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 ~ 2023
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
Volume 32 Issue 1 (2017년 3월) 77건
41.
2017.03
구독 인증기관 무료, 개인회원 유료
We performed systematic observations of the Hi Brα line (4.05 μm) in 51 nearby (z<0.3) ultraluminous infrared galaxies (ULIRGs), using AKARI near-infrared spectroscopy. The Brα line is predicted to be the brightest among the Hi recombination lines in ULIRGs with visual extinction higher than 15 mag. We detected the Brα line in 33 ULIRGs. In these galaxies, the relative contribution of starburst to the total infrared luminosity (LIR) is estimated on the basis of the ratio of the Brα line luminosity (LBrα) to LIR. The mean LBrα/LIR ratio in LINERs or Seyferts is significantly lower (~50%) than that in Hii galaxies. This result indicates that active galactic nuclei contribute signi cantly (~50%) to LIR in LINERs, as well as Seyferts. We also estimate the absolute contribution of starburst to LIR using the ratio of star formation rates (SFRs) derived from LBrα (SFRBrα) and those needed to explain LIR (SFRIR). The mean SFRBrα/SFRIR ratio is only 0.33 even in Hii galaxies, where starburst is supposed to dominate the luminosity. We attribute this apparently low SFRBrα/SFRIR ratio to the absorption of ionizing photons by dust within Hii regions.
3,000원
42.
2017.03
구독 인증기관 무료, 개인회원 유료
Yoshiki Toba, Shinki Oyabu, Hideo Matsuhara, Daisuke Ishihara, Matt A. Malkan, Takehiko Wada, Youichi Ohyama, Hirokazu Kataza, Satoshi Takita, Chisato Yamauchi
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 m and 255 galaxies at 18 m. We then identi ed 64 AGNs at 9 μm and 105 AGNs at 18 μm 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 μm luminosity, regardless of the choice of type 2 AGN classification criteria.
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43.
2017.03
구독 인증기관 무료, 개인회원 유료
Angel Castro, Takamitsu Miyaji, Mai Shirahata, Kohei Ichikawa, Shinki Oyabu, David Clark, Masatoshi Imanishi, Takao Nakagawa, Yoshihiro Ueda
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 di erence 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.
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44.
2017.03
구독 인증기관 무료, 개인회원 유료
Marios Karouzos, Myungshin Im, Markos Trichas, Tomogotsu Goto, Matthew Malkan, Angel Ruiz, Yiseul Jeon, Ji Hoon Kim, Hyung Mok Lee, Seong Jin Kim, Nagisa Oi, Hideo Matsuhara, Toshinobu Takagi, Kazumi Murata, Takehiko Wada, Kensuke Wada, Hyunjin Shim, Hitoshi Hanami, Stephen Serjeant, Youichi Ohyama
There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi- wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio sources below redshift z = 2 and at a radio 1.4 GHz ux density limit of 0.1 mJy. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this eld, while also offering evidence showcasing a link between AGN activity and host galaxy star formation. In particular, we show results supporting a maintenance type of feedback from powerful radio-jets.
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45.
2017.03
구독 인증기관 무료, 개인회원 유료
Modelling and tting the spectral energy distribution (SED) of galaxies or regions of galaxies is one of the most useful methods available to the astronomer nowadays. By modelling the SEDs and comparing the models to the observations, we can collect important information on the physical processes at play in the formation and evolution of galaxies. The models allow to follow the evolution of the galaxies from their formation on. The versatility of code is crucial because of the diversity of galaxies. The analysis is only relevant and useful if the models can correctly reproduce this diversity now and across (as best as possible) all redshifts. On the other hand, the code needs to run fast to compare several million or tens of millions of models and to select the best (on a probabilistic basis) one that best resembles the observations. With this important point in mind, it seems logical that we should efficiently make use of the computer power available to the average astronomer. For instance, it seems difficult, today, to model and fit SEDs without a parallelized code. We present the new Python version of CIGALE SED fitting code and its characteristics. CIGALE comes in two main avours: CIGALE Classic to fit SEDs and CIGALE Model to create spectra and SEDs of galaxies at all redshifts. The latest can potentially be used in conjunction with galaxy evolution models of galaxy formation and evolution such as semi-analytic ones.
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46.
2017.03
구독 인증기관 무료, 개인회원 유료
We performed Principle Component Analysis (PCA) over 264 galaxies in the IRAS Revised Bright Galaxy Sample (Sanders et al., 2003) using 12, 25, 60 and 100 μm ux data observed by IRAS and 9, 18, 65, 90 and 140 μm ux data observed by AKARI. We found that (i)the first principle component was largely contributed by infrared to visible ux ratio, (ii)the second principal component was largely contributed by the ux ratio between IRAS and AKARI, (iii)the third principle component was largely contributed by infrared colors.
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47.
2017.03
구독 인증기관 무료, 개인회원 유료
H. Matsuhara, T. Wada, N. Oi, T. Takagi, T. Nakagawa, K. Murata, T. Goto, S. Oyabu, T. Takeuchi, K. Ma lek, A. Solarz, Y. Ohyama, T. Miyaji, M. Krumpe, H. M. Lee, M. Im, S. Serjeant, C. P. Pearson, G. J. White, M. A. Malkan, H. Hanami, T. Ishigaki, D. Burgarella, V. Buat, A. Pollo
The recent updates of the North Ecliptic Pole deep (0.5 deg2, NEP-Deep) multi-wavelength survey covering from X-ray to radio-wave is presented. The NEP-Deep provides us with several thousands of 15 μm or 18 μm selected galaxies, which is the largest sample ever made at these wavelengths. A continuous filter coverage in the mid-infrared wavelength (7, 9, 11, 15, 18, and 24 μm) is unique and vital to diagnose the contributions from starbursts and AGNs in the galaxies out to z=2. The new goal of the project is to resolve the nature of the cosmic star formation history at the violent epoch (e.g. z=1{2), and to find a clue to understand its decline from z=1 to present universe by utilizing the unique power of the multiwavelength survey. The progress in this context is brie y mentioned.
4,000원
48.
2017.03
구독 인증기관 무료, 개인회원 유료
Chris Pearson, Ryan Cheale, Stephen Serjeant, Hideo Matsuhara, Glenn J. White, Denis Burgarella, Ivan Valtchanov, Bruno Altieri, David L. Clements, Ros Hopwood
The preliminary data reduction, analysis and first results from the Herschel survey of the AKARI NEP field are presented. Herschel SPIRE observations of the NEP-Wide region and PACS observations of the NEP-Deep region have yielded galaxy catalogues of 4000 and 900 sources respectively down to ux density levels of approximately 15 mJy at 100-250 microns. Source counts produced from these catalogues reach cosmologically significant depths tracing the evolutionary upturn and turnover in the source counts. The source counts are in agreement with other large area surveys carried out with Herschel bridging the gap between the shallow and deep Herschel surveys.
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49.
2017.03
구독 인증기관 무료, 개인회원 유료
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, Denis Burgarella, Veronique Buat, Masahiro Takada, Satoshi Miyazaki, Masamune Oguri, Takamitsu Miyaji, Shinki Oyabu, Glenn White, Tsutomu Takeuchi, Hanae Inami, Chris Perason, Katarzyna Malek, Lucia Marchetti, Lee HyungMoK, Myung Im, Seong Jin Kim, Ekaterina Koptelova, Dani Chao, Yi-Han Wu, AKARI NEP Survey team, AKARI All Sky Survey Team
The extragalactic background suggests half the energy generated by stars was reprocessed into the infrared (IR) by dust. At z1.3, 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 deg2), using 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 ~25.9ABmag). Redshift and IR luminosity of these sources are unknown. These sources may contribute signi cantly 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 eld 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.
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50.
2017.03
구독 인증기관 무료, 개인회원 유료
Glenn J. White, Laia Barrufet de Soto, Chris Pearson, Stephen Serjeant, Tanya Lim, Hideo Matsuhara, S.K.Sirothia, S.Pal, Marios Karouzos, AKARI-NEP Team
We have imaged the AKARI Deep Field with the GMRT radio telescope at 610 MHz, detecting 1224 radio components, which are optically identified with 455 optical galaxies having a mean r0 magnitude brighter of 22.5 (to a completeness limit of 25.4 mag), and an average redshift ~ 0.8.
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51.
2017.03
구독 인증기관 무료, 개인회원 유료
T. Miyaji, M. Krumpe, H. Brunner, T. Ishigaki, H. Hanami, A. Markowitz, T. Takagi, T. Goto, M. A. Malkan, H. Matsuhara, C. Pearson, Y. Ueda, T. Wada
The AKARI NEP Deep Field Survey is an international multiwavelength survey over 0.4 deg2 of the sky. This is the deepest survey made by the InfraRed Camera (IRC) of the infrared astronomical satellite AKARI with 9 filters continuously covering the 2-25 μm range, including three filters in the Spitzer gap between the IRAC and MIPS coverages. This enabled us to make sensitive MIR detection of AGN candidates at z~ 1, based on hot dust emission in the AGN torus. It is also eficient in detecting highly obscured Compton-thick AGN population. In this article, we report the rst results of X-ray observations on this eld. The field was covered by 15 overlapping Chandra ACIS-I observations with a total exposure of ~300 ks, detecting 450 X-ray sources. We utilize rest-frame stacking analysis of the MIR AGN candidates that are not detected individually. Our preliminary analysis shows a marginal detection of the rest-frame stacked Fe Kα line from our strong Compton-thick candidates.
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52.
2017.03
구독 인증기관 무료, 개인회원 유료
L. Marchetti, A. Feltre, S. Berta, I. Baronchelli, S. Serjeant, M. Vaccari, D. Bulgarella, M. Karouzos, K. Murata, C. Pearson, G. Rodighiero, C. Segdwick, G.J. White
How does the presence of an AGN in uence the total SFR estimates of galaxies and change their distribution with respect to the Galaxy Main Sequence? To contribute to solving this question, we study a sample of 1133 sources detected in the North Ecliptic Pole field (NEP) by AKARI and Herschel. We create a multi-wavelength dataset for these galaxies and we fit their multi-wavelength Spectral Energy Distribution (SED) using the whole spectral regime (from 0.1 to 500 μm). We perform the fit using three procedures: LePhare and two optimised codes for identifying AGN tracers from the SED analysis. In this work we present an overview of the comparison between the estimates of the Infrared bolometric luminosi- ties (between 8 and 1000 μm) and the AGN fractions obtained exploiting these di erent procedures. In particular, by estimating the AGN contribution in four different wavelength ranges (5-40 μm, 10-20 μm, 20-40 μm and 8-1000 μm) we show how the presence of an AGN affects the PAH emission by suppressing the ratio L8 μm L4:5 μm as a function of the considered wavelength range.
4,000원
53.
2017.03
구독 인증기관 무료, 개인회원 유료
Nagisa Oi, Hideo Matsuhara, Chris Pearson, Veronique Buat, Denis Burgarella, Matt Malkan, Takamitsu Miyaji, AKARI-NEP team
We selected 47 DOGs at z ~ 1:5 using optical R (or r' ), AKARI 18 μm, and 24 μm color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and 9μm, 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 signi cantly 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 ( < 30 Kelvin).
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54.
2017.03
구독 인증기관 무료, 개인회원 유료
Submillimetre and millimetre-wave surveys with Herschel and the South Pole Telescope have revolu- tionised the discovery of strong gravitational lenses. Their follow-ups have been greatly facilitated by the multi-wavelength supplementary data in the survey fields. The forthcoming Euclid optical/near-infrared space telescope will also detect strong gravitational lenses in large numbers, and orbital constraints are likely to require placing its deep survey at the North Ecliptic Pole (the natural deep field for a wide class of ground-based and space-based observatories including AKARI, JWST and SPICA). In this paper I review the current status of the multi-wavelength survey coverage in the NEP, and discuss the prospects for the detection of strong gravitational lenses in forthcoming or proposed facilities such as Euclid, FIRSPEX and SPICA.
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55.
2017.03
구독 인증기관 무료, 개인회원 유료
V. Buat, N. Oi, K. Malek, H. Matsuhara, K. Murata, S. Serjeant, T. T. Takeuchi, M. Malkan, C. Pearson, T. Wada
We built a 8 μm selected sample of galaxies in the NEP-AKARI eld by defining 4 redshift bins with the four AKARI bands at 11, 15, 18 and 24 microns (0:15 < z < 0:49, 0:75 < z < 1:34, 1:34 < z < 1:7 and 1:7 < z < 2:05) . Our sample contains 4079 sources, 599 are securely detected with Herschel/PACS. Also adding ultraviolet (UV) data from GALEX, we fit the spectral energy distributions using the physically motivated code CIGALE to extract the star formation rate, stellar mass, dust attenuation and the AGN contribution to the total infrared luminosity (LIR). We discuss the impact of the adopted attenuation curve and that of the wavelength coverage to estimate these physical parameters. We focus on galaxies with a luminosity close the characteristic L* IR in the different redshift bins to study the evolution with redshift of the dust attenuation in these galaxies.
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56.
2017.03
구독 인증기관 무료, 개인회원 유료
We present the mid-infrared (MIR) luminosity function (LF) of local (z < 0.3) star-forming (SF) galaxies in the North Ecliptic Pole (NEP) field. This work is based on the NEP-Wide point source catalogue and the spectroscopic redshift (z) data for 1700 galaxies obtained by the optical follow-up survey with MMT/Hectospec and WIYN/Hydra. The AKARI's continuous 2 - 24 μm coverage and the spectroscopic redshifts enable us to determine the spectral energy distribution (SED) in the mid-infrared and derive the luminosity functions of galaxies. Our 8 μm LF finds good agreements with the results from SWIRE field over the wide luminosity range, while showing signi cant difference from the NOAO deep data in the faint end. The comparison with higher-z sample shows significant luminosity evolution from z > 0.3 to local universe. 12 μm LF also shows a clear indication of luminosity evolution.
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57.
2017.03
구독 인증기관 무료, 개인회원 유료
Laia Barrufet, Glenn J. White, Chris Pearson, Stephen Serjeant, Tanya Lim, Hideo Matsuhara, Nagisa Oi, Marios Karouzos, AKARI-NEP Team
We report the results of a multi-wavelength study in the North Ecliptic Pole (NEP) deep field and examine the far infrared-radio correlation (FIRC) for high and low redshift objects. We have found a correlation between the GMRT data at 610 MHz and the Herschel data at 250μm that has been used to define a spectral index. This spectral index shows no evolution against redshift. As a result of the study, we show a radio colour-infrared diagram that can be used as a redshift indicator.
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58.
2017.03
구독 인증기관 무료, 개인회원 유료
Laia Barrufet de Soto, Glenn J. White, Chris Pearson, Stephen Serjeant, Tanya Lim, Hideo Matsuhara, Nagisa Oi, Marios Karouzos, AKARI-NEP Team
The AKARI North Ecliptic Pole Deep Field is a natural location to accomplish deep extragalactic surveys. It is supported by comprehensive ancillary data extending from radio to X-ray wavelengths, which have been used to classify radio sources as radio-loud and radio-quiet objects and to create a catalogue of Active Galactic Nuclei (AGN). This has been achieved by using a radio-optical classification and colour- colour diagrams rather than the more usual way based on spectroscopy Furthermore, we explore whether this technique can be extended by using a far-Infrared (FIR) colour-colour diagram which has been used to identify 268 high redshift candidates.
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59.
2017.03
구독 인증기관 무료, 개인회원 유료
The AKARI Deep Field South (ADF-S) is a large extragalactic survey field that is covered by multiple instruments, from optical to far-IR and radio. I summarise recent results in this and related fields prompted by the release of the Herschel far-IR/submm images, including studies of cold dust in nearby galaxies, the identification of strongly lensed distant galaxies, and the use of colour selection to find candidate very high redshift sources. I conclude that the potential for significant new results from the ADF-S is very great. The addition of new wavelength bands in the future, eg. from Euclid, SKA, ALMA and elsewhere, will boost the importance of this field still further.
4,000원
60.
2017.03
구독 인증기관 무료, 개인회원 유료
Chris Sedgwick, Stephen Serjeant, Chris Pearson, Shuji Matsuura, Mai Shirahata, Hideo Matsuhara, Lucia Marchetti, Glenn J. White, Mattia Vaccari, Ivano Baronchelli, Giulia Rodighiero, Bunyo Hadsukade, David L. Clements, Simon Amber
We present a summary of our spectroscopic redshift catalogue of 404 sources in the AKARI Deep Field South (ADF-S). We have used the AAOmega spectrograph to target mid-infrared and far-infrared sources selected primarily from AKARI observations in this field for which we were able to obtain optical counterparts. Our sources with identified redshifts include 316 with Hα detections at z 0:345 and 15 sources at z > 1 with MgII or Ly emission lines. About 13% of our z 0:345 sources are dominated by active galactic nuclei (AGN) emission, although many show emission from both star formation and AGNs. The median Balmer decrement is 5.9. Ultra-luminous infrared galaxies (ULIRGs) were found only in the higher-redshift sources. Optical and near infrared data will be available shortly, enabling calibration of the line luminosities and spectral energy distribution (SED) tting for these sources.
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