Tariq Blecher (Astrophysics PhD Student SKA SA / Radio Astronomy Research Group (Rhodes University)


I am a South African Astrophysics PhD
 student. I am registered at Rhodes University  with the RATT group (http://www.ratt-ru.org/) but based at the SKA SA office in Cape Town. 


PhD thesis:

Supervisor : Dr Roger Deane, Professor Ian Haywood (Oxford)
Title & abstract:  

Lensed HI with GMRT, MeerKAT & SKA 

abstract coming..

Masters thesis

Supervisor : Dr Roger Deane, Professor Oleg Smirnov, Dr Gianni Bernardi
Title & abstract:  

MeqSilhouette : A mm-VLBI observation and signal corruption simulator

A global mm-VLBI network enables ultra-fine angular resolution on the order of 10s of micro-arcseconds. Recent observational efforts led by the EHT resolve event horizon scale structure in nearby SMBH's SgrA* and M87 in an attempt to gain a deeper understanding of jet, accretion and strong gravitational physics. The scientific potential however is limited by signal corruptions which take place in the troposphere and interstellar medium. In addition sources can be variable, violating the static sky assumption of interferometry. In this paper, we present a new simulation pipeline, MeqSilhouette. The pipeline, given an input variable source and configuration file, creates a simulated observation which incorporates tropospheric and interstellar corruptions. This work will help to map out the realistic scientific potential in the field, research calibration and parameter estimation strategies and optimise observations.

Honours thesis 

Supervisor : Dr Roger Deane
Title & abstract:  

Precessing radio jets as a proxy for binary supermassive black holes

Simulations of merger-driven growth of dark matter halo growth predict that a signification fraction of Active Galactic Nuclei (AGN) should host supermassive black hole (SMBH) binaries. However due to the resolution required, very few binaries have been directly observed. In addition the gravitational wave signal in the $\mu$Hz - nHz frequency band is expected to be dominated by the inspiral of SMBH binaries, measurable with pulsar timing arrays (PTA). If the position of a particular binary is known, it would enable a pointed gravitational wave experiment with a greater sensitivity than measuring the stochastic background. This thesis explores an indirect method to identify binary SMBH candidates, motivated by the possibility that it may be more efficient and that direct methods cannot resolve binaries in the gravitational wave-dominated phase of a merger. We argue the orbital dynamics of a SMBH binary system would be imprinted on the jet morphology, taking the form of jet precession. A search was made through the FIRST and COSMOS survey for AGN with precessing jets. We make novel use of proxies for extended structure to reduce the FIRST database size from 1 million to $\sim 6000$. Each of the remaining sources were viewed by eye. We present 14 precessing jet candidates from the FIRST survey and 2 candidates from the COSMOS survey. The observational results shows order of magnitude agreement with a theoretical prediction based on jet precession in X-ray binary systems. Follow up observations are recommended for the candidate sources to investigate the possibility of additional binary SMBH detections and new possibilities for pointed gravitational wave experiments.

Astrophysics Interests:

Ultra-high resolution observations of accreting compact objects to probe accretion, jet launch and strong gravitational physics. Searches for Super-Massive Black Hole binaries. Evolution of cosmic structure through observations of high redshift, strongly lensed galaxies and wide field surveys. Calibration of tropospheric phase noise for millimeter observatories. Subgrid physics.