ABBL-iTHEMS Joint Seminar
The Polarised ring of the Supermassive Black Hole in M87: EHT observations and theoretical modeling
September 3 at 14:00 - 16:00, 2021
Dr. Yosuke Mizuno (Tsung-Dao Lee Institute, Shanghai Jiao Tong University, China)
The Event Horizon Telescope has mapped the central compact radio source of the elliptical galaxy M87 at 1.3 mm with unprecedented angular resolution. These images show a prominent ring with a diameter of ~40 micro-arcsecond, consistent with the size and shape of the lensed photon orbit encircling the “shadow” of a supermassive black hole. Recently EHT has provided new images of the polarised emission around the central black hole in M87 on event-horizon scale. This polarised synchrotron emission probes the structure of magnetic fields and the plasma properties near the black hole. We found that the net azimuthal linear polarisation pattern may result from organised, poloidal magnetic fields in the emission region. In a quantitative comparison with a large simulated polarimetric image library, we found that magnetically arrested accretion disks are favoured to explain polarimetric EHT observations. In this talk, I also briefly discuss about a new modelling study of M87 jets in the collimation and acceleration region.
Venue: via Zoom
Event Official Language: English
The Evolution of Primordial Neutrino Helicities under Gravitational and Magnetic Fields and Implications for their Detection
February 22 at 10:00 - 11:30, 2021
Prof. Gordon Baym (Senior Visiting Scientist, iTHEMS / Professor Emeritus, University of Illinois, USA)
Feb.22 (Mon) 10:00am-11:30am (JST) Primordial neutrinos decoupled in the early universe in helicity eigenstates. As I will discuss, two effects -- dependent on neutrinos having a non-zero mass -- can modify their helicities as they propagate through the cosmos. First, finite mass neutrinos have a magnetic moment and thus their spins, but not their momenta, precess in cosmic and galactic magnetic fields. The second is the propagation of neutrinos past cosmic matter density fluctuations, which bend their momenta, and bend their spins by a smaller amount. (The latter is a general relativistic effect.) Both effects turn a fraction of left-handed neutrinos into right-handed neutrinos, and right-handed antineutrinos into left-handed. If neutrino magnetic moments approach that suggested by the XENON1T experiment as a possible explanation of their excess of low energy electron events -- a value well beyond the moment predicted by the standard model -- helicities of relic Dirac (but not Majorana) neutrinos could be considerably randomized. I finally will discuss the implications of neutrino helicity rotation, as well as their Dirac vs. Majorana nature, on their detection rates via the Inverse Tritium Beta Decay reaction.
Venue: via Online
Event Official Language: English
ABBL/iTHEMS seminar - talk on ultra-high energy cosmic rays
January 31 at 14:00 - 15:00, 2020
Dr. Eiji Kido (Astrophysical Big Bang Laboratory, RIKEN)
Venue: Seminar Room #132
Event Official Language: English
ABBL/iTHEMS seminar - talk on neutron stars
January 24 at 14:00 - 15:00, 2020
Dr. Hajime Sotani (Research Scientist, iTHEMS / Research Scientist, Astrophysical Big Bang Laboratory, RIKEN Cluster for Pioneering Research)
Venue: Seminar Room #132
Event Official Language: English
Constraining superheavy dark matter with the multi-messenger observations of accompanying radiation
December 20 at 14:00 - 15:00, 2019
Dr. Yana Zhezher (The Institute for Cosmic Ray Research (ICRR) of University of Tokyo)
Venue: Seminar Room #132
Event Official Language: English
Seminar talk on GRB190114C
December 11 at 13:45 - 15:30, 2019
Dr. Susumu Inoue (Research Scientist, iTHEMS)
Detection of very high energy gamma-rays (~TeV) from GRB190114C by MAGIC telescope is reported in the latest nature issue. Dr. Susumu Inoue (iThems) who is one of MAGIC team members will give a seminar talk on this exciting event.
Venue: Seminar Room #132
Event Official Language: English
A multiscale study of turbulent heating in hot accretion flows
November 18 at 14:00 - 15:00, 2019
Dr. Yohei Kawazura (Assistant Professor, Tohoku University)
Venue: #132, 1F, Main Research Building
Event Official Language: English
Dark matter search in extended dwarf spheroidal galaxies with CTA
October 11 at 14:00 - 15:00, 2019
Dr. Nagisa Hiroshima (Postdoctoral Researcher, iTHEMS)
Venue: #132, 1F, Main Research Building
Event Official Language: English
Angular power spectrum analysis on current and future high-energy neutrino data
September 18 at 14:00 - 15:00, 2019
Ms. Ariane Dekker (Faculty of Science, University of Amsterdam, Netherlands (the))
Venue: #160, 1F, Main Research Building
Event Official Language: English
ABBL/iTHEMS/r-EMU Joint Seminar
June 28 at 14:00 - 15:00, 2019
Dr. Haozhao Liang (Senior Research Scientist, Quantum Hadron Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science (RNC))
This is his 2nd seminar talk for non-experts of nuclear physics, following the 1st one on 18th Jan. 2019. Speaker: Haozhao Liang (RIKEN Nishina Center) Title: Towards systematic and consistent nuclear data inputs for astrophysical r-process with Bayesian approaches
Venue: 224-226, Main Research Building
Event Official Language: English
Using combined Particles-in-MHD-Cells to model particle acceleration in astrophysical shocks
June 17 at 14:00 - 15:00, 2019
Dr. Allard Jan van Marle (Research Professor, Ulsan National Institute of Science and Technology, Republic of Korea)
Venue: #132, 1F, Main Research Building
Event Official Language: English
ABBL-iTHEMS Joint Seminars (Following r-EMU seminar 13:30-15:00)
May 31 at 15:15 - 17:35, 2019
Venue: #435-437, Main Research Building
Event Official Language: English
ABBL-iTHEMS Joint Seminar 4
April 3 at 14:00 - 15:00, 2019
Dr. Toshiki Sato (Special Postdoctoral Researcher, High Energy Astrophysics Laboratory, RIKEN Cluster for Pioneering Research)
Title: The Origin of the X-ray Clumpy Ejecta in Type Ia Supernova Remnants
Venue: #433, Main Research Building
Event Official Language: English
ABBL-iTHEMS Joint Seminar 3
December 7 at 14:00 - 15:00, 2018
Dr. Takashi Sako (ICRR, U. Tokyo)
Title: Cosmic-ray air showers: new arrays for searching origins and link to the collider physics
Venue: Seminar Room #160
Event Official Language: English