442 research outputs found
Predictive Tracking in Vision-based Hand Pose Estimation Using Unscented Kalman Filter and Multi-viewpoint Cameras
巨大なスピン軌道相互作用を有する強相関電子系物質パイロクロア型イリジウム酸化物における金属絶縁体転移
学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 十倉 好紀, 東京大学教授 鹿野田 一司, 東京大学教授 求 幸年, 東京大学准教授 石渡 晋太郎, 東京大学教授 有馬 孝尚University of Tokyo(東京大学
Spatially-resolved Radio-to-Far-infrared SED of the Luminous Merger Remnant NGC 1614 with ALMA and VLA
We present the results of Atacama Large Millimeter/Submillimeter Array (ALMA)
108, 233, 352, and 691 GHz continuum observations and Very Large Array (VLA)
4.81 and 8.36 GHz observations of the nearby luminous merger remnant NGC 1614.
By analyzing the beam (1".0 * 1".0) and uv (> 45 k{\lambda}) matched ALMA and
VLA maps, we find that the deconvolved source size of lower frequency emission
(< 108 GHz) is more compact (420 pc * 380 pc) compared to the higher frequency
emission (> 233 GHz) (560 pc * 390 pc), suggesting different physical origins
for the continuum emission. Based on an SED model for a dusty starburst galaxy,
it is found that the SED can be explained by three components, (1) non-thermal
synchrotron emission (traced in the 4.81 and 8.36 GHz continuum), (2) thermal
free-free emission (traced in the 108 GHz continuum), and (3) thermal dust
emission (traced in the 352 and 691 GHz continuum). We also present the
spatially-resolved (sub-kpc scale) Kennicutt-Schmidt relation of NGC 1614. The
result suggests a systematically shorter molecular gas depletion time in NGC
1614 (average {\tau}_gas of 49 - 77 Myr and 70 - 226 Myr at the starburst ring
and the outer region, respectively) than that of normal disk galaxies (~ 2 Gyr)
and a mid-stage merger VV 114 (= 0.1 - 1 Gyr). This implies that the star
formation activities in U/LIRGs are efficiently enhanced as the merger stage
proceeds, which is consistent with the results from high-resolution numerical
merger simulations.Comment: 10 pages, 6 figures, accepted for publication in PAS
Host Galaxies of Hard X-ray Selected Type-2 Active Galactic Nuclei at Intermediate Redshifts
We study properties of the host galaxies of 15 hard X-ray selected type-2
active galactic nuclei (AGNs) at intermediate redshifts (0.050.6) detected
in surveys. The absorption corrected hard X-ray luminosities range from 10 erg s to erg s. We took
the -band image of these AGNs with the University of Hawaii 2.2 m telescope.
Thanks to the intrinsic obscuration of nuclear light, we can decompose the
galaxies with a spheroid component and a disk component. The resulting spheroid
luminosities correlate with ; higher (lower) X-ray luminosity
AGNs tend to reside in luminous (less luminous) spheroids. It is also found
that the hosts of luminous AGNs show a large spheroid-to-disk luminosity ratio
(1), while those of less luminous AGNs spread between 0 and 1. The
correlation between and spheroid luminosity indicates that
the relation between mass of a supermassive black hole (SMBH) and spheroid
luminosity (BS-relation) at the intermediate redshifts. The BS-relation agrees
with that in the local universe if the Eddington ratio of 0.24 is adopted,
which is a mean value determined from our type-1 AGN sample at similar
redshifts through the broad-line width and continuum luminosity. The present
study demonstrates the effectiveness of using type-2 AGNs at high redshifts to
study their host properties.Comment: 21 pages, 8 figures, ApJ accepte
Deep Collaborative Filtering Approaches for Context-Aware Venue Recommendation
In recent years, vast amounts of user-generated data have being created on Location-Based Social Networks (LBSNs) such as Yelp and Foursquare. Making effective personalised venue suggestions to users based on their preferences and surrounding context is a challenging task. Context-Aware Venue Recommendation (CAVR) is an emerging topic that has gained a lot of attention from researchers, where context can be the user's current location for example. Matrix Factorisation (MF) is one of the most popular collaborative filtering-based techniques, which can be used to predict a user's rating on venues by exploiting explicit feedback (e.g. users' ratings on venues). However, such explicit feedback may not be available, particularly for inactive users, while implicit feedback is easier to obtain from LBSNs as it does not require the users to explicitly express their satisfaction with the venues. In addition, the MF-based approaches usually suffer from the sparsity problem where users/venues have very few rating, hindering the prediction accuracy. Although previous works on user-venue rating prediction have proposed to alleviate the sparsity problem by leveraging user-generated data such as social information from LBSNs, research that investigates the usefulness of Deep Neural Network algorithms (DNN) in alleviating the sparsity problem for CAVR remains untouched or partially studied
Spatially resolved CO SLED of the Luminous Merger Remnant NGC 1614 with ALMA
We present high-resolution (1".0) Atacama Large Millimeter/submillimeter
Array (ALMA) observations of CO (1-0) and CO (2- 1) rotational transitions
toward the nearby IR-luminous merger NGC 1614 supplemented with ALMA archival
data of CO (3-2), and CO (6-5) transitions. The CO (6-5) emission arises from
the starburst ring (central 590 pc in radius), while the lower- CO lines are
distributed over the outer disk ( 3.3 kpc in radius). Radiative transfer
and photon dominated region (PDR) modeling reveal that the starburst ring has a
single warmer gas component with more intense far-ultraviolet radiation field
( 10 cm, 42 K, and
10) relative to the outer disk (
10 cm, 22 K, and
10). A two-phase molecular interstellar medium with a warm and
cold ( 70 K and 19 K) component is also an applicable model for the
starburst ring. A possible source for heating the warm gas component is
mechanical heating due to stellar feedback rather than PDR. Furthermore, we
find evidence for non-circular motions along the north-south optical bar in the
lower- CO images, suggesting a cold gas inflow. We suggest that star
formation in the starburst ring is sustained by the bar-driven cold gas inflow,
and starburst activities radiatively and mechanically power the CO excitation.
The absence of a bright active galactic nucleus can be explained by a scenario
that cold gas accumulating on the starburst ring is exhausted as the fuel for
star formation, or is launched as an outflow before being able to feed to the
nucleus.Comment: 20 pages, 19 figures, 2 tables, accepted for publication in Ap
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