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COSMIC STAR FORMATION HISTORY AND AGN EVOLUTION NEAR AND FAR: AKARI REVEALS BOTH
Goto, Tomotsugu,AKARI NEP team, AKARI NEP team,AKARI all sky survey team, AKARI all sky survey team The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
Understanding infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese infrared satellite, AKARI, provided unique data sets to probe this both at low and high redshifts. The AKARI performed an all sky survey in 6 IR bands (9, 18, 65, 90, 140, and $160{\mu}m$) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can measure the total infrared luminosity ($L_{TIR}$) of individual galaxies much more precisely, and thus, the total infrared luminosity density of the local Universe. In the AKARI NEP deep field, we construct restframe $8{\mu}m$, $12{\mu}m$, and total infrared (TIR) luminosity functions (LFs) at 0.15 < z < 2.2 using 4,128 infrared sources. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and $24{\mu}m$) by the AKARI satellite allows us to estimate restframe $8{\mu}m$ and $12{\mu}m$ luminosities without using a large extrapolation based on a SED fit, which was the largest uncertainty in previous work. By combining these two results, we reveal dust-hidden cosmic star formation history and AGN evolution from z = 0 to z = 2.2, all probed by the AKARI satellite.
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.
Choi, Yumi,Goto, Tomotsugu,Yoon, Suk-Jin Blackwell Publishing Ltd 2009 Monthly notices of the Royal Astronomical Society Vol.395 No.2
<P>ABSTRACT</P><P>Strong Balmer absorption lines and the lack of Hα and [O <SMALL>II</SMALL>] emission lines signify that E+A galaxies are post-starburst systems. Recent studies suggest that E+As may undergo the transition from the ‘blue cloud’ to the ‘red sequence’ and eventually migrate to red-sequence early-type galaxies. An observational validation of this scenario is to identify the intervening galaxy population between E+As and the red sequence. Motivated by recent findings with Galaxy Evolution Explorer (GALEX) that an unexpectedly large fraction of early-type galaxies exhibit ultraviolet (UV) excess (i.e. blue UV – optical colours) as a sign of recent star formation (RSF), we investigate the possible connection of the UV-excess galaxies to E+As. In particular, we examine the Fundamental Plane (FP) scaling relations of the currently largest sample of ∼1000 E+As selected from the Sloan Digital Sky Survey (SDSS) and ∼20 000 morphologically selected SDSS early-type galaxies with GALEX UV data. The FP parameters, combined with stellar population indicators, reveal a certain group of UV-excess early types that bridge between E+As and quiescent red galaxies. The newly identified galaxies are the post-starburst systems characterized by UV-excess but no Hα emission. This is essentially a conceptual generalization of ‘E+A’, in that the Balmer absorption line in the ‘E+A’ definition is replaced with UV – optical colours that are far more sensitive to RSF than the Balmer lines. We refer to these UV-excess galaxies as ‘E+a’ galaxies (named after ‘E+A’), which stand for elliptical (‘E’) galaxies with a minority of A-type (‘a’) young stars. The species are either (1) galaxies that experienced starbursts weaker than those observed in E+As (1 ∼ 10 per cent of E+As, ‘mild E+As’) or (2) the products of passively evolved E+As after quenching star formation quite a while ago (∼1 Gyr, ‘old E+As’). We suggest that the latter type of E+a galaxies (i.e. old ‘E+As’) represents the most recent arrival to the red sequence in the final phase of the E+A to red early-type transition.</P>
A COSMOLOGICAL PAH SURVEY WITH SPICA
Takehiko Wada,Eiichi Egami,Naofumi Fujishiro,Tomotsugu Goto,Masatoshi Imanishi,Hanae Inami,Daisuke Ishihara,Hidehiro Kaneda,Kotaro Kohno,Yusei Koyama,Hideo Matsuhara,Shuji Matsuura,Tohru Nagao,Youichi 한국천문학회 2017 天文學論叢 Vol.32 No.1
We propose a cosmological survey to probe star formation and nuclear activityin galaxies at redshifts of z = 2 - 4 by polycyclic aromatic hydrocarbon(PAH) features usingthe SPICA mid-infrared instrument (SMI)with a spectral resolution of R = 20. We will cover a wavelength range of 20-36 μmthat corresponds to z = 2 - 4 for the PAH features(11.3, 7.7, and 6.2 μm). The sensitivity will be $1\times10^{-19}$ W/m$^2$ (5 $\sigma$)in case of a referencesurvey that covers 4 arcmin$^2$ field in a one-hour observation. It corresponds to L$_{\rm IR}$=$2\times10^{11}$ $L_\odot$ at z=3and will give us more than 10000 galaxies in a 450 hour survey.
Optical – near-infrared catalog for the AKARI north ecliptic pole Deep field
Oi, Nagisa,Matsuhara, Hideo,Murata, Kazumi,Goto, Tomotsugu,Wada, Takehiko,Takagi, Toshinobu,Ohyama, Youichi,Malkan, Matthew,Im, Myungshin,Shim, Hyunjin,Serjeant, Stephen,Pearson, Chris Springer-Verlag 2014 Astronomy and astrophysics Vol.566 No.-
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.