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Relativistic Jets and Winds in Radio-Identified Supermassive Black Hole Binary Candidates
Andrew G. Sullivan, Roger D. Blandford, Anna Synani +4
Supermassive black hole binary systems (SMBHBs) are thought to emit the recently discovered nHz gravitational wave background; however, not a single individual nHz source has been…
Ultra High Energy Cosmic Rays
Noémie Globus, Roger Blandford
Ultra High Energy Cosmic Rays, UHECR, are charged particles with energies between and . They exhibit fundamenta…
A Hierarchical Shock Model of Ultra-High-Energy Cosmic Rays
Paul Simeon, Noémie Globus, Kirk S. S. Barrow +1
We propose that a hierarchical shock model$\unicode{x2014}$including supernova remnant shocks, galactic wind termination shocks, and accretion shocks around cosmic filaments and ga…
Fermi detection of gamma-ray Emission from the Hot Coronae of Radio-quiet Active Galactic Nuclei
Jun-Rong Liu, Jian-Min Wang, Fermi-LAT Collaboration
Relativistic jets around supermassive black holes (SMBHs) are well-known powerful -ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMB…
The Radio Spectra of High Luminosity Compact Symmetric Objects (CSO-2s): Implications for Studies of Compact Jetted Active Galactic Nuclei
P. V. de la Parra, A. C. S Readhead, T. Herbig +18
This paper addresses, for the first time, a key aspect of the phenomenology of Compact Symmetric Objects (CSOs) -- the characteristics of their radio spectra. We present a radio-sp…
PKS~J08050111: A Second Owens Valley Radio Observatory Blazar Showing Highly Significant Sinusoidal Radio Variability -- The Tip of the Iceberg
P. V. de la Parra, S. Kiehlmann, P. Mroz +23
Owens Valley Radio Observatory (OVRO) observations of supermassive black hole binary (SMBHB) candidate PKS~2131021 revealed, for the first time, six likely characteristics of th…
PKS 2131-021 -- Discovery of Strong Coherent Sinusoidal Variations from Radio to Optical Frequencies: Compelling Evidence for a Blazar Supermassive Black Hole Binary
S. Kiehlmann, P. V. de la Parra, A. G. Sullivan +31
Haystack and Owens Valley Radio Observatory (OVRO) observations recently revealed strong, intermittent, sinusoidal total flux-density variations that maintained coherence between 1…
Small-scale radio jets and tidal disruption events: A theory of high-luminosity compact symmetric objects
Andrew G. Sullivan, Roger D. Blandford, Mitchell C. Begelman +2
Double lobe radio sources associated with active galactic nuclei represent one of the longest studied groups in radio astronomy. A particular sub-group of double radio sources comp…
A Hierarchical Framework for explaining the Cosmic Ray Spectrum using Diffusive Shock Acceleration
Roger Blandford, Paul Simeon, Noémie Globus +3
The hypothesis that the entire cosmic ray spectrum, from to energy, can be accounted for by diffusive shock acceleration on increasin…
On the Comparison of AGN with GRMHD Simulations: II. M87
Richard Anantua, Angelo Ricarte, George Wong +6
Horizon-scale observations of the jetted active galactic nucleus M87 are compared with simulations spanning a broad range of dissipation mechanisms and plasma content in three-dime…
Extreme Energy Cosmic Rays "Treasure Maps": a new methodology to unveil the nature of cosmic accelerators
Noémie Globus, Anatoli Fedynitch, Roger Blandford
Extreme Energy Cosmic Rays, EECRs -- cosmic rays with energies beyond the GZK cutoff (i.e. greater than 100 EeV) are scarce. Only a few of such events have been detected by air sho…
Compact Symmetric Objects -- III Evolution of the High-Luminosity Branch and a Possible Connection with Tidal Disruption Events
A. C. S. Readhead, V. Ravi, R. D. Blandford +18
We use a sample of 54 Compact Symmetric Objects (CSOs) to confirm that there are two unrelated CSO classes: an edge-dimmed, low-luminosity class (CSO~1), and an edge-brightened, hi…
Ultra High Energy Cosmic Ray Source Models: Successes, Challenges and General Predictions
Noemie Globus, Roger Blandford
Understanding the acceleration of Ultra High Energy Cosmic Rays is one of the great challenges of contemporary astrophysics. In this short review, we summarize the general observat…
Reacceleration of Galactic Cosmic Rays Beyond the Knee at the Termination Shock of a Cosmic-Ray-Driven Galactic Wind
Payel Mukhopadhyay, Enrico Peretti, Noemie Globus +2
The origin of cosmic rays above the knee in the spectrum is an unsolved problem. We present a wind model in which interstellar gas flows along a non-rotating, expanding flux tube w…
Treasure Maps for Detections of Extreme Energy Cosmic Rays
Noemie Globus, Anatoli Fedynitch, Roger D. Blandford
The origin of Ultra High Energy Cosmic Rays is a 60-year old mystery. We show that with more events at the highest energies (above 150~EeV) it may be possible to limit the characte…
Evidence for PeV Proton Acceleration from Fermi-LAT Observations of SNR G106.3+2.7
Ke Fang, Matthew Kerr, Roger Blandford +2
The existence of a "knee" at energy ~1 PeV in the cosmic-ray spectrum suggests the presence of Galactic PeV proton accelerators called "PeVatrons". Supernova Remnant (SNR) G106.3+2…
HAWC observations of the acceleration of very-high-energy cosmic rays in the Cygnus Cocoon
A. U. Abeysekara, A. Albert, R. Alfaro +98
Cosmic rays with energies up to a few PeV are known to be accelerated within the Milky Way. Traditionally, it has been presumed that supernova remnants were the main source of very…
Fermi and Swift Observations of GRB 190114C: Tracing the Evolution of High-Energy Emission from Prompt to Afterglow
M. Ajello, M. Arimoto, M. Axelsson +147
We report on the observations of gamma-ray burst (GRB) 190114C by the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory. The early-time observations reveal mul…
Extreme Plasma Astrophysics
D. Uzdensky, M. Begelman, A. Beloborodov +22
This is a science white paper submitted to the Astro-2020 and Plasma-2020 Decadal Surveys. The paper describes the present status and emerging opportunities in Extreme Plasma Astro…
Unresolved Gamma-Ray Sky through its Angular Power Spectrum
M. Ackermann, M. Ajello, L. Baldini +107
The gamma-ray sky has been observed with unprecedented accuracy in the last decade by the Fermi large area telescope (LAT), allowing us to resolve and understand the high-energy Un…
Detection of polarized gamma-ray emission from the Crab nebula with Hitomi Soft Gamma-ray Detector
Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu +191
We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrom…
Multi-messenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A
The IceCube, Fermi-LAT, MAGIC +13
Individual astrophysical sources previously detected in neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neut…
Hitomi X-ray Observation of the Pulsar Wind Nebula G21.50.9
Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu +194
We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.50.9, whose emission is dominated by the pulsar wind nebula (PWN) cont…
Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope
LAT Collaboration
Black holes with masses below approximately g are expected to emit gamma rays with energies above a few tens of MeV, which can be detected by the Fermi Large Area Telesco…