Starship Asterisk*

Abstract: There is accumulating evidence that (fundamental) scalar fields may exist in Nature. The gravitational collapse of such a boson cloud would lead to a boson star (BS) as a new type of a compact object. Similarly as for white dwarfs and neutron stars, there exists a limiting mass, below which a BS is stable against complete gravitational collapse to a black hole. According to the form of the self-interaction of the basic constituents and the spacetime symmetry, we can distinguish mini-, axidilaton, soliton, charged, oscillating and rotating BSs. Their compactness prevents a Newtonian approximation, however, modifications of general relativity, as in the case of Jordan-Brans-Dicke theory as a low energy limit of strings, would provide them with gravitational memory. In general, a BS is a compact, completely regular configuration with structured layers due to the anisotropy of scalar matter, an exponentially decreasing 'halo', a critical mass inversely proportional to constituent mass, an effective radius, and a large particle number. Due to the Heisenberg principle, there exists a completely stable branch, and as a coherent state, it allows for rotating solutions with quantised angular momentum. In this review, we concentrate on the fascinating possibilities of detecting the various subtypes of (excited) BSs: Possible signals include gravitational redshift and (micro-)lensing, emission of gravitational waves, or, in the case of a giant BS, its dark matter contribution to the rotation curves of galactic halos.

Abstract: The possibility of stable or quasi--stable Planck mass black hole remnants as solution to the black hole information paradox is commonly believed phenomenologically unacceptable: since we have to expect a black hole remnant for every possible initial state, the number of remnants should be infinite. This would lead to remnant pair production in any physical process with a total available energy roughly exceeding the Planck mass, against trivial evidences. In this note I point out that the number of remnants in our Universe could be finite, at least if the value of the cosmological constant is positive, as present observational data could indicate. Nevertheless, it is not clear if a huge but finite number of states is phenomenologically allowed.

Abstract: We derive the theoretical distribution function of black hole masses by studying the formation processes of black holes. We use the results of recent 2D simulations of core-collapse to obtain the relation between remnant and progenitor masses and fold it with an initial mass function for the progenitors. We examine how the calculated black-hole mass distributions are modified by (i) strong wind mass loss at different evolutionary stages of the progenitors, and (ii) the presence of close binary companions to the black-hole progenitors. Thus, we are able to derive the binary black hole mass distribution. The compact remnant distribution is dominated by neutron stars in the mass range 1.2-1.6Msun and falls off exponentially at higher remnant masses. Our results are most sensitive to mass loss from winds which is even more important in close binaries. Wind mass-loss causes the black hole distribution to become flatter and limits the maximum possible black-hole mass (<10-15Msun). We also study the effects of the uncertainties in the explosion and unbinding energies for different progenitors. The distributions are continuous and extend over a broad range. We find no evidence for a gap at low values (3-5Msun) or for a peak at higher values (~7Msun) of black hole masses, but we argue that our black hole mass distribution for binaries is consistent with the current sample of measured black-hole masses in X-ray transients. We discuss possible biases against the detection or formation of X-ray transients with low-mass black holes. We also comment on the possibility of black-hole kicks and their effect on binaries.

kovil wrote:Hi Harry,
I suspect there are restraining mechanisms of physics and energy/matter functions, that will in reality prevent a black hole from ever becoming a reality.

harry wrote:G'day God

What the hell are you trying to say?

harry wrote:G'day God

Smile,,,,,,,,,,,I made a funny in the last post.

Sorry if you took it another way.

(God) ,,,,,,,,,,,,,, (Hell)

After nearly 30 years of arguing that a black hole destroys everything that falls into it, Stephen Hawking is saying he was wrong. It seems that black holes may after all allow information within them to escape. Hawking will present his latest finding at a conference in Ireland next week.

Stephen Hawking has put forward a new theory that changes the way scientists view black holes, saying he was wrong about them in the past.

In his lecture he says that the Andromedans told him that: "Everything in our universe, including us, came from a black hole."

This turn of events has bought time for the Big Island of Hawaii resident Walter Wagner, who has recently made headlines all over the world in his quest to get officials to reevaluate the science behind the enormous machine. Wagner believes there is a possibility that the LHC could produce a "stranglet", or a possible type of dark matter never before observed, that would grow to destroy Earth. He also fears the possible creation of a black hole during the tests, a scenario that could be just as bad for the planet.

• The Large Hadron Collider, poised to become the world’s most powerful atom smasher, won’t reopen for business until the end of June at the very earliest, rather than in April as scientists had previously estimated. Actual collisions between protons might not occur until even later in the summer.

harry wrote:Maybe a big hammer.