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Brandon Bisschoff16/04/2021, 18:20AGNPoster
Galaxies and galaxy clusters are separated by large distances of nearly empty
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space called the intergalactic space. In these large, nearly empty regions a weak magnetic field of strength < 10 nG is present that is predicted to be of primordial (early universe) origin. This is called the intergalactic magnetic field (IGMF) and knowledge about its strength, coherence length, origin etc. is... -
Saikat Das16/04/2021, 18:26AGNPoster
We explain the observed multiwavelength photon spectrum of some high energy BL Lac objects, using a lepto-hadronic model. The one-zone leptonic emission is employed to fit the synchrotron peak. Subsequently, the SSC spectrum is calculated, such that it extends up to the highest energy possible for the jet parameters considered. The data points beyond this and also in the entire VHE range (E>30...
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Yasushi Fukazawa16/04/2021, 18:29AGNPoster
FSRQs are important to study cosmic evolution of AGN jet and also interesting how they contribute to the cosmic MeV gamma-ray background. Past studies with hard X-ray (Swift/BAT 22 month catalog) and GeV gamma-ray (Fermi/LAT) reported the X-ray and gamma-ray luminosity function, but predicts a different evolution between X-ray and GeV gamma-ray. Here we used the Swift/BAT 105 month catalog to...
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Andrea Gokus16/04/2021, 18:32AGNPoster
While blazars are abundant in the gamma-ray sky, there is only a handful of narrow-line Seyfert 1 galaxies that Fermi/LAT detected in more than 10 years of observation. Flares from this elusive source class are among the rarest events that Fermi has seen so far.
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One of them is the radio- and gamma-ray loud source PKS 2004-447. It exhibits blazar-like features, i.e., a flat featureless X-ray... -
Nomthendeleko Motha16/04/2021, 18:35AGNPoster
The extragalactic radio background in the universe is mainly due to emission from the radio galaxies and normal galaxies. This emission is synchrotron radiation by relativistic electrons gyrating in the magnetic field of the galaxies. Synchrotron self-absorption and free-free absorptions by hot ionised gas in the interstellar medium play an important role to modify radio emission. In this...
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Laenita Oberholzer16/04/2021, 18:38AGNPoster
On the 28th of January, an orphan very-high-energy γ-ray flare from 3C279
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was detected, not accompanied by flaring in the adjacent GeV gamma-ray
regime. Orphan flares have to be caused by different processes than normal
γ-ray flares. Specifically, the Hadronic Synchrotron Mirror Model has been
proposed to provide a consistent explanation of this flare. The expected tar-
get photon... -
Mithun Randu16/04/2021, 18:41AGNPoster
An active galactic nucleus with a relativistic jet pointing within 10o of the line of the sight of the earth is known as a Blazar. Normally a Blazar has two relativistic jets. These jets are linear features instigating very close to the super massive black hole (SMBH) at the center of an Active Galactic Nucleus (AGN). A broad region of energies consist in these jets from radio rays to gamma...
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Hannes Thiersen16/04/2021, 18:44AGNPoster
Most research on blazar variability focuses on individual flares to explain acceleration
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and radiation mechanisms and improve on current models. These short-time events
(being minutes, hours, or days) might not be representative of the underlying mecha-
nisms causing small-amplitude variability and/or continuous emission which is present
most of the time. We will therefore investigate... -
Jacobus van den Berg16/04/2021, 18:47AGNPoster
We test different physically motivated models for the spectral shape of the gamma-ray emission in a sample of 128 blazars with known redshifts detected by Fermi-LAT at energies above 50 GeV. The first nine years of LAT data in the energy range from 300 MeV to 2 TeV are analyzed in order to extend the spectral energy coverage of the 2FHL blazars in our sample. We compare these spectral data to...
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Zacharias Michael16/04/2021, 18:50AGNPoster
The FSRQ CTA 102 (z=1.032) has been tremendously active over the last few years. During its peak activity lasting several months in late 2016 and early 2017, the gamma-ray and optical fluxes rose by up to a factor 100 above the quiescence level. We have interpreted the peak activity as the ablation of a gas cloud by the relativistic jet, which can nicely account for the months-long lightcurve...
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Natalia Zywucka16/04/2021, 18:53AGNPoster
We present the results of a preliminary investigation of a potential association of a blazar
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candidate behind the Large Magellanic Cloud (LMC) and a gamma-ray transient object.
The hint of flaring activity appeared at the position (RA,dec)∼(86.60 deg,-69.02 deg), while
the J0545-6846 blazar candidate is located at (RA,dec)=(86.47 deg,-68.77 deg). J0545-6846 is characterised by a... -
Marco Ajello16/04/2021, 18:56AGNPoster
Massive black holes at the centers of galaxies can launch powerful wide-angle winds, which if sustained over time can unbind the gas from the stellar bulges of galaxies. Propagating through the galaxy, the wind should interact with the interstellar medium creating a strong shock, similar to those observed in supernovae explosions, which is able to accelerate charged particles to high...
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Graziano Chiaro16/04/2021, 18:59AGNPoster
Radio-loud sources with blazar-like properties, but having a jet that does not directly point in the direction of the observer are among the most interesting classes of gamma-ray emitters. These sources are known as Misaligned Active Galactic Nuclei (MAGN). We searched for new MAGN candidates among the remaining blazars of uncertain type detected by the Fermi Large Area Telescope (LAT) using a...
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Melissa Hallum16/04/2021, 19:02AGNPoster
The quasar 1156+295 (4C 29.45, Ton599) underwent a dramatic nonthermal outburst in late 2017, with detection at energies > 100 GeV. The outburst was essentially simultaneous at gamma-ray and optical bands, indicating co-spatiality of the emission regions. We present multi-epoch optical spectra of 1156+295 obtained with the 4.3 m Lowell Discovery Telescope at various times, including the...
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330. Multiwavelength monitoring of gravitationally lensed blazar QSO B0218+357 between 2016 and 2020Francesco Longo16/04/2021, 19:05AGNPoster
QSO B0218+357 is currently the only gravitationally lensed source from which both high-energy (HE, >~100 MeV) and very-high-energy (VHE,>~100GeV) gamma-ray emission has been detected.
We report the Fermi/LAT and multiwavelength monitoring observations of this source in radio interferometry, optical and X-rays performed between 2016 and 2020. During the monitoring, individual flares in the...
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JP Marais16/04/2021, 19:08AGNPoster
The Fermi-LAT has detected more than 5000 gamma-ray sources which show emission above 50 MeV of which 58 per cent belong to the blazar class. However, the Fourth Fermi-LAT catalogue (4FGL) lists 1312 of these as blazar candidates of uncertain type (BCU). Increasing the number of classified Fermi-LAT sources is important for improving our understanding of extra-galactic gamma-ray sources and...
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Alex McDaniel16/04/2021, 19:11AGNPoster
Many star-forming galaxies and those hosting active galactic nuclei (AGN) show evidence of massive outflows of material in a variety of phases including ionized, neutral atomic, and molecular outflows. Molecular outflows in particular have been the focus of recent interest as they may be responsible for removing gas from the galaxy, thereby suppressing star formation. As the material is...
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Joseph Omojola16/04/2021, 19:14AGNPoster
Phenomenological spectral analysis of S5 1803+784 was done in both the high state and the low state using leptonic jet models. The jet energetic and spectral properties using single zone synchrotron-self Compton (SSC) and SSC with external photons (SSC+EC) jet models are presented. S5 1803+784 is a low synchrotron peak (LSP) blazar with the characteristics weak emission lines
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(EW < 5A ).... -
Zhiyuan Pei16/04/2021, 19:17AGNPoster
In this talk, we will present a two-component model of the γ-ray emission which assumes that the total γ-ray output of blazars consists of relativistically beamed and unbeamed components. 584 Fermi/LAT-blazars are listed in our compiled catalogue. This idea leverages the correlation between the radio core-dominance parameter and the γ-ray beaming factor. We firstly propose a so-called "γ-ray...
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Giacomo Principe16/04/2021, 19:20AGNPoster
According to radiative models, radio galaxies are predicted to produce gamma rays since the first stages of their evolution. The study of the high-energy emission from young radio sources is crucial for providing information on the most energetic processes associated with these sources, the actual region responsible for this emission, as well as the structure of the newly born radio jets....
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Bindu Rani16/04/2021, 19:23AGNPoster
Magnetic reconnection - relinking of magnetic field lines - has been proposed as a possible mechanism to power the high-energy flares in gamma-ray bright Active Galactic Nuclei but has not been confirmed via observations. Our study found observational evidence of magnetic reconnection generated gamma-ray flares in a radio galaxy, 3C 84. In a sequence of radio images, the radio-emitting region...
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Rozeena Ebrahim16/04/2021, 19:26AGNPoster
The Circinus galaxy is a composite starburst/Seyfert galaxy which exhibits radio lobes inflated by kpc scale outflows along its minor axis. Its proximity (4 Mpc) makes it a unique target to study the physical nature of these outflows. We investigate if they originate from nuclear star formation activity or if they are jets from an active galactic core. The MeerKAT radio observations allow us...
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