São Paulo Research Group meetings in Astro & Cosmo

Next meeting: November 28, 2025

São Paulo, Brazil

Venue: Instituto Principia

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ICTP-SAIFR is promoting monthly one-day meetings of the São Paulo community working in the related areas of Cosmology/Astrophysics/Astroparticles/Gravity to be held at the Instituto Principia. The idea is to have a light schedule, with a couple of talks and plenty of time for discussion. The main purpose is to explore synergies of the different groups.
The activity will be transmitted online by Zoom.
Next Meetings: November 28

If you want to receive mailings about the meetings, click HERE.

Organizers:

  • Raul Abramo (IFUSP)
  • Chee Sheng Fong (UFABC)
  • Rogério Rosenfeld (IFT-UNESP)
  • Riccardo Sturani (IFT-UNESP)

 

Announcement:

Invited Speakers

  • 10:00 Rainer Menote (UFES): CosmoDC2_BCO: A Gateway to Multi-Messenger Cosmology

In this talk, I introduce CosmoDC2_BCO, a synthetic multi-messenger catalog developed by embedding GW events and their EM counterparts into the LSST-DESC CosmoDC2 simulation. The framework includes source parameters, SNRs, parameter uncertainties, sky-localization areas, and kilonova magnitudes across LSST bands. I then present analyses that use these datasets to forecast GW–EM detection efficiencies, parameter degeneracies, and the cosmological reach of future third-generation detectors. Together, these results demonstrate how realistic end-to-end simulations can advance standard-siren cosmology toward the precision era.

  • 11:15 Tabata Aira (INPE): Exploring the Origins of Glitches in the LIGO Detectors Using Machine Learning Techniques
Gravitational waves are ripples in spacetime produced by some of the most energetic astrophysical events in the universe. Detecting them requires extremely precise instruments, such as the LIGO interferometers, which are also sensitive to a wide range of instrumental and environmental noise. Among these, glitches are short, non-Gaussian noise transients that can either mask or mimic genuine gravitational-wave signals, and understanding their origin is crucial to improving data quality and detector reliability. In this talk, I will discuss how these noises affect data analysis and detector characterization, and how auxiliary channels (sensors that monitor the interferometers) can be used to identify their sources. Then, I will describe how machine learning techniques are applied to glitches to reveal morphological similarities and provide insights into their possible causes. During the first part of LIGO’s fourth observing run, for instance, at the Livingston observatory, we found that the most common glitches were seasonal and associated with ground motion, while Hanford exhibited a predominance of glitches linked to instrumental factors.
  • 14:00 Germán Lugones (UFABC): New Stable Branches of Compact Stars Beyond the Maximum-Mass Turning Point

Compact stars lying beyond the maximum-mass turning point on the mass versus radius curve are usually regarded as dynamically unstable, based on the assumption that any Lagrangian fluid perturbation preserves instantaneous beta equilibrium. However, we show that when chemical equilibrium cannot be re-established during disturbances, previously overlooked sequences appear in models of purely hadronic stars, hybrid hadron–quark stars, and self-bound quark stars. Along these extended branches, linear-response calculations yield positive squared eigenfrequencies for the fundamental oscillation mode, confirming stability well past the classical mass peak. We discuss the microscopic mechanisms that suppress the growth of perturbations. Finally, we outline potential observational signatures and astrophysical implications of such configurations.

 

 

Previous Meetings

October 3, 2025
  • 11:15 Pedro Henrique Rossetto (USP): Continuous Gravitational Waves from Neutron Stars Magnetic Mountains – Video
  • 14:00 Joaquin Armijo (USP): Cosmological constraints from the first year data of the Hyper Suprime-Cam – Video
August 29, 2025
  • 11:00 Alexandre Le Tiec (IFT-UNESP — CNRS): What’s in a Name: the Anthropocene – Video
  • 14:00 Fernanda Lima (IF-USP): Ultra-light dark matter and power spectra emulators – Video
  • 15:15 João Ferri (IF-USP): What can we gain from small scales in shear analysis? A comparison between Fourier and Real spaces. – Video
June 13, 2025
  • 10:00 Walter Riquelme (IFT-UNESP): Imprints of Large-Scale Structures in the Anisotropies of the Cosmological Gravitational Wave Background – Video
  • 11:15 Ricardo Medina (UFEI): Determining self-force corrections to the equation of the separatrix of a Schwarzschild black hole – Video
  • 14:00 Gustavo Figueiredo Severiano Alves (IF-USP): Chasing Serendipity: Tackling Transient Sources with Neutrino Telescopes – Video
May 9, 2025
      • 10:00 Pedro Bittar (USP): Baryogenesis just around the corner: Generating the matter asymmetry at or below the weak scale – Video
      • 11:15 Rodrigo Voivodic (Donostia Int. Physics Cent. San Sebastian & IFT-UNESP): Likelihoods – Video
      • 14:00 Gustavo Henrique dos Santos (UFABC): ACT Constraints on Low Scale Inflation and a Mechanism for Vector Dark Matter Production – Video
April 4, 2025

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São Paulo Research Group meetings in Astro & Cosmo

Additional Information

How to reach the Principia Institute: The meeting will be held in the first-floor auditorium of the Science Center at Principia Institute located at Rua Pamplona, 145 near the Trianon-Masp metro station.