From dual to binary supermassive black holes


Contact : astrid.lamberts@oca.eu

The study of dual active galactic nuclei (AGN) and supermassive black hole binaries (SMBHB), at parsec-to-kpc and sub-pc scale separation respectively, is among the current observational and theoretical astrophysics hottest topics. It provides unique insights into the dynamics of galactic mergers, the evolution of galaxies, the growth of SMBH and the (low frequency) gravitational wave signatures.

Dual AGN (pc to kpc separation) can be spatially resolved and several systems have been observed. On the contrary, SMBHB (at milli-parsec) are very difficult to resolve and search for spectroscopically (using the Doppler shift in emission lines, or looking for periodicities in the light curves), with only a handful of candidates currently identified. So far definitive smoking-gun signatures of SMBHB have not been yet established when compared to single AGN.

Binary SMBHs separated at milli-parsec are gravitationally bound and can be loud emitters of gravitational waves in the low-frequency ranges (PTA and LISA). Recently, three different PTAs, EPTA, PPTA and NANOGrav, have independently reported on evidence for the presence of a background of low-frequency gravitational waves in their pulsar timing data. This background could either result from the incoherent superposition of gravitational waves from a large number of sources at cosmological distances, from one or a few supermassive black hole binaries in the local Universe, or from the addition of all these contributions. In the future, PTAs might be able to detect individual sources of gravitational wave emission. The mergers of SMBHBs are expected to be the loudest sources for the gravitational wave observatory LISA.

Novel techniques, such as probing the broad line regions with IR interferometry (e.g., GRAVITY, GRAVITY+) or the wealth of time-domain data that LSST with the Rubin Telescope promise important progress for binaries, while JWST is discovering many candidate dual AGN even at high redshift. The VLTI, in its current status, can directly detect chromatic shifts in emission regions down to microarcsecond scales. This is actively being used to directly observe the broad line regions (BLR) of AGN for the first time. This presents an opportunity for SMBHB detection when the binary is on sub-parsec scales and the detection signatures with SMBHB separation is an active and young field spurred by the upcoming GW facilities and recent ongoing upgrades to the VLTI.

At the same time simulations, from circumbinary disc scale to cosmological scales are including the modeling of binary and dual AGN. Understanding the dynamics of massive black hole pairs and binaries is a challenging feat, but recent progress has nevertheless predicted substantial populations of dual AGN, while the population of observable binaries is expected to be smaller. There are now several predictions for the populations of binary and dual AGN within reach of telescopes and surveys, but it’s still unclear which signatures are actually observable. For instance, periodicities are predicted, but observationally the intrinsic variability of AGN may mimic or hide such periodic signatures. Probing the SMBH merging process from dual system to milli-parsec system is key to our understanding of the last stage of galaxy mergers and for the expected LISA detection rate. Simulations also suggest that many SMBH binaries are surrounded by matter and therefore should provide for electromagnetic signatures from radio to X-rays/gamma-rays.

This workshop aims at bringing together the French community working on dual AGN and binary SMBHs, gathering PNCG, PNHE and GDR “Ondes gravitationnelles”.

SOC: Lucas Guillemot, Astrid Lamberts, James Leftley, Anne-Laure Melchior, Delphine Porquet, Marta Volonteri

14h-14h30 : Mikel Falxa (invité)
14h30-14h45: P.A. Duverne "Simulations of LISA observations of gravitational waves"
14h45-15h: R. Mignon-Risse "The last electromagnetic breath of binary black holes"
15h-15h15 : P. Varnière "How to distinguish binary variability from single black hole"
15h15-15h30: V. Foustoul "A sample of good milliparsec separation massive black hole binaries"
15h30-16h: E. Bonnasieux (invité) : Characterising the spectral energy distribution of OJ287 and its kpc jet knots from the X-rays to the GHz and MHz radio bands
16h-16h30 : Pause café, (time to be confirmed)
16h30-17h : M. Habouzit (invitée)
17h-17h15: R. Delpach : "Hierarchical galaxy merger estimation using machine-learning algorithm and MUSE galaxy catalogue for massive black hole merger detection with LISA. "
17h15-17h30: J. Leftley " Optical interferometry of AGN for direct distance measurements to quasars and detection of binary black holes."
17h30-17h45: A. Toubiana "Constraining the formation and evolution of massive black holes with gravitational wave and electromagnetic observations"
17h45-18h: F. Marin "Is there a binary supermassive black hole system in J1430+2303?"
18h-18h15: A. Lafkih " Gravitation modifiée et LISA"


Authors Title Type File
Pierre-Alexandre DUVERNE - Alexis Coleiro - Floriane Cangemi - Raphaël Mignon-Risse - Peggy Varniere Multi-Messenger astronomy: Observational follow-up strategies during the LISA mission orale Abstract_SF2A_DUVERNE.pdf
Aoulad Lafkih Samy, Christophe Le Poncin Laffite, Marie-Christine Angonin, Nils A. Nilsson Mesurer des violations de l\'invariance de Lorentz à partir d\'ondes gravitationnelles et du formalisme SME orale Abstract _.pdf
Frédéric Marin Is there a binary supermassive black hole system in J1430+2303? orale SF2A_Marin_S14.pdf
Foustoul V, Webb N, Mignon-Risse R, Kammoun E, Volonteri M, Dong-Páez C.A A sample of good miliparsec separation massive black hole binaries orale Foustoul_Abstract.pdf
Peggy Varniere, Fabien Casse, Fabrice Dodu and Lena Arthur Sculpting the outer disk of a super massive black-hole with a secondary disruptor poster abstract_SF2A_outer_edge.pdf
Peggy Varniere, Raphael Mignon-Risse and Fabien Casse How to distinguish binary black-hole variability from single black hole orale abstract_SF2A_BBHvariability_1.pdf
Raphaël Mignon-Risse (NTNU, CNES/APC), Peggy Varniere, Fabien Casse, Alexis Coleiro, Pierre-Alexandre Duverne (APC) The last electromagnetic breath of binary black holes orale abstract_S14.pdf
James Leftley, Romain Petrov, Astrid Lamberts, Nicole Nesvadba Optical interferometry of AGN for direct distance measurements to quasars and detection of binary black holes orale SF2A_S14_Leftley.pdf
A. Toubiana, L. Sberna, M. Volonteri, E. Barausse, J. Gair, S. Babak, E. Berti, Kaze W. K. Wong, S. Marsat, S.Taylor Constraining the formation and evolution of massive black holes with gravitational wave and electromagnetic observations orale abstract_7.pdf
Etienne Bonnassieux, Hrishikesh Shetgaonkar, Matthias Kadler Characterising the spectral energy distribution of OJ287 and its kpc jet knots from the X-rays to the GHz and MHz radio bands invite SF2A_abstract (1).pdf