Latex Template of sending poster's abstract for
% the Heidelberg Symposium on
% ``High Energy Gamma-Ray Astronomy''
% June 26-30, 2000, Heidelberg, Germany
%
% Send abstracts for the poster session to:
% HDGS@mpi-hd.mpg.de
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% This template is available at the web site,
% http://www.mpi-hd.mpg.de/voelk/hdgs
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%
\documentclass[11pt,dvips]{article}
\usepackage{epsfig,times}
% If you are using LaTeX2.09 please use two lines below instead of
% two lines above.
% \documentstyle[11pt]{article}
% \include{epsfig,times}
%
% Setting various length parameters (DO NOT ALTER):
%
\setlength{\textwidth}{150mm}
\setlength{\textheight}{260mm}
\setlength{\topmargin}{-10mm}
\setlength{\oddsidemargin}{5mm}
\setlength{\evensidemargin}{5mm}
\setlength{\parindent}{0pt}
%
% It is required that there be no pagination (DO NOT ALTER):
%
\pagestyle{empty}
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Beginning of Document:
%
\begin{document}
%
% Session and Paper Code:
%
\thispagestyle{myheadings}
%
% ***INSTRUCTIONS:*** Replace `GS' in the command argument below
% with your assigned session:
%
% GS - Galactic Sources
% ES - Extragalactic Sources
% PA - Particle Acceleration Models
% OC - Observational cosmology with Gamma Rays
% BL - Gamma-Ray Blazars
% GA - Sensitivity Threshold of Ground-Based Gamma-Ray Astronomy
%
\markright{GS:PA}
%
% Title:
%
\begin{center}
%
% ***INSTRUCTIONS:*** Replace `Instructions for Preparation of Abstract'
% with your abstract's title:
%
{\LARGE \bf Antigravity Theory }
\end{center}
%
% Author List:E.Valbonesi
%
\begin{center}
%
% ***INSTRUCTIONS:*** Replace authors and addresses below with your own:
%
{\bf }\\
{\it \\
$^ Author ENRICO VALBONESI }
\end{center}
% Abstract:
\begin{center}
{\large \bf Abstract\\}
The modelling of antigravity dont'is new.
\end{center}
\vspace{-0.5ex}
%
% ***INSTRUCTIONS:*** Replace text below with your own abstract:
%
the target that I am trying to realize and the demonstration that
in the introno of the black holes not are caused phenomena of jet from
elevations of the temperature but from caused phenomena of resonance
from the emission from part of the black hole of a bundle of
cancellations that hit with a sinuisoidale frequency the aglomerates
one of particles that are along the wings. it agglomerates you of
particles in conditions of high density after the borbandamento of
cancellations from part of the black hole will give origin to the
emissions of the get of high energy.
> italian version
l'obbiettivo che sto cercando di realizzare e la dimostrazione che
nell'introno dei buchi neri non ci sono fenomeni di jet causati da
innalzamenti della temperatura .
ma da fenomeni di risonanza causati dall'emissione da parte del buco nero
di un fascio di radiazioni che colpiscono con una frequenza sinuisoidale
l'aglomerato di particelle che sono lungo le ali .
gli agglomerati di particelle in condizioni di alta densita' dopo il
borbandamento di radiazioni da parte del buco nero daranno origine alle
emissioni dei get di alta energia.
you will send the article second the detailed lists of American Intitute of
Physics
vi mandero' l'articolo secondo le specifiche Dell' American Intitute of
Physics
dott. Enrico Valbonesi e-mail valbones@uniroma3.it
%
% Leave this line skip in place:
\vspace{1ex}
\end{document}
Per capire questo ti[po di onde isogna capire che sono onde di energia
gia' estrinsecate come rumore di fondo
A team of researchers that looked at data from more than 140,000
galaxies says the universe is far from heavy and has a density of next
to nothing.
"It's about 300 billion billion billion times less dense than water," said
John Peacock of the University of Edinburgh, "or one ten-thousandth
of an ounce in a volume the same size as the Earth."
Take a video journey through the galaxies.
Peacock and his colleagues got the answer using an instrument on the
Anglo-Australian Telescope that can detect the light from 400
galaxies simultaneously over a field of view four times as wide as the
full Moon. The research is part of a massive effort to create a
three-dimensional map of the universe.
The instrument shows the "redshift" of each galaxy (i.e., the extent to
which galactic light turns reddish as the galaxy moves away from the
observer), thereby suggesting the galaxies' relative distance to Earth.
That determination leads to the calculation of each galaxy's density
and mass, and also those properties of the universe.
The results were published in the March 8, 2001, issue of the journal
Nature.
Supercluster collapse
The analysis also claims to clarify astronomers' understanding of the
structure of the universe throughout which galaxies are sprinkled not
randomly, but in clusters that glom together in "superclusters."
Peacock and his colleagues found that superclusters form, as
suspected, from the inward gravitational collapse of galaxies upon one
another.
To get the density figure, the team looked at "peculiar" velocities
created when the superclusters tug and pull on nearby galaxies
whizzing by. That led them to calculate that the universe is one third as
populated as the calculated density that would halt an expanding
universe. Most theorists now agree the universe is expanding as a
result of the Big Bang -- the explosive instant thought to have given
birth to the universe.
"The actual figure is tiny," said Peacock, "about 3 times 10^{-27}
kilograms per cubic meter." That's much, much lighter -- a fraction of
a three kilograms with 27 zeroes in front of the decimal point -- than a
dust speck in a bucket the size of a wide-screen TV for a typical home.
Survey finished later this year
The results come from an ambitious effort, called the 2dF Galaxy
Redshift Survey, to detect light simultaneously from hundreds of
galaxies at a time. Eventually, the survey, conducted by British and
Australian researchers, will yield an inventory of about 10 percent of
the galaxies in Earth's cosmic neighborhood. It will map one-tenth of
the galaxies within 2 billion light-years of Earth (a light-year is the
distance light travels in a year -- about 6 trillion miles or 9.7 trillion
kilometers).
Last year, project scientists used earlier data from the survey to show
that the universe will continue to expand forever, rather than end in a
catastrophic collision like the opposite of the Big Bang.
Peacock is optimistic that future analyses of 2dF data will yield the
"fluctuation spectrum" -- jargon for how clumpy the distribution of
galaxies is in the universe.
"This can not only give us another independent way to measure the
mass density," he said, "it can also tell us what fraction of this mass is
in the form of ordinary matter (particles like electrons and protons --
the same as you are), as opposed to exotic elementary particles left
over as relics from the earliest phases of the Big Bang."
The survey, which should be done later this year after completing the
logging of data on 250,000 galaxies, has involved a vast array of
astronomical talent, including instrument designers and engineers,
observational astronomers and theorists who have cranked out
statistics on the results. (Other sky surveys currently under way
include the 2MASS Redshift Survey and the Sloan Digital Sky Survey.)
"The end result is something that no individual could have produced
unaided," Peacock said.
Marc Davis of the University of California, who wrote an
accompanying article in Nature on the new study, heralded the analysis
as moving cosmology to a new and more sophisticated level of
analysis.
"Cosmology, long considered a branch of philosophy rather than physics
because of the dearth of data, has made dramatic progress in the
past few years and is now entering an era of large-scale studies and
precision measurements," he said.
X-Ray Spectra Help
Astronomers Hunt Cosmic
Monsters
By The European Space Agency
posted: 06:27 am ET
08 March 2001
One must admit that spectra, the curves that plot the number of
photons and their energy, appear to be rather uninspiring to the
layman -- There's nothing worse than a graph! But like one?s body
temperature curve, they mean a lot.
For astronomers, spectra are like fingerprints from the stars and
galaxies. The information they hold may be incomplete, like a
tattered newspaper, but it tells a story. While images from a
telescope are attractive, spectra can reveal the innermost secrets
of certain cosmic monsters.
The image of XMM-Newton?s deepest observation of the "blank"
X-ray sky in the direction of the Lockman Hole -- where X-ray
absorbing extragalactic material is thinnest and one can best peek
into the confines of the universe -- has already been acclaimed. The
picture identifies about 150 new X-ray sources, most of them
among the faintest hard X-ray sources ever observed.
Many of the brighter X-ray emissions in the Lockman Hole were
previously identified with the ROSAT satellite. For these,
XMM-Newton has now provided very detailed spectra, as is shown
in a picture montage by Guenther Hasinger from the Astrophysics
Institute of Potsdam (AIP).
(courtesy Guenther Hasinger/AIP -- click to enlarge)
The main image [above] plots the soft X-ray photons, already
observed by ROSAT, in red. Green corresponds to intermediate
X-ray photons, also detectable by NASA?s Chandra X-ray
Observatory. Blue is used to show the hardest X-ray photons, only
detectable by XMM-Newton.
The individual spectra [right edge of this page] "roll out" this color
information into graphs, plotted in red, where the X-ray emission (the
number of arriving photons) is plotted against the energy at which it
is emitted. The green lines refer to model spectra fitted to these
graphs.
Many of the sources are associated with black holes, monstrous
gravitational wells into which matter is being sucked and in which
even light disappears. Stellar-mass black holes arise after the death
of a massive star that has used all its fuel. But there exist also
supermassive black holes, which are present in the center of almost
every galaxy.
"The origin of these supermassive ones remains a complete
mystery," said Guenther Hasinger. "Forming these from many single
black holes would probably take too much time. They might therefore
be part of the original collapse of gas into a galaxy, in other words the
seed objects of galaxy creation."
Next page: detectives of the invisible universe
X-Ray Spectra Help Astronomers Hunt Cosmic Monsters
(cont.)
Detectives of the invisible
The spectra of the X-ray emission from the sources can reveal a lot
about the properties of the active nucleus. If low-energy X-rays are
sparse compared with those at higher energies, it indicates that there
is much absorbing gas between us and the nucleus -- or possible black
hole.
The absorbing material may be in a ring or doughnut shape, surrounding
the X-ray source. In some extreme cases, when we are looking at this
accretion disk edge-on, the nucleus may be hidden from our view, and
only the highest energy X-rays can escape.
Alternatively when there is little absorption, and the low-energy X-rays
are strong, the spectra display practically straight lines (known as
"power-law spectra"). They indicate that we are getting a
close-to-face-on view, looking right down into the nucleus and
associated black hole.
Other sources show bumps or wiggles in their spectra. This can be
attributed to the emission of iron atoms very close to the maelstrom of
the black hole. From the shape of a bump, one can infer the geometry
of the emitting region -- for instance, our distance from the hole and
the angle at which we are observing the central accretion disk.
Clearly identified emission lines in the spectra are the fingerprints of
different elements that are swirling around very close to the event
horizon, where matter finally disappears. From the displacement of
these lines from their normal position in a spectrum one can measure
the velocities, close to the speed of light, at which these atoms are
moving. This, in turn, indicates how fast the black hole itself is rotating.
An iron line also tells us how close the accretion disk is reaching to the
very edge of the black hole.
A new black hole?
"All but one of these nine sources had already been identified by
ROSAT. Whether they are unobscured sources with straight
power-law profiles, or objects whose X-rays are partially absorbed, the
XMM-Newton spectra confirm the models -- the way we had
imagined we would see these sources in greater detail," explained
Guenther Hasinger.
"But the bright source -- practically in the center of the image -- is
one of XMM-Newton?s new discoveries!
"We have given it the number 24021. Its nature is still unclear; it has a
very different spectrum, practically no X-rays below the 2 keV energy
level and a power-law profile above 2 keV. We haven?t determined its
redshift (how far away it is), and to know more we will need to observe
this source with the new generation of 8- to 10-meter (315- to
395-inch) telescopes."
Those who say spectra are dull must be lacking in imagination. The
spectral fingerprints like those shown here are revealing how black holes
form and grow. If the Lockman Hole observation is an example,
XMM-Newton?s spectrometric mission promises to be extremely
rewarding.
Next page: detectives of the invisible universe
X-Ray Spectra Help Astronomers Hunt Cosmic Monsters
(cont.)
quinataeesenza:
Missing Energy
Quintessence (Q)
Cosmological Constant (L)
W?
Quintessence*
negative pressure (p) or -1 < w = p/r < 0
time-varying p and r
spatially inhomogeneous
Caldwell, Dave, PJS. (1998)*
Why quintessence?
logical possibility that is physically distinct from L
excellent fit to current data
may solve the ?cosmic coincidence problem?
Examples
scalar field Q rolling down a potential V(Q)
pressure = K.E. - P.E.
Slow-roll: K.E. << P.E. or p < 0
W =
KE - PE
KE + PE
Quintessence
= equation-of-state
Weiss (1987), Ratra & Peebles(1988), Wetterich (1995), Frieman et al (1995), Coble et al
(1997),
Ferreira & Joyce (1997), Caldwell et al. (1998), ...
W can be constant, monotonically increasing or decreasing, or oscillatory
Examples
web of nonabelian cosmic strings
network of nonabelian domain walls
W = - 1/3
Quintessence
Kamionkowski & Toumbas (1996), Spergel & Pen. (1997), Bucher & Spergel (1998),
W = - 2/3
Summary of Evidence for an
Exotic Energy Component
(Quintessence or Cosmological Constant)
L or Q
Sum rule: 1 = Wm + Wk + W?
Quintessence
vs.
Cosmological Constant
from Wang,Caldwell, Ostriker & PJS (1999)
See also Workshop Talk by Robert Caldwell
and Poster by Limin Wang
see also Turner, Perlmutter and White (1999)
Observational Differences
COBE +
low red shift tests
COBE:
COBE norm of
the mass power spectrum
ns:
spectral tilt
s8:
cluster abundance
peculiar velocities
SHAPE
shape of mass power
spectrum on scales > 10 Mpc
H+BBN+BF:
Hubble parameter +
Big Bang Nucleosynthesis +
Baryon Fraction
Bulk Flow
Age
Observational Differences
Conclusions:
Both cosmological constant and quintessence fit current observations well
Best hopes for discrimination:
- CMB anisotropy
- Supernovae
- gravitational lens statistics (esp. arcs)
Quintessence
vs.
Cosmological Constant
Theoretical Advantages
The Quintessential Solution:
Tracker Fields
&
Tracker Solutions
Zlatev, Wang, & PJS (1998); PJS, Wang,Zlatev (1999)
See also Poster by Ivaylo Zlatev
For a wide class of potentials
G = V? V/(V? 2) > 5/6
and nearly constant
The Quintessential Solution:
there are attractor solutions
to the equations of motion
which lead to cosmic acceleration today
nearly independent of initial conditions !
Tracker potential:
V(Q) = M4 f(Q/M)
The Quintessential Solution:
The values of WQ and Wm are determined by M
Trackers: New Prediction
Wm - w relation
More Exotic Possibilities ?
Evidence mounting
Curvature disfavored but still uncertain at present
Near-future cosmological observations may decide the issue
Profound implications for cosmology & fundamental physics
New Problems (?coincidence?) and perhaps novel solutions (?trackers?) and new predictions
(Wm - w relation)
Per capire questo ti[po di onde isogna capire che sono onde di energia
gia' estrinsecate come rumore di fondo
A team of researchers that looked at data from more than 140,000
galaxies says the universe is far from heavy and has a density of next
to nothing.
"It's about 300 billion billion billion times less dense than water," said
John Peacock of the University of Edinburgh, "or one ten-thousandth
of an ounce in a volume the same size as the Earth."
Take a video journey through the galaxies.
Peacock and his colleagues got the answer using an instrument on the
Anglo-Australian Telescope that can detect the light from 400
galaxies simultaneously over a field of view four times as wide as the
full Moon. The research is part of a massive effort to create a
three-dimensional map of the universe.
The instrument shows the "redshift" of each galaxy (i.e., the extent to
which galactic light turns reddish as the galaxy moves away from the
observer), thereby suggesting the galaxies' relative distance to Earth.
That determination leads to the calculation of each galaxy's density
and mass, and also those properties of the universe.
The results were published in the March 8, 2001, issue of the journal
Nature.
Supercluster collapse
The analysis also claims to clarify astronomers' understanding of the
structure of the universe throughout which galaxies are sprinkled not
randomly, but in clusters that glom together in "superclusters."
Peacock and his colleagues found that superclusters form, as
suspected, from the inward gravitational collapse of galaxies upon one
another.
To get the density figure, the team looked at "peculiar" velocities
created when the superclusters tug and pull on nearby galaxies
whizzing by. That led them to calculate that the universe is one third as
populated as the calculated density that would halt an expanding
universe. Most theorists now agree the universe is expanding as a
result of the Big Bang -- the explosive instant thought to have given
birth to the universe.
"The actual figure is tiny," said Peacock, "about 3 times 10^{-27}
kilograms per cubic meter." That's much, much lighter -- a fraction of
a three kilograms with 27 zeroes in front of the decimal point -- than a
dust speck in a bucket the size of a wide-screen TV for a typical home.
Survey finished later this year
The results come from an ambitious effort, called the 2dF Galaxy
Redshift Survey, to detect light simultaneously from hundreds of
galaxies at a time. Eventually, the survey, conducted by British and
Australian researchers, will yield an inventory of about 10 percent of
the galaxies in Earth's cosmic neighborhood. It will map one-tenth of
the galaxies within 2 billion light-years of Earth (a light-year is the
distance light travels in a year -- about 6 trillion miles or 9.7 trillion
kilometers).
Last year, project scientists used earlier data from the survey to show
that the universe will continue to expand forever, rather than end in a
catastrophic collision like the opposite of the Big Bang.
Peacock is optimistic that future analyses of 2dF data will yield the
"fluctuation spectrum" -- jargon for how clumpy the distribution of
galaxies is in the universe.
"This can not only give us another independent way to measure the
mass density," he said, "it can also tell us what fraction of this mass is
in the form of ordinary matter (particles like electrons and protons --
the same as you are), as opposed to exotic elementary particles left
over as relics from the earliest phases of the Big Bang."
The survey, which should be done later this year after completing the
logging of data on 250,000 galaxies, has involved a vast array of
astronomical talent, including instrument designers and engineers,
observational astronomers and theorists who have cranked out
statistics on the results. (Other sky surveys currently under way
include the 2MASS Redshift Survey and the Sloan Digital Sky Survey.)
"The end result is something that no individual could have produced
unaided," Peacock said.
Marc Davis of the University of California, who wrote an
accompanying article in Nature on the new study, heralded the analysis
as moving cosmology to a new and more sophisticated level of
analysis.
"Cosmology, long considered a branch of philosophy rather than physics
because of the dearth of data, has made dramatic progress in the
past few years and is now entering an era of large-scale studies and
precision measurements," he said.
X-Ray Spectra Help
Astronomers Hunt Cosmic
Monsters
By The European Space Agency
posted: 06:27 am ET
08 March 2001
One must admit that spectra, the curves that plot the number of
photons and their energy, appear to be rather uninspiring to the
layman -- There's nothing worse than a graph! But like one?s body
temperature curve, they mean a lot.
For astronomers, spectra are like fingerprints from the stars and
galaxies. The information they hold may be incomplete, like a
tattered newspaper, but it tells a story. While images from a
telescope are attractive, spectra can reveal the innermost secrets
of certain cosmic monsters.
The image of XMM-Newton?s deepest observation of the "blank"
X-ray sky in the direction of the Lockman Hole -- where X-ray
absorbing extragalactic material is thinnest and one can best peek
into the confines of the universe -- has already been acclaimed. The
picture identifies about 150 new X-ray sources, most of them
among the faintest hard X-ray sources ever observed.
Many of the brighter X-ray emissions in the Lockman Hole were
previously identified with the ROSAT satellite. For these,
XMM-Newton has now provided very detailed spectra, as is shown
in a picture montage by Guenther Hasinger from the Astrophysics
Institute of Potsdam (AIP).
(courtesy Guenther Hasinger/AIP -- click to enlarge)
The main image [above] plots the soft X-ray photons, already
observed by ROSAT, in red. Green corresponds to intermediate
X-ray photons, also detectable by NASA?s Chandra X-ray
Observatory. Blue is used to show the hardest X-ray photons, only
detectable by XMM-Newton.
The individual spectra [right edge of this page] "roll out" this color
information into graphs, plotted in red, where the X-ray emission (the
number of arriving photons) is plotted against the energy at which it
is emitted. The green lines refer to model spectra fitted to these
graphs.
Many of the sources are associated with black holes, monstrous
gravitational wells into which matter is being sucked and in which
even light disappears. Stellar-mass black holes arise after the death
of a massive star that has used all its fuel. But there exist also
supermassive black holes, which are present in the center of almost
every galaxy.
"The origin of these supermassive ones remains a complete
mystery," said Guenther Hasinger. "Forming these from many single
black holes would probably take too much time. They might therefore
be part of the original collapse of gas into a galaxy, in other words the
seed objects of galaxy creation."
Next page: detectives of the invisible universe
X-Ray Spectra Help Astronomers Hunt Cosmic Monsters
(cont.)
Detectives of the invisible
The spectra of the X-ray emission from the sources can reveal a lot
about the properties of the active nucleus. If low-energy X-rays are
sparse compared with those at higher energies, it indicates that there
is much absorbing gas between us and the nucleus -- or possible black
hole.
The absorbing material may be in a ring or doughnut shape, surrounding
the X-ray source. In some extreme cases, when we are looking at this
accretion disk edge-on, the nucleus may be hidden from our view, and
only the highest energy X-rays can escape.
Alternatively when there is little absorption, and the low-energy X-rays
are strong, the spectra display practically straight lines (known as
"power-law spectra"). They indicate that we are getting a
close-to-face-on view, looking right down into the nucleus and
associated black hole.
Other sources show bumps or wiggles in their spectra. This can be
attributed to the emission of iron atoms very close to the maelstrom of
the black hole. From the shape of a bump, one can infer the geometry
of the emitting region -- for instance, our distance from the hole and
the angle at which we are observing the central accretion disk.
Clearly identified emission lines in the spectra are the fingerprints of
different elements that are swirling around very close to the event
horizon, where matter finally disappears. From the displacement of
these lines from their normal position in a spectrum one can measure
the velocities, close to the speed of light, at which these atoms are
moving. This, in turn, indicates how fast the black hole itself is rotating.
An iron line also tells us how close the accretion disk is reaching to the
very edge of the black hole.
A new black hole?
"All but one of these nine sources had already been identified by
ROSAT. Whether they are unobscured sources with straight
power-law profiles, or objects whose X-rays are partially absorbed, the
XMM-Newton spectra confirm the models -- the way we had
imagined we would see these sources in greater detail," explained
Guenther Hasinger.
"But the bright source -- practically in the center of the image -- is
one of XMM-Newton?s new discoveries!
"We have given it the number 24021. Its nature is still unclear; it has a
very different spectrum, practically no X-rays below the 2 keV energy
level and a power-law profile above 2 keV. We haven?t determined its
redshift (how far away it is), and to know more we will need to observe
this source with the new generation of 8- to 10-meter (315- to
395-inch) telescopes."
Those who say spectra are dull must be lacking in imagination. The
spectral fingerprints like those shown here are revealing how black holes
form and grow. If the Lockman Hole observation is an example,
XMM-Newton?s spectrometric mission promises to be extremely
rewarding.
Next page: detectives of the invisible universe
X-Ray Spectra Help Astronomers Hunt Cosmic Monsters
(cont.)
quinataeesenza:
Missing Energy
Quintessence (Q)
Cosmological Constant (L)
W?
Quintessence*
negative pressure (p) or -1 < w = p/r < 0
time-varying p and r
spatially inhomogeneous
Caldwell, Dave, PJS. (1998)*
Why quintessence?
logical possibility that is physically distinct from L
excellent fit to current data
may solve the ?cosmic coincidence problem?
Examples
scalar field Q rolling down a potential V(Q)
pressure = K.E. - P.E.
Slow-roll: K.E. << P.E. or p < 0
W =
KE - PE
KE + PE
Quintessence
= equation-of-state
Weiss (1987), Ratra & Peebles(1988), Wetterich (1995), Frieman et al (1995), Coble et al
(1997),
Ferreira & Joyce (1997), Caldwell et al. (1998), ...
W can be constant, monotonically increasing or decreasing, or oscillatory
Examples
web of nonabelian cosmic strings
network of nonabelian domain walls
W = - 1/3
Quintessence
Kamionkowski & Toumbas (1996), Spergel & Pen. (1997), Bucher & Spergel (1998),
W = - 2/3
Summary of Evidence for an
Exotic Energy Component
(Quintessence or Cosmological Constant)
L or Q
Sum rule: 1 = Wm + Wk + W?
Quintessence
vs.
Cosmological Constant
from Wang,Caldwell, Ostriker & PJS (1999)
See also Workshop Talk by Robert Caldwell
and Poster by Limin Wang
see also Turner, Perlmutter and White (1999)
Observational Differences
COBE +
low red shift tests
COBE:
COBE norm of
the mass power spectrum
ns:
spectral tilt
s8:
cluster abundance
peculiar velocities
SHAPE
shape of mass power
spectrum on scales > 10 Mpc
H+BBN+BF:
Hubble parameter +
Big Bang Nucleosynthesis +
Baryon Fraction
Bulk Flow
Age
Observational Differences
Conclusions:
Both cosmological constant and quintessence fit current observations well
Best hopes for discrimination:
- CMB anisotropy
- Supernovae
- gravitational lens statistics (esp. arcs)
Quintessence
vs.
Cosmological Constant
Theoretical Advantages
The Quintessential Solution:
Tracker Fields
&
Tracker Solutions
Zlatev, Wang, & PJS (1998); PJS, Wang,Zlatev (1999)
See also Poster by Ivaylo Zlatev
For a wide class of potentials
G = V? V/(V? 2) > 5/6
and nearly constant
The Quintessential Solution:
there are attractor solutions
to the equations of motion
which lead to cosmic acceleration today
nearly independent of initial conditions !
Tracker potential:
V(Q) = M4 f(Q/M)
The Quintessential Solution:
The values of WQ and Wm are determined by M
Trackers: New Prediction
Wm - w relation
More Exotic Possibilities ?
Evidence mounting
Curvature disfavored but still uncertain at present
Near-future cosmological observations may decide the issue
Profound implications for cosmology & fundamental physics
New Problems (?coincidence?) and perhaps novel solutions (?trackers?) and new predictions
(Wm - w relation)
web site :
http://feynman.princeton.edu/~steinh/pritzker/tsld041.htm
Per capire questo ti[po di onde isogna capire che sono onde di energia
gia' estrinsecate come rumore di fondo
A team of researchers that looked at data from more than 140,000
galaxies says the universe is far from heavy and has a density of next
to nothing.
"It's about 300 billion billion billion times less dense than water," said
John Peacock of the University of Edinburgh, "or one ten-thousandth
of an ounce in a volume the same size as the Earth."
Take a video journey through the galaxies.
Peacock and his colleagues got the answer using an instrument on the
Anglo-Australian Telescope that can detect the light from 400
galaxies simultaneously over a field of view four times as wide as the
full Moon. The research is part of a massive effort to create a
three-dimensional map of the universe.
The instrument shows the "redshift" of each galaxy (i.e., the extent to
which galactic light turns reddish as the galaxy moves away from the
observer), thereby suggesting the galaxies' relative distance to Earth.
That determination leads to the calculation of each galaxy's density
and mass, and also those properties of the universe.
The results were published in the March 8, 2001, issue of the journal
Nature.
Supercluster collapse
The analysis also claims to clarify astronomers' understanding of the
structure of the universe throughout which galaxies are sprinkled not
randomly, but in clusters that glom together in "superclusters."
Peacock and his colleagues found that superclusters form, as
suspected, from the inward gravitational collapse of galaxies upon one
another.
To get the density figure, the team looked at "peculiar" velocities
created when the superclusters tug and pull on nearby galaxies
whizzing by. That led them to calculate that the universe is one third as
populated as the calculated density that would halt an expanding
universe. Most theorists now agree the universe is expanding as a
result of the Big Bang -- the explosive instant thought to have given
birth to the universe.
"The actual figure is tiny," said Peacock, "about 3 times 10^{-27}
kilograms per cubic meter." That's much, much lighter -- a fraction of
a three kilograms with 27 zeroes in front of the decimal point -- than a
dust speck in a bucket the size of a wide-screen TV for a typical home.
Survey finished later this year
The results come from an ambitious effort, called the 2dF Galaxy
Redshift Survey, to detect light simultaneously from hundreds of
galaxies at a time. Eventually, the survey, conducted by British and
Australian researchers, will yield an inventory of about 10 percent of
the galaxies in Earth's cosmic neighborhood. It will map one-tenth of
the galaxies within 2 billion light-years of Earth (a light-year is the
distance light travels in a year -- about 6 trillion miles or 9.7 trillion
kilometers).
Last year, project scientists used earlier data from the survey to show
that the universe will continue to expand forever, rather than end in a
catastrophic collision like the opposite of the Big Bang.
Peacock is optimistic that future analyses of 2dF data will yield the
"fluctuation spectrum" -- jargon for how clumpy the distribution of
galaxies is in the universe.
"This can not only give us another independent way to measure the
mass density," he said, "it can also tell us what fraction of this mass is
in the form of ordinary matter (particles like electrons and protons --
the same as you are), as opposed to exotic elementary particles left
over as relics from the earliest phases of the Big Bang."
The survey, which should be done later this year after completing the
logging of data on 250,000 galaxies, has involved a vast array of
astronomical talent, including instrument designers and engineers,
observational astronomers and theorists who have cranked out
statistics on the results. (Other sky surveys currently under way
include the 2MASS Redshift Survey and the Sloan Digital Sky Survey.)
"The end result is something that no individual could have produced
unaided," Peacock said.
Marc Davis of the University of California, who wrote an
accompanying article in Nature on the new study, heralded the analysis
as moving cosmology to a new and more sophisticated level of
analysis.
"Cosmology, long considered a branch of philosophy rather than physics
because of the dearth of data, has made dramatic progress in the
past few years and is now entering an era of large-scale studies and
precision measurements," he said.
X-Ray Spectra Help
Astronomers Hunt Cosmic
Monsters
By The European Space Agency
posted: 06:27 am ET
08 March 2001
One must admit that spectra, the curves that plot the number of
photons and their energy, appear to be rather uninspiring to the
layman -- There's nothing worse than a graph! But like one?s body
temperature curve, they mean a lot.
For astronomers, spectra are like fingerprints from the stars and
galaxies. The information they hold may be incomplete, like a
tattered newspaper, but it tells a story. While images from a
telescope are attractive, spectra can reveal the innermost secrets
of certain cosmic monsters.
The image of XMM-Newton?s deepest observation of the "blank"
X-ray sky in the direction of the Lockman Hole -- where X-ray
absorbing extragalactic material is thinnest and one can best peek
into the confines of the universe -- has already been acclaimed. The
picture identifies about 150 new X-ray sources, most of them
among the faintest hard X-ray sources ever observed.
Many of the brighter X-ray emissions in the Lockman Hole were
previously identified with the ROSAT satellite. For these,
XMM-Newton has now provided very detailed spectra, as is shown
in a picture montage by Guenther Hasinger from the Astrophysics
Institute of Potsdam (AIP).
(courtesy Guenther Hasinger/AIP -- click to enlarge)
The main image [above] plots the soft X-ray photons, already
observed by ROSAT, in red. Green corresponds to intermediate
X-ray photons, also detectable by NASA?s Chandra X-ray
Observatory. Blue is used to show the hardest X-ray photons, only
detectable by XMM-Newton.
The individual spectra [right edge of this page] "roll out" this color
information into graphs, plotted in red, where the X-ray emission (the
number of arriving photons) is plotted against the energy at which it
is emitted. The green lines refer to model spectra fitted to these
graphs.
Many of the sources are associated with black holes, monstrous
gravitational wells into which matter is being sucked and in which
even light disappears. Stellar-mass black holes arise after the death
of a massive star that has used all its fuel. But there exist also
supermassive black holes, which are present in the center of almost
every galaxy.
"The origin of these supermassive ones remains a complete
mystery," said Guenther Hasinger. "Forming these from many single
black holes would probably take too much time. They might therefore
be part of the original collapse of gas into a galaxy, in other words the
seed objects of galaxy creation."
Next page: detectives of the invisible universe
X-Ray Spectra Help Astronomers Hunt Cosmic Monsters
(cont.)
Detectives of the invisible
The spectra of the X-ray emission from the sources can reveal a lot
about the properties of the active nucleus. If low-energy X-rays are
sparse compared with those at higher energies, it indicates that there
is much absorbing gas between us and the nucleus -- or possible black
hole.
The absorbing material may be in a ring or doughnut shape, surrounding
the X-ray source. In some extreme cases, when we are looking at this
accretion disk edge-on, the nucleus may be hidden from our view, and
only the highest energy X-rays can escape.
Alternatively when there is little absorption, and the low-energy X-rays
are strong, the spectra display practically straight lines (known as
"power-law spectra"). They indicate that we are getting a
close-to-face-on view, looking right down into the nucleus and
associated black hole.
Other sources show bumps or wiggles in their spectra. This can be
attributed to the emission of iron atoms very close to the maelstrom of
the black hole. From the shape of a bump, one can infer the geometry
of the emitting region -- for instance, our distance from the hole and
the angle at which we are observing the central accretion disk.
Clearly identified emission lines in the spectra are the fingerprints of
different elements that are swirling around very close to the event
horizon, where matter finally disappears. From the displacement of
these lines from their normal position in a spectrum one can measure
the velocities, close to the speed of light, at which these atoms are
moving. This, in turn, indicates how fast the black hole itself is rotating.
An iron line also tells us how close the accretion disk is reaching to the
very edge of the black hole.
A new black hole?
"All but one of these nine sources had already been identified by
ROSAT. Whether they are unobscured sources with straight
power-law profiles, or objects whose X-rays are partially absorbed, the
XMM-Newton spectra confirm the models -- the way we had
imagined we would see these sources in greater detail," explained
Guenther Hasinger.
"But the bright source -- practically in the center of the image -- is
one of XMM-Newton?s new discoveries!
"We have given it the number 24021. Its nature is still unclear; it has a
very different spectrum, practically no X-rays below the 2 keV energy
level and a power-law profile above 2 keV. We haven?t determined its
redshift (how far away it is), and to know more we will need to observe
this source with the new generation of 8- to 10-meter (315- to
395-inch) telescopes."
Those who say spectra are dull must be lacking in imagination. The
spectral fingerprints like those shown here are revealing how black holes
form and grow. If the Lockman Hole observation is an example,
XMM-Newton?s spectrometric mission promises to be extremely
rewarding.
Next page: detectives of the invisible universe
X-Ray Spectra Help Astronomers Hunt Cosmic Monsters
(cont.)
quinataeesenza:
Missing Energy
Quintessence (Q)
Cosmological Constant (L)
W?
Quintessence*
negative pressure (p) or -1 < w = p/r < 0
time-varying p and r
spatially inhomogeneous
Caldwell, Dave, PJS. (1998)*
Why quintessence?
logical possibility that is physically distinct from L
excellent fit to current data
may solve the ?cosmic coincidence problem?
Examples
scalar field Q rolling down a potential V(Q)
pressure = K.E. - P.E.
Slow-roll: K.E. << P.E. or p < 0
W =
KE - PE
KE + PE
Quintessence
= equation-of-state
Weiss (1987), Ratra & Peebles(1988), Wetterich (1995), Frieman et al (1995), Coble et al
(1997),
Ferreira & Joyce (1997), Caldwell et al. (1998), ...
W can be constant, monotonically increasing or decreasing, or oscillatory
Examples
web of nonabelian cosmic strings
network of nonabelian domain walls
W = - 1/3
Quintessence
Kamionkowski & Toumbas (1996), Spergel & Pen. (1997), Bucher & Spergel (1998),
W = - 2/3
Summary of Evidence for an
Exotic Energy Component
(Quintessence or Cosmological Constant)
L or Q
Sum rule: 1 = Wm + Wk + W?
Quintessence
vs.
Cosmological Constant
from Wang,Caldwell, Ostriker & PJS (1999)
See also Workshop Talk by Robert Caldwell
and Poster by Limin Wang
see also Turner, Perlmutter and White (1999)
Observational Differences
COBE +
low red shift tests
COBE:
COBE norm of
the mass power spectrum
ns:
spectral tilt
s8:
cluster abundance
peculiar velocities
SHAPE
shape of mass power
spectrum on scales > 10 Mpc
H+BBN+BF:
Hubble parameter +
Big Bang Nucleosynthesis +
Baryon Fraction
Bulk Flow
Age
Observational Differences
Conclusions:
Both cosmological constant and quintessence fit current observations well
Best hopes for discrimination:
- CMB anisotropy
- Supernovae
- gravitational lens statistics (esp. arcs)
Quintessence
vs.
Cosmological Constant
Theoretical Advantages
The Quintessential Solution:
Tracker Fields
&
Tracker Solutions
Zlatev, Wang, & PJS (1998); PJS, Wang,Zlatev (1999)
See also Poster by Ivaylo Zlatev
For a wide class of potentials
G = V? V/(V? 2) > 5/6
and nearly constant
The Quintessential Solution:
there are attractor solutions
to the equations of motion
which lead to cosmic acceleration today
nearly independent of initial conditions !
Tracker potential:
V(Q) = M4 f(Q/M)
The Quintessential Solution:
The values of WQ and Wm are determined by M
Trackers: New Prediction
Wm - w relation
More Exotic Possibilities ?
Evidence mounting
Curvature disfavored but still uncertain at present
Near-future cosmological observations may decide the issue
Profound implications for cosmology & fundamental physics
New Problems (?coincidence?) and perhaps novel solutions (?trackers?) and new predictions
(Wm - w relation)
web site :
http://feynman.princeton.edu/~steinh/pritzker/tsld041.htm
web site :
http://feynman.princeton.edu/~steinh/pritzker/tsld041.htm
\newlabel{G e la costante gravitazionale mp la massa del protone
c la velocita della luce il denominatore e' la sezione thomson }