Séminaire

Cosmic String Interpretation of NANOGrav Pulsar Timing Data and its impact on Cosmic Archaeology with Gravitational Waves

The NANOGrav Collaboration has recently reported strong evidence for a stochastic common-spectrum process, which we interpret as a SGWB in the framework of cosmic strings. The possible NANOGrav signal would correspond to a string tension Gμ∈(4×10^{−11},10^{−10}) at the 68% confidence level, with a different frequency dependence from supermassive black hole mergers.

Gravitation seminar: Chiranjib Mondal, A flexible model for neutron star equation of state from nuclear physics

The gravitation group is inviting you to the following seminar:

A flexible model for neutron star equation of state from nuclear physics

Development in multi-messenger astronomy over the last few years has
opened new facets to the hadronic matter at densities beyond our terrestrial
reach. It provides new constraints to the theories of nuclear physics, where an
absolute energy density functional is desired from ab-initio mechanisms. Under
the realm of general relativity, there is a one-to-one correspondence between

New eyes on the X-ray sky: First Results from eROSITA on SRG

The emergence of the three-dimensional structure of the cosmic web over
the history of the Universe displays very distinctive features when
observed in X-rays, where both the most massive collapsed structure
(clusters of galaxies) and the most energetic events in the life of
galaxies (AGN and Quasars) reveal themselves unambiguously. The next
generation of wide-area, sensitive X-ray surveys designed to map the hot
and energetic Universe will be heralded by eROSITA (extended ROentgen

Seminar of Philosophy of Science: Method-driven experiments and the search for dark matter


We are organising a cycle of seminars of philosophy of science at APC.
During 30 min, philosophers will present their research on a topic related to the themes of research of the laboratory. The presentation will be folllowed by a 30-min discussion between the audience and the speaker.
The event is open to all APC members, external members can attend on request.
A zoom link is communicated by email for the ones who wish to attend remotely.


A numerical approach to stochastic inflation and primordial black holes

Primordial black holes are a dark matter candidate, which may originate from strong perturbations created during inflation. These perturbations can be studied using the formalism of stochastic inflation. I present a numerical approach to this problem, where the stochastic dynamics is solved by generating a large number of random realizations. This makes it possible to go beyond analytical approximations and take into account additional effects such as backreaction between the perturbations and the background.

From pulsars to supermassive black holes and gravitational waves in between

Pulsar Timing Arrays (PTAs) aim to detect nHz gravitational waves (GWs) from supermassive black hole binaries (SMBHBs). This is done by looking for correlated variations of the Time of Arrivals (TOA) across an array of ultra-stable millisecond pulsars. Comparing the predicted TOAs from our timing model against the measured TOAs gives us the residuals. These contain the imprint of GWs, but also other effects and sources of noise processes.

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