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AKARI mid-infrared slitless spectroscopic survey of star-forming galaxies at <i>z</i> ≲ 0.5
Ohyama, Y.,Wada, T.,Matsuhara, H.,Takagi, T.,Malkan, M.,Goto, T.,Egami, E.,Lee, H.-M.,Im, M.,Kim, J.H.,Pearson, C.,Inami, H.,Oyabu, S.,Usui, F.,Burgarella, D.,Mazyed, F.,Imanishi, M.,Jeong, W.-S.,Miya EDP Sciences 2018 Astronomy and astrophysics Vol.618 No.-
<P><I>Context.</I> Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift <I>z</I> ≲ 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy.</P><P><I>Aims.</I> We aim to study star-forming galaxies by using a blind spectroscopic survey at MIR wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to <I>z</I> ≃ 0.5, by paying particular attention to their PAH properties.</P><P><I>Methods.</I> We conducted a low-resolution (<I>R</I> ≃ 50) slitless spectroscopic survey at 5-13 <I>μ</I>m of 9 <I>μ</I>m flux-selected sources (>0.3 mJy) around the north ecliptic pole with the infrared camera (IRC) onboard AKARI. After removing 11 AGN candidates by using the IRC photometry, we identify 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 <I>μ</I>m features at <I>z</I> < 0.5. The rest-frame optical-MIR spectral energy distributions (SEDs) based on CFHT and IRC imaging covering 0.37-18 <I>μ</I>m were produced, and analysed in conjunction with the PAH spectroscopy. We defined the PAH enhancement by using the luminosity ratio of the 7.7 <I>μ</I>m PAH feature over the 3.5 <I>μ</I>m stellar component of the SEDs.</P><P><I>Results.</I> The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 <I>μ</I>m bumps, except that the PAH enhancement significantly varies as a function of the PAH luminosities. We identify a PAH-enhanced population at <I>z</I> ≳ 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a very young and optically very thick starburst with a very old population can successfully reproduce most of their SED characteristics, although we cannot confirm this optically think component from our spectral analysis.</P>
The North Ecliptic Pole Wide survey of AKARI: a near- and mid-infrared source catalog
Kim, S. J.,Lee, H. M.,Matsuhara, H.,Wada, T.,Oyabu, S.,Im, M.,Jeon, Y.,Kang, E.,Ko, J.,Lee, M. G.,Takagi, T.,Pearson, C.,White, G. J.,Jeong, W.-S.,Serjeant, S.,Nakagawa, T.,Ohyama, Y.,Goto, T.,Takeuch EDP Sciences 2012 Astronomy and astrophysics Vol.548 No.-
OVERVIEW OF THE NORTH ECLIPTIC POLE DEEP MULTI-WAVELENGTH SURVEY (NEP-DEEP)
Matsuhara, H.,Wada, T.,Takagi, T.,Nakagawa, T.,Murata, K.,Churei, S.,Goto, T.,Oyabu, S.,Takeuchi, T.T.,Ohyama, Y.,Miyaji, T.,Krumpe, M.,Lee, H.M.,Im, M.,Serjeant, S.,Peason, C.P.,White, G.,Malkan, M.A The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
An overview of the North Ecliptic Pole (NEP) deep multi-wavelength survey covering from X-ray to radio wavelengths is presented. The main science objective of this multi-wavelength project is to unveil the star-formation and AGN activities obscured by dust in the violent epoch of the Universe (z=0.5-2), when the star formation and black-hole evolution activities were much stronger than the present. The NEP deep survey with AKARI/IRC consists of two survey projects: shallow wide (8.2 sq. deg, NEP-Wide) and the deep one (0.6 sq. deg, NEP-Deep). The NEP-Deep provides us with a $15{\mu}m$ or $18{\mu}m$ selected sample of several thousands of galaxies, the largest sample ever made at these wavelengths. A continuous filter coverage at mid-IR wavelengths (7, 9, 11, 15, 18, and $24{\mu}m$) is unique and vital to diagnose the contribution from starbursts and AGNs in the galaxies at the violent epoch. The recent updates of the ancillary data are also provided: optical/near-IR magnitudes (Subaru, CFHT), X-ray (Chandra), FUV/NUV (GALEX), radio (WSRT, GMRT), optical spectra (Keck/DEIMOS etc.), Subaru/FMOS, Herschel/SPIRE, and JCMT/SCUBA-2.
Identification of marneral synthase, which is critical for growth and development in Arabidopsis
Go, Young S.,Lee, Saet B.,Kim, Hae J.,Kim, Jungmook,Park, Hyo‐,Young,Kim, Jeong‐,Kook,Shibata, Kyomi,Yokota, Takao,Ohyama, Kiyoshi,Muranaka, Toshiya,Arseniyadis, Simé,on,Suh, Mi C. Blackwell Publishing Ltd 2012 The Plant journal Vol.72 No.5
<P><B>Summary</B></P><P>Plants produce structurally diverse triterpenoids, which are important for their life and survival. Most triterpenoids and sterols share a common biosynthetic intermediate, 2,3‐oxidosqualene (OS), which is cyclized by 2,3‐oxidosqualene cyclase (OSC). To investigate the role of an OSC, marneral synthase 1 (MRN1), <I>in planta</I>, we characterized a Arabidopsis <I>mrn1</I> knock‐out mutant displaying round‐shaped leaves, late flowering, and delayed embryogenesis. Reduced growth of <I>mrn1</I> was caused by inhibition of cell expansion and elongation. Marnerol, a reduced form of marneral, was detected in Arabidopsis overexpressing <I>MRN</I>1, but not in the wild type or <I>mrn1</I>. Alterations in the levels of sterols and triterpenols and defects in membrane integrity and permeability were observed in the <I>mrn1</I>. In addition, GUS expression, under the control of the <I>MRN1</I> gene promoter, was specifically detected in shoot and root apical meristems, which are responsible for primary growth, and the mRNA expression of Arabidopsis clade II OSCs was preferentially observed in roots and siliques containing developing seeds. The eGFP:MRN1 was localized to the endoplasmic reticulum in tobacco protoplasts. Taken together, this report provides evidence that the unusual triterpenoid pathway via marneral synthase is important for the growth and development of Arabidopsis.</P>