Seminar

ECL 2018 Autumn Workshop

Date/Venue:
September 26, 28, 2018; NU, Block C4, room 268
October 3-4, 2018; NU, Block C4, room 268

Speakers:


Prof. Blake D. Sherwin
University of Cambridge, UK

Prof. Xuelei Chen
National Astronomical Observatories,
Chinese Academy of Sciences, China

Program:

Wednesday, Sep 26
ECL science seminar, Block C4, room 268

15:00-16:00

Title:Seeing the beginning:the Cosmic Microwave Background and what it can tell us about our Universe
Speaker: Prof. Blake D. Sherwin
Abstract: By studying the cosmic microwave background (CMB), we can look back in time and reveal the fiery early
universe when it was only 0.003% of its present age. In this talk, I will discuss how, by studying the CMB, we can find out about the origin, composition, and ultimate fate of the universe. I will also briefly outline some of the CMB data analysis methods that may be applicable in other fields.

Friday, Sep 28
ECL general seminar, Block C4, room 268

15:00-16:00

Title: CMB Lensing: Fundamental Physics from Maps of the Invisible
Speaker: Prof. Blake D. Sherwin
Abstract: Dark matter not only forms an invisible cosmic scaffolding within which galaxies form, its distribution in the universe also contains a wealth of information about neutrinos, dark energy, and physics at the earliest times. Measurements of gravitational lensing in the cosmic microwave background (CMB) allow this matter distribution to be directly seen and mapped. In my talk, I will first discuss recent measurements of CMB lensing and their scientific implications. I will then explain why upcoming measurements of the CMB lensing signal, with experiments such as AdvancedACT and Simons Observatory, will be remarkably powerful probes of cosmology. Lensing is not only a signal, however, but also a source of noise that limits how much we can learn about the very early universe. With illustrations from recent work, I will explain why delensing – removing the lensing effect to reveal the primordial sky – is crucial for the future of CMB cosmology.
16:00- 16:30 Coffee- break

Wednesday, Oct 3
ECL science seminar, Block C4, room 268

15:00- 16:00
TitleCosmology Research in China»
Speaker: Prof. Xuelei Chen
Abstract: I’ll give a brief overview on the major cosmology-related research institutes in mainland China, which includes the Chinese Academy of Science institutes as well as universities. I’ll also describe some on-going projects, including the DAMPE dark matter satellite, the PANDAX dark matter search experiment, the FAST telescope, the Tianlai experiment. I’ll also describe some future projects, such as the Ali-CPT experiment, the QiTai Telescope (QTT), the Discovering the Sky at Longest wavelength lunar satellite array, the China Space Station Telescope, etc. China is also involved in a number of international collaboration projects, including the SKA and TMT.

Thursday, Oct 4,
ECL general seminar, Block C4, room 268

15:00- 16:00
Title: «The Cosmic Dawn and Epoch of Reionization»
Speaker: Prof. Xuelei Chen
Abstract: As the first stars and galaxies formed at the end of cosmic dark age, the gas surrounding them get ionized by their radiation, forming ionized bubbles. These bubbles grow until they finally the whole Universe is reionized. After reviewing this general picture of reionization, I describe our model of “neutral islands”, which are large under-dense regions ionized at a later stage of the epoch of reionization. We apply the excursion set theory of large scale structure to this problem and developed analytical and semi-numerical models for reionization. I then discuss the 21cm signatures for the cosmic dawn and epoch of reionization, and also our lunar orbit array project which is designed to probe the EoR.

ECL 2018 Summer Seminar

Date/Venue:
August 14, 2018; NU, Block C4, room 266

Speakers:


Prof. Pawan Kumar
University of Texas at Austin, USA

Tuesday, Aug 14,
ECL general seminar, Block C4, room 266

14:30- 16:00
Title: The Mystery of Fast Radio Bursts and its possible resolution
Speaker: Prof. Pawan Kumar
Abstract: Fast radio bursts (FRBs) are millisecond duration transient events of unknown physical origin that were discovered in pulsar surveys at GHz radio frequency in 2007. It has now been established that these bursts are located at a distance of several billion light years away. And therefore the energy release in the radio band in these events is quite large. Using very general arguments I will show that the radio emission is coherent, the magnetic field strength associated with the source of these events should be 10^{14}Gauss or more, and the electric field is of order 10^{11} esu. I will describe the recent work of my group that magnetic reconnection is likely to be responsible for the strong electric field and the coherent radiation produced in these enigmatic events. I will also address polarization properties of the well known repeater.

ECL 2017 Autumn Workshop

Date/Venue:
September 28-29, 2017;   NU, Block C2 ,   Orange hall
October 2-3, 2017;   NU, Block C3,   room 1010

Speakers:


Prof. Arman Shafieloo
(KASI)

Prof. Robert Caldwell
(Dartmouth College)

Program:

Thursday, Sep 28
ECL science seminar, Block 1, Senate hall

09:30-10:00   Registration
10:00- 11:30

Title: Search for evidences beyond the concordance model of cosmology
Speaker: Arman Shafieloo

Abstract:  In the standard model of cosmology, dark energy and dark matter constitute about 96% of the total energy budget of the cosmos. The nature of both dark energy and dark matter are still unknown to us but we know that they exist. I go through the discoveries and the developments that informed us about their presence and I discuss about how we are trying to learn more about these mysterious components of our universe using astronomical observations and high performance computations.

Friday, Sep 29
ECL general seminar, C2 building, Blue hall

10:00- 11:30

Title: Dark Side of the Universe
Speaker: Arman Shafieloo

Abstract: In the standard model of cosmology, dark energy and dark matter constitute about 96% of the total energy budget of the cosmos. The nature of both dark energy and dark matter are still unknown to us but we know that they exist. I go through the discoveries and the developments that informed us about their presence and I discuss about how we are trying to learn more about these mysterious components of our universe using astronomical observations and high performance computations.
11:30- 12:00 Coffee- break

Monday, Oct 2
ECL science seminar,C3 building, 1010

09:30- 10:00     Registration
10:00- 11:30
Title:A unique and observable imprint of inflation
Speaker: Robert Caldwell

Abstract: Inflation is the leading paradigm for the physics of the early Universe. In the inflationary scenario, the size of the Universe grows exponentially, stretching quantum fluctuations to macroscopic scales. These fluctuations are the seeds of the large scale structures of the Universe, observed in the distribution of galaxies and in the cosmic microwave background. In this talk, I will review the inflationary paradigm and explain how quantized fluctuations of the gravitational field are produced and leave a unique signature in the cosmic microwave background. I will also present recent results which consider the possibility that such a primordial gravitational wave background has a net handedness.

Tuesday, Oct 3,
ECL general seminar, C3 building, 1010

10:00-11:30
Title: Primordial Gravitational Waves
Speaker: Robert Caldwell

Abstract:  We consider the possibility of a spectrum of gravitational waves as a relic from the early Universe. Detection of these waves could reveal information about the earliest moments of the hot Big Bang, as well as the composition and structure of the Universe. In this talk, we review several scenarios for the emission of primordial gravitational waves and the methods of detection. In particular, we highlight new geometries for gravitational wave detectors that could enhance the sensitivity to these elusive waves.
11:30-12:00    Coffee-break