Astrophysics Seminar

Astrophysics Seminar: "Radiative magnetohydrodynamics simulations of IR and UV radiative pressure on dusty AGN tori"

Location: 
Kaplun building, Room No. 200
Tue, 22/11/2016 - 12:30 to 13:30

Lecturer: Mr. Chi Ho (Edwin) Chan Affiliation: Department of Physics and Astronomy, Johns Hopkins University Abstract: Substantial evidence points to dusty, geometrically thick tori obscuring the central engines of AGNs, but so far no mechanism satisfactorily explains why cool dust in the torus remains in a puffy geometry. IR and UV radiation pressure on dust can play a significant role in shaping the torus, yet the separation of hydrodynamic evolution from radiative transfer in previous work on radiation- supported tori precluded a self-consistent

Astrophysics Seminar: "Fast transients: gravitational wave counterparts and optical-radio"

Location: 
Kaplun buildilng, Room No. 200
Thu, 15/12/2016 - 14:00 to 15:00

Lecturer: Prof. Paul Groot Affiliation: Radboud University Abstract: The short time-scale transient universe is still very poorly explored but holds strong promises for breakthrough discoveries. The detection of gravitational wave counterparts and the optical identification of fast radio bursts are but two outstanding examples. In the lecture I will overview the results of our group at Radboud University to understand the population of gravitational wave emitters in our Universe, to understand the fast synoptic sky at optical wavelengths and two major, upcoming projects.

Astrophysics Seminar: "Collisionless dynamics of ions in the shock front"

Location: 
Kaplun building, Room No. 200
Tue, 07/06/2016 - 12:30 to 13:30

Lecturer: Prof. Michael Gedalin Affiliation: Ben-Gurion University of the Negev Abstract: The magnetic field profile of a collisionless shock is shaped mainly by ions. Upon crossing the shock ions begin to gyrate and form a non- gyrotropic distribution. The ion pressure tensor oscillates with the distance from the ramp. These oscillations damp due to collisionless gyrophase mixing. The latter is sensitive to the basic shock parameters. Chances to observe this relaxation are higher for shocks with lower upstream ion temperature. Additional details of the upcoming Astrophysics'

Astrophysics Seminar: "An extremely luminous tidal disruption event from a massive rotating black hole"

Location: 
Kaplun building, Room No. 200
Tue, 06/12/2016 - 12:30 to 13:30

Lecturer: Dr. Giorgos Leloudas Affiliation: Weizmann Institute of Science Abstract: ASASSN-15lh was proposed to be the most luminous supernova ever discovered. Based on new evidence we suggest that this event is not a superluminous supernova but a tidal disruption event around a supermassive black hole. Arguments in favor of this interpretation include: the light curve and temperature evolution, the spectroscopic properties of the event and the surrounding medium and its location being consistent with the nucleus of a passive and massive galaxy.

Astrophysics Seminar: "Near field cosmology and the local group of Galaxies"

Location: 
Kaplun building, Room No. 200
Thu, 04/05/2017 - 13:30 to 14:30

Lecturer: Dr. Edoardo Carlesi Affiliation: Racah Institute of Physics, The Hebrew University of Jerusalem Abstract: Near field cosmology aims at exploiting the high-quality astrophysical observations of the local Universe for cosmological pourposes. In recent years, observations Local Group (LG) of galaxies (e.g. relative to abundance and anisotropy of substructure), have been used to claim inconsistencies within the Lambda Cold Dark Matter (LCDM) standard model of cosmology. However, the comparison between random-phase N-body simulations and

Astrophysics Seminar: "The LIGO Discovery and Primordial Black Hole Dark Matter"

Location: 
Kaplun buildilng, Room No. 200
Sun, 18/12/2016 - 12:30 to 13:30

Lecturer: Dr. Ely Kovetz Affiliation: Johns Hopkins University Abstract: The LIGO observatory has recently reported several detections of gravitational waves from the coalescence of binary black holes. We consider the extraordinary possibility that the detected events involving heavier masses are mergers of primordial black holes making up the dark matter in the Universe. We will describe various ways of testing this proposition once more gravitational wave data is gathered, survey some of the existing constraints and present a novel probe of

Astrophysics Seminar: "The Galactic distribution of X-ray binaries and its implications for compact object formation and natal kicks"

Location: 
Kaplun building, Room No. 200
Tue, 17/05/2016 - 12:30 to 13:30

Lecturer: Dr. Serena Repetto Affiliation: Technion - Israel Institute of Technology Abstract: The aim of this work is to study the imprints that different models for black hole (BH) and neutron star (NS) formation have on the Galactic distribution of X-ray binaries (XRBs) which contain these objects. We find that the root mean square of the height above the Galactic plane of BH- and NS-XRBs is a powerful proxy to discriminate among different formation scenarios, and that binary evolution following the BH/NS formation does not significantly affect the Galactic

Astrophysics Seminar: "A Martian Origin to the Mars Trojan Asteroids"

Location: 
Kaplun building, Room No. 200
Tue, 24/01/2017 - 12:30 to 13:30

Lecturer: Dr. David Polishook Affiliation: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT) Abstract: Seven out of nine Mars Trojan asteroids belong to an orbital grouping and likely a single progenitor (Christou 2014, Cuk et al. 2015). Here we report new near-infrared observations of two of them (311999 and 385250) and we find that both present an identical olivine-rich reflectance spectrum, that is similar to the reflectance spectrum of 5261 Eureka, the largest of these seven Trojans (Rivkin et al. 2007). These

Astrophysics Seminar: "Inhomogeneities as a bias and as a probe"

Location: 
Kaplun building, Room No. 200
Tue, 08/11/2016 - 12:30 to 13:30

Lecturer: Dr. Ido Ben-Dayan Affiliation: DESY, Theory Group, Universität Hamburg Abstract: Precision Cosmology requires us to take into account the small scale inhomogeneities in the Universe when discussing cosmology. After a general introduction, I will discuss the effect of small scale inhomogeneities on the luminosity distance - redshift relation within LCDM: 1) How inhomogeneities bias the Hubble parameter due to peculiar velocities. This bias ameliorates the tension between CMB and and Supernovae measurements of the Hubble parameter. 2) How inhomogeneities serve