포스터발표초록
한국천문학회보 제44권 2호, 2019년 10월 / 75 far-infrared (250-500 ㎛), mid-infrared (18 ㎛),
near-infrared (2-4 ㎛), and optical (i-band) source catalog. We are going to present morphologies and physical properties of 850 ㎛ selected submillimeter galaxies with the help of ancillary multi-wavelength datasets over the NEP area.
[포 GC-08] Weak Lensing Mass Map Reconstruction of Merging Clusters with Convolutional Neural Network
Sangnam Park1, James M. Jee2, Sungwook E. Hong1, Dongsu Bak1,3
1
Natural Science Research Institute, University of Seoul,2
Department of Astronomy, YonseiUniversity,
3
Department of Physics, University of SeoulWe introduce a novel method for reconstructing the projected dark matter mass maps of merging galaxy clusters by applying the convolutional neural network (CNN) to their weak lensing maps.
We generate synthesized grayscale images from given weak lensing maps that preserve their averaged galaxy ellipticity. We then apply them to multi-layered CNN with architectures of alternating convolution and trans-convolution filters to predict the mass maps. We train our architecture with 1,000 Subaru/Suprime-Cam mock weak lensing maps, and our method have better mass map prediction than the Kaiser-Squires method with the following three aspects: (1) better pixel-to-pixel correlation, (2) more accurate finding of density peak position, and (3) free from mass-sheet degeneracy. We also apply our method to the HST weak lensing map of the El Gordo cluster and compare our result to the previous studies.
[포 GC-09] Narrow-band Ca Photometry for Dwarf Spheroidal Galaxies: Recent Results and Future Work
Hak-Sub Kim1, Sang-Il Han2, Suk-Jin Yoon2
1
Korea Astronomy and Space Science Institute,2
Yonsei UniversityThis poster introduces the ongoing
"Narrow-band Ca Photometry for Dwarf Spheroidal Galaxies" project and presents the latest results.
The project aims to explain the formation and evolution of dwarf spheroidal galaxies by examining the structural properties of stellar populations as a function of metallicity. To overcome the lack of stars with known spectroscopic metallicities for dwarf spheroidal galaxies, we apply the hk index as a photometric metallicity indicator to three galaxies—Draco,
Sextans, and Canes Venatici I. For all three galaxies, we found that metal-poor and metal-rich groups of red-giant-branch stars have distinct spatial distributions, in which metal-rich stars are centrally concentrated while metal-poor stars are relatively dispersed. In Sextans, we found an off-centered peak of metal-poor stars which is presumed to be a disrupting star cluster in this galaxy. We will discuss the implications of our results for the dwarf galaxy formation and possible directions on future work of this project.
[포 GC-10] Chemical properties of star-forming galaxies in Virgo-related large-scale filamentary structures.
Jiwon Chung1, Soo-Chang Rey2, Suk Kim2, Youngdae Lee2, Eon-Chang Sung1
1
Korea Astronomy and Space Science Institute,2
Chungnam National UniversityThe filament is an interesting structure in the Universe because clusters form at the nodes of filaments and grow through the continuous accretion of individual galaxies and groups from the surrounding filaments. We study the chemical properties of star-forming (SF) galaxies in the five large-scale filamentary structures (Leo II A, Leo II B, Leo Minor, Canes Venatici, and Virgo III) related with the Virgo cluster, with the spectroscopic data taken with the SDSS DR12, and compare them with those of the Virgo cluster and field galaxies. In mass-metallicity relation, most of the SF galaxies in Virgo-related filaments (except Virgo III filament) show lower metallicity on average than the Virgo cluster SF galaxies, but similar to field counterparts. These chemically less evolved feature of SF galaxies in the filaments and field are more pronounced for lower mass galaxies. This is probably because low mass galaxies have low potential wells and are therefore likely to be sensitive to cluster environmental effects.
Interestingly, we find that the metallicity enhancement of SF galaxies in the Virgo III filament. In chemical and morphological perspectives, SF galaxies in the Virgo III thought to be transitional objects possibly transformed from SF late-type galaxies and are on the way to red early-type galaxies in the filament environment.
This is the first discovery of systematic ‘chemical pre-processing’ signature for filament galaxies in Local Universe before they fall into the cluster.
[포 GC-11] Gas dynamics and star formation in dwarf galaxies: the case of DDO 210 Se-Heon Oh1, Yun Zheng2 and Jing Wang2
2019 가을 학술대회
76 / Bull. Kor. Astron. Soc. Vol. 44 No.2, Oct. 2019
1
Department of Physics and Astronomy, Sejong University, Korea,2
The Kavili Institute for Astronomy and Astrophysics, Peking University, ChinaWe present a quantitative analysis of the relationship between the gas dynamics and star formation history of DDO 210 which is an irregular dwarf galaxy in the local Universe. We perform profile analysis of an high-resolution neutral hydrogen (HI) data cube of the galaxy taken with the large Very Large Array (VLA) survey, LITTLE THINGS using newly developed algorithm based on a Bayesian Markov Chain Monte Carlo (MCMC) technique. The complex HI structure and kinematics of the galaxy are decomposed into multiple kinematic components in a quantitative way like 1) bulk motions which are most likely to follow the underlying circular rotation of the disk, 2) non-circular motions deviating from the bulk motions, and 3) kinematically cold and warm components with narrower and wider velocity dispersion. The decomposed kinematic components are then spatially correlated with the distribution of stellar populations obtained from the color-magnitude diagram (CMD) fitting method.
The cold and warm gas components show negative and positive correlations between their velocity dispersions and the surface star formation rates of the populations with ages of < 40 Myr and 100~400 Myr, respectively. The cold gas is most likely to be associated with the young stellar populations. Then the stellar feedback of the young populations could influence the warm gas. The age difference between the populations which show the correlations indicates the time delay of the stellar feedback.
[포 GC-12] Optical follow-up observation of three binary black hole merger events with the KMTNet.
Joonho Kim
1
, Myungshin Im1
, Gregory S. H. Paek1
, Chung-Uk Lee2
, Seung-Lee Kim2
, Changsu Choi1
, Gu Lim1
, Hyung Mok Lee1,2
, Sophia Kim1
, and Sungyong Hwang1
1
Center for the Exploration of the Origin of the Universe (CEOU), Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 08826, Korea,2
Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Korea.After the first identification of electromagnetic counterpart of gravitational wave source (GW170817), era of multi-messenger astronomy has begun. For specifying coordinate, magnitude, and host galaxy information, optical follow-up
observation of GW source becomes important. The O3 run of LIGO / VIRGO started after April 2019.
We present searching strategy of GW optical counterpart using the KMTNet. By performing tiling observation of high probability area in GW localization map, we expect to observe early light-curve of GW optical counterpart. We will also present observation result for three gravitational wave events of binary black hole mergers. After identification of optical counterpart, we will study collision mechanism, progenitor, and characteristics of host galaxy using observation data of GW source.
[포 GC-13] Gravitational-wave EM
Counterpart Korean Observatory (GECKO):
Network of Telescopes and Follow-up Result for S190425z
Gregory SungHak Paek1, Myungshin Im
1
, and SNU GW EM follow-up team1
1
CEOU, Astronomy program, Department of Physics and Astronomy, Seoul National University, Republic of KoreaRecent observation of the neutron star merger event, GW170817, through both gravitational wave (GW) and electromagnetic wave (EM) observations opened a new way of exploring the universe, namely, multi-messenger astronomy (MMA). One of the keys to the success of MMA is a rapid identification of EM counterpart.
We will introduce the strategy for prioritization of GW source host galaxy candidates. Our method relies on recent simulation results regarding plausible properties of GW source host galaxies and the low latency localization map from LIGO/Virgo. We will show the test results for both NS merger and BH merger events using previous events and describe observing strategy with our facilities for GW events during the ongoing LIGO/Virgo O3 run. Finally, we report the result of follow-up observation on, the first neutron star merger event, S190425z, during LIGO/VIrgo O3 run.
[포 GC-14] Intracluster Light Study of the Distant Galaxy Cluster SPT2106-5844 at z=1.132 with Hubble Space Telescope Infrared Imaging Data
Hyungjin. Joo1, Myungkook. James. Jee1, Jongwan.
Ko2
