65 research outputs found
ヒトiPS細胞の分化能はエピゲノム状態にて予測可能である
京都大学0048新制・課程博士博士(医学)甲第20077号医博第4170号新制||医||1018(附属図書館)33193京都大学大学院医学研究科医学専攻(主査)教授 江藤 浩之, 教授 斎藤 通紀, 教授 山田 泰広学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA
A novel efficient feeder-free culture system for the derivation of human induced pluripotent stem cells
Nakagawa, M.et al. A novel efficient feeder-free culture system forthe derivation of human induced pluripotent stem cells.Sci. Rep.4, 3594; DOI:10.1038/srep03594 (2014)
Subaru high-z exploration of low-luminosity quasars (SHELLQs). I. Discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9
We report the discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9.
This is the initial result from the Subaru High-z Exploration of Low-Luminosity
Quasars (SHELLQs) project, which exploits the exquisite multiband imaging data
produced by the Subaru Hyper Suprime-Cam (HSC) Strategic Program survey. The
candidate selection is performed by combining several photometric approaches
including a Bayesian probabilistic algorithm to reject stars and dwarfs. The
spectroscopic identification was carried out with the Gran Telescopio Canarias
and the Subaru Telescope for the first 80 deg2 of the survey footprint. The
success rate of our photometric selection is quite high, approaching 100 % at
the brighter magnitudes (zAB < 23.5 mag). Our selection also recovered all the
known high-z quasars on the HSC images. Among the 15 discovered objects, six
are likely quasars, while the other six with interstellar absorption lines and
in some cases narrow emission lines are likely bright Lyman-break galaxies. The
remaining three objects have weak continua and very strong and narrow Ly alpha
lines, which may be excited by ultraviolet light from both young stars and
quasars. These results indicate that we are starting to see the steep rise of
the luminosity function of z > 6 galaxies, compared with that of quasars, at
magnitudes fainter than M1450 ~ -22 mag or zAB ~24 mag. Follow-up studies of
the discovered objects as well as further survey observations are ongoing.Comment: Published in ApJ (828:26, 2016
AGN number fraction in galaxy groups and clusters at z < 1.4 from the Subaru Hyper Suprime-Cam survey
One of the key questions on active galactic nuclei (AGN) in galaxy clusters
is how AGN could affect the formation and evolution of member galaxies and
galaxy clusters in the history of the Universe. To address this issue, we
investigate the dependence of AGN number fraction () on cluster
redshift () and distance from the cluster center ().
We focus on more than 27,000 galaxy groups and clusters at with more than 1 million member galaxies selected from the Subaru Hyper
Suprime-Cam. By combining various AGN selection methods based on infrared (IR),
radio, and X-ray data, we identify 2,688 AGN. We find that (i)
increases with and (ii) decreases with . The main contributors to the rapid increase of towards
high- and cluster center are IR- and radio-selected AGN, respectively. Those
results indicate that the emergence of the AGN population depends on the
environment and redshift, and galaxy groups and clusters at high- play an
important role in AGN evolution. We also find that cluster-cluster mergers may
not drive AGN activity in at least the cluster center, while we have tentative
evidence that cluster-cluster mergers would enhance AGN activity in the
outskirts of (particularly massive) galaxy clusters.Comment: 16 pages, 21 figures, and 2 tables, accepted for publication in PAS
Discovery of the First Low-Luminosity Quasar at z > 7
We report the discovery of a quasar at z = 7.07, which was selected from the
deep multi-band imaging data collected by the Hyper Suprime-Cam (HSC) Subaru
Strategic Program survey. This quasar, HSC J124353.93+010038.5, has an order of
magnitude lower luminosity than do the other known quasars at z > 7. The
rest-frame ultraviolet absolute magnitude is M1450 = -24.13 +/- 0.08 mag and
the bolometric luminosity is Lbol = (1.4 +/- 0.1) x 10^{46} erg/s. Its spectrum
in the optical to near-infrared shows strong emission lines, and shows evidence
for a fast gas outflow, as the C IV line is blueshifted and there is indication
of broad absorption lines. The Mg II-based black hole mass is Mbh = (3.3 +/-
2.0) x 10^8 Msun, thus indicating a moderate mass accretion rate with an
Eddington ratio 0.34 +/- 0.20. It is the first z > 7 quasar with sub-Eddington
accretion, besides being the third most distant quasar, known to date. The
luminosity and black hole mass are comparable to, or even lower than, those
measured for the majority of low-z quasars discovered by the Sloan Digital Sky
Survey, and thus this quasar likely represents a z > 7 counterpart to quasars
commonly observed in the low-z universe.Comment: Accepted for publication in ApJ Letter
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