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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.
Kim, Dae-Won,Protopapas, Pavlos,Byun, Yong-Ik,Alcock, Charles,Khardon, Roni,Trichas, Markos IOP Publishing 2011 The Astrophysical journal Vol.735 No.2
<P>We present a new quasi-stellar object (QSO) selection algorithm using a Support Vector Machine, a supervised classification method, on a set of extracted time series features including period, amplitude, color, and autocorrelation value. We train a model that separates QSOs from variable stars, non-variable stars, and microlensing events using 58 known QSOs, 1629 variable stars, and 4288 non-variables in the MAssive Compact Halo Object (MACHO) database as a training set. To estimate the efficiency and the accuracy of the model, we perform a cross-validation test using the training set. The test shows that the model correctly identifies similar to 80% of known QSOs with a 25% false-positive rate. The majority of the false positives are Be stars. We applied the trained model to the MACHO Large Magellanic Cloud (LMC) data set, which consists of 40 million light curves, and found 1620 QSO candidates. During the selection none of the 33,242 known MACHO variables were misclassified as QSO candidates. In order to estimate the true false-positive rate, we crossmatched the candidates with astronomical catalogs including the Spitzer Surveying the Agents of a Galaxy's Evolution LMC catalog and a few X-ray catalogs. The results further suggest that the majority of the candidates, more than 70%, are QSOs.</P>