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High-z QSO survey at z ~ 6 and 7 with Suprime-Cam / The new black hole mass estimator: Paα

【日時】4月25日(水) 10:30~12:00
【場所】国立天文台・三鷹 中央棟(北)1階 講義室
【発表者1】Yoshifumi Ishizaki (総研大 D2・三鷹、指導教員 : Nobunari Kashikawa)
【タイトル】High-z QSO survey at z ~ 6 and 7 with Suprime-Cam
We are on going deep zB/zR imagings for 7 deg^2 in total of UKIDSS-DXS fields in order to detect high-z QSOs around z ∼ 7 down to J<23.5. This observation is a new search for the most distant QSOs around z = 6 and 7 utilizing the unique capabilities of wide-field imaging of Subaru/Suprime-Cam, its high-sensitivity CCDs at 〜 1μm, and special filters to effectively isolate high-z QSOs from M/L/T dwarfs. I will speak about the unique way of observation mainly. 【発表者2】Keisuke Imase (総研大 D2・三鷹、指導教員 : Masatoshi Imanishi) 【タイトル】The new black hole mass estimator: Paα アブストラクト Active Galactic Nuclei (AGNs) are luminous objects, found in the centre of galaxies. It is believed that they have supermassive black hole and accretion disk in their central region, surrounded with broad-line region(BLR). This picture is called "Unified model for AGN" (e.g., Antonucci 1993) Today, the correlation between masses of black holes of AGNs (MBHs) and the properties of their host galaxies has been found (so-called "co-evolution"). Therefore, it is very important to estimate MBHs of more AGNs in more accurate way. MBHs are mainly estimated with broad optical and UV emission lines (Hβ, MgII), using their line width and flux. More than half of AGNs, however, are affected with the foreground gas and dust. For such AGNs (so-called "dusty AGNs"), it is difficult to use UV/optical lines as estimators of MBHs. On the other hand, Paα line, the strongest line in near-infrared(NIR) and free of blending, are detectable in "dusty AGNs" and ultra luminous IR galaxy(ULIRG). We have observed 21 nearby PG QSOs with IRTF/SpeX in order to establish Paα lines as a new estimator of MBHs for dusty AGNs. In the colloquium, we report the present results and our future work.

Galactic Outer Rotation Curve project with VERA

【日時】4月18日(水) 10:30~12:00
【場所】国立天文台・三鷹 中央棟(北)1階 講義室
【発表者(敬称略)】(総研大 D2 坂井 伸行・三鷹、指導教員:本間 希樹
Galactic Outer Rotation Curve project with VERA
I will talk mainly about two topics,
(1) Sakai et al. 2012 in accepted and
(2) Future prospects of our project.
The abstract of (1) is shown as below:
We report measurement of trigonometric parallax of IRAS 05168+3634 with VERA.
The parallax is 0.532 +/- 0.053 mas, corresponding to a distance of 1.88+0.21 -0.17 kpc. This result is significantly smaller than the previous distance estimate of 6 kpc based on kinematic distance. This drastic change in the source distance revises not only physical parameters of IRAS 05168+3634, but also its location of the source, placing it in the Perseus arm rather than the Outer arm. We also measure proper motions of the source. A combination of the distance and the proper motions with systemic velocity
yields rotation velocity (Θ) of 227+9-11 km s-1 at the source, assuming Θ0 = 240 km s-1. Our result combined with previous VLBI results for six sources in the Perseus arm indicates that the sources rotate systematically slower than the Galactic rotation velocity at the LSR. In fact, we show observed disk peculiar motions averaged over the seven sources in the Perseus arm as (Umean, Vmean) = (11 +/- 3, -17 +/- 3) km s-1, indicating that these seven sources are systematically moving toward the Galactic center, and lag behind the Galactic rotation.

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