F3 : The transient catastrophic Universe
The capability to study transient phenomena on time scales from milliseconds to years has recently increased and shown large discovery potential. Yet, the time domain of the sky has been sparsely explored. Fermi and Swift are now showing the way at high energies, the former by mapping the whole sky every 3 hours, the latter by its rapid follow-up across many wavelengths.
With the construction of wide field imagers dedicated to sky surveys on a daily timescale in the radio (Lofar, ASKAP, MeerKAT), optical (Pan-STARRS, LSST), infrared (Akari), and X-ray (eRosita/SRG), and with the ongoing surveillance in gamma rays from Fermi, there are new motivations to explore transients. Discovering new classes of fast transients is one, as it could represent new exotic or explosive events out to cosmological distances, such as merging neutron stars or evaporating black holes.
Over the next decade, a combination of increased sensitivity, larger field of view, and algorithmic developments will open up the time domain to a wide range of astronomical fields, from stellar flares and supernovae to neutron-star and black-hole births, quakes and instabilities. Near-coincidence searches with high-energy neutrino and gravitational wave signals will be actively pursued across the world. The dynamic and bursting events represent the new terra incognita.
Radio astronomy is leading this effort. Transient science is identified as a key goal for LOFAR (Europe), ASKAP (Autralia) and MeerKAT (South Africa) that are the precursor instruments of the major international SKA facility to be developed for the 2020+. The synchrotron radio emission probes with unequalled angular resolution the cooling in the ambient magnetic field of the relativistic particles ejected by compact accretors or explosions. It also constrains the kinetic feedback of such events on their environment.
Artistic view of a small part of the SKA kilometer array (a decision regarding the selection of the SKA site is expected in the next months).
Algorithmic improvements for transient detection would yield improved use of the different combinations of fields-of-view and unprecedented sensitivities offered by these instruments. The vast storage and computational requirements of transient searches, in particular for imaging interferometers, also requires the development of near real-time detection pipelines. The LOFAR project is engaged in the development of first-generation pipelines. The characterization of transients and their identification at other wavelengths represents another challenge.
LOFAR is a radio telescope currently being built in The Netherlands and neighboring countries)
Image from one of the Lofar low frequency station in Nançay (France)
Stéphane Corbel (Professor, AIM)
Isabelle Grenier (Professor, AIM)
Jean-Luc Starck (Researcher CEA, AIM)
Julien Girard (Post-doc, LabEx UnivEarthS)
Hugh Garsden (LEDA Project, Harvard Observatory, ex post-doc, LabEx UnivEarthS)
In collaboration with Cyril Tasse (GEPI, Observatoire de Paris) and the LOFAR (TKP), MeerKAT (ThunderKAT) and ASKAP(VAST) collobarations
The SKA pathfinders
LOFAR Core located in The Netherlands, with international stations located in France, UK, Germany and Sweden Now operational |
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MeerKAT 64 antennas of 13.5 m to be operating from 0.6 to 15 GHz Location: South Africa Completion: 2016-18 |
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KAT-7 7 dishes to be used as a MeerKAT precursor. 0.9 to 1.6 GHz Location: SOuth Africa Now operational |
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ASKAP 36 antennas of 12-m diameter located in Western Australia operating around 1.4 GHz. Large field of view. Operational around 2016, with a subset of antennas already working |
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22 February 2013, 17:41
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28 November 2012, 12:28
Publications in refereed journals:
- Hassall et al. 2012, Astronomy & Astrophysics, 543, 66: Wide-band simultaneous observations of pulsars: disentangling dispersion measure and profile variations
- Garsden et al., Submitted to Astronomy & Astrophysics: LOFAR Sparse Image Reconstruction
Conference proceedings:
- LSS/NenuFAR: The LOFAR Super Station project in Nançay, SF2A-2012: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics.
Presentations of work during:
- LOFAR TKP (Transient Key Project) meeting, Amsterdam (Nl), 3 to 5 december 2012. SC + HG attended. Talk by HG (website here)
- Joint meeting of LOFAR TKP, ThunderKAT and TRAPUM, Oxford (GB), 12 to 15 June 2012. HG attended. Talk by HG (website here)
- Day of Action Spécifique SKA-LOFAR during SF2Ameeting in Nice on 6 JUne2012. SC + HG attended. Talk by SC and HG (website here)