The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy...
Transcript of The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy...
![Page 1: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/1.jpg)
The Dark Side of the Universe
Are Dark Matter and Dark Energy “real” or
Einstein gravity breaks down at astrophysical scales?
PART I: Dark Matter vs. New Gravity
David F. MotaInstitute of Theoretical Astrophysics
University of Oslo
![Page 2: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/2.jpg)
Understanding the Universe and its laws
Standard Model Particle Physics General Relativity
Cosmologists cannot explain nor understand the observations!
spacetime
Space and TimeMatter
![Page 3: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/3.jpg)
Non-Standard (Dark) matter crucial to explain observations at many different scales!
Dis
trib
utio
n of
Mat
ter
![Page 4: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/4.jpg)
All Observations indicate we need the same amount of Non-Standard (Dark) Matter!
Matter Density
Dar
k En
ergy
Den
sity
0.7
0.3
![Page 5: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/5.jpg)
Dark Stuff dominates the Universe: 95% !!
Not something you would sweep under the carpet…
![Page 6: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/6.jpg)
• New exotic particles were proposed as dark matter, but have never been observed (after decades searching)!
• All the previous conclusions were assuming General Relativity as the theory of gravity
• We infer Dark Matter and Dark Energy from the behaviour of ordinary matter in a gravitational field
• So... Is it possible that there is no dark stuff, but Einstein’s General Relativity does not work at large scales?
Why Modified Gravity as an alternative to Dark Matter and Dark Energy?
![Page 7: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/7.jpg)
• 1830s astronomers noticed Uranus did not follow the expected Kepler orbit• Could Newton law of Gravity be wrong?!?
The anomalous orbit of Uranus
![Page 8: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/8.jpg)
• Le Verrier and Adams predicted presence and position of Neptune from Uranus’s anomalous orbit
•Neptune was found in 1846 exactly at the predicted position!!
Dark Matter vs.
New Gravity Law?
• There are no reason to expect all planets except Uranus to obey Newton’s gravity • There must be another planet out there one has not seen yet…
New (Dark) planet provided the explanation!
![Page 9: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/9.jpg)
Observed Mercury's perihelion precession: 5600.73 arcseconds per century
Calculated Newtonian corrections: 5557.62 arcseconds per century
Dark Matter vs. New Gravity Law?
1855 Le Verrier and others tried to explain it with “dark matter”: new planet Vulcan, new asteroid belt, etc
New Law Gravity (General Relativity) provided the explanation!
spacetime
![Page 10: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/10.jpg)
Planet velocities in the Solar System
Rotation Curve in Solar System decreases, because
most of the mass in the Sun, therefore the force is smaller at larger distances
![Page 11: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/11.jpg)
•Stars in galaxy bulge should move fast
•Stars at the galaxy edge should move slower
Stars rotating in a galaxy (Vera Rubin 50 years ago)
![Page 12: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/12.jpg)
Evidence for Dark Matter: Stars’ velocity does not decrease!
• Gravitational attraction is not decreasing with distance from galaxy centre
• Mass must increase with distance from galaxy centre!
• This Mass one cannot see is: Dark Matter!
Even outside!
![Page 13: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/13.jpg)
Dark Matter Halo
![Page 14: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/14.jpg)
Dark Matter represents 90% of the total mass, normal matter only contributes with 10%
![Page 15: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/15.jpg)
Galaxy rotation curves: dark matter only explanation?
• Gravitational attraction not decreasing with distance from centre
• 1) Either mass increase with distance from galaxy centre!
• 2) …or the force does not decay as 1/r2
![Page 16: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/16.jpg)
Modified Newtonian Dynamics: an alternative to dark matter
• Milgrom(1984) proposed a phenomenological force law: gravity falls off more slowly far away (MOND)
Explains galaxy rotation curves very well and many other galactic properties with standard matter only!
![Page 17: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/17.jpg)
Cluster of Galaxies+ Intergalactic gas + Dark Matter Galaxies
(10%) (90%) ( 90% of total cluster mass )
![Page 18: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/18.jpg)
How do we “see” in cosmology
(Credit: X-ray: NASA/CXC/CfA/M.Markevitch et al. Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al. Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.)
90%10%
![Page 19: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/19.jpg)
Mass curves spacetime, and that makes light bend
spacetime
Gravitational Lensing: probe to “see” dark matter
![Page 20: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/20.jpg)
The larger the mass (large spacetime curvature) the bigger is the image distortion!
Mass (spacetime curvature) distorts images
![Page 21: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/21.jpg)
Gravitational Lensing can be used to map spacetime curvature (mass concentrations)
![Page 22: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/22.jpg)
Collision of Clusters: galaxies separated from intergalactic gas
(Credit: KIPAC/John Wise)
10% mass in galaxies
90% mass in x-ray gas
![Page 23: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/23.jpg)
x-ray gas, although 90% of standard matter, does not contribute to spacetime
curvature!
Lensing contours: large spacetime curvatures
There is something very massive (and dark!) around
the galaxies!
Dark matter exists and cannot be explained by a
new gravitational law
Strong spacetime curvature (Mass) with galaxies
![Page 24: The Dark Side of the Universe · The Dark Side of the Universe Are Dark Matter and Dark Energy “real” or Einstein gravity breaks down at astrophysical scales? PART I: Dark Matter](https://reader035.fdocuments.net/reader035/viewer/2022062317/5fbee9a8c1c6cc5ea4289edf/html5/thumbnails/24.jpg)
Summary of PART I Dark Matter or… Beyond Einstein’s Gravity?
Most probably a new undiscovered particle beyond the Standard Model of Particle Physics
It must be very massive and does not interact electromagnetically!
Hopefully we will detect it in the Large Hadron Collider!