We propose a cosmological survey to probe star formation and nuclear activity in galaxies at redshifts of z=2-4 by polycyclic aromatic hydrocarbon (PAH) features using the SPICA mid-infrared instrument (SMI) with a spectral resolution of R=20. We will cover a wavelength range of 20-36 μm that corresponds to z=2-4 for the PAH features (11.3, 7.7, and 6.2 μm). The sensitivity will be 1 X 10-19 W/m2 (5 σ) in case of a reference survey that covers 4 arcmin2 field in a one-hour observation. It corresponds to LIR=2 X 1011 L⊙ at z=3 and will give us more than 10000 galaxies in a 450 hour survey.

Using the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI we study the 3.3 μm polycyclic aromatic hydrocarbon (PAH) feature and its connection to active galactic nucleus (AGN) properties for a sample of 54 hard X-ray selected bright AGN, including both Seyfert 1 and Seyfert 2 type objects. The sample is selected from the 9-month Swift/BAT survey in the 14-195 keV band and all of the sources have known neutral hydrogen column densities (NH). The 3.3 μm PAH luminosity (L3:3μm) is used as a proxy for star-formation (SF) activity and hard X-ray luminosity (L14-195keV) as an indicator of the AGN power. We explore for possible dierence of SF activity between type 1 (un-absorbed) and type 2 (absorbed) AGN. We use several statistical analyses taking the upper-limits of the PAH lines into account utilizing survival analysis methods. The results of our log(L14-195keV) versus log(L3:3μm) regression shows a positive correlation and the slope for the type 1/unobscured AGN is steeper than that of type 2/obscured AGN at a 3σ level. Also our analysis shows that the circum-nuclear SF is more enhanced in type 2/absorbed AGN than type 1/un-absorbed AGN for low L14-195keV luminosity/low Eddington ratio AGN, while there is no significant dependence of SF activity on the AGN type in the high L14-195keV luminosities/Eddington ratios.

Polycyclic aromatic hydrocarbons (PAHs) are considered to be carriers of the unidentified infrared bands, which are ubiquitously observed in the Universe. PAHs are mainly formed around evolved carbon-rich stars and injected into interstellar space. Planetary nebulae (PNe), a late stage of low- and intermediate stellar mass evolution, are suitable objects to investigate the formation and evolution of PAHs. The shortest PAH feature is located in 3.3 μm, which is important to examine the excitation and size distribution of PAHs. While the number of samples had been limited before, the high sensitivity of AKARI/IRC has drastically increased the number of samples. We obtained the 2-5 μm spectra of Galactic PNe with AKARI/IRC and compiled a near-infrared spectral catalog, containing 73 PNe. We investigate the detection rate and the evolution of the PAH features. The characteristics of the catalog are illustrated and the origin of the evolution of the PAH features is discussed.

Using extensive mid-IR datasets from AKARI, i.e. 9-band photometry covering the wavelength range from 2μm to 24μm and the unbiased spectroscopic survey for sources with Sν(9μm)>0.3 mJy, we study starburst galaxies specifically at the redshift of z ~ 0.5, whose mid-IR spectra are clearly dominated by the PAH emission features. PAH-selected galaxies, selected with extremely red mid-IR colour due to PAHs, have high rest-frame PAH-to-stellar luminosity ratios, comparable to those in the most active regions in nearby starburst galaxies. Thus, they seem to have active starburst regions spreading over the whole body. Furthermore, some of PAH-selected galaxies are found to have peculiar rest-frame 11-to- 8μm flux ratios, which is systematically smaller than nearby starburst/AGN spectral templates. This may indicate a systematic difference in the physical condition of ISM between nearby and distant starburst galaxies.

We investigate the relation between star formation activity and PAH 3.3 μm emission. Our targets are mid-infrared-excess galaxies selected from the AKARI all-sky survey point source catalog. We performed AKARI near-infrared spectroscopy for them. As a result, we obtained 2.5 − 5 μm spectra of 79 galaxies, and selected 35 star-forming galaxies out of them. Comparing the PAH 3.3 μm luminosities with the infrared luminosities, we find a linear correlation between them. However, by adding the results from literatures for luminous infrared galaxies and ultra-luminous infrared galaxies that are more luminous than our sample, the ratio of the PAH to the infrared luminosity is found to decrease towards the luminous end.

We utilize AKARI's slitless spectroscopic capability to detect the 3.3 μm polycyclic aromatic hydrocarbons (PAHs) emission and measure star formation (SF) activity for various AKARI programs. First, we obtain 2∼5μm spectra of 20 flux-limited galaxies with mixed SED classes in order to calibrate the 3.3 μm PAH luminosity (LPAH 3.3) as a star formation rate (SFR) indicator. We find that LPAH3.3 correlates with LIR as well as with the 6.2 μm PAH luminosity ( LPAH 6.2). The correlations does not depend on SED classes. We find that ULIRGs deviate from the correlation between PAH luminosities and LIR, while they do not for the correlation between PAH luminosities. We suggest possible effects to cause this deviation. On the other hand, how AGN activity is linked to SB activity is one of the most intriguing questions. While it is suggested that AGN luminosity of quasars correlates with starburst (SB) luminosity, it is still unclear how AGN activity is connected to SF activity based on host galaxy properties. We are measuring SFRs for the LQSONG sample consisting of reverberation mapped AGNs and PG-QSOs. This is an extension of the ASCSG program by which we investigated the connection between SB and AGN activities for Seyferts type 1s at z ~ 0.36. While we found no strong correlation between LPAH3.3 and AGN luminosity for these Seyferts 1s, LPAH3.3 measured from the central part of galaxies correlates with AGN luminosity, implying that SB and AGN activities are directly connected in the nuclear region.

매연과 다중고리 방향족 탄화수소의 생성에 대하여 n-헵탄의 혼합의 영향을 알아보기 위하여 순수에틸렌 대향류 확산화염에 n-헵탄을 소량 혼합하여 실험을 수행하였다. 매연체적분율과 PAH의 생성 계측에서는 레이저 유도 형광법 (laser-induced fluorescence; LIF)과 레이저 유도 백열법(laser-induced incandescence; LII)의 레이저 계측법을 이용하였다. 실험결과로 순수 에틸렌 화염에 소량의 n-헵탄을 혼합한 경우에는 매연과 다중고리 방향족 탄화수소가 상승하였다. 그러나 20% n-헵탄 혼합화염의 경우 LIF 신호가 감소하였다. 소량의 혼합화염의 경우, 다중고리 방향족 탄화수소와 매연의 상승은 n-헵탄 혼합에 의해 저온 영역에서의 메틸 라디칼의 증가로 의한다고 사료된다. 10% n-헵탄 혼합화염에 대한 화학반응 프로세스를 살펴본 결과 H 라디칼에 의한 반응율이 벤젠 생성에 결정적인 역할을 한다는 것을 알 수 있었다.

In this study, the concentrations of polycyclic aromatic hydrocarbons (PAHs) were investigated in meat process food and for cooking methods (pan-frying and charcoal fire). The methodology involved liquid-liquid extraction, silica gel cartridge clean-up and determination by gas chromatography/mass spectrometry (GC/MS). The recovery of 17 PAHs spiked into these samples ranged from 66.6 % to 98.0% and the coefficient of variation was less than 10%, but that of dibenz(a,h)anthracene was 16.39%. The mean concentration of total PAHs in processed samples was ND∼7.2 ng/g, whereas that pan-fried and charcoal-fired samples were ND∼22.1 ng/g and, 12.7∼367.8 ng/g, respectively. Therefore, the concentrations of total PAHs in cooked samples were higher than in original samples and charcoal-fired samples had the highest total PAH levels.