Modeling the X-ray light curves of Cygnus X-3. Possible role of the jet

Context: Physics behind the soft X-ray light curve asymmetries in Cygnus X-3, a well-known microquasar, was studied. AIMS: Observable effects of the jet close to the line-of-sight were investigated and interpreted within the frame of light curve physics. METHODS: The path of a hypothetical imprint of the jet, advected by the WR-wind, was computed and its crossing with the line-of-sight during the binary orbit determined. We explore the possibility that physically this 'imprint' is a formation of dense clumps triggered by jet bow shocks in the wind ("clumpy trail"). Models for X-ray continuum and emission line light curves were constructed using two absorbers: mass columns along the line-of-sight of i) the WR wind and ii) the clumpy trail, as seen from the compact star. These model light curves were compared with the observed ones from the RXTE/ASM (continuum) and Chandra/HETG (emission lines). Results: We show that the shapes of the Cygnus X-3 light curves can be explained by the two absorbers using the inclination and true anomaly angles of the jet as derived in Dubus et al. (2010) from gamma-ray Fermi/LAT observations. The clumpy trail absorber is much larger for the lines than for the continuum. We suggest that the clumpy trail is a mixture of equilibrium and hot (shock heated) clumps. Conclusions: A possible way for studying jets in binary stars when the jet axis and the line-of-sight are close to each other is demonstrated. The X-ray continuum and emission line light curves of Cygnus X-3 can be explained by two absorbers: the WR companion wind plus an absorber lying in the jet path (clumpy trail). We propose that the clumpy trail absorber is due to dense clumps triggered by jet bow shocks.Comment: 7 pages, 8 figures, Accepted for publication in Astronomy and Astrophysics 16.12.201

How and how much should depositors be protected? The Japanese case

The issue of depositor insurance has great immediacy and saliency in Japan today. After March 31, 2002 the government's unlimited guarantee of all deposits is scheduled to revert to 10 million yen (about $95,000) per depositor in each bank. Three major concerns will accompany this transition. First, a number of weaker banks will fail as the bad loan problems are gradually resolved. Second, if deposit insurance is limited, then weak banks will be made even weaker by depositor withdrawals in favor of deposits in stronger banks, or other financial assets, and hence are even more likely to fail. Third, until March 31, 2002 government financia1 aid to assist the merger of weak financial institutions can be greater than the amount of formal deposit insurance coverage. On March 23, 2000, the Center on Japanese Economy and Business and the Mitsui USA Foundation, co-sponsored a symposium to discuss whether Japan should develop and maintain market discipline on banks to reduce moral hazard, or to provide additional deposit insurance coverage, or other forms of guarantees for depositors and even banks. The symposium featured Professor Mitsuhiro Fukado of Keio University and Curtis Milhaupt, Fuyo Professor of Law and Director of the Center for Japanese Legal Studies at Columbia Law School. Frederick Mishkin, Alfred Lerner Professor of Banking and Financial Institutions, Columbia University, and David Weinstein, Carl S. Shoup Professor of the Japanese Economy served as commentators. The symposium was moderated by Professor Hugh Patrick. Excerpts of the presentations are presented below along with highlights of the intrapanel discussion

Intentionality without biological naturalism

La habitación china es una versión del test de Turing que permite a Searle defender su naturalismo biológico, según el cual la computación no es ni suficiente ni constitutiva de la mente. en este ensayo, investigo las dos versiones de su postura anticomputacionalista, sostengo que la computación forma parte de la comprensión del lenguaje natural y sugiero una vía para la reducción fisicalista de la intencionalidad en los actos de habla proposicionales.The Chinese Room argument is a variant of Turing’s test which enables Searle to defend his biological naturalism, according to which computation is neither sufficient nor constitutive of the mind. In this paper, I examine both strands of his anticomputationalist stance, argue that computation is constitutive of natural language understanding and suggest a path toward the physicalist reduction of intentionality for propositional speech acts

The nature of the infrared counterpart of IGR J19140+0951

The INTEGRAL observatory has been (re-)discovering new X-ray sources since the beginning of nominal operations in early 2003. These sources include X-ray binaries, Active Galactic Nuclei, cataclysmic variables, etc. Amongst the X-ray binaries, the true nature of many of these sources has remained largely elusive, though they seem to make up a population of highly absorbed high-mass X-ray binaries. One of these new sources, IGR J19140+0951, was serendipitously discovered on 2003 Mar 6 during an observation of the galactic microquasar GRS 1915+105. We observed IGR J19140+0951 with UKIRT in order to identify the infrared counterpart. Here we present the H- and K-band spectra. We determined that the companion is a B0.5-type bright supergiant in a wind-fed system, at a distance \la 5 kpc.Comment: 5 pages, 2 figures, accepted for publication in MNRA