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  • 1
    In: Publications of the Astronomical Society of Japan, Oxford University Press (OUP), Vol. 69, No. 5 ( 2017-10-01)
    Abstract: We present monitoring campaign observations at optical and near-infrared (NIR) wavelengths for a radio-loud active galactic nucleus (AGN) at z = 0.840, SDSS J110006.07+442144.3 (hereafter, J1100+4421), which was identified during a flare phase in late 2014 February. The campaigns consist of three intensive observing runs from the discovery to 2015 March, mostly within the scheme of the OISTER collaboration. Optical–NIR light curves and simultaneous spectral energy distributions (SEDs) are obtained. Our measurements show the strongest brightening in 2015 March. We found that the optical–NIR SEDs of J1100+4421 show an almost steady shape despite the large and rapid intranight variability. This constant SED shape is confirmed to extend to ∼5 μm in the observed frame using the archival WISE data. Given the lack of absorption lines and the steep power-law spectrum of αν ∼ −1.4, where $f_{\nu }\propto \nu ^{\alpha _{\nu }}$, synchrotron radiation by a relativistic jet with no or small contributions from the host galaxy and the accretion disk seems most plausible as an optical–NIR emission mechanism. The steep optical–NIR spectral shape and the large amplitude of variability are consistent with this object being a low νpeak jet-dominated AGN. In addition, sub-arcsecond resolution optical imaging data taken with Subaru Hyper Suprime-Cam does not show a clear extended component and the spatial scales are significantly smaller than the large extensions detected at radio wavelengths. The optical spectrum of a possible faint companion galaxy does not show any emission lines at the same redshift, and hence a merging hypothesis for this AGN-related activity is not supported by our observations.
    Type of Medium: Online Resource
    ISSN: 0004-6264 , 2053-051X
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2017
    detail.hit.zdb_id: 282483-8
    detail.hit.zdb_id: 2083084-1
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 2
    In: The Astronomical Journal, American Astronomical Society, Vol. 152, No. 6 ( 2016-12-01), p. 169-
    Abstract: Multiple outbursts of a Jupiter-family comet (JFC), 15P/Finlay, occurred from late 2014 to early 2015. We conducted an observation of the comet after the first outburst and subsequently witnessed another outburst on 2015 January 15.6–15.7. The gas, consisting mostly of C 2 and CN, and dust particles expanded at speeds of 1110 ± 180 m s −1 and 570 ± 40 m s −1 at a heliocentric distance of 1.0 au. We estimated the maximum ratio of solar radiation pressure with respect to the solar gravity β max  = 1.6 ± 0.2, which is consistent with porous dust particles composed of silicates and organics. We found that 10 8 –10 9 kg of dust particles (assumed to be 0.3 μ m–1 mm) were ejected through each outburst. Although the total mass is three orders of magnitude smaller than that of the 17P/Holmes event observed in 2007, the kinetic energy per unit mass (10 4 J kg −1 ) is equivalent to the estimated values of 17P/Holmes and 332P/2010 V1 (Ikeya–Murakami), suggesting that the outbursts were caused by a similar physical mechanism. From a survey of cometary outbursts on the basis of voluntary reports, we conjecture that 15P/Finlay-class outbursts occur 〉 1.5 times annually and inject dust particles from JFCs and Encke-type comets into interplanetary space at a rate of ∼10 kg s −1 or more.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    RVK:
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2016
    detail.hit.zdb_id: 127191-X
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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