Related papers: Early Detection of Multiwavelength Blazar Variabil…
Understanding the high-energy emission processes and variability patterns are two of the most challenging research problems associated with relativistic jets. In particular, the long-term (months-to-years) flux variability at very high…
We present the development of a real-time flare monitor for the High Altitude Water Cherenkov (HAWC) observatory. The flare monitor has been fully operational since 2017 January and is designed to detect very high energy (VHE; $E\gtrsim100$…
Blazars are high-energy engines providing us natural laboratories to study particle acceleration, relativistic plasma processes, magnetic field dynamics, black hole physics. Key informations are provided by observations at high-energy (in…
The origin of extremely fast variability is one of the long-standing questions in the gamma-ray astronomy of blazars. While many models explain the slower, lower energy variability, they cannot easily account for such fast flares reaching…
The very-high-energy (VHE, E>100 GeV) extragalactic sky is dominated by blazars, a class of active galactic nuclei which show rapid variability at all wavelengths. Target of Opportunity (ToO) observations triggered by flaring activity…
Blazars are among the most energetic and violent objects in the universe. By observing blazars at very high energies (VHE, E > 100 GeV) we can better understand blazar emission mechanisms, jet structure, black hole accretion and the…
Several models have been suggested to explain the fast gamma-ray variability observed in blazars, but its origin is still debated. One scenario is magnetic reconnection, a process that can efficiently convert magnetic energy to energy of…
We review the main topics in the field of blazar multiwavelength variability as a tool to understand the physics and structure of extragalactic jets and their central engine. We address issues such as the cross-correlation between flux…
Quasars exhibit stochastic variability across wavelengths, typically well described by a Damped Random Walk (DRW). Occasionally, however, they undergo extreme luminosity changes--known as flares--that represent significant departures from…
Various attempts have been made in the literature at describing the origin and the physical mechanisms behind flaring events in blazars with radiative emission models, but detailed properties of multi-wavelength (MWL) light curves still…
Blazars are known to show periods of quiescence followed by outbursts visible throughout the electromagnetic spectrum. We present a novel maximum likelihood approach to capture this bimodal behavior by examining blazar radio variability in…
Blazars, a subset of powerful active galactic nuclei, feature relativistic jets that shine in a broadband electromagnetic radiation, e. g. from radio to TeV emission. Here I present the results of the studies that explore gamma-ray and…
Blazars are active galactic nuclei with relativistic jets pointed at the Earth, making them extremely bright at essentially all wavelengths, from radio to gamma rays. I review the modeling of this broadband spectral energy distributions of…
Variable \gama-ray emission from blazars, one of the most powerful classes of astronomical sources featuring relativistic jets, is a widely discussed topic. In this work, we present the results of a variability study of a sample of 20…
Blazars are characterized by rapid variability at virtually all wavelengths from radio through TeV gamma-rays. The challenge since their discovery has been to understand the origin of their luminous, apparently nonthermal, nuclear emission.…
Blazars are radio-loud Active Galactic Nuclei (AGN) whose jets have a very small angle to our line of sight. Observationally, the radio emission are mostly compact or a compact-core with a 1-sided jet. With 2.5$^{\prime\prime}$ resolution…
In recent years, blazar surveys at radio and X-ray energies have greatly increased our understanding of this type of active galaxy. The combination of multi-wavelength data has shown that blazars follow a well defined sequence in terms of…
The extreme variability of blazars, in both timescale and amplitude, is generally explained as the effect of a relativistic jet closely aligned to the observer's line-of-sight. Due to causality arguments, variability characteristics…
Blazars are a remarkable type of Active Galactic Nuclei (AGN) that are playing an important and rapidly growing role in today's multi-frequency and multi-messenger astrophysics. In the past several years, blazars have been discovered in…
Astrophysical flares are one of the possible prominent source classes of ultra-high-energy (UHE, $E > 10^{17}$ eV) cosmic rays, which can be detected by recording clusters of extensive air showers in arrays of detectors. The search for…