Recent Changes - Search:

Overview

Organizers

Venue

Invited Speakers

Registration

Abstract Submission

Program

Participants

Proceedings

Accommodation

Contact

edit SideBar

HEASA 2015


3rd Annual Conference on
High Energy Astrophysics in Southern Africa


18-20 June 2015, University of Johannesburg, South Africa


Invited Speakers
Rob Adams (SKA South Africa Project)
Michael Backes (University of Namibia)
Markus Böttcher (North-West University Potchefstroom)
David Buckley (South African Astronomical Observatory)
Sergio Colafrancesco (University of Witwatersrand)
Bernie Fanaroff (SKA South Africa Project)
Justin Finke (US Naval Research Laboratory)
Vanessa McBride (University of Cape Town)
Pieter Meintjes (University of the Free State)
Kavilan Moodley (University of Kwa-Zulu Natal)
Soebur Razzaque (University of Johannesburg)
K.P. Singh (Tata Institute of Fundamental Research)
Iurii Sushch (North-West University Potchefstroom)
Giacomo Vianello (Stanford University)
Brian Warner (University of Cape Town)


Titles and abstracts
Michael Backes (University of Namibia)
Current status of the Namibian bid to host the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is the next generation instrument for very high energy (VHE) gamma-ray astronomy. Being successor to the vastly successful instruments H.E.S.S. in Namibia, MAGIC on the Canary Island of La Palma, and VERITAS in Arizona, USA, it is expected to outperform the former by a factor of 10, both in sensitivity as well as in the accessible energy range. To achieve these goals, the best possible operational conditions must be met and thus a world-wide site investigation campaign was launched. Based on the experience of successfully hosting the H.E.S.S. telescopes since 2002, proposals were submitted to host CTA in Namibia. Thorough investigations of the atmospheric and climatic conditions were carried out to estimate the average annual observation time. The scientific performance was estimated by means of Monte Carlo simulations, taking both the altitude and the local geomagnetic field into account. Eventually, the proposed site in Namibia was singled out as the scientifically best site in the world to host the CTA and in April 2014, the decision was taken to engage into official negotiations with the Republic of Namibia and with ESO, being patron to the competitor site in Chile. Details of the bidding process as well as the current status will be presented.
Markus Böttcher (North-West University Potchefstroom)
Diagnostics of leptonic and hadronic emission from relativistic jets in AGN
The nature of the high-energy emission in jet-dominated AGN (especially blazars) as well as the location and mode of acceleration of particles to ultra- relativistic energies are a matter of intensive debate. Both leptonic and hadronic origins of the high-energy emission are still possible, although hadronic models require extreme jet powers. In this talk, I will provide an overview of the state of the art of leptonic and hadronic jet models for blazars. I will then discuss two possible diagnostics to distinguish leptonic from hadronic models: Multiwavelength polarization and variability patterns. In particular, I will show that substantial X-ray and gamma-ray polarization would be a tell-tale signature of hadronic high energy emission, and discuss prospects of detecting such polarization signatures. Also, apparently uncorrelated optical and gamma-ray variability in blazars is more easily explained by hadronic models, while specific patterns of correlated multiwavelength variability (also in tandem with polarization-angle swings) in leptonic models allow for strong constraints on the driving mechanism of variability and the physical conditions in the gamma-ray emitting region.
David Buckley (South African Astronomical Observatory)
Detecting and Observing Transients at the SAAO
In this talk I will describe the new node of the MASTER optical transient detection network, recently commissioned (in Dec 2014) at the SAAO in Sutherland, and review its capabilities and performance to date. This includes the detection of many accretion driven outbursts in CVs, a flaring FSRQ blazar and also detection of optical counterparts for two gamma ray bursts. Plans for conducting optical followup observations of transients by undertaking Target of Opportunity (ToO) observations using the SAAO facilities, including SALT, will be discussed. SALT is an ideal telescope to conduct Target of Opportunity (ToO) observations, being a 100% queue scheduled telescope with a wide variety of observing modes, and this has been demonstrated with successful followup observations of supernovae, flare stars, X-ray transients and other time critical observations. Prompt optical observations of GRBs is more challenging, however, due to SALT's viewing limitations, but not impossible, as has been demonstrated. Later in 2015 a robotic 1-m telescope will be installed in Sutherland, which will increase the capabilities for rapid ToO followups of transients detected by our own facilities, like MASTER.
Justin Finke (US Naval Research Laboratory)
Modeling multiwavelength data from blazars
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. Recently, a number of intensive multi-wavelength monitoring campaigns have been performed on several objects, resulting in some of the most complete spectral energy distributions ever made. I will review the modeling of this broadband spectral energy distributions of these objects, and what we have learned, with a focus on gamma rays.
Vanessa McBride (University of Cape Town)
A multiwavelength perspective on massive X-ray binaries
From accreting binaries to the puzzling gamma-ray binaries, I will discuss the signatures of massive X-ray binaries across the electromagnetic spectrum. Multi wavelength data is crucial for interpretation of these systems, and I will highlight what we hope to achieve with optical, X-ray and radio monitoring of these sources in the southern hemisphere and how these observations complement the high energy emission.
Pieter Meintjes (University of the Free State)
Transient Sources in Astrophysics: From Radio to Gamma-Rays
In this talk I will focus on the magneto-hydrodynamic processes that may lead to eruptions and episodes of particle acceleration and non- thermal emission in accretion driven systems, especially the cataclysmic variables, super Soft X-ray Sources and X-ray Binaries. I will discuss the physics of propeller driven mass outflow in these systems and non-thermal outbursts. A special example of one such system is the novalike variable star AE Aquarii. Evidence of a highly spun up white dwarf and magnetospheric mass outflow is also present in the super Soft X-ray source CAL83, which may point to magnetic fields that are under severe stress. These environments are conducive for episodic release of magnetic energy that may lead to rapid outbursts, burst-like particle acceleration and associated non-thermal emission up to very high energies.
Kavilan Moodley (University of Kwa-Zulu Natal)
Concordance cosmology and its current status
In this talk I will provide an introduction to the cosmological model, focusing on the key observations that have allowed us to pin down the essential parameters of the model. I will point out how upcoming observations will tackle pivotal open questions of the model. As examples, I will discuss specific observational programmes that we are engaged in, such as probing high energy processes in clusters and measuring the properties of dark energy with 21cm intensity mapping experiments.
Soebur Razzaque (University of Johannesburg)
Theories of multi-wavelength emission from Gamma-Ray Bursts: Prompt to afterglow
Gamma-Ray Bursts (GRBs) are powerful transient phenomena originating at cosmological distances. They outshine the entire gamma-ray sky for a brief period of time, less than 2 seconds for short-duration bursts and greater than 2 seconds for long-duration bursts. Non-thermal radiation from particles accelerated in shocks is widely thought to be the origin of GRB. Initial prompt radiation, which is dominated by keV-MeV gamma rays, is followed by fainter and long-lasting afterglow emission in gamma ray to radio wavelengths. In this talk I will give an overview of theoretical models for GRB emission from radio to very high-energy gamma rays, up to 100 GeV.
K.P. Singh (Tata Institute of Fundamental Research)
ASTROSAT- India's first multi-wavelength satellite
ASTROSAT, currently under integration at the ISRO Satellite Centre, Bengaluru, will carry an array of instruments capable of simultaneous observations in a broad range of wavelengths: visible, near-ultraviolet (NUV), far-UV (FUV), soft X-rays to hard X-rays. There are five principal scientific payloads to be carried aboard the satellite: (i) a Soft X-ray Telescope (SXT), (ii) three Large Area Xenon Proportional Counters (LAXPCs), (iii) a Cadmium-Zinc-Telluride Imager (CZTI), (iv) two Ultra-Violet Imaging Telescopes (UVITs) one for visible and near-UV channels and another for far-UV, and (v) three Scanning Sky Monitors (SSMs). It will also carry a charged particle monitor (CPM). All the instruments have qualified and are currently in different stages of integration. ASTROSAT is due to be launched by India’s Polar Satellite Launch Vehicle (PSLV) in the second half of 2015 in a circular 600 km orbit with an inclination of ~6 degrees, from the Sriharikota launching station. A brief description of the design, construction, capabilities and scientific objectives of all the main scientific payloads will be presented.
Iurii Sushch (North-West University Potchefstroom)
Modelling emission from supernova remnants
Supernova remnants (SNRs), the leftovers of massive star explosions, are one of the most interesting objects on the sky. They are observed across the whole electromagnetic spectrum from radio to very high energies (VHE; E > 100 GeV) playing a role of natural laboratories which shed the light on various physical process in SNRs and properties of surrounding media. They are also believed to be the origin of Galactic cosmic rays. In this talk I will discuss the non-thermal emission from SNRs as an instrument to probe physical processes, evolution and environments of SNRs.
Giacomo Vianello (Stanford University)
Observation of Gamma-Ray Bursts and short duration transients with the Fermi Large Area Telescope
Observations of Gamma-Ray Bursts with the Fermi Large Area Telescope have prompted theoretical advances and posed big challenges, despite the fact that GRB emission above 100 MeV is a fairly rare event. The first Fermi/LAT GRB catalog, based on the first 3 years of observations, estabilished many interesting features and opened new questions, despite being based on only 35 detections. Then, the observation of the record- breaking GRB 130427A took the challenge even further, underlining even more the need for new theoretical development. I will review such results. I will also present a new detection algorithm which is 40% more efficient than the previous one. Using this improved procedure, as well as a new and improved event analysis ("Pass 8"), we now detect more than 110 GRBs in the first 6.5 years of observations. The characterization of this sample is ongoing. At the same time, I am developing a blind search which will look for short duration transients (< 3 hours), with a high potential for discoveries. I will briefly describe such development and its possible outcomes.
Brian Warner (University of Cape Town)
Celestial Optical Transients from 532 BCE TO 2015 AD
The earliest recorded optical transients occur in oriental records at least as early as 532 BCE. Among these are events now recognised as novae and supernovae, the most famous of which is the supernova of AD 1054, with the Crab Nebula as remnant. Within the past few years some of the ancient ordinary novae have been identified from their ejected shells or from the nature of the remnant binary star; more can be expected to be found with the upcoming all sky surveys, such as LSST and Pan-STARRS. Here I discuss the current status of the observations and the recent discovery of an eclipsing dwarf nova, with an ejected shell, that is probably the remnant of the Chinese nova of AD 483.
Edit - History - Print - Recent Changes - Search
Page last modified on May 20, 2015, at 04:44 PM