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PROPERTIES OF DUST OBSCURED GALAXIES IN THE NEP-DEEP FIELD
Nagisa Oi,Hideo Matsuhara,CHRIS PEARSON,Veronique Buat,Denis Burgarella,Matt Malkan,Takamitsu Miyaji 한국천문학회 2017 天文學論叢 Vol.32 No.1
We selected 47 DOGs at z ~ 1.5 using optical $R$ (or $r^{'}$), AKARI 18 $\mu$m, and 24 $\mu$m color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and $9\mu$m, we classified them into 3 groups; bump DOGs (23 sources), power-law DOGs (16 sources), and unknown DOGs (8 sources). We built spectral energy distributions (SEDs) with optical to far-infrared photometric data and investigated their properties using SED fitting method. We found that AGN activity such as a AGN contribution to the infrared luminosity and a Chandra detection rate for bump and power-law DOGs are significantly different, while stellar component properties like a stellar mass and a star-formation rate are similar to each other. A specific star-formation rate range of power-law DOGs is slightly higher than that of bump DOGs with wide overlap. Herschel/PACS detection rates are almost the same between bump and power-law DOGs. On the other hand SPIRE detection rates show large differences between bump and power-law DOGs. These results might be explained by differences in dust temperatures. Both groups of DOGs host hot and/or warm dust (~ 50 Kelvin), and many bump DOGs contain cooler dust ($\hspace{0.3em}\raisebox{0.4ex}{$<$}\hspace{-0.75em}\raisebox{-.7ex}{$\sim$}\hspace{0.3em}$ 30 Kelvin).
HYPER SUPRIME-CAMERA SURVEY OF THE AKARI NEP WIDE FIELD
Tomotsugu Goto,Yoshiki Toba,Yousuke Utsumi,Nagisa Oi,Toshinobu Takagi,Matt Malkan,Youichi Ohayma,Kazumi Murata,Paul Price,Marios Karouzos,Hideo Matsuhara,TAKAO NAKAGAWA,Takehiko Wada,Steve Serjeant,De 한국천문학회 2017 天文學論叢 Vol.32 No.1
The extragalactic background suggests half the energy generated by stars was reprocessed into the infrared (IR) by dust. At z$\sim$1.3, 90\% of star formation is obscured by dust. To fully understand the cosmic star formation history, it is critical to investigate infrared emission. AKARI has made deep mid-IR observation using its continuous 9-band filters in the NEP field (5.4 deg$^2$), using $\sim$10\% of the entire pointed observations available throughout its lifetime. However, there remain 11,000 AKARI infrared sources undetected with the previous CFHT/Megacam imaging ($r\sim$25.9ABmag). Redshift and IR luminosity of these sources are unknown. These sources may contribute significantly to the cosmic star-formation rate density (CSFRD). For example, if they all lie at 1$<z<$2, the CSFRD will be twice as high at the epoch. We are carrying out deep imaging of the NEP field in 5 broad bands ($g,r,i,z,$ and $y$) using Hyper Suprime-Camera (HSC), which has 1.5 deg field of view in diameter on Subaru 8m telescope. This will provide photometric redshift information, and thereby IR luminosity for the previously-undetected 11,000 faint AKARI IR sources. Combined with AKARI's mid-IR AGN/SF diagnosis, and accurate mid-IR luminosity measurement, this will allow a complete census of cosmic star-formation/AGN accretion history obscured by dust.
A TALE OF TWO FEEDBACKS: STAR FORMATION IN THE HOST GALAXIES OF RADIO AGNs
Karouzos, Marios,Im, Myungshin,Trichas, Markos,Goto, Tomo,Malkan, Matt,Ruiz, Angel,Jeon, Yiseul,Kim, Ji Hoon,Lee, Hyung Mok,Kim, Seong Jin,Oi, Nagisa,Matsuhara, Hideo,Takagi, Toshinobu,Murata, K.,Wada IOP Publishing 2014 The Astrophysical journal Vol.784 No.2
<P>Several lines of argument support the existence of a link between activity at the nuclei of galaxies, in the form of an accreting supermassive black hole, and star formation activity in these galaxies. Radio jets have long been argued to be an ideal mechanism that allows active galactic nuclei (AGNs) to interact with their host galaxies and affect star formation. We use a sample of radio sources in the North Ecliptic Pole (NEP) field to study the nature of this putative link, by means of spectral energy distribution (SED) fitting. We employ the excellent spectral coverage of the AKARI infrared space telescope and the rich ancillary data available in the NEP to build SEDs extending from UV to far-IR wavelengths. We find a significant AGN component in our sample of relatively faint radio sources (<mJy). A positive correlation is found between the luminosity of the AGN component and that of star formation in the host galaxy, independent of the radio luminosity. In contrast, for narrow redshift and AGN luminosity ranges, we find that increasing radio luminosity leads to a decrease in the specific star formation rate. The most radio-loud AGNs are found to lie on the main sequence of star formation for their respective redshifts. For the first time, we potentially see such a two-sided feedback process in the same sample. We discuss the possible suppression of star formation, but not total quenching, in systems with strong radio jets, that supports the maintenance nature of feedback from radio AGN jets.</P>
THE 18 ㎛ LUMINOSITY FUNCTION OF GALAXIES WITH AKARI
Toba, Yoshiki,Oyabu, Shinki,Matsuhara, Hideo,Ishihara, Daisuke,Malkan, Matt,Wada, Takehiko,Ohyama, Youichi,Kataza, Hirokazu,Takita, Satoshi The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We present the $18{\mu}m$ luminosity function (LF) of galaxies at 0.006 < z < 0.8 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected 243 galaxies at $18{\mu}m$ from the Sloan Digital Sky Survey (SDSS) spectroscopic region. These galaxies then have been classified into five types; Seyfert 1 galaxies (Sy1, including quasars), Seyfert 2 galaxies (Sy2), low ionization narrow emission line galaxies (LINER), galaxies that are likely to contain both star formation and Active Galactic Nuclei (AGN) activities (composites), and star forming galaxies (SF) using optical emission lines such as the line width of $H{\alpha}$ or the emission line ratios of [OIII]/$H{\beta}$ and [NII]/$H{\alpha}$. As a result of constructing the LF of Sy1 and Sy2, we found the following results; (i) the number density ratio of Sy2 to Sy1 is $1.64{\pm}0.37$, larger than the results obtained from optical LF and (ii) the fraction of Sy2 in the entire AGN population may decrease with $18{\mu}m$ luminosity. These results suggest that most of the AGNs in the local universe are obscured by dust and the torus structure probably depends on the mid-infrared luminosity.
Yoshiki Toba,SHINKI OYABU,Hideo Matsuhara,DAISUKE ISHIHARA,Matt A. Malkan,Takehiko Wada,YOUICHI OHYAMA,Hirokazu Kataza,SATOSHI TAKITA,Chisato Yamauchi 한국천문학회 2017 天文學論叢 Vol.32 No.1
We demonstrate the luminosity dependence of the covering factor (CF) of active galactic nuclei (AGNs), based on AKARI mid-infrared all-sky survey catalog. Combining the AKARI with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 243 galaxies at 9 $\mu$m and 255 galaxies at 18 $\mu$m. We then identified 64 AGNs at 9 $\mu$m and 105 AGNs at 18 $\mu$m by their optical emission lines. Following that, we estimated the CF as the fraction of type 2 AGN in all AGNs. We found that the CF decreased with increasing 18 $\mu$m luminosity, regardless of the choice of type2 AGN classification criteria.
PROPERTIES OF THE SCUBA-2 850 μm SOURCES IN THE AKARI NEP-DEEP FIELD
서현종,정웅섭,김민진,김성진,고종완,표정현,김민규,Chris Pearson,Laia Barrufet,Maria del Carmen Campos Varillas,Hideo Matsuhara,Matt Malkan,Helen K. Kim,Toshinobu Takagi,Takamitsu Miyaji,Jorge Diaz Tello,Tomotsugu Goto,Nagi 한국천문학회 2018 Journal of The Korean Astronomical Society Vol.51 No.3
We carry out the study of SMGs in the $AKARI$ NEP-Deep field using James Clerk Maxwell Telescope (JCMT) SCUBA-2 850 $\mu$m source catalog released as a part of SCUBA-2 Cosmology Legacy Survey (S2CLS) program. The SCUBA-2 850 $\mu$m map has a root mean square (rms) noise of 1.2 mJy beam$^{-1}$ and covers an area of 0.60 degree$^{2}$. We find 4 sub-millimeter galaxies (SMGs) which have counterparts to $Herschel$ sources with spectroscopic redshifts in the literature. In addition, 3 dust obscured galaxies (DOGs) detected in $Herschel$ bands are also selected as a comparison sample. We derive IR luminosities of SMGs using CIGALE code, which are similar to those of high redshift SMGs from previous studies. The contribution of AGN to the total IR luminosity in SMG (2\%$-$11\%) is smaller than lower limit of that in DOG (19\%$-$35\%), which is consistent with the expectation from the evolutionary scenario of massive galaxies. We search for SMGs in the overdense region as candidates of protocluster and investigate 4 candidates among them including candidates around three DOGs. Finally, we argue that follow-up spectroscopic observation for the NEP-Deep field will provide crucial information to understand the role of SMGs in the evolution of massive galaxies.
The Seoul National University AGN Monitoring Project (SAMP) : Photometric Light Curves
Donghoon Son,Jong-Hak Woo,Hyun-Jin Bae,Yiseul Jeon,Huynh Anh Le,Songyoun Park,Jaejin Shin,Minjin Kim,Daeseong Park,Hyun-il Sung,Ellena Gallo,Edmund Hodges-Kluck,Aaron Barth,Tommaso Treu,Matt Malkan,Va 한국천문학회 2017 天文學會報 Vol.42 No.1