Description
AGN - GRBs - SNR/PWNe - Future Missions/Instruments - Analysis Techniques - Pulsars - Binaries - Neutrinos - Diversity and Equity - Dark Matter - Solar System Gravitational Waves
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Mr Tej Bahadur Chand (Centre for Space Research, North-West University Potchefstroom, South Africa)11/10/2022, 10:30Poster
Both observational evidence and theoretical considerations from MHD simulations of jets suggest that the relativistic jets of active galactic nuclei (AGN) are radially stratified, with a fast inner spine surrounded by a slower-moving outer sheath. The resulting relativistic shear layers are a prime candidate for the site of relativistic particle acceleration in the jets of AGN and gamma-ray...
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Lea Alina Heckmann (Max-Planck-Institut für Physik, D-80805 München, Germany)11/10/2022, 10:30Poster
Blazars are among the brightest objects in the γ-ray sky. Nonetheless, even after decades of γ-ray and multiwavelength observations, they are far from being understood.
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In this contribution, we introduce a multiwavelength data set of the archetypal blazar, Mrk 501. The data set spans the period from 2017 to 2020 and is complemented by a 12-year data set that starts in 2008 for some of the... -
Mr ABHRADEEP ROY (Tata Institute of Fundamental Research, Mumbai, India)11/10/2022, 10:31Poster
We report the detection of a transient quasi-periodic flux modulation in the 6-hour binned $\gamma$-ray light curve of blazar PKS 0903-57 observed by Fermi-LAT. Several independent periodicity search analyses revealed a periodicity of $\sim$6 days that lasted for 5 full cycles during its outburst in March-April 2020. Using Monte-Carlo light curve simulation technique, we found the QPO...
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Ogochukwu Chibueze (NORTH WEST UNIVERSITY, POTCHEFSTROOM, SOUTH AFRICA)11/10/2022, 10:31Poster
We present the results of the multiwavelength study of several blazars at redshift z >~1 that have been observed by the High Energy Stereoscopic System (H.E.S.S.) since 2016 in target-of-opportunity observations, triggered by gamma-ray flaring states detected by the Fermi Large Area Telescope (LAT). We collect data from the Fermi-LAT, SWIFT and H.E.S.S. telescopes and model the broadband...
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Anshu Chatterjee (TATA INSTITUTE OF FUNDAMENTAL RESEARCH)11/10/2022, 10:32Poster
Blazars are a special kind of active galactic nuclei (AGNs) with jets oriented at small angles to our line of sight. Due to the relativistic motion of plasma along the jet, it constitutes one of the most rapidly varying classes of objects over a broad energy band (radio to γ-ray). S5 1044+71 (z = 1.15) is a known distant blazar observed in the GeV energy band. In the latest Fermi-LAT source...
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Joseph Omojola11/10/2022, 10:32Poster
We report the spectral and temporal analysis of S5 1803+784, a low synchrotron peaked (LSP) BL Lac object, during the 2020 and 2021 flaring states. The spectral energy distributions (SEDs) were studied in the framework of the single-zone leptonic jet model and broken power-law leptonic electron distribution. BL Lacertae objects (BL Lacs) high energy emissions can often be modelled as a...
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Dr Haocheng Zhang (NPP Fellow/NASA GSFC)11/10/2022, 10:33Poster
Blazars are among the most powerful cosmic particle accelerators in our Universe. Strong multi-wavelength variability suggests extreme particle acceleration locally in the blazar emission region. Previous studies find that shock, magnetic reconnection, and turbulence can be the underlying particle acceleration mechanisms in the emission region. However, most theoretical models involve...
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Dr Haocheng Zhang (NPP Fellow/NASA GSFC)11/10/2022, 10:33Poster
Polarimetry is a direct measurement of the magnetic field in astrophysical objects. With the launch of IXPE, as well as future MeV polarimeters under development, such as COSI and AMEGO-X, multi-wavelength polarimetry will shed light on the magnetic field and particle acceleration in blazars. Here we present our theoretical predictions of multi-wavelength blazar polarization signatures. We...
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Joleen Barnard11/10/2022, 10:34Poster
At optical wavelengths, blazar SEDs show a superposition of non-thermal (polarised) emission from the jet, and thermal (unpolarised) emission from the accretion disc, broad-line region, dust torus and host galaxy itself. Due to their variability, the level of polarisation present in blazar emission changes as the non-thermal jet emission becomes more/less prominent. Hence, polarisation studies...
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Mr Justin Cooper (University of the Free State)11/10/2022, 10:34Poster
Blazars are active galactic nuclei with jets aligned very closely to our line of sight. The optical emission of blazars is often dominated by the polarised, non-thermal emission arising in the jet, with an underlying unpolarised, thermal emission component arising from the host galaxy, dusty torus, and accretion disk components. As the emission of blazars varies between flaring/high states and...
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Daniel Kulik (University of the Free State)11/10/2022, 10:35Poster
Active Galactic Nuclei (AGN) are compact
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and highly luminous regions at the centre of galaxies. Relativistic
jets from radio loud AGN have been shown to exhibit variability over
various time-scales and frequencies. A contributing component to the
formation of variability results from the injection and propagation of
blob/shock structures within the jet. We have investigated this
through... -
Andrea Gokus (Dr. Karl Remeis-Observatory/ECAP)11/10/2022, 10:35Poster
The extragalactic gamma-ray sky observed by Fermi-LAT is dominated by blazars, with only a handful of narrow-line Seyfert 1 (NLS1) galaxies detected in 10 years of observation. Flares from this elusive source class are among the rarest events that the Fermi-LAT has seen so far, and we are presenting the analysis on one such event from the radio- and gamma-ray loud source PKS 2004–447.
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On... -
Mr Mfuphi Ntshatsha (University of Johannesburg)11/10/2022, 10:36Poster
Active galaxies are complex astrophysical objects in that many physical processes occur almost simultaneously. They emit at all electromagnetic frequencies. Active galactic nuclei (AGNs) are the parent class of blazars which are the brightest of active galaxies. There are a number of models that can explain the spectral energy distribution (SED) of blazars. However, the complexity of blazars...
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Gunjan Tomar (Raman Research Institute)11/10/2022, 10:36Poster
Despite occupying ∼40% of the local Universe, Low Luminosity Active Galactic Nuclei (LLAGNs) are less explored due to their faintness. Detection of a few in gamma rays by Fermi-LAT allows us to constrain the physical parameters of the jet by modeling their broadband spectral energy distributions. While a one-zone model explains the broadband emission up to a few GeV, another component is...
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Laenita Lorraine Oberholzer11/10/2022, 10:37Poster
Blazars show variability across the electromagnetic spectrum on a variety of time scales. In some cases, flaring events in one frequency band are not accompanied by flaring in other bands. Such events are termed ”orphan flares”. The causes of this variability and conditions in and location of the high-energy emission region are not entirely understood. The hadronic synchrotron mirror model is...
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Pranjupriya Goswami (North-West University), Dr Sunil Chandra (South African Astronomical Observatory, Cape Town)11/10/2022, 10:37Poster
Blazars are a subclass of Active Galactic Nuclei (AGN) seen almost along the relativistic jet, which emanate from very close to the central super massive black hole. As these jets are close to our line of sight, blazars represent a unique sample to study the extreme particle energisation, nature of the magnetic field and many other physical properties of jets. Blazars are well known to show...
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Amit Kumar (Aryabhatta Research Institute of Observational Sciences), Mr Amit Kumar (Aryabhatta Research Institute of Observational Sciences)11/10/2022, 10:38Poster
Gamma-ray bursts are the most energetic cosmic explosions in the Universe, covering a spectral domain from all the way radio to gamma-ray up to tens of GeV. Recently, the detection of very high energy emissions (z ~ 0.0785 to 1.1) associated with the afterglows of a few GRBs by HESS and MAGIC telescopes has provided new insights into the research area of these fascinating objects. This work...
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Tamador Aldowma (Johannesburg University, Omdurman Islamic University)11/10/2022, 10:38Poster
A wealth of Gamma-Ray Burst (GRB) data is available today with known redshifts (observed up to z =9.4), provided by different instruments with well-measured prompt gamma-ray flux and spectral information. In order to estimate redshifts of GRBs using a theoretical estimate (so-called pseudo-redshifts) from spectral relations, several phenomenological relations have been developed. Amati...
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Özge Keskin (Sabancı University)11/10/2022, 10:39Poster
Gamma-Ray Burst Monitor (GBM) on board Fermi, designed to detect short transient events, has been continuously observing the entire sky in gamma-ray since its launch in 2008. Over the 14 years, GBM has produced the largest database of all-sky observations in gamma rays with high time resolution continuous data (2 µs; CTTE since July 2010). Such continuous data contain a wealth of relatively...
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Saeeda Sajjad (Institute of Space Technology (IST), Islamabad Pakistan, Space and Astrophysics Research Lab (SARL), National Center for GIS and Space Applications (NCGSA), Islamabad, Pakistan)11/10/2022, 10:40Poster
The composition of the jet and the nature of the prompt non-thermal emission are open questions in gamma-ray bursts astrophysics. In this work, we study the degree of magnetisation of the jet and the prompt emission for 14 Fermi LAT GRBs with sub-dominant black-body components. We first carry out the joint spectral analysis of these GRBs with the GBM and LAT data using multi-component...
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Dr Monica Barnard (University of Johannesburg)11/10/2022, 10:41Poster
Gamma-ray bursts (GRBs) comprise of short, bright, energetic flashes of emission from extragalactic sources followed by a longer afterglow phase of decreased brightness. Recent discoveries of GRB 180720B and GRB 190829A afterglow emission up to very-high-energy $\gamma$-rays by H.E.S.S. have raised questions regarding the emission mechanism responsible. We interpret these observed afterglows...
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Francesco Longo11/10/2022, 10:41Poster
Since the beginning of its operations, the MAGIC telescopes were optimised to perform fast observations of gamma-ray bursts (GRBs). The follow-up strategy and the specific design of these telescopes, namely a fast slewing system (7 deg/s), a low energy threshold (around 50 GeV) and the possibility of performing observations in not standard conditions (such as large zenith angle of observations...
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Pedro De la Torre Luque11/10/2022, 10:42Poster
TeV halos have become a new class of astrophysical objects which were not predicted before their recent observation. They offer evidence that diffusion around sources (concretely, pulsars) is not compatible with the effective average diffusion that our models predict for the Galaxy. This directly impacts Galaxy formation, our knowledge of the propagation process throughout the Galaxy and our...
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Robert B.11/10/2022, 10:43Poster
Supernova Remnants (SNRs) are considered as the primary sources of galactic cosmic rays (CRs), where CRs are assumed to be accelerated by diffusive shock acceleration (DSA) mechanism, specifically at SNR shocks. In the core-collapse scenario, the SNR shocks expand
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inside the complex ambient environment as the core-collapse SNRs have massive progenitor stars (> 8M⊙) and those stars generate... -
Dr Masha Chernyakova (DCU)11/10/2022, 10:44Poster
HESS J1702-420 is an unidentified multi-TeV gamma-ray source with a peculiar energy-dependent morphology which most naturally can be explained as a composition of two independent emission components with significantly different spatial and energy distributions. Here we propose an alternative interpretation assuming that we deal with a single hadronic accelerator injecting protons with...
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Mr Jacobus Frederik le Roux (North-West University)11/10/2022, 10:45Poster
Supernovae remnants (SNRs) are widely believed to be one of the prime sources of Galactic cosmic rays. They are known to be efficient particle accelerators which is indirectly confirmed by detection of non-thermal emission across the whole electromagnetic spectrum from radio to very-high-energy gamma-rays. Protons and electrons can be accelerated to very high energies of at least several tens...
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Dr Werner Collmar (Max-Planck-Institut für extraterrestrische Physik)11/10/2022, 10:47Poster
The first catalog of Fermi-LAT sources below 100 MeV (1FLE catalog, Principe et 2018) covers the energy range from 30 to 100 MeV. The catalog contains 198 sources of different nature, having a detection significance above 3 sigma. Most of these sources are of extragalactic nature with flat spectrum radio quasars (FSRQs) being the majority. The COMPTEL experiment aboard the Compton Gamma-Ray...
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Pi Nuessle (NASA Goddard Space Flight Center)11/10/2022, 10:47Poster
Fermi’s observations of gamma-ray bursts (GRBs) allow us to model the next generation of GRB instruments, including CubeSats such as the soon-to-be launched BurstCube. Over the first 14 years of its operation, GBM has studied nearly 3500 GRBs, many in stunning detail, which is a significant sample for simulating aspects of BurstCube’s observations when combined with detailed simulations of the...
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Makoto Arimoto11/10/2022, 10:48Poster
High-z Gamma-ray bursts UNraveling the Dark Ages and extreme space-time Mission (HiZ-GUNDAM) is a future astronomical space mission in the 2030s (a pre-project candidate of the competitively-chosen Middle-class ISAS missions) that performs wide-field X-ray surveys of X-ray transients such as gamma-ray bursts (GRBs) and follow-up observations in the infrared band.
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By the observations in the... -
Nomthendeleko Motha11/10/2022, 10:49Poster
Next-generation radio surveys from the Square Kilometre Array (SKA) mid-frequency telescope and its precursors will observe the universe with high spectral precision. The 21-cm neutral hydrogen (HI) emission line detected from these surveys is ideal for obtaining more accurate constraints on cosmological parameters. However, the HI line is intrinsically faint and difficult to detect at high...
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Jean Ballet11/10/2022, 10:50Poster
The latest Fermi-LAT source catalog (4FGL DR3: 6658 sources above 50 MeV) was based on twelve years (2008 - 2020) of data. Since neither the event reconstruction (Pass 8) nor the interstellar emission model (gll_iem_v07) has evolved since 2019, we provide incremental 4FGL releases at regular intervals of two years, until one of those two key ingredients changes. The next incremental catalog,...
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Prof. Stefan Wagner (LSW, ZAH, U Heidelberg)11/10/2022, 10:51Poster
We present a catalog of LAT information on VHE sources. The purpose of the catalog is a compilation of complementary information from LAT and ground-based gamma-ray arrays on sources detected in the VHE energy band (E> 100 GeV)
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mete uzuner (Sabancı University)11/10/2022, 10:52Poster
Magnetars are isolated, young ($<10^5$ years), highly magnetic ($>10^{14}$ G) neutron stars with long spin periods (2-12 s). All magnetars emit short repeated bursts in soft gamma rays; however, only a handful of magnetars show radio pulsations. After the detection of magnetar-like bursts from highly magnetic ($>10^{13}$ G) Rotation Powered Pulsars (RPPs), the question of whether magnetar-like...
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Ms Hend Hamed (North-West University)11/10/2022, 10:53Poster
Millisecond pulsars are old recycled pulsars with a rotation period of less than 30 ms. The pulsed GeV emission mechanism of the MSPs is not fully understood. The Fermi LAT Third Pulsar Catalogue (3PC) will present light curves of unprecedented quality for more than 275 gamma-ray pulsars, with more than 100 of them being MSPs. As a part of our project, we are studying the morphology of the...
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Diego F Torres11/10/2022, 10:54Poster
LS I +61 303 303 is one of the rare gamma-ray binaries, emitting most of their luminosity in photons with energies beyond 100 MeV. The ~26.5 d orbital period is clearly detected at many wavelengths. Additional aspects of its multi-frequency behavior make it the most interesting example of the class. The morphology of high-resolution radio images changes with orbital phase displaying a cometary...
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Bhuti Nkosi (University of the Witwatersrand, KM3NeT Group)11/10/2022, 10:55Poster
After the detection of neutrinos from blazar TXS 0506+056 in a flaring state, there have been advancements in neutrino astronomy including a detection of neutrinos from a tidal disruption event. Blazar TXS 0506+056 and other neutrino sources were detected by the first-generation neutrino telescopes during transient states. The spectral energy distributions of blazars jet emissions can be...
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Giovanna Senatore11/10/2022, 10:56Poster
The Fermi-LAT/GBM Mentoring Program (MP) was formed in 2020. The primary goal of the MP is to establish an effective mentoring structure, which provides a resource for graduate students to form strong and lasting relationships with their mentors, communicate any questions they have, discuss any issues that arise, help the student feel well-integrated within the Fermi-LAT/GBM Collaborations,...
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Tjark Miener (IPARCOS, UCM)11/10/2022, 10:57Poster
One of the most pressing questions for modern physics is the nature of dark matter (DM). Several efforts have been made to model this elusive kind of matter, whose presence has been assessed only by gravitational effects so far. The largest fraction of DM cannot be made of any of the known particles of the Standard Model (SM). The ground-based gamma-ray telescope system MAGIC could potentially...
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Pertti Makela (The Catholic University of America, Washington DC, USA and NASA Goddard Space Flight Center, Greenbelt MD, USA)11/10/2022, 10:58Poster
Sustained gamma-ray emission (SGRE) events observed by FERMI/LAT at >100 MeV energies are associated with fast and wide coronal mass ejections (CMEs) from the Sun. These CMEs are similar to those that cause ground level enhancement in solar energetic particle (SEP) events. CME-driven shocks have been suggested to be the acceleration site of the >300 MeV protons producing the >100 MeV gamma-ray...
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Lynn Cominsky11/10/2022, 10:59Poster
As part of the international gravitational wave collaboration for education and public outreach (IGRAV), Fermi communications and outreach is supporting the development of the gamma-ray content for a Multi-Messenger Astrophysics Master Class. The Master Class is being created for use in high schools, and represents how scientists work together using different types of data to make sense out of...
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