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On primary decompositions and radicals of submodules
M. Alkan,B. Saraç 장전수학회 2007 Proceedings of the Jangjeon mathematical society Vol.10 No.1
In this paper, we give some characterizations for prime and primary submodules of a nitely generated free modules over PIDs and determine the height of prime submodules. We also char- acterize the minimal primary decompositions and radicals of submodules of any nitely generated free module over a PID.
ACTIVE GALACTIC NUCLEUS BLACK HOLE MASS ESTIMATES IN THE ERA OF TIME DOMAIN ASTRONOMY
Kelly, Brandon C.,Treu, Tommaso,Malkan, Matthew,Pancoast, Anna,Woo, Jong-Hak IOP Publishing 2013 The Astrophysical journal Vol.779 No.2
<P>We investigate the dependence of the normalization of the high-frequency part of the X-ray and optical power spectral densities (PSDs) on black hole mass for a sample of 39 active galactic nuclei (AGNs) with black hole masses estimated from reverberation mapping or dynamical modeling. We obtained new Swift observations of PG 1426+015, which has the largest estimated black hole mass of the AGNs in our sample. We develop a novel statistical method to estimate the PSD from a light curve of photon counts with arbitrary sampling, eliminating the need to bin a light curve to achieve Gaussian statistics, and we use this technique to estimate the X-ray variability parameters for the faint AGNs in our sample. We find that the normalization of the high-frequency X-ray PSD is inversely proportional to black hole mass. We discuss how to use this scaling relationship to obtain black hole mass estimates from the short timescale X-ray variability amplitude with precision similar to 0.38 dex. The amplitude of optical variability on timescales of days is also anticorrelated with black hole mass, but with larger scatter. Instead, the optical variability amplitude exhibits the strongest anticorrelation with luminosity. We conclude with a discussion of the implications of our results for estimating black hole mass from the amplitude of AGN variability.</P>
THE 18 ㎛ LUMINOSITY FUNCTION OF GALAXIES WITH AKARI
Toba, Yoshiki,Oyabu, Shinki,Matsuhara, Hideo,Ishihara, Daisuke,Malkan, Matt,Wada, Takehiko,Ohyama, Youichi,Kataza, Hirokazu,Takita, Satoshi The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We present the $18{\mu}m$ 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 $18{\mu}m$ 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 $H{\alpha}$ or the emission line ratios of [OIII]/$H{\beta}$ and [NII]/$H{\alpha}$. 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 $1.64{\pm}0.37$, larger than the results obtained from optical LF and (ii) the fraction of Sy2 in the entire AGN population may decrease with $18{\mu}m$ 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.
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.
A TALE OF TWO FEEDBACKS: STAR FORMATION IN THE HOST GALAXIES OF RADIO AGNs
Karouzos, Marios,Im, Myungshin,Trichas, Markos,Goto, Tomo,Malkan, Matt,Ruiz, Angel,Jeon, Yiseul,Kim, Ji Hoon,Lee, Hyung Mok,Kim, Seong Jin,Oi, Nagisa,Matsuhara, Hideo,Takagi, Toshinobu,Murata, K.,Wada IOP Publishing 2014 The Astrophysical journal Vol.784 No.2
<P>Several lines of argument support the existence of a link between activity at the nuclei of galaxies, in the form of an accreting supermassive black hole, and star formation activity in these galaxies. Radio jets have long been argued to be an ideal mechanism that allows active galactic nuclei (AGNs) to interact with their host galaxies and affect star formation. We use a sample of radio sources in the North Ecliptic Pole (NEP) field to study the nature of this putative link, by means of spectral energy distribution (SED) fitting. We employ the excellent spectral coverage of the AKARI infrared space telescope and the rich ancillary data available in the NEP to build SEDs extending from UV to far-IR wavelengths. We find a significant AGN component in our sample of relatively faint radio sources (<mJy). A positive correlation is found between the luminosity of the AGN component and that of star formation in the host galaxy, independent of the radio luminosity. In contrast, for narrow redshift and AGN luminosity ranges, we find that increasing radio luminosity leads to a decrease in the specific star formation rate. The most radio-loud AGNs are found to lie on the main sequence of star formation for their respective redshifts. For the first time, we potentially see such a two-sided feedback process in the same sample. We discuss the possible suppression of star formation, but not total quenching, in systems with strong radio jets, that supports the maintenance nature of feedback from radio AGN jets.</P>
GALAXIES ON DIET: FEEDBACK SIGNATURES IN RADIO-AGN HOST GALAXIES
Marios Karouzos,임명신,Markos Trichas,Tomogotsu Goto,Matthew Malkan,Angel Ruiz,전이슬,김지훈,이형목,김성진,Nagisa Oi,Hideo Matsuhara,Toshinobu Takagi,Kazumi Murata,Takehiko Wada,Kensuke Wada,심현진,Hitoshi Hanami,STEPH 한국천문학회 2017 天文學論叢 Vol.32 No.1
There exists strong evidence supporting the co-evolution of central supermassive black holesand their host galaxies; however it is still under debate how such a relation comes about and whether itis relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their hostgalaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedbackmay hence be responsible for the eventual quenching of star formation and halting of galaxy growth. Arich multi-wavelength dataset ranging from the X-ray regime (\textit{Chandra}), to far-IR (\textit{Herschel}), and radio(\textit{WSRT}) is available for the North Ecliptic Pole field, most notably surveyed by the \textit{AKARI} infraredspace telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formationproperties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radiosources below redshift z = 2 and at a radio 1.4 GHz flux density limit of 0.1 mJy. Using broadbandSED 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 field, 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.
PROPERTIES OF DUST OBSCURED GALAXIES IN THE NEP-DEEP FIELD
Nagisa Oi,Hideo Matsuhara,CHRIS PEARSON,Veronique Buat,Denis Burgarella,Matt Malkan,Takamitsu Miyaji 한국천문학회 2017 天文學論叢 Vol.32 No.1
We selected 47 DOGs at z ~ 1.5 using optical $R$ (or $r^{'}$), AKARI 18 $\mu$m, and 24 $\mu$m color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and $9\mu$m, 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 significantly 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 ($\hspace{0.3em}\raisebox{0.4ex}{$<$}\hspace{-0.75em}\raisebox{-.7ex}{$\sim$}\hspace{0.3em}$ 30 Kelvin).