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Black Holes
maryalien
post Dec 7 2005, 04:04 PM
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any one wanna talk black holes. i'm not a professional or anything. i vaguely remember hearing s. hawkin revising his opinion on it saying it wasnt a "worm hole" anymore and that it just destroys all matter and worth nothing else.

i only make my observations, childlike actually, to that of what happens on earth, and why shouldnt it happen in the rest of the universe. why should anything here (goverening law of physics, etc.) be different anywhere else?

just like a tornado, or water running down a drain (or that infamous lake that was drained by accident by some guys drilling and all the water drained into the salt mine, i cant remember the name now but a 6 inch hole sucked in a tanker), why wouldnt a black hole be that "event" that punched a hole into another "dimension/galaxy whatever" with less pressure.

and maybe all that "dark matter" is the "reminant" of what comes out of a black hole.

i dont know, just talking. my head is always "out there, out of earth..."

maryalien
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Guest_Richard Trigaux_*
post Dec 12 2005, 04:24 PM
Post #2





Guests






An intriguing thing about black hole evaporation is as follows.

As Hawking stated, a black hole may elit a black body-like thermal electromagnetic radiation, becomming hotter and hotter when the black hole becomes smaller.

But if so, what become the electric charge and the baryonic number* of the black hole? In order to decay, a black hole has to emit also protons and electrons. The same process Hawking described allows for emission of protons and electrons too, but what is said about this?

A black hole with a mass LESS than allowed by its baryonic number (its equivalent mass in hydrogen) need to receive energy to emit protons, and if it emits only protons, its electric charge will become so enormous that it will mandatorily call back any emitted particle.



*baryonic number is a fundamental constant of quantum physics, which is 1 for the proton and any other particle of the same family of 16 (neutron, hyperon, etc...) and -1 for the corresponding anti-particules. In any nuclear reaction, the baryonic number cannot change, and this sets the possible and impossible reactions. The baryonic number of a potato is the number of protons and neutrons it contains. In order to go to a fully rationalized metric system, grocers should price potatoes after their baryonic number rather than their mass. rolleyes.gif
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ljk4-1
post Dec 12 2005, 05:40 PM
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Paper: astro-ph/0512211

Date: Thu, 8 Dec 2005 01:21:59 GMT (429kb)

Title: On The Nature of the Compact Dark Mass at the Galactic Center

Authors: Avery E. Broderick (1) and Ramesh Narayan (1,2) ((1) Institute for
Theory and Computation, (2) Harvard University)

Comments: 6 pages, 2 figures, submitted to ApJ Letters
\\
We consider a model in which Sgr A*, the 3.5x10^6 M_sun supermassive black
hole candidate at the Galactic Center, is a compact object with a surface.
Given the very low quiescent luminosity of Sgr A* in the near infrared, the
existence of a hard surface, even in the limit in which the radius approaches
the horizon, places severe constraints upon the steady mass accretion rate in
the source, requiring dM/dt < 10^-12 M_sun/yr. This limit is well below the
minimum accretion rate needed to power the observed submillimeter luminosity of
Sgr A*. We thus argue that Sgr A* does not have a surface, i.e., it must have
an event horizon. The argument could be made more restrictive by an order of
magnitude with microarcsecond resolution imaging, e.g., with submillimeter
VLBI.

\\ ( http://arXiv.org/abs/astro-ph/0512211 , 429kb)


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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ljk4-1
post Dec 16 2005, 05:44 AM
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Group: Members
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Paper: astro-ph/0512350

Date: Tue, 13 Dec 2005 23:58:06 GMT (110kb)

Title: Supermassive Black Holes at the Center of Galaxies

Authors: Christopher J. Greenwood

Comments: 11 pages, 3 figures
\\
This was my final paper for the AST 308 Galaxies class at Michigan State
University. Using many sources I was able to compile a moderate amount of
information concerning the evidence for, and the formation of Supermassive
Black Holes.

\\ ( http://arXiv.org/abs/astro-ph/0512350 , 110kb)


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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ljk4-1
post Dec 16 2005, 05:46 AM
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Group: Members
Posts: 2454
Joined: 8-July 05
From: NGC 5907
Member No.: 430



Paper: astro-ph/0512358
Date: Wed, 14 Dec 2005 09:58:30 GMT (34kb)

Title: GRB 050911: a black hole - neutron star merger or a naked GRB

Authors: K.L. Page (1), A.R. King (1), A.J. Levan (2), P.T. O'Brien (1), J.P
Osborne (1), S.D. Barthelmy (5), A.P. Beardmore (1), D.N. Burrows (3), S.
Campana (4), N. Gehrels (5), J. Graham (6), M.R. Goad (1), O. Godet (1), Y.
Kaneko (7), J.A. Kennea (3), C.B. Markwardt (5), D.E. Reichart (8), T.
Sakamoto (5) & N.R. Tanvir (2) ((1) University of Leicester; (2) University
of Hertfordshire; (3) PSU; (4) Osservatorio di Brera, Merate; (5) GSFC;
(6)STScI; (7) NSSTC; (8) University of North Carolina)

Comments: 4 pages using emulateapj; 2 figures. Accepted for publication in ApJ
Letters
\\
GRB 050911, discovered by the Swift Burst Alert Telescope, was not seen 4.6
hr later by the Swift X-ray Telescope, making it one of the very few X-ray
non-detections of a Gamma-Ray Burst (GRB) afterglow at early times. The
gamma-ray light-curve shows at least three peaks, the first two of which (~T_0
- 0.8 and T_0 + 0.2 s, where T_0 is the trigger time) were short, each lasting
0.5 s. This was followed by later emission 10-20 s post-burst. The upper limit
on the unabsorbed X-ray flux was 1.7 x 10^-14 erg cm^-2 s^-1 (integrating 46 ks
of data taken between 11 and 18 September), indicating that the decay must have
been rapid. All but one of the long bursts detected by Swift were above this
limit at ~4.6 hr, whereas the afterglows of short bursts became undetectable
more rapidly. Deep observations with Gemini also revealed no optical afterglow
12 hr after the burst, down to r=24.0 (5-sigma limit). We speculate that GRB
050911 may have been formed through a compact object (black hole-neutron star)
merger, with the later outbursts due to a longer disc lifetime linked to a
large mass ratio between the merging objects. Alternatively, the burst may have
occured in a low density environment, leading to a weak, or non-existent,
forward shock - the so-called 'naked GRB' model.

\\ ( http://arXiv.org/abs/astro-ph/0512358 , 34kb)

Paper: astro-ph/0512344
Date: Tue, 13 Dec 2005 21:05:40 GMT (212kb)

Title: Hypervelocity intracluster stars ejected by supermassive black hole
binaries

Authors: Kelly Holley-Bockelmann, Steinn Sigurdsson, J. Christopher Mihos, John
J. Feldmeier, Robin Ciardullo, and Cameron McBride

Comments: 4 pages, 3 color figures. Submitted to ApJ Letters
\\
Hypervelocity stars have been recently discovered in the outskirts of
galaxies, such as the unbound star in the Milky Way halo, or the three
anomalously fast intracluster planetary nebulae (ICPNe) in the Virgo Cluster.
These may have been ejected by close 3-body interactions with a binary
supermassive black hole (SMBBH), where a star which passes within the semimajor
axis of the SMBBH can receive enough energy to eject it from the system. Stars
ejected by SMBBHs may form a significant sub-population with very different
kinematics and mean metallicity than the bulk of the intracluster stars. The
number, kinematics, and orientation of the ejected stars may constrain the mass
ratio, semimajor axis, and even the orbital plane of the SMBBH. We investigate
the evolution of the ejected debris from a SMBBH within a clumpy and
time-dependent cluster potential using a high resolution, self-consistent
cosmological N-body simulation of a galaxy cluster. We show that the predicted
number and kinematic signature of the fast Virgo ICPNe is consistent with
3-body scattering by a SMBBH with a mass ratio $10:1$ at the center of M87.

\\ ( http://arXiv.org/abs/astro-ph/0512344 , 212kb)


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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Posts in this topic
- maryalien   Black Holes   Dec 7 2005, 04:04 PM
- - mike   Actually I think Hawking recently said that some i...   Dec 7 2005, 06:05 PM
- - Jeff7   ...which is why his field is theoretical physics.   Dec 7 2005, 07:19 PM
- - dvandorn   First, though it's likely redundant for most o...   Dec 7 2005, 08:20 PM
- - maryalien   i got the feeling i was out of my league when i re...   Dec 8 2005, 12:43 AM
|- - Richard Trigaux   QUOTE (maryalien @ Dec 8 2005, 12:43 AM)i got...   Dec 8 2005, 08:21 AM
- - maryalien   thank you for your explanations and time. i hope ...   Dec 8 2005, 11:49 AM
- - dvandorn   Mind? Of course not! That's what we do h...   Dec 8 2005, 01:52 PM
|- - ljk4-1   --- Thursday, December 1, 2005 --- =============...   Dec 8 2005, 02:14 PM
|- - Richard Trigaux   QUOTE (dvandorn @ Dec 8 2005, 01:52 PM)Mind? ...   Dec 8 2005, 02:14 PM
|- - Marcel   QUOTE (dvandorn @ Dec 8 2005, 01:52 PM)But, a...   Dec 8 2005, 02:30 PM
|- - Richard Trigaux   QUOTE (Marcel @ Dec 8 2005, 02:30 PM)As far a...   Dec 8 2005, 03:31 PM
||- - ljk4-1   Paper: astro-ph/0512194 Date: Wed, 7 Dec 2005 15:...   Dec 8 2005, 03:40 PM
|- - maryalien   QUOTE (Marcel @ Dec 8 2005, 02:30 PM)As far a...   Dec 10 2005, 01:18 PM
|- - ljk4-1   Paper: astro-ph/0512241 Date: Fri, 9 Dec 2005 06:...   Dec 12 2005, 03:54 PM
|- - ljk4-1   Paper: astro-ph/0512241 Date: Fri, 9 Dec 2005 06:...   Dec 12 2005, 03:58 PM
- - Richard Trigaux   An intriguing thing about black hole evaporation i...   Dec 12 2005, 04:24 PM
|- - ljk4-1   Paper: astro-ph/0512211 Date: Thu, 8 Dec 2005 01...   Dec 12 2005, 05:40 PM
|- - ljk4-1   Paper: astro-ph/0512350 Date: Tue, 13 Dec 2005 2...   Dec 16 2005, 05:44 AM
|- - ljk4-1   Paper: astro-ph/0512358 Date: Wed, 14 Dec 2005 09...   Dec 16 2005, 05:46 AM
|- - ljk4-1   Paper: astro-ph/0512455 Date: Sat, 17 Dec 2005 09...   Dec 20 2005, 03:40 PM
|- - ljk4-1   Paper: astro-ph/0512515 Date: Wed, 21 Dec 2005 0...   Dec 22 2005, 04:41 PM
|- - ljk4-1   Paper (*cross-listing*): hep-th/0512268 Date: Wed...   Dec 23 2005, 05:08 PM
|- - ljk4-1   Just in case anyone is wondering what a Black Hole...   Dec 26 2005, 06:40 PM
|- - nprev   QUOTE (ljk4-1 @ Dec 26 2005, 11:40 AM)Ju...   Dec 27 2005, 02:18 AM
|- - ljk4-1   Paper: astro-ph/0512621 Date: Tue, 27 Dec 2005 18...   Dec 30 2005, 05:27 PM
|- - ljk4-1   Paper: astro-ph/0512625 Date: Wed, 28 Dec 2005 10...   Dec 30 2005, 05:33 PM
|- - Richard Trigaux   QUOTE (ljk4-1 @ Dec 30 2005, 05:33 PM)Th...   Dec 30 2005, 05:45 PM
|- - ljk4-1   Paper: astro-ph/0512657 Date: Fri, 30 Dec 2005 20...   Jan 4 2006, 03:07 AM
|- - ljk4-1   A DYING STAR REVEALS MORE EVIDENCE FOR A NEW KIND ...   Jan 5 2006, 06:31 PM
|- - ljk4-1   Paper (*cross-listing*): gr-qc/0512160 Date: Thu,...   Jan 9 2006, 04:03 PM
|- - Richard Trigaux   So that we shall be able to HEAR the black holes r...   Jan 9 2006, 06:29 PM
|- - ljk4-1   Astrophysics, abstract astro-ph/0601161 From: Clo...   Jan 10 2006, 03:16 PM
|- - ljk4-1   Dewayne Washington Goddard Space Flight Center, G...   Jan 10 2006, 05:34 PM
|- - ljk4-1   QUOTE (ljk4-1 @ Jan 10 2006, 12:34 PM)Do...   Jan 11 2006, 04:36 PM
|- - ljk4-1   General Relativity and Quantum Cosmology, abstract...   Jan 19 2006, 04:29 PM
|- - ljk4-1   Paper: astro-ph/0601406 Date: Wed, 18 Jan 2006 2...   Jan 20 2006, 04:03 PM
|- - ljk4-1   Paper: astro-ph/0601450 Date: Thu, 19 Jan 2006 1...   Jan 20 2006, 07:02 PM
|- - ljk4-1   Astrophysics, abstract astro-ph/0601662 From: Leo...   Jan 31 2006, 09:27 PM
|- - ljk4-1   Astrophysics, abstract astro-ph/0601705 From: Alb...   Feb 1 2006, 04:07 PM
|- - ljk4-1   Astrophysics, abstract astro-ph/0602013 From: Mas...   Feb 2 2006, 10:30 PM
|- - ljk4-1   Paper: astro-ph/0602029 Date: Thu, 2 Feb 2006 20:...   Feb 3 2006, 04:18 PM
|- - ljk4-1   LOOKING FOR BLACK HOLES IN THE ATMOSPHERE is one o...   Feb 6 2006, 07:43 PM
|- - ljk4-1   General Relativity and Quantum Cosmology, abstract...   Feb 10 2006, 03:39 PM
|- - ljk4-1   Life inside a black hole NewScientist (subscripti...   Feb 15 2006, 02:44 PM
|- - ljk4-1   Astrophysics, abstract astro-ph/0602307 From: Rob...   Feb 16 2006, 03:49 PM
|- - ljk4-1   Astrophysics, abstract astro-ph/0602363 From: Mit...   Feb 17 2006, 09:07 PM
|- - ljk4-1   DEEP X-RAY SURVEYS REVEAL BLACK HOLE POPULATION --...   Feb 22 2006, 07:30 PM
- - ljk4-1   Astrophysics, abstract astro-ph/0603761 From: Pe...   Mar 29 2006, 04:28 PM
- - ljk4-1   Spacecraft may be able to determine if braneworld ...   Jun 5 2006, 03:30 PM


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