AMI-LA Transients: a new collaboration

On June 12, members of a new collaboration visited the AMI telescopes in Cambridge. A team led by Assaf Horesh, of the Hebrew University, Jerusalem, will work together with 4 PI SKY and Cambridge to perform a systematic study of radio supernovae with AMI-LA. We will also work together on the radio follow-up of Tidal Disruption Events.

AMIphotoHere are members of the teams from Cambridge, Oxford and Jerusalem in front of the telescopes of the AMI Large Array. Typical English weather, but the telescopes working fine, observing targets for the 4 PI SKY transients programme as we stood there. From left to right: Patrick Elwood, Assaf Horesh, Richard Saunders, Rob Fender, Joe Bright, Sara Motta, Itai Sfaradi, Paul Scott.

Small_arrayThe teams in the AMI Small Array enclosure. AMI-SA was performing an extensive AGN monitoring programme at the time.

MeerLICHT telescope inaugurated!

On May 25, Africa Day 2018, the MeerLICHT optical telescope was officially inaugurated at South Africa’s Sutherland observatory. Oxford, via the 4 pi sky project, is a key founding member of MeerLICHT.

The unique aspect of this telescope is that it will robotically track, all the time, where the MeerKAT radio telescope (expected to be itself inaugurated in the near future, and to commence full time survey operations by 2019) is pointing. The key science goals are astrophysical transients: if a radio transient is observed with MeerKAT, there will be simultaneous optical data (at night!) and vice versa. This is a very exciting and new exploration of parameter space.

ML_launch

Left to right: Patrick Woudt (UCT), Steven van Straten and Paul Groot (Radboud), Rudy Wijnands (Amsterdam), Dave Buckley (SAAO), Ben Stappers (Manchester), Rob Fender (Oxford and UCT)

Below is one of several first-light images released. This one is of Baade’s window, in the direction of the galactic centre, and this single image contains an estimated two millions stars.

mlicht-baade

There was a lot of press interest in the inauguration, and we even made the national tv:

Rob Fender MeerLICHT TV interview

The official Oxford press release is here:

Oxford press release

For more information see the MeerLICHT website at

MeerLICHT official web site

 

 

4 PI SKY Studies Evolution of Tidal Disruption Event

The 4 PI SKY research group has been involved in the study of a rare transient phenomena, known as a tidal disruption event (TDE). A TDE is the result of a star straying too close to a supermassive black hole, and being ripped apart by its strong gravitational field. The remains of the star then fall down onto the black hole, and emit across the electromagnetic spectrum (see illustration).

14li_artist_impression

Image credit: NASA/CXC/U. Michigan/J. Miller et al.; Illustration: NASA/CXC/M. Weiss

Members of the 4 PI SKY group have been continually observing radio emission from this source using the Arcminute Microkelvin Imager located in Cambridge, with observations spanning 3 years. Their research has indicated the possible presence of ultra-fast outflows emanating from the black hole, known as jets.

Further reading: https://arxiv.org/abs/1511.08803https://arxiv.org/abs/1801.03094

 

The MeerKAT core

OLYMPUS DIGITAL CAMERA

This a photo of the MeerKAT core, taken on Oct 17 (2017) [credit Thomas Abbott, SKA South Africa]. All 64 MeerKAT primary antennas are now in place. In this picture 44 antennas are visible.

4 PI SKY co-leads the ThunderKAT Large Survey Programme (LSP) on MeerKAT, which has 1380 hours of guaranteed time during the MeerKAT survey phase (~2018-2023) as well as an agreement to search all other LSP data commensally to search for transients.

http://www.thunderkat.uct.ac.za/

Exciting times ahead!

4 PI SKY involved in jets breakthrough

The 4 PI SKY research group was involved in a significant measurement of the size and associated timescales very close to the base of a black hole relativistic jet, in a project led by collaborators at The University of Southampton.

Picture of black hole jet

High time resolution X-ray and infrared observations during flares from the black hole V404 Cyg in 2015 revealed a ~0.1 sec time delay between the emission in the two bands. There are good arguments already that the infrared emission arises from the ‘base’ of the relativistic jet, and AMI-LA radio observations provided simultaneously by the 4 PI SKY group confirmed this. This allowed the team, led by Dr Poshak Gandhi from Southampton, to establish a size scale of ~0.1 light seconds between the X-ray emitting region (inner parts of the accretion flow) and the first synchrotron emitting zone (the jet base). The research is published in Nature Astronomy, and the article can be found on the arXiv as arXiv:1710.09838.

For the full Southampton press release (including movie!) go to:

https://www.southampton.ac.uk/news/2017/10/black-hole-jets.page