Introducing Monte Carlo Methods with R Solutions to Odd-Numbered Exercises

This is the solution manual to the odd-numbered exercises in our book "Introducing Monte Carlo Methods with R", published by Springer Verlag on December 10, 2009, and made freely available to everyone.Comment: 87 pages, 11 figure

Radio-loudness in black hole transients: evidence for an inclination effect

Accreting stellar-mass black holes appear to populate two branches in a radio:X-ray luminosity plane. We have investigated the X-ray variability properties of a large number of black hole low-mass X-ray binaries, with the aim of unveiling the physical reasons underlying the radio-loud/radio-quiet nature of these sources, in the context of the known accretion-ejection connection. A reconsideration of the available radio and X-ray data from a sample of black hole X-ray binaries confirms that being radio-quiet is the more normal mode of behaviour for black hole binaries. In the light of this we chose to test, once more, the hypothesis that radio loudness could be a consequence of the inclination of the X-ray binary. We compared the slope of the `hard-line' (an approximately linear correlation between X-ray count rate and rms variability, visible in the hard states of active black holes), the orbital inclination, and the radio-nature of the sources of our sample. We found that high-inclination objects show steeper hard-lines than low-inclination objects, and tend to display a radio-quiet nature (with the only exception of V404 Cyg), as opposed to low-inclination objects, which appear to be radio-loud(er). While in need of further confirmation, our results suggest that - contrary to what has been believed for years - the radio-loud/quiet nature of black-hole low mass X-ray binaries might be an inclination effect, rather than an intrinsic source property. This would solve an important issue in the context of the inflow-outflow connection, thus providing significant constraints to the models for the launch of hard-state compact jets.Comment: 16 pages, 6 figures, accepted for pubblication on MNRA

A continuous Flaring- to Normal-branch transition in Sco X-1

We report the first resolved rapid transition from a Flaring Branch Oscillation to a Normal Branch Oscillation in the RXTE data of the Z source Sco X-1. The transition took place on a time scale of ~100 seconds and was clearly associated to the Normal Branch-Flaring Branch vertex in the color-color diagram. We discuss the results in the context of the possible association of the Normal Branch Oscillation with other oscillations known both in Neutron-Star and Black-Hole systems, concentrating on the similarities with the narrow 4-6 Hz oscillations observed at high flux in Black-Hole Candidates.Comment: 5 pages, 4 figures, accepted for publication in Astronomy & Astrophysic

Intermittent accreting millisecond pulsars: light houses with broken lamps?

Intermittent accreting millisecond X-ray pulsars are an exciting new type of sources. Their pulsations appear and disappear either on timescales of hundreds of seconds or on timescales of days. The study of these sources add new observational constraints to present models that explain the presence or not of pulsations in neutron star LMXBs. In this paper we present preliminary results on spectral and aperiodic variability studies of all intermittent AMSPs, with a particular focus on the comparison between pulsating and non pulsating periods.Comment: 4 pages, 2 figures; to appear in the proceedings of the workshop "A Decade of Accreting Millisecond X-ray Pulsars", Amsterdam, April 2008, eds. R. Wijnands et al. (AIP Conf. Proc.

Evolution of the bursting-layer wave during a Type 1 X-ray burst

In a popular scenario due to Heyl, quasi periodic oscillations (QPOs) which are seen during type 1 X-ray bursts are produced by giant travelling waves in neutron-star oceans. Piro and Bildsten have proposed that during the burst cooling the wave in the bursting layer may convert into a deep crustal interface wave, which would cut off the visible QPOs. This cut-off would help explain the magnitude of the QPO frequency drift, which is otherwise overpredicted by a factor of several in Heyl's scenario. In this paper, we study the coupling between the bursting layer and the deep ocean. The coupling turns out to be weak and only a small fraction of the surface-wave energy gets transferred to that of the crustal-interface wave during the burst. Thus the crustal-interface wave plays no dynamical role during the burst, and no early QPO cut-off should occur.Comment: 8 pages, submitted to MNRA

The ABC of low-frequency quasi-periodic oscillations in Black-Hole Candidates: analogies with Z-sources

Three main types of low-frequency quasi-periodic oscillations (LFQPOs) have been observed in Black Hole Candidates. We re-analyzed RXTE data of the bright systems XTE J1859+226, XTE J1550-564 and GX 339-4, which show all three of them. We review the main properties of these LFQPOs and show that they follow a well-defined correlation in a fractional rms vs. softness diagram. We show that the frequency behavior through this correlation presents clear analogies with that of Horizontal-, Normal- and Flaring-Branch Oscillations in Z sources, with the inverse of the fractional rms being the equivalent of the curvilinear coordinate Sz through the Z track.Comment: 5 pages, 4 figures, accepted by ApJ, uses emulateap