Events Archive

Galaxy Proto-clusters as an Interface Between Structure, Cluster, and Galaxy Formation

Tue, Oct 27, 2015 at 1:00 pm

131A Campbell Hall

Yi-Kuan Chiang (Austin)

Proto-clusters, the ancestor large-scale structures of present-day galaxy clusters, are ideal laboratories to study dark matter assembly, cosmic baryon cycle, galaxy growth, and environmental impact on galaxy evolution. We extract LCDM predictions for the physical properties and observational signatures of galaxy proto-clusters as a function of time and cluster mass. I will talk about …

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Cosmic-ray ionization and heating in molecular clouds

Mon, Oct 26, 2015 at 3:00 pm

131A Campbell Hall

Daniele Galli (INAF)

Low-energy cosmic rays are an important source of ionization for the interstellar medium, influencing its chemical, thermal and dynamical evolution. Available observational determinations of the cosmic-ray ionization rate in diffuse clouds and recent data from the Voyager I spacecraft support the existence of a significant flux of cosmic-ray nuclei and electrons below ~100 MeV. However, the …

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Sweating the small stuff: simulating dwarf galaxies, ultra-faint dwarf galaxies, and their own tiny satellites.

Mon, Oct 26, 2015 at 12:00 pm

131A Campbell Hall

Coral Wheeler (UCI)

If LCDM is correct, then all dark matter halos hosting galaxies, from those hosting dwarfs to those hosting giant clusters, are filled with abundant substructure down to very low mass scales (<< 10^9 Msun). Specifically, even the dark matter halos of Local Group field dwarfs should be filled with subhalos, many of which should be fairly massive (~ 10^8 Msun), and thus are potential …

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Numerical Simulations of Black Hole Accretion

Thu, Oct 22, 2015 at 4:00 pm

1 LeConte Hall

Ramesh Narayan (CfA Harvard)

Accreting black holes are observed in a large variety of systems in astronomy: active galactic nuclei, X-ray binaries, tidal disruption events, gamma-ray bursts. While analytical one-dimensional models have been enormously useful for understanding several aspects of accretion physics, other aspects such as the formation of jets and winds are beyond the scope of …

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Department Lunch 10-22

Thu, Oct 22, 2015 at 12:30 pm

131A Campbell Hall

Jon Mauerhan (UCB)
Davide Martizzi (UCB)
Ramesh Narayan (Harvard)

The Department Lunch Talk series is a weekly event that features three 20 minute talks presented mainly by local scientists of any level to present their work to a broad spectrum of the department and usually includes one short talk by the astronomy colloquium speaker of the day. Subjects can include personal scientific research, reporting on other work appearing in journals, education and public outreach efforts, science policy, and professional development issues. Continue reading for this week's talk titles.

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CIPS Seminar 10-21

Wed, Oct 21, 2015 at 3:00 pm

131A Campbell Hall

Eric Nielsen (SETI/Stanford)
Michael Manga (UC Berkeley)

This weeks CIPS Seminar will feature two speakers (please continuing reading for complete abstracts and titles).

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Constraining Gravity at the Largest Scales through CMB Lensing and Galaxy Velocities

Tue, Oct 20, 2015 at 1:00 pm

131A Campbell Hall

Anthony Pullen, CMU

We discuss recent work exploring the use of CMB lensing to probe E_G, the ratio between curvature and velocity perturbations. This quantity is distinct for various gravity models, breaking the degeneracy in current cosmological probes of gravity and dark energy. While the lensing signal within E_G has traditionally been probed with galaxy-galaxy lensing, galaxy-CMB lensing is a more robust …

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The streams, disks, and jets from tidal disruption events

Mon, Oct 19, 2015 at 12:00 pm

131A Campbell Hall

Eric Coughlin (U of Colorado, Boulder)

When a star comes within a critical distance of a supermassive black hole, the tidal force exerted by the hole overwhelms the stellar self-gravity, which subsequently tears the star apart and creates a stream of tidally-shredded debris. Approximately half of this debris eventually returns to the black hole, forms an accretion disk and generates a highly luminous …

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Stardust: Analyses of cometary and interstellar dust in the laboratory

Sat, Oct 17, 2015 at 11:00 am

100 Genetics & Plant Biology Building

Andrew Westphal (UC Berkeley)

Stardust was the first spacecraft ever to bring back to Earth extraterrestrial materials from beyond the Moon. It was two missions in one spacecraft. Stardust returned the first samples from a known primitive solar system body, the Jupiter-family comet Wild 2. Stardust also carried a separate collector that was exposed the interstellar dust stream for 200 days before the encounter with the …

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The Demographics of Exoplanets

Thu, Oct 15, 2015 at 4:00 pm

1 LeConte Hall

Scott Gaudi (Ohio State)

Measurements of the demographics of exoplanets over a range of planet and host star properties provide fundamental empirical constraints on theories of planet formation and evolution.  I will discuss various efforts to measure and synthesize exoplanet demographics over broad regions of parameter space, and show results from combining microlensing, radial velocity, and direct imaging …

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Department Lunch Talk 10-15

Thu, Oct 15, 2015 at 12:30 pm

131A Campbell Hall

Kenta Hotokezaka (Hebrew University)
Isaac Shivers (UCB)
Scott Gaudi (OSU)

The Department Lunch Talk series is a weekly event that features three 20 minute talks presented mainly by local scientists of any level to present their work to a broad spectrum of the department and usually includes one short talk by the astronomy colloquium speaker of the day. Subjects can include personal scientific research, reporting on other work appearing in journals, education and public outreach efforts, science policy, and professional development issues. Continue reading for this week's talk titles.

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The KELT Transit Survey: Hot Planets around Hot, Bright Stars

Wed, Oct 14, 2015 at 3:00 pm

131A Campbell Hall

Scott Gaudi (Ohio)

The KELT Transit Survey consists of a pair of small-aperture, wide-angle automated telescope located at Winer Observatory in Sonoita, Arizona and the South African Astronomical Observatory (SAAO) in Sutherland, South Africa. Together, they are surveying roughly 60% of the sky for transiting planets. By virtue of their small apertures (42 mm) and large fields-of-view (26 degrees x 26 …

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How Halo Concentration Impacts Subhalo Abundance and the Galaxy-halo Connection

Tue, Oct 13, 2015 at 1:00 pm

131A Campbell Hall

Yao-Yuan Mao (Stanford)

The existence of dark matter substructures is one of the most distinct predictions of the cold dark matter model, and the relation between dark matter substructures and satellite galaxies is one of the most critical questions about galaxy formation. We address some aspects of these theoretical questions with new suites of cosmological simulations and zoom-in …

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A CPU/GPU/FGPA telescope upgrade for Fast Radio Burst searching

Tue, Oct 13, 2015 at 12:00 pm

121 Campbell Hall

Matthew Bailes (Swinburne University)

Fast Radio Bursts (FRBs) are examples of dispersed radio pulses with such large sweeps in time that they appear to come from cosmological distances. Swinburne has provided a new custom 250 Tflop GPU cluster for the 18,000 m^2 Molonglo Observatory Synthesis Telescope to find more FRBs. This upgrade combines FGPAs, CPUs and GPUs to produce fan beams that can be searched in …

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Revealing X_CO and the CIB: globally modelling dust and gas in the Milky Way

Mon, Oct 12, 2015 at 3:00 pm

131A Campbell Hall

Daniel Lenz (Bonn)

The IRAS discovery of infrared cirrus clouds was the starting point of correlation studies of neutral atomic hydrogen and dust far-infrared emission. These yield important insights into the gas and dust physics, the accretion history of the Milky Way, the X_CO factor, and the distribution of the CO-dark molecular gas. So far, full-sky analyses were limited by the angular resolution of the HI …

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