Science Forums 2

[Pluto]

G'day from the land of ozzzz

Hello Modest. My main computer crashed and will not be fixed for a few days.

Until than th back up is working. You may need to read further the ABS and maybe open some of the links.

[0812.2483] Statistical Properties of Gamma-Ray Burst Polarization
Statistical Properties of Gamma-Ray Burst Polarization
(Submitted on 12 Dec 2008)

The emission mechanism and the origin and structure of magnetic fields in gamma-ray burst (GRB) jets are among the most important open questions concerning the nature of the central engine of GRBs. In spite of extensive observational efforts, these questions remain to be answered and are difficult or even impossible to infer with the spectral and lightcurve information currently collected. Polarization measurements will lead to unambiguous answers to several of these questions.

[0811.0158] Transient jets in the symbiotic prototype Z Andromedae
Transient jets in the symbiotic prototype Z Andromedae
(Submitted on 2 Nov 2008)

Simultaneously, high-velocity satellite components appeared on both sides of the H-alpha and H-beta emission line profiles. They were launched asymmetrically with the red/blue velocity ratio of 1.2 - 1.3. From about mid-August they became symmetric. Their spectral properties indicated ejection of bipolar jets collimated within an average opening angle of 6.1 degrees.

[0810.5470] INTEGRAL and XMM-Newton Spectroscopy of GX 339-4 During Hard/Soft Intermediate and High/Soft States in the 2007 Outburst
INTEGRAL and XMM-Newton Spectroscopy of GX 339-4 During Hard/Soft Intermediate and High/Soft States in the 2007 Outburst
(Submitted on 30 Oct 2008)

Our results imply evolution in the coronal properties, the most important one being the transition from a compact corona in the first observation to the disappearance of coronal material in the second and re-appearance in the third. This fact, accompanied by the plasma ejection events detected in radio on February 4 to 18, suggest that the ejected medium is the coronal material responsible for the hard X-ray emission.

[0810.5311] Super-Orbital Variability in Hard X-rays
Super-Orbital Variability in Hard X-rays
(Submitted on 29 Oct 2008)

This phase shift, when taken together with the near-coincident onset of the $\sim$46 d modulation and the low/hard X-ray state, leads us to speculate that the modulation could herald transient jet formation.

http://arxiv.org/abs/0806.3185
Jets and environment of microquasars
(Submitted on 19 Jun 2008)

A generic scenario for microquasar jets is proposed, classifying the observed jets into three main categories, with different jet morphologies (and sizes) corresponding to different scales of vacuous environments surrounding them.

Interesting reading
http://arxiv.org/abs/0806.3045
Evidence for polar jets as precursors of polar plume formation

Authors: N.-E. Raouafi, G. J. D. Petrie, A. A. Norton, C. J. Henney, S. K. Solanki
(Submitted on 18 Jun 2008)


And

http://arxiv.org/abs/0805.1700
On the X-ray/TeV connection in Galactic jet sources

Authors: V. Bosch-Ramon, D. Khangulyan, F. A. Aharonian
(Submitted on 12 May 2008 (v1), last revised 13 May 2008 (this version, v2))

Abstract: There are three Galactic jet sources, from which TeV emission has been detected: LS 5039, LS I +61 303 and Cygnus X-1. These three sources show power-law tails at X-rays and soft gamma-rays that could indicate a non-thermal origin for this radiation. In addition, all three sources apparently show correlated and complex behavior at X-ray and TeV energies. In some cases, this complex behavior is related to the orbital motion (e.g. LS 5039, LS I +61 303), and in some others it is related to some transient event occurring in the system (e.g. Cygnus X-1, and likely also LS I +61 303 and LS 5039). Based on modeling or energetic grounds, it seems difficult to explain the emission in the X-/soft gamma-ray and the TeV bands as coming from the same region (i.e. one-zone). We also point out the importance of the pair creation phenomena in these systems, which harbor a massive and hot star, for the radio and the X-ray emission, since a secondary pair radiation component may be significant in these energy ranges. Finally, we discuss that in fact the presence of the star can indeed have strong impact on, beside the non-thermal radiation production, the jet dynamics.

It seems that if the Ultra compact objects are treated as compact objects without the constraints of Black hole restrictions research untaps further information about compact bodies and the resultant jet formation.

Modest, by far I have not even read 1% of the papers given to me.

This link is quite interesting
http://arxiv.org/abs/0804.1337
Coupled radio and X-ray emission and evidence for discrete ejecta in the jets of SS 433
(Submitted on 8 Apr 2008)


and this one

http://arxiv.org/abs/0803.0322
Advection-Dominated Accretion and the Black Hole Event Horizon

Authors: Ramesh Narayan, Jeffrey E. McClintock
(Submitted on 3 Mar 2008)

Abstract: As the luminosity of an accreting black hole drops to a few percent of Eddington, the spectrum switches from the familiar soft state to a hard state that is well-described by a distended and tenuous advection-dominated accretion flow (ADAF). An ADAF is a poor radiator, and the ion temperature can approach 10^{12} K near the center, although the electrons are cooler, with their temperature typically capped at ~10^{9-11} K. The foundational papers predicted that the large thermal energy in an ADAF would drive strong winds and jets, as later observed and also confirmed in computer simulations. Of chief interest, however, is the accreting gas that races inward. It carries the bulk of the accretion energy as stored thermal energy, which vanishes without a trace as the gas passes through the hole's event horizon. One thus expects black holes in the ADAF regime to be unusually faint. Indeed, this is confirmed by a comparison of accreting stellar-mass black holes and neutron stars, which reside in very similar transient X-ray binary systems. The black holes are on average observed to be fainter by a factor of ~100-1000. The natural explanation is that a neutron star must radiate the advected thermal energy from its surface, whereas a black hole can hide the energy behind its event horizon. The case for an event horizon in Sagittarius A*, which is immune to caveats on jet outflows and is furthermore independent of the ADAF model, is especially compelling. These two lines of evidence for event horizons are impervious to counterarguments that invoke strong gravity or exotic stars.