Taiki Kawamuro

THE COMPLETE INFRARED VIEW OF ACTIVE GALACTIC NUCLEI FROM THE 70 MONTH SWIFT/BAT CATALOG

We systematically investigate the near- (NIR) to far-infrared (FIR) photometric properties of a nearly complete sample of local active galactic nuclei (AGN) detected in the Swift/Burst Alert Telescope (BAT) all-sky ultra hard X-ray (14-195 keV) survey. Out of 606 non-blazar AGN in the Swift/BAT 70-month catalog at high galactic latitude of

BROADBAND X-RAY SPECTRA OF TWO LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI NGC 1566 AND NGC 4941 OBSERVED WITH SUZAKU

|b|>10^{\circ}

SUZAKU observation of the black hole binary 4U 1630-47 in the very high state.

, we obtain IR photometric data of 604 objects by cross-matching the AGN positions with catalogs from the WISE, AKARI, IRAS, and Herschel infrared observatories. We find a good correlation between the ultra-hard X-ray and mid-IR (MIR) luminosities over five orders of magnitude (

MAXI INVESTIGATION INTO THE LONG-TERM X-RAY VARIABILITY FROM THE VERY-HIGH-ENERGY γ-RAY BLAZAR Mrk 421

41 < \log (L_{14-195}/{\rm erg}~{\rm s}^{-1})< 46

Study of Swift/BAT Selected Low-luminosity Active Galactic Nuclei Observed with Suzaku

). Informed by previous measures of the intrinsic spectral energy distribution of AGN, we find FIR pure-AGN candidates whose FIR emission is thought to be AGN-dominated with low starformation activity. We demonstrate that the dust covering factor decreases with the bolometric AGN luminosity, confirming the luminosity-dependent unified scheme. We also show that the completeness of the WISE color-color cut in selecting Swift/BAT AGN increases strongly with 14-195 keV luminosity.

SUZAKU OBSERVATIONS OF MODERATELY OBSCURED (COMPTON-THIN) ACTIVE GALACTIC NUCLEI SELECTED BY SWIFT/BAT HARD X-RAY SURVEY

We report the first broadband X-ray spectra of the low-luminosity active galactic nuclei (LLAGNs), NGC?1566 (type 1.5) and NGC?4941 (type 2), observed with Suzaku and Swift/BAT covering the 0.5-195?keV band. Both targets have hard X-ray luminosities of ~1041-42?erg?s?1 in the 15-55?keV band. The spectra of the nucleus are well reproduced by a sum of partially or fully covered transmitted emission and its reflection from the accretion disk, reprocessed emission from the torus accompanied by a strong narrow iron-K? line, and a scattered component (for NGC?4941). We do not significantly detect a broad iron-K? line from the inner accretion disk in both targets, and obtain an upper limit on the corresponding solid angle of ?/2? < 0.3 in NGC?1566. The reflection strength from the torus is moderate, in NGC?1566 and in NGC?4941. Comparison of the equivalent width of the narrow iron-K? line with a model prediction based on a simple torus geometry constrains its half-opening angle to be ?oa 60?-70? in NGC?4941. These results agree with the obscured AGN fraction obtained from hard X-ray and mid-infrared selected samples at similar luminosities. Our results support the implication that the averaged covering fraction of AGN tori is peaked at L ~ 1042-43?erg?s?1 but decreases toward lower luminosities.

MAXI observations of gamma-ray bursts

We report the results from an X-ray and near-infrared observation of the Galactic black hole binary 4U 1630--47 in the very high state, performed with {\it Suzaku} and IRSF around the peak of the 2012 September-October outburst. The X-ray spectrum is approximated by a steep power law, with photon index of 3.2, identifying the source as being in the very high state. A more detailed fit shows that the X-ray continuum is well described by a multi-color disc, together with thermal and non-thermal Comptonization. The inner disc appears slightly truncated by comparison with a previous high/soft state of this source, even taking into account energetic coupling between the disc and corona, although there are uncertainties due to the dust scattering correction. The near-infrared fluxes are higher than the extrapolated disc model, showing that there is a contribution from irradiation in the outer disk and/or the companion star at these wavelengths. Our X-ray spectra do not show the Doppler shifted iron emission lines indicating a baryonic jet which were seen four days previously in an XMM-Newton observation, despite the source being in a similar state. There are also no significant absorption lines from highly ionized irons as are seen in the previous high/soft state data. We show that the increased source luminosity is not enough on its own to make the wind so highly ionized as to be undetectable. This shows that the disc wind has changed in terms of its launch radius and/or density compared to the high/soft state.

Suzaku follow-up of heavily obscured active galactic nuclei detected in Swift/BAT survey: NGC 1106, UGC 03752, and NGC 2788A

The archetypical very-high-energy gamma-ray blazar Mrk 421 was monitored for more than 3 years with the Gas Slit Camera onboard Monitor of All Sky X-ray Image (MAXI), and its longterm X-ray variability was investigated. The MAXI lightcurve in the 3 -- 10 keV range was transformed to the periodogram in the frequency range

Signs of active galactic nucleus quenching in a merger remnant with radio jets

f = 1 \times 10^{-8}

Hard X-ray luminosity function of tidal disruption events: First results from the MAXI extragalactic survey

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