Astrophysics seminars are held at 1:30 PM on Thursdays in room 401, with refreshments to follow in room W332. Departmental colloquia are at 10:30 AM on Wednesdays in the Physics Lecture Hall. Special dates and/or times are noted in bold in the table below.


Date/Time Location Speaker Title Hosts
Thu Jan. 24
1:30 PM
Serin 401 TBA TBA TBA
Thu Jan. 31
1:30 PM
Serin 401 Amiel Sternberg (Tev Aviv University, Flatiron Institute, Max Planck Institute for Extraterrestrial Physics) The Atomic to Molecular (HI-to-H2) Transition in Galaxy Star-Forming Regions
The atomic to molecular hydrogen (HI-to-H2) phase transition is of fundamental importance for star-formation and the emergence of chemical complexity in the interstellar medium of galaxies. I will present an overview, and discuss recent theoretical studies, numerical and analytic, of the HI-to-H2 transition in irradiated systems, with applications to the multi-scale behavior observed in star-forming galaxy disks from low- to high-redshift.
Andrew Baker
John Wu
Thu Feb. 7
1:30 PM
Serin 401 Phil Chang (U. Wisconsin, Milwaukee) TBA TBA
Thu Feb. 14
1:30 PM
Serin 401 TBA TBA TBA
Thu Feb. 21
1:30 PM
Serin 401 Elisabeth Mills (Brandeis) The Journey or the Destination: Isolating the Origin of the Physics Driving Gas Conditions in Galaxy Nuclei
Centers of galaxies are some of the most extreme objects in our universe: hosting starbursts and active supermassive black holes that can launch jets and winds far outside the compact galaxy nucleus. While there are relics of an active past in the center of our own Milky Way, at present it does not exhibit any of this activity. However, the central 300 parsecs of our Galaxy does contain a sizable reservoir of molecular gas that is the fuel for future star formation and black hole accretion. Constraining the physical conditions of this gas is critical for understanding how this reservoir will evolve to influence future activity in the Milky Way’s nucleus. Determining the origin of these conditions is also key to determining whether the same physics that govern gas conditions in this region can help us interpret more distant and active galaxy nuclei. I will present the results of my recent work following the changes in physical properties of this gas as it approaches the black hole; increasing in temperature, density, and turbulence, while largely resisting the onset of star formation. This work provides evidence that the extreme gas conditions in this region are driven largely by infall processes: the journey it takes to reach the central parsecs, rather than the energetic phenomena (supernovae, cosmic rays, massive star winds, UV radiation, and occasional X-ray flaring) encountered at its destination. However, as our Galactic center is relatively inactive, the next challenge is determining the extent to which the understanding gained from a detailed study of this region can be applied to more active systems. I will end by discussing work underway to double my sample size of galaxy nuclei by making parsec-scale observations of the ionized and molecular gas in the center of NGC 253, a nearby galaxy with an order of magnitude more star formation. Comparison of these two galaxy centers will isolate the gas conditions that both govern and are influenced by a nuclear starburst, and allow the definition of local templates for understanding the gas physics in these regions.
Andrew Baker
Thu Feb. 28
1:30 PM
Serin 401 Wolfgang Kerzendorf (NYU/Michigan State) TBA TBA
Thu Mar. 7
1:30 PM
Serin 401 Tina Peters (Toronto) TBA Eric Gawiser
Thu Mar. 14
1:30 PM
Serin 401 Karen Masters (Haverford) TBA TBA
Wed Mar. 27
10:30 AM
PLH Gabriela González (LSU/LIGO)
Robbins Lecture
TBA Matthew Buckley
Thu Mar. 28 Serin 401 NO SEMINAR THIS WEEK
Thu Apr. 4
1:30 PM
Serin 401 Senior Honors Talks TBA TBA
Thu Apr. 11
1:30 PM
Serin 401 Vivienne Baldassare (Yale) Searching for Active Galactic Nuclei in Low-Mass Galaxies
The population of massive black holes (BHs) at the centers of nearby low-mass galaxies provides some of the best observational constraints on the masses of “black hole seeds” at high redshift. Furthermore, while BHs are ubiquitous and well-studied in Milky Way-sized and larger galaxies, relatively little is known about the population and properties of BHs in smaller galaxies. I will discuss recent observational efforts to find accreting BHs in low-mass galaxies via an array of multi-wavelength techniques, concentrating on searches using optical spectroscopy and optical photometric variability. I will also describe the multi-wavelength properties of active galactic nuclei in low-mass galaxies and discuss how they compare to more massive systems. Finally, I will discuss the properties of the active dwarf galaxy RGG 118, host to the smallest reported nuclear black hole.
TBA
Thu Apr. 18
1:30 PM
Serin 401 Jennifer Barnes (Columbia) TBA TBA
Thu Apr. 25
1:30 PM
Serin 401 Evan Schneider (Princeton) The origin of multiphase galaxy outflows
Star-forming galaxies are often observed to host galactic winds - gas that is flowing out of the galaxy in phases ranging from cold molecular clouds to hot X-ray emitting plasma. While these multiphase outflows are routinely observed, theoretically constraining their origin and evolution has proven difficult. Explaining the prevalence and velocities of the cool ionized phase (T~10^4 K) in particular poses a challenge. In this talk, I will discuss a potential dual origin for this cool gas. Through a series of extremely high-resolution simulations run with the GPU-based Cholla code, I will show that in high star formation surface density systems, dense disk gas can be pushed out by the collective effect of clustered supernovae, explaining the low-velocity material. Simultaneously, shredding and mixing of these clouds increases the density of the hot phase of the wind, leading to large-scale radiative losses that produce high velocity cool gas. In addition to explaining the nature of outflows themselves, these multiphase winds could potentially be a source of the cool photo-ionized gas that is found in abundance in galaxy halos.
TBA
Thu May 2
1:30 PM
Serin 401 Wynn Ho (Haverford) TBA TBA