Seminar

Ultrafast VHE Gamma-Ray Flares of AGN

 

dr. Maxim Barkov 

Sveučilište Purdue
 
 

Mjesto i vrijeme:

Srijeda, 17. srpnja 2019. u 10:00 sati
Predavaona O-153
Sveučilišni Kampus na Trsatu
Radmile Matejčić 2
51000 Rijeka


Sažetak:
 

We analyze three scenarios to address the challenge of ultrafast gamma-ray variability reported from active galactic nuclei. We focus on the energy requirements imposed by these scenarios: (i) external cloud in the jet, (ii) relativistic blob propagating through the jet material, and (iii) production of high-energy gamma-rays in the magnetosphere gaps. We show that while the first two scenarios are not constrained by the flare luminosity, there is a robust upper limit on the luminosity of flares generated in the black hole magnetosphere. This limit depends weakly on the mass of the central black hole and is determined by the accretion disk magnetization, viewing angle, and the pair multiplicity. For the most favorable values of these parameters, the luminosity for 5-minute flares is limited by 2×1043 erg s-1, which excludes a black hole magnetosphere origin of the flare detected from IC 310. In the scopes of scenarios (i) and (ii), the jet power, which is required to explain the IC 310 flare, exceeds the jet power estimated based on the radio data. To resolve this discrepancy in the framework of scenario (ii), it is sufficient to assume that the relativistic blobs are not distributed isotropically in the jet reference frame. A realization of scenario (i) demands that the jet power during the flare exceeds by a factor 102 the power of the radio jet relevant to a timescale of 108 years.

 

Računalna potraga za novim materijalima

 

dr. sc. Predrag Lazić

Institut Ruđer Bošković, Zagreb
 
 

Mjesto i vrijeme:

Srijeda, 24. siječnja 2018. u 13:00 sati
Predavaona O-153
Sveučilišni Kampus na Trsatu
Radmile Matejčić 2
51000 Rijeka


Sažetak:
 

Materijali kroz ljudsku povijest imaju značajnu ako ne i ključnu ulogu. Istraživanje i razvoj novih materijala je tipično dugotrajan, mukotrpan i skup proces gdje sreća često igra veliku ulogu. No, otkrićem kvantne mehanike omogućeno je puno bolje razumijevanje svojstava materijala, a naglim razvojem računala u posljednjih 20-30 godina polako ali sigurno se potpuno mijenja paradigma u otkrivanju novih materijala.
 
U predavanju će se pokazati nekoliko primjera iz istraživanja novih materijala na računalu koristenjem ab initio računa (konkretno teorijom funkcionala gustoće). Konkretni primjeri su rađeni u sklopu materials projecta (materials genome) i bit će iz područja obnovljive energije - fotokatalize (water splitting) i termoelektrika.
 
[1] Wu, Y., Lazic, P., Hautier, G., Persson, K., and Ceder, G., First principles high throughput screening of oxynitrides for water-splitting photocatalysts, Energy and Enviromental Science 6, 157-168, (2013).
[2] Persson, K. A., Waldwick, B., Lazic, P., and Ceder, G., Prediction of solid-aqueous equilibria: Scheme to combine first-principles calculations of solids with experimental aqueous states, Physical Review B, 85, 235438, (2012).
[3] http://www.materialsproject.org/

Putovanje svemirom - fantazija i stvarnost

 

prof. dr. sc. Slobodan Danko Bosanac

 
 

Mjesto i vrijeme:

Srijeda, 10. siječnja 2018. u 13:00 sati
Predavaona O-029
Sveučilišni Kampus na Trsatu
Radmile Matejčić 2
51000 Rijeka


Sažetak:
 

Putovanje svemirom san je mnogih. Nekolicini ljudi bio je ispunjen taj san, astronauti, ostali su prepušteni fantaziji filmskih redatelja ili piscima znanstvene fantastike. Astronauti su svojim činom pokazali da ljudi mogu u svemir dok fantazija ostavlja utisak da je to lako. O stvarnim problemima putovanja svemirom malo se govori, a pogotovo o teškoćama s kojima se astronauti susreću. Kada se ti problemi izlože putovanje svemirom je izazov koji će trebati dugi razvoj i više o njima u predavanju.
 
Na kraju, ako vrijeme dozvoli, kratki osvrt na nedavno osnovanu udrugu Adriatic Aerospace Association.

The quest for the Dark Side with CAST, KWISP and beyond

 

Izv. prof. dr. sc. Giovanni Cantatore

INFN Sezione di Trieste, Italija i Università di Trieste, Italija
 
 

Mjesto i vrijeme:

Srijeda, 29. studenog 2017. u 13:00 sati
Predavaona O-153
Sveučilišni Kampus na Trsatu
Radmile Matejčić 2
51000 Rijeka


Sažetak:
 

The Dark Side of the Universe has recently gained center stage in contemporary science. Comprehending the nature and composition of dark matter and dark energy is now considered a key problem of frontier research in physics. The CAST experiment at CERN is a prime player in the quest for this understanding: several advanced detection techniques are exploited there, including the KWISP opto-mechanical sensor, which is searching for dark energy components. KWISP has spawned the innovative “advanced-KWISP” concept, with the ambition of extending the reach into the realm of short-distance interactions, where many portals beyond the Standard Model of particle physics may well lie hidden.
 
 
CV:
 
Associate Professor of physics at the Physics Department of the University of Trieste. Awarded with the National Scientific Qualification as Full Professor. Scientific Associate at CERN, Geneva. Currently teaching basic physics courses at the School of Architecture at the School of Engineering of the University of Trieste. The main research interests are focused on the dark universe, more specifically on experimental searches for WISP (Weakly Interacting Slim Particles)-type particles, such as chameleons and axions, which are possible constituents of the dark energy and of the dark matter. He has been the spokesperson of the PVLAS experiment of INFN (Istituto Nazionale di Fisica Nucleare, Italy) in 2002-2008 which studied the magnetized quantum vacuum, and subsequently project leader of the INFN BaRBE_LT experiment, which studied the application of TES (Transition Edge Sensor)-based sensors to single photon counting at low energy with low background. Currently, he is Deputy Spokesperson of the CAST (Cern Axion Solar Telescope) collaboration at CERN.

 

Biomedical Application Technologies and Sensors at BATS-lab of UMG

 

Izv. prof. dr. sc. Antonino Fiorillo

Università degli Studi "Magna Graecia" di CATANZARO, Italija

 

Mjesto i vrijeme:

Ponedjeljak, 12. lipnja 2017. u 11:00 sati
Predavaona O-152
Sveučilišni Kampus na Trsatu
Radmile Matejčić 2
51000 Rijeka


Sažetak:

The research at BATS lab is focused mainly on electronic sensors fabrication. The most investigated and advanced device consists of a piezo-polymer film shaped in semicircular geometry to manufacture ultrasonic sensors in air. These devices are suitable to mimic the echolocation system of bats and rats. Interesting results on the cerebral activity of rat’s brain stimulation, after implantation, demonstrated that the inferior colliculus can be directly stimulated by ultrasound acquired with the sensor, located outside and bypassing the  biological inner ear.

The same polymer, PVDF, is used as pyroelectric sensor to measure the temperature of biological fluids in microchannels for Lab-on-Chip application. In a different arrangement it is used to monitor apnoea events in prenatal babies.

Capillaroscopy is also investigated and a low cost prototype has been fabricated by a students Start-Up, as well as a sensorized can for blinds.

Finally, zeolite nanoporous structures are investigated to match, in terms of bio-energy conversion, iono-to-electronic devices.