Dear Colleagues, as you may know, a series of events are ongoing by the Astronomy Society of Iran. You can find the events on the web-page of the ASI

Please note that

* Friday   24 Ordibehesht / 14 May Professor Yousef Sobouti will be the guest of the program.

* Sunday 26 Ordibehesht / 16 May Professor Sohrab Rahvar will participate in a discussion on professional and amateur astronomy.

Also, there are two colloquiums in the Physics Departments of Tehran University and Sharif University as

*Nima Khosravi on “Cosmological tensions”- Saturday 25 Ordibehesht 1400 / 15 May 2021 @ 15:30 – UT – Please see the attachment.

*Shant Baghram on ” Cosmology’s century: Large scale structure of Dark Universe”-  Sunday 26 Ordibehesht 1400 / 16 May 2021 @ 13:30 – SUT – Please see the attachment.

Zeinab Kalantari

Department of Physics, Sharif University of Technology

Imprints of Gravitational Microlensing on the Light Curve of Gamma-Ray Bursts

Abstract: Gamma-ray bursts (GRBs) are one of the most luminous and prolific high-energy transients that have been observed since their discovery in 1963. The theoretical investigations of gravitational lensing of GRBs have been carried out in the past half-century. In this talk, I will briefly review of Gamma_Ray Bursts (GRBs) detections and GRBs progenitors. Next, I will give a general overview of gravitational microlensing and its observable signature on a GRB light curve for a point mass model of lens. Then, I will concentrate on the Autocorrelation method and its efficiency in finding microlensed candidates. Finally, I will highlight the results of our recent probe in the Fermi/GBM catalog and the estimation of the dark matter density parameter in the form of black holes in the Universe.

یکشنبه 26 اردیبهشت 1400، ساعت 15:00

Sunday 16 May 2021 – 15:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest

Martin Kunz

Department of Theoretical Physics and Center for Astroparticle Physics, University of Geneva

A brief introduction to Euclid and what we can learn from it 

Abstract: Euclid is an ESA medium class astronomy and astrophysics space mission. Euclid was selected by ESA in October 2011 and its launch is planned for 2022. Euclid will explore how the Universe evolved over the past 10 billion years to address questions related to fundamental physics and cosmology on the nature and properties of dark energy, dark matter and gravity. Euclid will also provide insightful information on the physics of the early universe and on the initial conditions which seed the formation of cosmic structure.

I will give a brief general overview of the Euclid satellite and its mission, and describe the main probes and how they observe the evolution of the Universe. Focusing particularly on dark energy models, I will then briefly review what we know now, and how Euclid will improve our knowledge.

یکشنبه 19 اردیبهشت 1400، ساعت 19:00

Sunday 9 May 2021 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest

Maryam Saberi

Rosseland Centre for Solar Physics, University of Oslo

Institute of Theoretical Astrophysics, University of Oslo

UV chemistry in the circumstellar envelopes around evolved stars

Abstract: Low- and intermediate-mass stars (M < 8M☉) evolve towards the asymptotic giant branch (AGB) phase, where they eject a substantial amount of their material (up to 80%) into the interstellar medium (ISM). Therefore, AGB stars play a significant role in the galactic chemical evolution by ejecting the synthesised elements to the ISM through strong stellar winds. An extended circumstellar envelope (CSE) will be created around the star as a consequence of the intense mass loss. Observations of molecular species and dust content in CSEs help us to broaden our knowledge on mass-loss process, stellar properties, and the CSE chemistry. In this presentation, I will give an introduction to the CSE chemistry with a focus on the ultraviolet (UV) chemistry. Then, I will show how high spectral and spatial resolution observations of the Atacama large millimetre array (ALMA) can help us to quantify the impact of various sources of UV radiation in the CSE chemistry around evolved stars.

یکشنبه 12 اردیبهشت 1400، ساعت 19:00

Sunday 2 May 2021 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest

Dragan Huterer

Department of Physics, University of Michigan

Mapping the Universe with Dark Energy Survey

Abstract: I will briefly review how progress in cosmology over the past two decades has greatly improved our measurements of dark-energy parameters, yet has not really shed light on the physical nature of this component. Then I will discuss measurements of cosmological parameters from the Dark Energy Survey. In particular, I will concentrate on the so-called “3×2” correlation-function measurements, and technical innovations in year 1 and the forthcoming year-3 analysis. I will highlight results that are most interesting to general-purpose cosmologists.  Finally, I will highlight how these and other upcoming measurements of dark energy will help us better understand the physical mechanism behind the accelerating universe.

یکشنبه  5 اردیبهشت 1400، ساعت 19:00

Sunday 25 April 2021 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest

The mystery of the distance of galaxies that apparently lacking dark matter

Hosein Haghi

Physics Department, Institute for advanced studies in basic sciences (IASBS)

Abstract: Recently, van Dokkum et al. reported the detection of a couple of ultra-diffuse dwarf (UDG) galaxies lacking dark matter (NGC 1052-DF2 and NGC 1052-DF4). If correct, this could be one of the most important discoveries in Extragalactic Astrophysics and represents a possible challenge to our understanding of the properties of these galaxies and galaxy formation in general. They used surface brightness fluctuation technique yielding a distance of about 20 Mpc implying these galaxies to be dark matter deficient with the larger than expected size, and brighter and larger than expected globular clusters system. But, if the galaxy is a factor of two or three closer to us than the adopted distance of 20 Mpc nearly all the unusual properties vanish. Several authors asked whether these galaxies could be at a smaller distance. Different distance measurement methods that have been applied on these galaxies so far, yielding a distance in the range 10 to 20 Mpc implying it to be “normal” or “dark matter deficient” galaxies. In this talk, first, I will briefly review the current challenge in determining the distance of these galaxies. Then, I will give you a brief report on our recent publication on the IMF-induced intrinsic uncertainties on measuring the ultra-diffuse galaxy distances based on the surface brightness fluctuation technique. 

یکشنبه 22 فروردین 1400، ساعت 19:00

Sunday 11 April 2021 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest

Tracing the stellar mass assembly within galaxies over the past 10 Gyr

Moein Mosleh

Biruni Observatory, School of Science, Shiraz University 

Department of Physics, School of Science, Shiraz University

Abstract: One of the important questions in galaxy formation and evolution is to understand how the stellar mass has been assembled within galaxies. The formation of prominent central densities known as bulges is an example of this evolution and the true mechanisms behind this transformation are a matter of debate. In this talk, I will overview the importance of addressing this question and describe the observational methods that we used for tracing the assembly of stellar mass within galaxies. I will also explain how we can benefit from studying the scaling relations such as size-mass relations. In addition, possible connections of the structural evolutions with star-formation activities and environments will be discussed.

یکشنبه 24 اسفند 1399، ساعت 19:00

Sunday 14 March 2021 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest

Primordial Black Holes and Gravitational Waves

Antonio Riotto

Department of Theoretical Physics, University of Geneva

 Abstract:  We will discuss the relation between primordial black holes and gravitational waves in the view of the recent Ligo/Virgo and NanoGrav data.

سه شنبه 19 اسفند 1399، ساعت 19:00

Tuesday 9 March 2021 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest

The Hubble-constant crisis

Valerio Marra

Núcleo de Astrofísica e Cosmologia & Departamento de Física, Universidade Federal do Espírito Santo, Brazil

 INAF – Osservatorio Astronomico di Trieste, Italy.

IFPU – Institute for Fundamental Physics of the Universe, Italy.

Abstract:  The determination of the Hubble constant H0 – the present-day expansion rate of the universe – is one of the key goals of cosmology, for it impacts all measurements of cosmological properties. Determinations of H0 from Cosmic Microwave Background observations disagree with local determinations from calibrated supernovas Ia: this tension is now approaching the 5 sigma level. After reviewing the present status of cosmology, I will present recent work on model-independent determinations of H0 and their implications for cosmologies beyond LCDM.

سه شنبه 12 اسفند 1399، ساعت 13:30

Tuesday 2 March 2021 – 13:30 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest