Home > 理論コロキウム | 総研大コロキウム > 2013.11.25-12.1


11月25日(月)13:30~14:30  理論コロキウム   コスモス会館 会議室
Nov 25 Mon       DTA Colloquium   Conference Room, Cosmos Lodge

11月27日(水)10:30~12:00  総研大コロキウム   中央棟(北)1F講義室
Nov 27 Wed       SOKENDAI colloquium       Lecture Room



日下部 元彦 氏
Korea Aerospace University
Observational signatures of reactions associated with long-lived exotic interacting particles during big bang nucleosynthesis and early cosmic ray nucleosynthesis
 Primordial 7Li abundance inferred from observations of metal-poor stars (MPSs), so-called Spite plateau abundance, is a factor of 3 lower than the standard big bang nucleosynthesis (BBN) prediction. On the other hand, only upper limits have been derived for primordial abundances of 6Li, 9Be and heavier nuclei from observations of MPSs.
In particle theories beyond the standard model to be searched in collider experiments, new exotic particles are predicted, and they possibly live longer than the BBN time scale of 200 s. If such particles are electrically charged or colored, they bind to nuclei and new chemical and nuclear reactions are made possible. Their existences can then change light element abundances in BBN. It is shown that 7Li abundances can be reduced by the long-lived particles.
In addition, we identify reactions through which observational signatures are left on abundances of 6Li, 9Be, and 10B. Early cosmic ray nucleosynthesis before and during the Galaxy formation can also affect the light element abundances. Future spectroscopic observations of MPSs, therefore, probe the physical processes in the early universe.
名前:山崎 大


Seminar Name
SOKENDAI colloquium
10:30-12:00, Nov 27, 2013
Lecture Room
Speaker 1
Yuriko Saito
D1, SOKENDAI, Hawaii(supervisor : Masatoshi Imanishi)
Investigating the coevolution between SMBHs and galaxies at z~3
-our first result-
In the local universe, there is a tight correlation between the masses
of super massive black holes (SMBHs) and stars in the spheroidal
components (bulge and elliptical galaxies), suggesting that their formation
is physically closely related. Various models assuming different physical
mechanisms are proposed to explain the observational result at z=0.
Since these models predict different redshift evolution of the
SMBH-spheroid mass ratio, it is important to observationally constrain
the mass ratio at high redshift. As the predicted difference becomes
larger at higher redshift, going to higher redshift is better to distinguish
among these models, but at the same time observational difficulties
increase at higher redshift. By taking into account these factors,
we have concluded that z=3-3.5 is practically the best redshift range.
However, previous studies have mostly been limited to z<2.

We have embarked on (1) systematic near-infrared spectroscopy of
z=3-3.5 QSOs, to derive the SMBH masses, based on the the Balmer
beta emission line width and nearby continuum luminosity,
and (2) Subaru LGS-AO near-infrared multi-color imaging observations,
to estimate spheroidal stellar masses in the host galaxies of these QSOs.

We obtained spectroscopic data for 34 objects, and succeeded to derive
BH masses for 24 objects among them. We have also performed Subaru AO
imaging observations of 8 QSOs with estimated SMBH masses, and so far
completed AO imaging data analysis of J0725.
In this talk, I will present our first result of SMBH mass – bulge
mass ratio calculated for J0725.

Speaker 2
Shogo Ishikawa
M2, SOKENDAI, Mitaka(supervisor : Nobunari Kashikawa)
The clustering properties of star-forming galaxies at z~2 by extremely wide-field survey
One of the most critical method to trace the evolution history of galaxies is to compare the mass of dark haloes. Dark halo mass monotonically grows by merging with cosmic time、 so this parameter reflects the growing history of galaxy directly. In recent years, a number of LBGs/LAEs at z>3 are obtained and dark halo masses of z>3 galaxies are revealed.
On the other hand, dark halo masses at z~2 is not so much explored because there are technical difficulties to observe galaxies at z~2. That is why z~2 is known as “redshift-desert”; however, z~2 is also thought to be a important era to study galaxy formation and evolution.
We conducted the wide field survey to obtain star-forming galaxies at z~2, applying so called “BzK selection technique”. In this talk, we report the results of clustering analysis of star-forming galaxies at z~2. Especially, we performed the full HOD analysis of z~2 galaxies the first in the world.
Name : Ayumu Matsuzawa

TV conference system is available connecting from Nobeyama, Hawaii,
Mizusawa, and Okayama


Home > 理論コロキウム | 総研大コロキウム > 2013.11.25-12.1

Return to page top