Fall 2017 Russell Frank Astronomy Lecture Held

This semester's Russell Frank Astronomy Lecture will take place 7:30PM, Thursday December 1 2016 in the Bigelow Physics Building room 102 at UNLV.

Professor Fiona Harrison of Caltech will give the talk entitled: From Spinning Black Holes to Exploding Stars: A New View of the High Energy Universe.

Space-based telescopes have greatly expanded our view of the cosmos, extending our ‘eyes’ into the X-ray band, where we can now observe some of the hottest and most energetic phenomena in the Universe. This talk centers on the remarkable discoveries made by NASA’s NuSTAR X-ray telescope, and the fascinating story of how a small space mission was able to make high energy X-ray images of our cosmos crisper and deeper than ever before.

This talk is intended for a general audience including enthusiasts of all backgrounds and ages.

Testing Einstein’s Weak Equivalence Principle with Gravitational Waves

Prof. Xuefeng Wu from Purple Mountain Observatory (former UNLV postdoc) and Prof. He Gao from Beijing Normal University (former UNLV PhD student) published one paper with Prof. Bing Zhang and other coauthors to suggest the use of gravitational waves to directly test Einstein’s Weak Equivalence Principle .

Prof. Bing Zhang recent work reported in AAS NOVA

Prof. Zhang recently published a paper in ApJ Letters suggesting that mergers of charged black holes can give rise to electromagnetic signals from gravitational wave events due to black hole - black hole mergers.

This work is reported in AAS NOVA .

First UNLV/Caltech Astrophysics Workshop Held

The first UNLV/Caltech astrophysics workshop was held in the Department of Physics and Astronomy on Apr. 11-12. The theme of this workshop is radio transients, specifically, a new type of cosmological transients named Fast Radio Bursts (FRBs). Sixteen external scientists from Caltech, National Radio Astronomical Observatory (NRAO), NASA Jet Propulsion Laboratory (JPL), Cornell Univ., Univ. West Virginia, Univ. Washington, Univ. McGill gathered at UNLV and discussed with Prof. Bing Zhang’s group and other faculty members, postdoc fellows and students in the department these mysterious cosmic transients. The workshop was opened with a welcome speech by the department chair Prof. Stephen Lepp, which is followed by more than 20 talks with a lot of discussion sessions in between. Prof. Zhang and graduate students Ye Li and Divya Palaswamy gave oral presentations at the workshop. During the workshop, UNLV astronomers also discussed with Caltech astronomers possible future collaborations in the direction of radio astronomy.

Prof. Rebecca Martin and Mario Livio featured in UNLV News

UNLV News reports on Rebecca Martin and Mario Livio's paper on a possible Super-Earth.

May 6, 2016 3:30PM BPB-217. Dipanjan Mitra. On the nature of coherent radio emission from pulsars.

Pulsars, are rotating and radiating neutron stars and are superb astrophysical laboratories of extreme physics. A typical neutron star has radius of ∼ 10 km, magnetic field of ∼ 10¹² Gauss, density of ∼ 10¹⁷ kg/m³, rotating at a frequency ∼ 1 Hz and has a surface gravity of ∼ 10¹²m/s². We observe pulsars as a sequence of periodic pulses mostly in the radio wavelength. What is mind-boggling is that the radio emission arises from a kilometer-sized emission patch which is at a distance of ∼ 10¹⁹ meter from us, and yet we see it!! The equivalent blackbody temperature of this radio emission is in the range 10²⁵--10³⁰ K, which exceeds the limit for any incoherent emission process. The physical mechanism of how this emission is generated is considered as one of the most challenging problems in astrophysics. In this talk I will discuss the wide spectrum of physical phenomena (like the QED phenomenon of magnetic pair creation, effect on the structure of neutron star surface, relativistic plasma dynamics etc) that takes place around the fast rotating, highly magnetized neutron star. These processes lead to generation of a highly relativistic flow of electron positron plasma in which we believe the radio emission is excited by a process called coherent curvature radiation, where charged ``bunches'' are accelerated in curved magnetic field. I will mention how evidence from high quality radio and X-ray observations of pulsars is putting stringent constraints to these ideas.

April 29, 2016 3:30PM BPB-217. Alexandre Lazarian. Turbulent reconnection and particle acceleration.

I shall explain how turbulence makes magnetic reconnection fast and will compare this approach with other ideas in the field, e.g. related to tearing instability. I shall discuss both non-relativistic and relativistic reconnection. I shall demonstrate that turbulent reconnection inevitably leads to the particle acceleration. Finally, I shall discuss the implications of the process for the famous ICMART model by Zhang & Yan.