRs of rigidity 10 EV are escaping from the source, and determine the corresponding photon frequencies that probe escaping UHECRs. Our results demonstrate the link between the history of an astrophysical particle accelerator and its particle contents, nonthermal emission and UHECR spectrum, with consequences for observations of radio galaxies and UHECR source models.
Weakly accreting black hole X-ray binaries launch compact radio jets that persist even in the quiescent spectral state, at X-ray luminosities <1e-5 of the Eddington luminosity. However, radio continuum emission has been detected from only a few of these quiescent systems, and little is known about their radio variability. Jet variability can lead to misclassification of accreting compact objects in quiescence, and affects the detectability of black hole X-ray binaries in next-generation radio surveys. Here we present the results of a radio monitoring campaign of A0620-00, one of the best-studi…
Revisiting the XMM-Newton Observations of the Galactic Microquasar SS 433: Implications for the Origin of the Ultrahigh-Energy Emission Detected by LHAASO
School of Astronomy and Space Science, Nanjing University(南京大学天文与空间科学学院);Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Ministry of Education(南京大学现代天体学与天体物理教育部重点实验室);Tianfu Cosmic Ray Research Center(天府宇宙线研究中心)
Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences(高能物理研究所,中国科学院粒子天体物理重点实验室);TIANFU Cosmic Ray Research Center(天府宇宙线研究中心)
Particle Acceleration in Mildly Relativistic Shearing Flows: the Interplay of Systematic and Stochastic Effects, and the Origin of the Extended High-energy Emission in AGN Jets
Relativistic jets originating from protomagnetar central engines can lead to long duration gamma-ray bursts (GRBs) and are considered potential sources of ultrahigh-energy cosmic rays and secondary neutrinos. We explore the propagation of such jets through a broad range of progenitors, from stars which have shed their envelopes to supergiants which have not. We use a semi-analytical spindown model for the strongly magnetised and rapidly rotating PNS to investigate the role of central engine properties such as the surface dipole field strength, initial rotation period, and jet opening angle on …
Microquasar remnants as reservoirs of PeV cosmic rays
Instituto Argentino de Radioastronomía (CCT La Plata, CONICET(阿根廷射电天文研究所);CICPBA(拉普拉塔国立大学天文学与地球物理学学院);UNLP)(巴塞罗那大学量子物理与天体物理系、宇宙科学研究所);Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata;Departament de Física Quàntica i Astrofísica, Institut de Ciències del Cosmos (ICC), Universitat de Barcelona (IEEC-UB)
Unveiling Multimessenger Emission from Hidden Cores of Microquasars
The Pennsylvania State University(宾夕法尼亚州立大学);Yukawa Institute for Theoretical Physics, Kyoto University(京都大学汤川理论物理研究所);Institute of High Energy Physics, Chinese Academy of Sciences(中国科学院高能物理研究所);TIANFU Cosmic Ray Research Center(天府宇宙线研究中心)