Name: Multimessenger astronomy and source populations: joint WG meeting, GdR Gravitational Waves
Start: 2021-03-10T13:55:00+01:00
End: 2021-03-11T17:00:00+01:00
Location: Webinar

mercredi 10 mars
- mer. 10 mars
- jeu. 11 mars
- Massive black holes
  
  Président de session: Irina Dvorkin (Institut d'Astrophysique de Paris)
  - 1
    
    Massive black hole astrophysics with gravitational waves
    
    I’ll review the main astrophysical processes shaping the merger rate and the distributions of properties of merging massive black holes in the gravitational wave domain (LISA and PTAs), highlighting uncertainties and unknowns. Turning the question around, gravitational waves can inform us on poorly known processes in the cosmic history of massive black holes.
    
    Orateur: Marta Volonteri
    
    MMPop_MV.pdf
  - 2
    
    Discriminating between different scenarios for the formation and evolution of massive black holes with LISA
    
    Different scenarios for the formation and evolution of massive black holes lead to different predictions for the population of massive black holes in the Universe. By reverse engineering the problem, we can use LISA observations to discriminate between different scenarios. However, the Universe is unlikely to be described by a single model. This can be accounted for by introducing mixing fractions between the different models.
    In this talk, I will present simulated results for the inference of the mixing fraction between two models from LISA observations using a hierarchical Bayesian framework. I will also discuss of the robustness of this approach by using different models to generate the simulated data.
    
    Orateur: Alexandre Toubiana (APC/IAP)
    
    toubiana_mbhs_pop.pdf
- 14:48
  
  Pause
- Multi-messenger astrophysics
  
  Président de session: Olivier GODET (IRAP)
  - 3
    
    Electromagnetic observations of multi-messenger sources: successes and challenges
    
    Orateur: Nial Tanvir (University of Leicester)
    
    Tanvir_GdR_GW_2021.pdf
  - 4
    
    Binary neutron star mergers as multimessenger sources: population prospects and applications
    
    The binary neutron star merger GW170817 was a gravitational-wave event rich with electromagnetic counterparts: a short gamma-ray burst, a kilonova, afterglow radiation from the relativistic outflow and—if further data confirms—afterglow radiation from the slowly expanding nebula. However, this richness is due to the proximity and favorable inclination of this historic event. During upcoming gravitational-wave observing runs, which electromagnetic counterparts should we expect to observe? We will focus on the kilonova and the relativistic afterglow and rely on state-of-the-art modelling for the emission and detection of these signals. For various gravitational-wave and electromagnetic follow-up instrument sensitivities, we will predict detection rates and brush a portrait of the multimessenger population to come: distances, inclination angles, magnitudes and afterglow flux levels, etc. Finally, we will present the insight that this population model provides on the viability of using these counterparts for multimessenger cosmology, and how it allows to constrain the sources detected during the latest O3 run of the Ligo-Virgo-Kagra network.
    
    Orateur: Raphaël Duque (Institut d'Astrophysique de Paris)
    
    GdR_MM.pdf
  - 5
    
    Fink: harnessing LSST’s optical time-domain data to study extreme astrophysical events
    
    In the next decade, the Vera Rubin Observatory Legacy Survey of Space and Time (LSST) will provide an unprecedented volume of optical data of the southern sky. Its public alert stream will communicate the detection of millions of potential transient objects every night. The key to use this stream for GW and high-energy science is to be able to select the small number of extreme astrophysical transients within this large dataset. I will introduce Fink, a broker developed on high-end technology and designed for fast and efficient analysis of big data streams. Fink enables the selection of promising transients by providing preliminary classifications and combining information from multiple channels (multi-messenger and multi-wavelength surveys and catalogues). Within minutes, Fink is able to communicate these candidates to teams and follow-up facilities. Fink opens a new way of combining data from LSST and other time-domain surveys and will be key to study the most extreme astrophysical transients in the next decade.
    
    Orateur: Anais Moller (CNRS / LPC Clermont)
    
    Fink_Multimessenger_GdRGW.pdf
  - 6
    
    Monitoring the transient hard X-ray sky with 3UTransat
    
    We present the 3UTransat space mission under study at IRAP for the surveillance of the hard X-ray sky with a constellation of cubesats.
    The talk will quickly go through the science goals of the mission, the design of the satellites and constellation, the preliminary results of on-going phase-0 study at CNES and science simulations at IRAP, and the planned agenda for the development of the mission, which aims at flying 3 prototypes during the run O5 of the Advanced LIGO, Advanced Virgo and KAGRA collaborations.
    
    Orateur: Jean-Luc ATTEIA (IRAP - CNRS/UPS/CNES)
    
    210310_3UT_GWmeeting.pdf
- 7
  
  Discussion
jeudi 11 mars
- mer. 10 mars
- jeu. 11 mars
- Stellar binaries
  
  Président de session: Prof. Sylvain Chaty (Université de Paris, CEA)
  - 8
    
    O1/O2/O3 events fro LIGO/Virgo: astro perspective
    
    Is there one or many formation channels to BH-BH mergers detected by LIGO/Virgo? Have we learned anything about stellar evolution from binary BH detections? Do we really need LIGO/Virgo anymore, or the job is done? ...
    
    Orateur: Chris Belczynski
    
    talk2021.pdf
  - 9
    
    StarTrack predictions of the stochastic gravitational-wave background from compact binary mergers
    
    Nowdays we are able to resolve more and more compact binary merger events as our detector sensitivities improve. However the detected sources are loud and close events, suggesting a large number of non-resolved binary mergers participating to a background. I will present this background computed from the StarTrack population synthesis in a large frequency range (1$\mu$Hz - 2kHz). For the first time the calculation includes the redshift and orbital evolution of binary systems as well as new merger channels : the stars from population III and the non-merging systems population. For several detector networks scenario (2G : LIGO, Virgo, KAGRA; 3G : Einstein Telecope, Cosmic Explorer and the space antenna : LISA) we compute the residual background by substracting the corresponding resolved sources and evaluate its detectability.
    
    Orateur: Carole Perigois
    
    Gdr_11_03_20.pdf
  - 10
    
    The importance of population assumptions for gravitational-wave dark sirens cosmology
    
    Gravitational waves (GWs) from compact binary coalesce are cosmological standard sirens and provided with an electromagnetic (EM) counterpart can be used to probe cosmology. Unfortunately, with the rapid increase of GW detector sensitivity, it will be less and less likely that GW sources are accompagnied by an EM counterpart. Furthermore, the completeness of galaxy catalogs rapidily decreases and the statistical association of GW and EM data is less and less effective. In this talk, I will show how population assumptions on the formation channel for binary black holes can be used to study GW-based cosmology. I will discuss how population assumptions can impact, and possibly introduce systematics in GW cosmology and how it is possible by collecting more and more GW events to jointly infer population properties and cosmology.
    
    Orateur: Konstantin Leyde (APC Université de Paris)
    
    presentation_dark_siren_analysis_gdr_LEYDE.pdf
- 15:08
  
  Pause
- Source catalogues and cross-identifications
  
  Président de session: Gilles THEUREAU (GEPI, Paris Observatory and LPC2E, CNRS-Orléans)
  - 11
    
    The Gaia stellar binary population
    
    The Gaia DR3 release, planned for mid 2022, expects to present a large range of new kind of data, among which Non-Single Stars, detected through the astrometric, photometric and spectroscopic instruments, i.e. a Catalogue of astrometric, eclipsing or spectroscopic binaries, plus combined solutions. We will give a summary of the current Gaia capabilities and limitations that are currently foreseen.
    
    Orateur: Dr Frédéric Arenou (CNRS/GEPI, Observatoire de Paris)
  - 12
    
    X-ray active lifetime of BH+O binaries - implications for natal kicks of black holes
    
    Within a few kiloparsecs around the Sun, we have access to a complete sample of ~20 Wolf-Rayet+O-star binaries. On the other hand, only one BH+O binary, Cygnus X-1, is detected in the solar neighbourhood thanks to the X-ray emission produced by the wind accretion process. If the former binaries are the progenitors of the latter, this discrepancy can be explained either by large natal kicks at BH formation which disrupted most binaries or by short X-ray active lifetimes.
    
    In this talk, I will present new results on the fraction of time BH+O binaries spend emitting X-rays at a detectable level. We evolved the sample of observed Wolf-Rayet+O binaries up to the collapse of the Wolf-Rayet star into a BH. Assuming a zero natal kick, we continue the evolution of the binary and monitor the moment when conditions are matched for a formation of a wind-captured disk around the BH and for an X-ray emission detectable within a few kiloparsecs. We find that the formation of accretion disk is very sensitive to the wind velocity of the O star companion. With revised values for the wind speed thanks to an accurate description of the line-acceleration, we find little to no X-Ray active lifetime for the BH+O star systems. It implies a large reduction in the predicted number of observable wind-fed high-mass X-Ray binaries hosting a BH and an O-star compared to what was recently found by Vanbeveren et al. (2020). High natal kicks or direct collapse of the Wolf-Rayet star into a neutron star are thus not necessary to reproduce the scarcity of systems like Cygnus X-1 in the solar neighbourhood.
    
    Orateur: Ileyk El Mellah (IPAG - CNRS)
  - 13
    
    The LOFAR Two Meter Sky Survey(s)
    
    The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168MHz survey of the entire northern sky for which observations. LoTSS has a source density approximately 10 times higher than the most sensitive existing very wide-area radio-continuum surveys and we have already catalogued over 3,000,000 radio sources making it the largest survey to date. In this talk I will describe the current status of the survey and outline what can be expected from LoTSS in the near future.
    
    Orateur: Cyril Tasse (Observatoire de Paris)
    
    LoTSS_110320.pdf
- 14
  
  Discussion