447 research outputs found
The Fate of Dead Radio-loud Active Galactic Nuclei: A New Prediction of Long-lived Shell Emission
We examine the fate of a dead radio source in which jet injection from the
central engine has stopped at an early stage of its evolution ( yr). To this aim, we theoretically evaluate the evolution of the
emission from both the lobe and the shell, which are composed of shocked jet
matter and a shocked ambient medium, respectively. Based on a simple dynamical
model of expanding lobe and shell, we clarify how the broadband spectrum of
each component evolves before and after the cessation of the jet activity. It
is shown that the spectrum is strongly dominated by the lobe emission while the
jet is active (). On the other hand, once the jet activity has
ceased (), the lobe emission fades out rapidly, since fresh electrons
are no longer supplied from the jet. Meanwhile, shell emission only shows a
gradual decrease, since accelerated electrons are continuously supplied from
the bow shock that is propagating into the ambient medium. As a result, overall
emission from the shell overwhelms that from the lobe at wide range of
frequencies from radio up to gamma-ray soon after the jet activity has ceased.
Our result predicts a new class of dead radio sources that are dominated by
shell emission. We suggest that the emission from the shell can be probed in
particular at a radio wavelengths with the Square Kilometer Array (SKA) phase
1.Comment: 9 pages, 3 figures, accepted for publication in Ap
Effects of Magnetic Fields on Proto-Neutron Star Winds
We discuss effects of magnetic fields on proto-neutron star winds by
performing numerical simulation. We assume that the atmosphere of proto-neutron
star has a homogenous magnetic field (ranging from ~10^{12} G to ~10^{15} G)
perpendicular to the radial direction and examine the dependence of the three
key quantities (dynamical time scale, electron fraction, and entropy per
baryon) for the successful r-process on the magnetic field strength. Our
results show that even with a magneter-class field strength, ~10^{15} G, the
feature of the wind dynamics varies only little from that of non-magnetic
winds, and that the condition for successful r-process is not realized.Comment: submitted to Progress of Theoretical Physics. 28 pages, 13 figure
The young radio lobe of 3C 84: inferred gas properties in the central 10 parsec
We analyse the environment of the supermassive black hole (SMBH) in the
centre of a massive elliptical galaxy NGC 1275 in the Perseus cluster, hosting
the radio source 3C 84. We focus on the young radio lobe observed inside the
estimated Bondi accretion radius. We discuss the momentum balance between the
jet associated with the lobe and the surrounding gas. The results are compared
with the proper motion of the radio lobe obtained with the very long baseline
interferometry. We find that under assumption of a high-density environment >~
100 cm^-3), the jet power must be comparable to the Eddington luminosity ---
this is clearly inconsistent with the current moderate activity of 3C 84, which
indicates instead that the jet is expanding in a very low density region (<~1
cm^-3), along the rotation axis of the accretion flow. The power required for
the jet to expand in the low-density environment is comparable to the past
average jet power estimated from the X-ray observations. We estimate the
classical Bondi accretion rate, assuming that (1) gas accretion is spherically
symmetric, (2) accretion is associated with the jet environment, and (3) the
medium surrounding the jet is representative of the properties of the dominant
accreting gas. We find that Bondi accretion is inconsistent with the estimated
jet power. This means that either accretion of the cold gas in the NGC 1275 is
more efficient than that of the hot gas, or the jets are powered by the SMBH
spin.Comment: Replaced with published versio
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Air transport policy in Japan
This paper reviews the development and status of the airline industry of Japan and the points of debate in the recent Japan-U.S. airline dispute. Until 1986, international routes were given only to Japan Air Lines, while domestic routes were dominated by All Nippon Airways, with minor shares given to JAL (major routes only) and Japan Air System (local, short-haul routes only). A policy change in 1986 allowed the three airlines to mutually expand into each other's routes. Major deregulation on airfares did not come until 1995-96. The original Japan-U.S. treaty of 1952 was "unfair" in the sense that the U.S. carriers were given more freedom than their Japanese counterparts, especially in "beyond rights." The amendments of 1982, 1985, and 1989 expanded the routes of Japanese airlines (JAL and new entries of ANA and JAS) as well as those of the new U.S. entrants (American and Delta). However, disputes remain between the two countries over routes, frequencies of flights, and beyond rights. Interestingly, these disputes are not always divided along national boundaries: Carriers with large market shares (JAL, United, Northwest and FEDEX) have an incentive to stall negotiations, while restricted carriers (ANA, Nippon Cargo Airlines, AA, DL, Continental, and UPS) are eager to open negotiations in order to expand their routes
Fluorescence properties of nanoaggregates of pyrene ammonium derivative and its photoinduced dissolution and reaction in tetrahydrofuran/aqueous solutions
We studied the fluorescence properties of nanoaggregates of pyrene ammonium derivative (PyAm) and their photoinduced dissolution and reaction in tetrahydrofuran (THF)/aqueous solution. The final concentration (dye concentration after reprecipitation) dependence of the fluorescence peak was measured. The fluorescence peak of PyAm that originated from the excimer is shifted to the long wavelength side increasing with the final concentration, which is ascribable to the characteristic fluorescence spectral changes depending on their size. The size-dependent fluorescence change in the nanoaggregates is related to some molecular conformation, packing, and elastic properties of the nanoparticles at the surface. To understand the fluorescence properties of the intermediates from aggregates to crystals is important for the studies of organic nanocrystals/aggregates prepared by the reprecipitation methods. We also determined the fluorescence spectra of the PyAm nanoaggregates in a THF/aqueous solution by photoinduced dissolution and reaction. It originated from the photochemical reaction between PyAm and THF. Changes in the perpendicular light scattering intensity by photoirradiation supports the photoinduced dissolution of PyAm in the THF/aqueous solution. These findings are important in the research field of photochemical reactions in organic nanocrystals.ArticleRESEARCH ON CHEMICAL INTERMEDIATES. 41(9):6897-6906 (2015)journal articl
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