Astrophysics Brown Bag Lunch Talk 1/31/2022: Speakers: Jan Scholtz (Cambridge University) And Mark Ivan Ugalino (UMass Dartmouth)

Monday January 31, 2022 12:00 pm
via Zoom

Monday, January 31, 2022

12:00 – 12:30pm

Jan Scholtz, Cambridge University

Do powerful AGN really rapidly suppress star formation?

Abstract: Cosmological simulations predict that AGN feedback is responsible for suppressing the growth of massive galaxies and is believed to be a key process in reproducing basic properties of galaxies (such as luminosity function, the black hole–spheroid relationships, galaxy sizes, galaxy colour bi-modality). There have been a number studies (Cano Diaz et al 2012, Cresci et al 2015, Carniani et al 2016 ) that have suggested an anti-correlation between ionised outflows (traced with [O III] in IFU data) and star formation (traced using H-alpha in IFU data) in the host galaxies of high-luminosity AGN. However, the H-alpha line as a tracer of star formation is susceptible to obscuration by dust, therefore this anti-correlation between star formation and outflows might be caused by dust obscuration, rather than star-formation suppression. We have utilised the largest sample of AGN observed with IFU at high redshift (the KASHz survey) to select AGN with high-quality IFU data, to map both the H-alpha and [OIII] kinematics, and that also have ancillary ALMA (870 micron) data, to map the dust. Using this unique sample of AGN, with a range of luminosities, as well as a new ALMA data for the quasars mentioned above, I will re-investigate the evidence for rapid suppression of star formation by AGN outflows and answer the question: Do powerful AGN really rapidly suppress star formation?

Bio: have finished my PhD at Durham in 2019 and I started a postdoc in Sweden at Chalmers University with prof. Kirsten Knudsen. In September 2021 I have moved to KICC at Cambridge to join prof. Roberto Maiolino’s group.



12:30 – 1:00

Mark Ivan Ugalino (UMass Dartmouth)

Turbulently-driven deflagration-to-detonation transition in near-Chandrasekhar mass white dwarfs

Abstract: Type Ia supernovae (SNe Ia) are luminous transients that serve as cosmological standardizable candles.  Normal SNe Ia enable high-precision measurements of both the Hubble constant and cosmic acceleration, yet their stellar progenitors and explosion mechanism remain an area of active investigation. All major explosion channels for normal SNe Ia share in common a transition between slow deflagration burning and a rapid detonation. In this talk, I will discuss a new, laboratory-validated turbulently-driven deflagration-to-detonation transition (tDDT) mechanism. I will present full-star 3D simulations of near-Chandrasekhar mass white dwarfs incorporating the tDDT mechanism, and help shed light on this classic stellar transient scenario.

Bio: Mark is currently a second-year PhD student at the University of Massachusetts Dartmouth. He works on large-scale computational simulations of type Ia supernovae, and is generally interested in turbulence, high-energy astrophysics, and numerical methods. He obtained his undergraduate and master’s degree from the University of the Philippines Diliman, where he studied Newtonian and relativistic prescriptions of dynamical friction in the context of extreme mass ratio inspirals and planet formation.


Event Contact

Josh Borrow