간행물
천문학논총 KCI 등재 Publications of the Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 연3회
- ISSN 1225-1534 (Print)2287-6936 (Online)
- 수록기간 1984 ~ 2024
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
Volume 27 Issue 4 (2012년 9월) 71건
41.
2012.09
구독 인증기관 무료, 개인회원 유료
We present the result of systematic AKARI IRC infrared 2.5−5 μm spectroscopy of >100 nearby luminous infrared galaxies, to investigate the energetic roles of starbursts and optically-elusive buried AGNs. Based on (1) the equivalent widths of the 3.3μm PAH emission features, (2) the optical depths of absorption features, and (3) continuum slopes, we can disentangle emission from starbursts and AGNs. We find that the energetic importance of buried AGNs increases with increasing galaxy infrared luminosities, suggesting that the AGN-starburst connections (and thereby possible AGN feedback to host galaxies) are luminosity dependent.
3,000원
42.
2012.09
구독 인증기관 무료, 개인회원 유료
KOHEI ICHIKAWA, YOSHIHIRO UEDA, YUICHI TERASHIMA, SHINKI OYABU, POSHAK GANDHI, KEIKO MATSUTA, TAKAO NAKAGAWA
We investigate the mid-infrared (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the infrared survey catalogs of AKARI, IRAS and WISE. Out of 135 non-blazar AGNs in the Swift/BAT 9-month catalog, we obtain the MIR photometric data for 128 sources in either the 9, 12, 18, 22, and $25{\mu}m$ band. We find a good correlation between their hard X-ray and MIR luminosities ranging three orders of magnitude (42 < log λLλ(9,18 μm ) < 45), which is tighter than that with the FIR luminosities at 90 μm . Both X-ray unabsorbed and absorbed AGNs follow the same correlation, implying isotropic infrared emission, as expected in clumpy dust tori models rather than homogeneous ones.
4,000원
43.
2012.09
구독 인증기관 무료, 개인회원 유료
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.
3,000원
44.
2012.09
구독 인증기관·개인회원 무료
K. MATSUTA, P. GANDHI, T. DOTANI, T. NAKAGAWA, N. ISOBE, Y. UEDA, K. ICHIKAWA, Y. TERASHIMA, S. OYABU, I. YAMAMURA, L. STAWARZ
We combine data from two all-sky surveys, the Swift/Burst Alert Telescope 22 Month Source Catalog and the AKARI Point Source Catalogue, in order to study the connection between the hard X-ray (> 10 keV) and infrared (IR) properties of local active galactic nuclei (AGN). We find two photometric diagnostics are useful for source classification: one is the X-ray luminosity vs. IR color diagram, in which type 1 radio-loud AGN are well isolated from other AGN. The second one uses the X-ray vs. IR color-color diagram as a redshift-independent indicator for identifying Compton-thick (CT) AGN. Importantly, CT AGN and starburst galaxies in composite systems can also be separated in this plane based upon their hard X-ray fluxes and dust temperatures. This diagram may be useful as a new indicator to classify objects in new surveys such as with WISE and NuSTAR.
45.
2012.09
구독 인증기관·개인회원 무료
Radio-loud active galaxies have been found to exhibit a close connection to galactic mergers and host galaxy star-formation quenching. We present preliminary results of an optical spectroscopic investigation of the AKARI NEP field. We focus on the population of radio-loud AGN and use photometric and spectroscopic information to study both their star-formation and nuclear activity components. Preliminary results show that radio-AGN are associated with early type, massive galaxies with relatively old stellar populations.
46.
2012.09
구독 인증기관·개인회원 무료
Feedback from accreting BH (AGN) is thought to be responsible for the co-evolution of BHs and galaxies. It is likely to be prominent in the most luminous dust-obscured quasars, particularly those containing radio sources too luminous to be powered by starbursts. In order to investigate the feedback mechanism in detail, we select a unique sample containing ~ 200 of the most luminous obscured QSOs by cross-matching the WISE catalog with the FIRST and NVSS radio surveys. We present overall statistics for the observed range of colors and radio/mid-IR flux density ratio. We also present our efforts to understand the physical and evolutionary nature of these extreme feedback candidates using various telescopes such as Magellan, SOAR, Herschel, and ALMA.
47.
2012.09
구독 인증기관·개인회원 무료
We select infrared-luminous galaxies by cross-matching the SDSS spectroscopic sample of galaxies with the WISE all-sky survey catalog. Based on photometric data points covering from SDSS u-band to WISE 22 μm , their spectral energy distributions (SEDs) are separated into AGN, elliptical, spiral, and irregular galaxy components. The derived luminosities of spiral galaxy and AGN are well correlated with Hα and [OIII] line luminosities, respectively. Most galaxies are dominated by young stellar populations even for optical AGNs, but at least 10% of optical non-AGNs appear to harbor buried AGNs. The AGN contribution increases dramatically with the total luminosity. These results show that the SED decomposition is successful and is useful to understand the true nature of dusty galaxies.
48.
2012.09
구독 인증기관·개인회원 무료
We established a separation scheme to distinguish galaxies from stars with the aid of AKARI/FIS color-color (CC) diagrams. In all the combinations of CC diagrams we can distinguish two separate clouds. It was shown that in all cases one of them contains more than 95% of galaxies and the other one, in most cases, consists in more than 80% of stars (Pollo et al., 2010). Currently we are looking into more detailed classifications. We are especially interested in separating different morphological types of galaxies, mainly within spiral galaxies. Moreover, we study the properties of infrared galaxies.
49.
2012.09
구독 인증기관·개인회원 무료
We provide a new physical insight on the hot molecular clouds near the nucleus of the heavily obscured AGN IRAS 01250+2832, based on the results of near-infrared high-resolution spectroscopy of gaseous CO ro-vibrational absorption lines with Subaru/IRCS. The detected CO absorption lines up to highly excited rotational levels reveal that hot dense molecular clouds exist around the AGN under the peculiar physical conditions.
50.
2012.09
구독 인증기관·개인회원 무료
KEN TATEUCHI, KENTARO MOTOHARA, MASAHIRO KONISHI, HIDENORI TAKAHASHI, NATSUKO KATO, YUKA K. UCHIMOTO, KOJI TOSHIKAWA, RYOU OHSAWA, YUTARO KITAGAWA, YUZURU YOSHII, MAMORU DOI, KOTARO KOHNO, KIMIAKI KAWARA, MASUO TANAKA, TAKASHI MIYATA, TOSHIHIKO TANABE, TAKEO MINEZAKI, SHIGEYUKI SAKO, TOMOKI MOROKUMA, YOICHI TAMURA, TSUTOMU AOKI, TAKEO SOYANO, KENFICHI TARUSAWA, SHINTARO KOSHIDA, TAKAFUMI KAMIZUKA, TOMOHIKO NAKAMURA, KENTARO ASANO, MIZUHO UCHIYAMA, KAZUSHI OKADA, YOSHIFUSA ITA
ANIR (Atacama Near InfraRed camera) is a near infrared camera for the University of Tokyo Atacama 1m telescope, installed at the summit of Co. Chajnantor (5,640 m altitude) in northern Chile. The high altitude and extremely low water vapor (PWV = 0.5 mm) of the site enable us to perform observation of hydrogen Paα emission line at 1.8751 μm . Since its first light observation in June 2009, we have been carrying out a Paα narrow-band imaging survey of nearby luminous infrared galaxies (LIRGs), and have obtained Paα for 38 nearby LIRGs listed in AKARI/FIS-PSC at the velocity of recession between 2,800 km/s and 8,100 km/s. LIRGs are affected by a large amount of dust extinction ( AV~ 3 mag), produced by their active star formation activities. Because Paα is the strongest hydrogen recombination line in the infrared wavelength ranges, it is a good and direct tracer of dust-enshrouded star forming regions, and enables us to probe the star formation activities in LIRGs. We find that LIRGs have two star-forming modes. The origin of the two modes probably come from differences between merging stage and/or star-forming process.
51.
2012.09
구독 인증기관·개인회원 무료
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.
52.
2012.09
구독 인증기관 무료, 개인회원 유료
We present the result of our near infrared J- (λ=1.25μm), H- (λ=1.63μm), and Ks-band (λ=2.14μm) imaging of ultraluminous (LI > 1012L⊙) and uminous(LIR=1011−12L⊙) infrared galaxies (ULIRGs and LIRGs), to investigate their relationship through properties of their host galaxies. We find that (1) for single-nucleus ULIRGs and LIRGs, their spheroidal host galaxies have similar properties, but ULIRGs display a substantially higher level of nuclear activity than LIRGs, suggesting that their infrared luminosity difference comes primarily from the different level of current nuclear activity. We infer that LIRGs and ULIRGs have similar progenitor galaxies, follow similar evolutionary processes, and may evolve into optically-selected QSOs. (2) Largely-separated multiple-nuclei ULIRGs have significantly brighter host galaxies than single-nucleus ULIRGs and LIRGs in Ks-band, indicating that multiple-nuclei ULIRGs have a bias towards mergers of intrinsically large progenitor galaxies, in order to produce high infrared luminosity (LIR > 102L⊙) even at the early merging stage. (3) We derive dust extinction of host galaxies of ULIRGs and LIRGs to be AV ~ 14 mag in the optical or quivalently AK ~ 0.8 mag in the near-infrared Ks-band, based on the comparison of host galaxy's uminosities in the J-, H-, and Ks-bands.
3,000원
53.
2012.09
구독 인증기관 무료, 개인회원 유료
AKARI's all-sky survey resolves the far-infrared emission in many thousands of nearby galaxies, providing essential local benchmarks against which the evolution of high-redshift populations can be measured. This review presents some recent results in the resolved galaxy populations, covering some well-known nearby targets, as well as samples from major legacy surveys such as the Herschel Reference Survey and the JCMT Nearby Galaxies Survey. This review also discusses the prospects for higher redshifts surveys, including strong gravitational lens clusters and the AKARI NEP field.
4,000원
54.
2012.09
구독 인증기관 무료, 개인회원 유료
Lyman break Galaxies are galaxies selected in the rest-frame ultraviolet. But, one important and missing information for these Lyman break galaxies is the amount of dust attenuation. This is crucial to estimate the total star formation rate of this class of objects and, ultimately, the cosmic star formation density. AKARI, Spitzer and Herschel are therefore the major facilities that could provide us with this information. As part of the Herschel Multi-tiered Extragalactic Survey, we have began investigating the rest-frame far-infrared properties of a sample of more than 4,800 Lyman Break Galaxies in the GOODS-North fiels. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 < z <1.6 and one object at z = 2.0. The ones detected by Herschel SPIRE have redder observed NUV-U and U-R colors than the others, while the undetected ones have colors consistent with average LBGs at z > 2.5. We have analysed their UV-to-FIR spectral energy distributions using the code cigale to estimate their physical parameters. We find that LBGs detected by SPIRE are high mass, luminous infrared galaxies. They also appear to be located in a triangle-shaped region in the AFUV vs. logLFUV diagram limited by AFUV = 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom-right to the top-left of the diagram. In a second step, we move to the larger COSMOS field where we have been able to detect 80 Lyman break galaxies (out of ~ 15,600) in the far infrared. They form the largest sample of Lyman break galaxies at z > 2.5 detected in the far-infrared. We tentatively name them Submillimeter Lyman break galaxies (S-LBGs).
4,000원
55.
2012.09
구독 인증기관 무료, 개인회원 유료
A sample of nearby galaxies was built from the AKARI/FIS all sky survey cross-correlated with the SDSS and GALEX surveys. The spectral energy distributions from 0.15 to 160 microns of these galaxies are analysed to study dust attenuation and star formation properties. The calibrations of the amount of dust attenuation as a function of the IR-to-UV flux ratio and the FUV-NUV colour are re-investigated: the former one is confirmed to be robust and accurate whereas the use of the FUV-NUV colour to measure dust attenuation is found highly uncertain. The current star formation rate given by the SED fitting process is compared to that directly obtained from the UV and total IR luminosities. It leads to an accurate estimate of dust heating by old stars. We emphasize the importance of such a sample as a reference for IR selected star forming galaxies in the nearby universe.
3,000원
56.
2012.09
구독 인증기관 무료, 개인회원 유료
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.
3,000원
57.
2012.09
구독 인증기관 무료, 개인회원 유료
We will report our recent study on the properties of more than 1,600 galaxies detected by the AKARI All-Sky Survey with physical quantities based on optical and 21-cm observations, to understand the physics determining the infrared spectral energy distribution (Totani et al., 2011). We discover a tight linear correlation for normal star-forming galaxies between the radiation field strength of dust heating (corresponding to dust temperature) and the galactic-scale infrared radiation field, LTIR/R2 . This is the tightest correlation of dust temperature ever known, and the dispersion along the mean relation is 13% in dust temperature. This relation can be explained physically by a thin layer of heating sources embedded in a thicker, optically-thick dust screen. We also find that the number of galaxies sharply drops when galaxies become optically thin against dust-heating radiation, indicating that a feedback process to galaxy formation (e.g., by the photoelectric heating) is working when dust-heating radiation is not self-shielded on a galactic scale. We discuss implications from these findings for the MHI -size relation, the Kennicutt-Schmidt relation, and galaxy formation in the cosmological context.
4,000원
58.
2012.09
구독 인증기관 무료, 개인회원 유료
We investigate the role of galaxy environment in the evolution of individual galaxies through the AKARI observations of the merging galaxy cluster A2255. MIR diagnostics using N3-S11 colors are adopted to select star-forming galaxies and galaxies in transition between star-forming galaxies and quiescent galaxies. We do not find particular enhancement of star formation rates as a function of galaxy environment, reflected in cluster-centric distance and local surface density of galaxies. Instead, the locations of intermediate MIR-excess galaxies (-1.2 < N3 - S11 < 0.2) show that star-forming galaxies are transformed into passive galaxies in the substructures of A2255, where the local surface density of galaxies is relatively high.
3,000원
59.
2012.09
구독 인증기관 무료, 개인회원 유료
YOSHIKI TOBA, SHINKI OYABU, HIDEO MATSUHARA, DAISUKE ISHIHARA, MATT MALKAN, TAKEHIKO WADA, YOUICHI OHYAMA, HIROKAZU KATAZA, SATOSHI TAKITA
We present the 18μm 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 18μm 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 α or the emission line ratios of [OIII]/ Hβ and [NII]/ Hα . 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±0.37 , larger than the results obtained from optical LF and (ii) the fraction of Sy2 in the entire AGN population may decrease with 18μm 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.
3,000원
60.
2012.09
구독 인증기관 무료, 개인회원 유료
It is a long known fact that there exists a tight correlation between far-infrared and radio emission both for galaxies hosting active galactic nuclei and for star forming galaxies. We probe the radio - infrared correlation for a sample of extragalactic sources constructed by the cross-correlation of the AKARI/IRC All-Sky Survey Point Source Catalogue, the AKARI/FIS All-Sky Survey Bright Source Catalogue, and the NRAO VLA Sky Survey. Additionally, all objects of our sample were identified as galaxies in NED and SIMBAD databases, and a part of them is known to host active galactic nuclei (AGNs). After remeasuring all the fluxes, in order to avoid small aperture effects, we compare the ratio of radio to infrared emission from different types of extragalactic sources, and discuss the FIR/radio correlation as seen by AKARI and make a comparison to the previous results obtained thanks to IRAS.
3,000원
