Astrophysics Brown Bag Lunch Talk 10/4/2021: Speakers: Dhruba Chowdhury (Yale) And Hayley Macpherson (Cambridge)

Monday October 4, 2021 12:00 pm
TBA in person or via Zoom

Monday, October 4 

12:00 – 12:30pm

Dhruba Chowdhury (Yale)

Constraining Dark Matter through Gravitational Heating and Cooling Processes

Abstract:  Fuzzy Dark Matter (FDM),  consisting of ultralight bosons, is an intriguing alternative to Cold Dark Matter. Using high-resolution numerical simulations corresponding to a particular boson mass, I will discuss the various sources of gravitational potential fluctuations in an FDM halo and present results from novel studies demonstrating how they dynamically heat nuclear objects (e.g., central star clusters and supermassive black holes) and galaxies. Generalizing these results for other halo and boson masses and comparing them with observations (such as galaxy size-age relation, measured offsets of supermassive black holes and nuclear star clusters from the centers of their host galaxies) will be able to constrain the boson mass.

Short Bio – I am a final year PhD student in Astronomy at Yale University. I have broad interests in dark matter physics, galaxy formation, and dynamics and have worked/work on topics related to ultra diffuse galaxies, globular clusters, and fuzzy dark matter. Email:



12:30 – 1:00pm

Hayley Macpherson (Cambridge)

Low-redshift cosmic anisotropy in simulations using numerical relativity

Abstract: Most cosmological data analysis today relies on the Friedmann-Lemaitre-Robertson-Walker (FLRW) geometry, providing the basis of the current standard cosmological model. Within this framework, interesting tensions between our data and theoretical predictions are emerging. Cosmological analysis outside of the exact FLRW models is therefore timely. I will discuss our recent work using a generalised low-redshift analysis framework with no assumptions of homogeneity or isotropy. We explore potentially important low-redshift anisotropies in effective cosmological parameters of the luminosity-distance redshift relation in cosmological simulations using numerical relativity, i.e., free of any kind of background cosmology. Our results suggest the consideration of low-redshift anisotropy in cosmological analysis could be important for drawing correct conclusions about global properties of the Universe.

Bio: I am currently a Herchel Smith fellow at DAMTP at the University of Cambridge, UK. I received my PhD from Monash University in Melbourne, Australia, in 2019. My main research area is in cosmological simulations using numerical relativity, though I am also dipping my toes into cosmological data analysis and gravitational waves. Email:


Event Contact

Josh Borrow