Missions

The postdoc will be the active center of the IP2I gravitational waves joint experimental and theoretical activities, with a strong involvement in parameter estimation activities within the LIGO-Virgo-KAGRA collaborations.

Activités

The postdoc will join the Virgo Collaboration (and the LIGO-Virgo-KAGRA - LVK - network), where they will participate to the analysis of merger signals from the fourth observing run. Within the LVK, the postdoc will be mainly involved in the Parameter Estimation working group and will help the IP2I Virgo group to gain visibility on new research subjects in the collaboration.
They will also join the IP2I theory group, where they will exploit the parameter estimation expertise to perform phenomenology studies on analyses of gravitational waves data for constraining the neutron stars equations of state. For neutron star physics, they will be helped by the local expertise in the theory group, which will provide nuclear equations of state in a format readable by the numerical simulations. Eventually, and depending on the skills of the selected candidate, they will perform numerical simulations in HPC environments of compact object mergers, in particular of binary black holes, of binary neutron stars and of binaries composed of one black hole and one neutron star.

Compétences

The candidate must hold a PhD in physics or astrophysics (to be defended before December 1st, 2023). They are expected to have knowledge on common programming languages such as Python or C++. Some experience with analysis of data from gravitational wave interferometers and Bayesian inference is highly appreciated, as this will be the central activity during the postdoc. Candidates with theoretical background in general relativity, nuclear matter or cosmology, but willing to learn about GW data analysis can also apply. Any knowledge about numerical general relativity and HPC environments is also appreciated, although not requested.

Contexte de travail

Since the discovery of gravitational waves (GWs) in 2015, LIGO and Virgo have observed numerous gravitational wave signals originating from the mergers of compact objects such as black holes or neutron stars. While confirming directly a 100-year old prediction of general relativity, the observations of gravitational waves offer new ways to observe the Universe in absence of, or in a complementary way to, electromagnetic counterparts, together with the possibility to test the properties of ultra-dense nuclear matter or general relativity. In particular the LIGO-Virgo-KAGRA experimental program is an ambitious way to better understand our Universe by detecting the extremely faint GW emitted by compact objects.

At IP2I, two groups are active in the context of gravitational waves: a theory group, which simulates mergers of binary black holes and neutron stars in order to find constraints on black hole and neutron star models and also study the cosmological phase transitions (composite Higgs models) and its impact on the stochastic background; an experimental group, which contributes to the analysis of the LIGO-Virgo-KAGRA data in particular for the search and characterization of signals emitted by the coalescences of black holes and neutron stars. The group contributed strongly to this topic during the data taking in 2019-2020, which made it possible to record the signals from dozens of new sources, and is involved in the new observation period that started on May 2023. The theory and experimental groups at IP2I collaborate for studying the implication of GW observations for nuclear models, and investigating the perspectives of multi-messenger observations for light primordial black hole mergers, a topic of increasing interest and still poorly studied in the literature. The latter project implies new challenges for the simulation of the compact object coalescences, exploiting numerical relativity for the GW emission, and hydrodynamics simulations requiring a deep understanding of the compact objects and possible matter effects for the EM signal. The two groups have already published studies as: [1] on the possibility to clearly disentangle gravitational waves emitted by light primordial black hole mergers from the ones emitted by neutron star mergers ; [2] on the implications of the 2017 BNS GW observation on the NS equation of state if it were detected with the nominal sensitivity of the current O4 run of the collaboration.

Contraintes et risques

none

Informations complémentaires

Requested documents for application :

Applicants must email a CV, a statement of interest, a letter of recommendation and contact details for 2 references to v.sordini@ip2i.in2p3.fr before September 20, 2023. The contract is 2 years long, and must start before December 2023.

Candidates on the short list will be informed end of September and interviewed in early October.


[1] J.-F. Coupechoux, A. Arbey, R. Chierici, H. Hansen, J. Margueron and V. Sordini ; Discriminating same-mass neutron stars and black holes gravitational waveforms ; Phys. Rev. D 105, 064063

[2] J.-F. Coupechoux, R. Chierici, H. Hansen, J. Margueron, R. Somasundaram and V. Sordini ; Impact of O4 future detections on the determination of the dense matter equations of state ; Phys.Rev.D 107 (2023) 12, 124006

Candidates must apply via the CNRS job portal.