今後のセミナー
4月のセミナー
発表者
赤間進吾
日程/場所
5月27日(水)11:00-@ES606
題名
Observational Predictions of General Bounce Cosmology
概要
Inflation is widely regarded as the most successful paradigm for the early
universe. Nevertheless, alternative scenarios have also been studied,
motivated in particular by the conceptual problems of inflation, such as
the initial singularity problem and the trans-Planckian problem. In this
talk, I will first introduce various aspects of bouncing cosmology as an
alternative to inflation, including its successes and challenges. In the
latter half, I will present a general framework of bouncing cosmology that
admits a parameter space capable of explaining the observed CMB
fluctuations, as inflation does. Finally, among its observational
predictions, I will discuss the statistical properties of CMB B-mode
polarization.
発表者
Federica Tarsitano
日程/場所
5月20日(水)11:00-@ES606
題名
Optical-to-near-infrared studies of AGN and dual AGN systems with Euclid and the HSC-Niji survey
概要
Supermassive black holes (SMBHs), almost ubiquitous in galaxies, are
polyglot citizens of the Universe: we observe them igniting as Active
Galactic Nuclei (AGN) across the electromagnetic spectrum, and
potentially hear the ripples in spacetime, the gravitational waves (GW),
they create in collisions. The upcoming Laser Interferometer Space
Antenna (LISA) mission will be sensitive to the GW signals from SMBH
coalescence, complementing Pulsar Timing Array (PTA) observatories. The
ESA Euclid space mission, surveying billions of galaxies in the optical
to near-infrared (NIR) with unmatched high-resolution imaging and wide
field of view, will bring remarkable advances in the study of the
co-evolutionary path of SMBHs and their host galaxies. A fundamental yet
poorly explored stage of this evolution is represented by dual AGN
systems, which trace the pathway to SMBH coalescence, and can be used to
set empirical priors for LISA GW events. Despite their high scientific
value, instrumental challenges have limited the number of dual AGN
detections confirmed so far, as exquisite spatial and spectral
resolution is needed to characterise the galaxy nuclear light, and most
surveys lack the necessary statistical power. In this talk, I will
discuss recent efforts to build up the first systematic census of dual
AGN in Euclid, and to advance our understanding of AGN activity and
feedback by exploiting unprecedented synergies with HSC-Niji, a new
medium-band survey with the Subaru telescope. The latter will also
enable the study of AGN-linked populations, such as Little Red Dots, as
well as cosmology-focused analyses, including the multi-wavelength
characterisation of galaxy shapes and more accurate galaxy SED
reconstruction and photo-z estimates, all relevant for weak-lensing
analyses in current and future Stage IV surveys.
発表者
吉浦伸太郎
日程/場所
5月13日(水)11:00-@ES606
概要
After the birth of the Universe, the universe went through three important
epochs: the Dark Ages, when no astronomical objects had yet formed; the
Cosmic Dawn, when the first stars were born; and the Epoch of Reionization,
when ultraviolet radiation from young galaxies ionized hydrogen in
intergalactic medium. Although these epochs are crucial for understanding
the early history of galaxy formation and cosmology, many aspects remain
observationally unexplored.
One promising approach is to observe the 21-cm line, a radio signal emitted
by neutral hydrogen atoms at a rest frequency of approximately 1420 MHz. By
detecting the signal from hydrogen that filled the early Universe, we can
probe the cosmology of the Dark Ages and the formation of the first cosmic
structures. Due to the expansion of the Universe, this 21-cm signal is
redshifted to lower frequencies and is observed as low-frequency radio
signal below about 200 MHz. In particular, for the Dark Ages, the 21-cm
line is almost the only available observational probe.
To correctly extract physical information from 21-cm observations,
researchers are developing cosmological models as well as instruments and
analysis methods that can deal with foreground emission, such as radio
emission from our Galaxy. In this seminar, I will first give a brief
introduction to studies of the distant Universe using the 21-cm line. I
will then explain how the latest observational experiments are working
toward the detection of this signal.
発表者
市來淨與
日程/場所
4月15日(水)11:00-@ES606
題名
所信表明
概要
所信表明