Our last AstroParticle Lunch meeting of the year will be held tomorrow (Friday, December 6th), starting at 11:30 am (EST) in Price Place (PRB) and on Zoom.
We are excited to host three guest speakers this week:
- Dr. Stephan Meighen-Berger, Postdoctoral Fellow at University of Melbourne and CCAPP Affiliate Fellow.
- Chingam Fong, PhD student at The Chinese University of Hong Kong.
- Hector Afonso Cruz, PhD student at Johns Hopkins University (joining via Zoom).
Here are the titles and abstracts of the talks:
Dr. Stephan Meighen-Berger
Title: Extending the Dark Matter Reach of Water Cherenkov Detectors using Jupiter
Abstract: We propose the first method for water Cherenkov detectors to constrain GeV-scale dark matter (DM) below the solar evaporation mass. While previous efforts have highlighted the Sun and Earth as DM capture targets, we demonstrate that Jupiter is a viable target. Jupiter’s unique characteristics, such as its lower core temperature and significant gravitational potential, allow it to capture and retain light DM more effectively than the Sun, particularly in the mass range below 4 GeV where direct detection sensitivity diminishes. Our calculations provide the first sensitivities to GeV-scale annihilating DM within Jupiter using neutrino detectors, showing that these surpass current solar limits and direct detection results.
Chingam Fong
Title: The Role of Corona Field in Solar Gamma Ray, Revealed by Simulation
Abstract: The Sun shines bright in gamma rays. The current leading theory is that it comes from cosmic ray interaction in the Sun's atmosphere. In this talk, I will go through my current work, in which we use Geant4 simulation to study the propagation of cosmic ray in different solar coronal field models and subsequent gamma ray production.
Hector Afonso Cruz
Title: The First Billion Years in Seconds: An Effective Model for the 21-cm Signal with Population III Stars
Abstract: In the next few years, observations of the 21-cm signal will open a window to the cosmic dawn epoch, when the first stars formed. It is conventional to interpret these observations through semi-numerical or hydrodynamical simulations, which are often computationally intensive and inflexible to exotic cosmological or astrophysical effects. I will present a new approach to predict the 21-cm global signal and fluctuations in the presence of PopIII stars in seconds. PopIII stars, residing in low-mass molecular-cooling halos, are highly sensitive to feedback, especially from H2-dissociating Lyman-Werner radiation and dark matter-baryon relative velocities. To bypass expensive numerical simulations, we develop an effective prescription of the star formation rate density in the presence of PopIII stars. Our method recovers the full nonlinear distributions of radiative fields that determine the 21-cm signal including anisotropic feedback. I will show how PopIII stars impact the 21-cm global signal and power spectrum across cosmic time and at different distance scales. I will also highlight how the spatial modulation of the relative velocities induces Velocity Acoustic Oscillations in 21-cm power spectra, providing us with a new and robust cosmological standard ruler. Our public code, Zeus21, can predict 21-cm observables in seconds, presenting a meaningful first step towards rapid precision astrophysics and cosmology in the first billion years.
After this meeting, AstroParticle Lunch will resume with the start of the spring semester in January. Wishing you all happy holidays and a wonderful new year!