F3: The transient catastrophic Universe

Check out the project news!

  • 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)

    WP leader Corbel Stéphane AIM Professor, University Paris Diderot
    WP co-leader Grenier Isabelle AIM Professor, University Paris Diderot
    WP co-leader Starck Jean-Luc AIM Researcher/CEA
    WP member Girard Julien AIM Ass. Prof., University Paris Diderot
    WP member Migliori Giulia AIM Post-doc, LabEx UnivEarthS (Dec 14-Dec 17)
    WP member Loh Alan LESIA Post-doc at LESIA/OP (former AIM PhD)
    WP member Jiang Ming AIM PhD Student (Start Oct 14)
    WP member Evangelia Tremou AIM New post-doc (Start Nov 17)
    WP member Floriane Cangemi AIM New PhD Student (Start Oct 17)
    WP member Pires Sandrine AIM Researcher/CEA
    WP member Bobin Jérôme AIM Researcher/CEA
    WP member Rodriguez Jérôme AIM Researcher/CEA

    In collaboration with Cyril Tasse (GEPI, Observatoire de Paris) and the LOFAR (TKP), MeerKAT (ThunderKAT) and ASKAP(VAST) collobarations

  • 2016 Milestones:

    • Deconvolution algorithm (SASIR) was implemented in the new radio imager DDFacet which is the most advanced analyse tool actually. In parallel, development of two extensions (temporal and spectral) for the reconstruction of the temporal and spectral profile of radio sources.
    • First detection at high energies with Fermi/LAT of the transitory gamma ray emission of an accreting small mass black hole (Loh et al. 2016) and of a new class of AGN (Migliori et al. 2016).
    • First detection of a radio transitory at low frequency with LOFAR (Stewart et al. 2016).
    • Many publications regarding the variability of the behavior of compact sources




    The SKA pathfinders


    Core located in The Netherlands, with international stations located in France, UK, Germany and Sweden

    Now operational


    64 antennas of 13.5 m to be operating from 0.6 to 15 GHz

    Location: South Africa

    Completion: 2016-18


    7 dishes to be used as a MeerKAT precursor. 0.9 to 1.6 GHz

    Location: SOuth Africa

    Now operational


    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






    • Curran, P.A. …Corbel, S. et al. The evolving polarized jet of black hole candidate Swift J174526, 2014, MNRAS, 437, 3265
    • Bassa, C. … Corbel, S. et al. A state change in the low-mass X-ray binary XSS J122704859 2014, MNRAS, 441, 1825
    • Marlowe, H. … Corbel, S. et al. Spectral state transitions of the Ultraluminous X-ray Source IC 342 X-1, 2014, MNRAS, 444, 642
    • Gallo, E. … Corbel, S. et al. The radio/X-ray domain of black hole X-ray binaries at the lowest radio luminosities, 2014, MNRAS, 445, 290
    • Cseh, D. …, Corbel, S. et al. On the radio properties of the intermediate mass black hole ESO 243-49 HLX-1 2014, MNRAS, 446, 3268



    • Garsden, H., Girard, J., Starck, J.L., Corbel, S. et al. “LOFAR Sparse Image Reconstruction, 2015, A&A 575, A90.
    • Swinbank, J.D., … Garsden, H., Corbel, S. et al. “The LOFAR transients pipeline”, A&C, 2015, 11, 25
    • Cseh, D. …, Corbel, S. et al. “The evolution of a jet ejection of the ultraluminous X-ray source Holmberg II X-1”, 2015, MNRAS, 452, 24.
    • Rahoui, F, … Corbel, S. et al. “Optical and near-infrared spectroscopy of the black hole Swift J1753.5-0127”, 2015, ApJ, 810, 161.
    • Tomsick, J.A., … Corbel, S. et al. “The Accreting Black Hole Swift J1753.5–0127 from Radio to Hard X-Ray”, 2015, ApJ, 808, 85.
    • Russell, T. D. … Corbel, S. et al. “Radio monitoring of the hard state jets in the 2011 outburst of MAXI J1836−194”, 2015, MNRAS, 450, 1745.
    • Rodriguez, J., … Corbel, S. et al. “Correlated optical, X-ray, and gamma-ray flaring activity seen with INTEGRAL during the 2015 outburst of V404 Cygni”, A&A, 581, L9.



    • Loh,, Corbel, S., Dubus, G., Rodriguez, J., Grenier, I., Hovatta, T., Pearson, T., Readhead, A., Fender, R., Mooley, K. “High-energy gamma-ray observations of the accreting black hole V404 Cygni during its 2015 June outburst”, 2016, MNRAS, 462, L111.
    • Carbone, D., ., … Corbel, S. et al. “New methods to constrain the radio transient rate: results from a survey of four fields with LOFAR”, MNRAS, 459, 316.
    • Broderick, J.W., … Corbel, S. et al. “Low-radio-frequency eclipses of the redback pulsar J2215+5135 observed in the image plane with LOFAR», 2016, MNRAS, 459, 2681.
    • Del Santo, M., … Corbel, S, … Rodriguez, J. et al. “Spectral and timing evolution of the bright failed outburst of the transient black hole Swift J174510.8-262411» 2016, MNRAS, 456, 3585.
    • Stewart, A. … Corbel, S. et al. “LOFAR MSSS: detection of a low-frequency radio transient in 400 h of monitoring of the North Celestial Pole» 2016, MNRAS, 456, 2321.
    • Marcotte, B. … Corbel, S. et al. “Orbital and superorbital variability of LS I +61 303 at low radio frequencies with GMRT and LOFAR», 2016, MNRAS, 456, 1791.
    • Migliori, G., …, Loh, A., Corbel, S. et al. « First Detection in Gamma-Rays of a Young Radio Galaxy: Fermi-LAT Observations of the Compact Symmetric Object PKS 1718-649» 2016, ApJ, 821, 103.
    • Rana, V., Loh, A., Corbel, S. et al. “Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence», 2016, ApJ, 821, 103.
    • Girard, J., … Corbel, S. et al., “Imaging Jupiter’s radiation belts down to 127 MHz with LOFAR”, 2016, A&A, 587, 3.
    • Kondratiev, V.I. … Corbel, S. et al. “A LOFAR Census of Millisecond Pulsars”, 2016, A&A, 585, 128.
    • Siemiginowska, A., … Migliori G. et al. “X-Ray properties of the youngest radio sources and their environments”, 2016, ApJ, 823, 57.
    • Migliori, G, « The high-energy view of young radio sources: X-ray and gamma-ray observations» 2016, AN, 337, 52.
    • Füerst, F. …Corbel, S., … Loh, A. et al. “GRS 1739-278 observed at very low luminosity with XMM-Newton and NuSTAR», 2016, ApJ, 832, 115.




    • Jiang, PhD Thesis

    Papers submitted or in press:

    • Jiang, J. Bobin, J.-L.Starck, “Joint Multichannel Deconvolution and Blind Source Separation”, SIAM Journal on Imaging Sciences, in press.
    • Margutti, R… Migliori, G. et al « Results from the first systematic survey of X-ray emission from Hydrogen-poor Super-luminous SNe » 2017, in press
    • Hopkins, A.M. …, Garsden, H. et al. “The ASKAP/EMU source finding data challenge”, PASA, in press.
    • Carbone, D. , Garsden, H. et al. « PySE: Software for Extracting Sources from Radio Images » , Astronomy & Computing, 2016, submitted
    • Girard, J., Jiang, M., Starck, J.-L., Corbel, S., et al., “Sparse spatio-temporal imaging of radio transients”, A&A, submitted, in rev.
    • Crosley, M.K. …Corbel, S. et al. “The Search for Signatures Of Transient Mass Loss in Active Stars», 2017, submitted.
    • Egron, E. …Corbel, S., Rodriguez, J. … et al. “Single-dish and VLBI observations of Cygnus X-3 during the 2016 giant flare episode”, MNRAS, 2017, 471, 2703.
    • Loh, A., Corbel, S., Dubus, G., “Fermi/LAT detection of a transient gamma-ray flare in the vicinity of the binary star DG CVn”, MNRAS, 2017, 467, 4462.
    • Coughlan, C.P., …. Corbel, S. et al. “A LOFAR Detection of the Low-mass Young Star T Tau at 149 MHz”, MNRAS,
    • Migliori, G., Corbel, S. et al.« Multi-band time lapse of the transient large-scale relativistic jet of XTE J1550-564 » 2017, MNRAS, 472, 141.
    • Margutti, R.… Migliori, G. et al « X-rays from the location of the Double-humpedTransient ASASSN-15lh », 2017, ApJ, 836, 25



    • Girard, J., Garsden, H., Starck, J.L., Corbel, S. … Bobin J. , “Sparse representations and convex optimization as tools for LOFAR radio interferometric imaging”, JINST Vol. 10 (C08013) August 2015 ArXiv:1504.03896v2
    • Migliori G. “The high energy view of young radio sources: X-ray and Gamma-ray observations”, Proceedings of the 5th Workshop on Compact Steep Spectrum and GHz-Peaked Spectrum Radio Sources
    • Migliori, G, « The high-energy view of young radio sources: X-ray and gamma-ray observations » 2016, AN, 337, 52.
    • Migliori G., “Tracing the high energy emission of γ-ray detected radio loud quasars”, Proceedings of the International Astronomical Union, Volume 10, Issue S313 (Symposium) September 2014, pp. 225-230, March 2015
    • Jiang, M., Girard, J.N., Starck, J.L., Corbel, S., Tasse, C. “Interferometric Radio Transient Reconstruction in Compressed Sensing Framework”, SF2A-2015: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics. Eds.: F. Martins, S. Boissier, V. Buat, L. Cambrésy, P. Petit, pp.231-236

    Conference proceedings:


    • Techniques for Radio Weak Lensing, Fall 2014, UK – invited talk (Girard)



    • LOFAR Sparse Image Reconstruction, International BASP Frontiers workshop, January 25-30, Villars- sur-Ollon, Switzerland, 2015 (Starck)
    • “Wavelets and Inverse Problems in Astrophysics”, 30 Years of Wavelets: Impact and Future, January 23/24, CIRM (Marseille), France, 2015 (Starck)
    • Black holes and related objects: universal coupling along the mass scale, MG 2015 Roma – invited talk (Corbel)
    • Relativistic Jets: Creation, Dynamics, and Internal Physics, Krakow, Poland, April 20-24, 2015 (Migliori)
    • “Tracing the High-energy Emission of γ-ray Radio-loud Quasars: the Case of RGB 1512+020” (poster Migliori)
    • 5th Workshop on Compact Steep Spectrum and GHz-Peaked Spectrum Radio Sources (Rimini, Italy, May 27-29, 2015) – “Young Radio Sources: X-ray and Gamma-ray properties” – invited review – (Migliori)
    • International Workshop on the missing data problem, Nice May 11, 2015 (Starck)
    • Magnetosphere of outer planets, , 2015, Atlanta, USA – invited talk (Girard)
    • Session Chair onAstronomy and Remote Sensing, Eusipco, Nice, September 3, 2015 (Starck)
    • NRAO Imaging Workshop, October 2015, Socorro, New Mexico, USA – talk (Girard)
    • Unmixing, Astroinformatics 2015, Dubrovnik, October 5-9, 2015 (Starck)
    • Sparsity and Inverse Problems in Astrophysics, International Meeting on High-Dimensional Data- Driven Science, (HD3-2015), Kyoto, December 14th -17th, 2015 (Starck)
    • Morphological Diversities in Astrophysics, The National Astronomical Observatory of Japan (NAOJ) , Tokyo, Japan, Dec 10, 2015 (Starck)



    • Learning and Blind Source Separation”, CosmoStat day on machine learning in Astrophysics, January, 22, 2016 (Starck)
    • « Radio interferometry Image Reconstruction», Cosmic Kick-off meeting, 2016 (Jiang)
    • « Joint Multichannel deconvolution and blind source separation», 23-26 May 2016, USA (Jiang)
    • ”2D and 3D mapping techniques”, Workshop on Cosmology with Maps, Astronomical Royal Society, Burlington House, February 12, London, 2016 (Starck)
    • “Low Complexity Models and Astrophysical Maps Reconstruction”, Statistical Challenges to Modern Astronomy VI, June 6-10, Pittsburg, 2016 (Starck)
    • “La Cosmologie face l’avalanche des données”, Workshop on Calcul intensif et deluge de données : de nouveaux outils pour les sciences astrophysique, Academie des Sciences, Paris, June, 2016 (Starck)
    • Journées de la SF2A, June 2016 (Poster, Girard)
    • Cosmology and its Data Flood Challenge”, star2016 : Journées de Statistique de Rennes, Oct. 2016 (Starck)
    • CALIM Workshop, October 2016, Socorro, New Mexico, USA – talk (Girard)
    • AGN 12, Napoli, Italy, September 2016 – talk (Migliori)
    • 6th Nepal meeting – Kathmandu, October 2016, – talk (Migliori)
    • 3GC4, November 2016, Port Alfred, South Africa –talk (Girard)
    • 7 years of MAXI: monitoring X-ray transients, Riken, Japon, December 2016 – invited talk (Corbel)



    • International BASP Frontiers workshop, January 2017, Switzerland – invited talk (Girard)
    • International BASP Frontiers workshop, January 2017, Switzerland – invited talk (Starck)
    • Microquasars: From Quiescence to outburst when microquasars go wild !, September 2017, France, Invited Talk (Corbel)
    • Microquasars: From Quiescence to outburst when microquasars go wild !, September 2017, France, Talks (Girard) + LOC
    • Microquasars: From Quiescence to outburst when microquasars go wild !, September 2017, France, Talks (Loh)
    • Microquasars: From Quiescence to outburst when microquasars go wild !, September 2017, France, Talks (Migliori)
    • Séminaire Migliori: “Back to the future: the large scale jets of XTE J1550-564” invited seminar at Nicolaus Copernicus Astronomical Center, 31 May 2017, Warsaw, Poland
    • Séminaire Migliori: ““Probing the physics of relativistic jets” invited seminar at Strasbourg Astronomical Observatory, 6 october, Strasbourg, France.
    • Journées PNHE, June 2017, France – invited talk (Girard)
    • Journées PNHE, June 2017, France – invited talk (Corbel)
    • Journées Transient TS2020, France – invited talk (Corbel)
    • ThunderKAT meeting, September 2017, Oxford, UK (Team Meeting)

    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)
    • Journée de l’Action Spécifique SKA-LOFAR – SF2A meeting – Nice -6 june 2012. SC + HG attended. talk by SC & HG (website here)
    • Techniques for Radio Weak Lensing meeting – Manchester – 6 to 7 october 2014 – Manchester. JLS + JG attended. talk by JG (website here)
    • Journée de l’Action Spécifique SKA-LOFAR – SF2A meeting – Toulouse – 5 june 2015. SC + MJ attended. talk by MJ (prepared by JG) (site website here)

    Contribution to Schools:

    • INFIERI à l’IN2P3 – Paris – 14 to 25 july 2014 – Lecture by JG – 23 Juillet (1h30), Radio Aperture synthesis as a practical example of sparse signal reconstruction – numerica hands-on session by François Lanusse (CosmoStat/AIM) (website here)
    • Large Ground-based 21st Century Radio Instrument: ALMA/NOEMA / SKA/LOFAR – CIEP Sèvres – 16 to 20 novembre 2015 ( here)
    • Nov 2015: International Young Astronomers School on Large Ground-Based 21st century radio instruments (ALMA/NOEMA, SKA/LOFAR/NenuFAR) (Corbel, Girard) + practical sessions
    • XXVI Canary Islands Winter School of Astrophysics, Instituto de Astrofisica de Canarias, Course on “Inverse Problems in Astrophysics”(6h Starck).
    • NASSP 2016 MSc course: writing, teaching and examination of chapter “The visibility space” + practical sessions (24h Girard)
    • Tutorials on Compressed Sensing / Machine Learning, Nice, France, September 2016 (Starck + CosmoStat team members).