Theoretical Cosmology and Particle Astrophysics at Caltech
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Transcript of Theoretical Cosmology and Particle Astrophysics at Caltech
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Theoretical Cosmology and Theoretical Cosmology and Particle Astrophysics at Particle Astrophysics at
CaltechCaltech
Marc KamionkowskiJuly 21, 2004
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HEP Experiment at Caltech:
People: Hitlin, Barish, Weinstein, Peck, Porter, Newman, Doug Michael....
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NuclearPhysics at Caltech
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HENP Theory at Caltech:• Strings •Phenomenology•Nuclear/Neutrino Physics•QFT/QC/QI
Active postdoc program (e.g., Rajagopal, Horava....)
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Astronomy/Astrophysics at Caltech:
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Also, SIRTF, GALEX, Hershel..... and everything at JPL. And Carnegie Observatories down the road....
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Caltech/JPL will be US center for experimental early-
Universe cosmology over next decade
• Caltech faculty: Readhead, Lange, Zmuidzinas, Golwala
• Boomerang was first experiment to map acoustic peaks in CMB
• CBI was first to measure power on smaller scales• Have vigorous ongoing ground/balloon-based
programs (BICEP, QUaD, QUIET, B2K, CBI, ACBAR, JAKNIFE….)
• Are US PI institution for Planck LFI and HFI, and will have US Planck data analysis center
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Theoretical Astrophysics and Relativity:
Thorne, Sari, Phinney, Goldreich (part)
stellar astrophysics, relativity, gravitationalwaves, cosmology, high-energyastrophysics....
Strong postdoc program (Narayan, Tremaine, Bildsten, Hogan....)
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Cosmology/ Particle/Nuclear Astrophysics Physics
•Dark matter•Dark energy•Inflation•Neutrino astrophysics•Ultrahigh-energy cosmic rays•Baryogenesis
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People now (at least loosely) affiliated with Caltech
theoretical cosmology and particle astrophysics
Postdocs:• Asantha Cooray (Sherman Fairchild
Senior Research Fellow; DoE research expenses)
• Milos Milosavljevic (Fairchild Fellow)
• Steven Furlanetto (DuBridge Fellow; ~20% Task B)
• Andriy Kurylov (~30% Task B)• L. Arielle Phillips (Irvine Fellow)• Amr El-Zant (other sources)• Nicole Bell (Fairchild Fellow
beginning Fall 2004)• James Taylor (arriving this fall;
supported by R. Ellis)
Graduate Students:• Mike Kesden (NASA GSRP)• Nevin Weinberg (NASA ATP)• Kris Sigurdson (NSERC/DoE)• Jonathon Pritchard (TA)• Tristan Smith (NSF Fellow)
• 3 more arriving this fall, one with NSF fellowship, one with 4-year Moore fellowship, and one with 1-year Caltech fellowship
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People now (at least loosely) affiliated with Caltech
theoretical cosmology and particle astrophysics
Other Researchers:
• Kris Gorski (JPL Visiting associate)
• Elena Pierpaoli (senior research fellow supported by NSF ADVANCE fellowship; arriving fall 2005)
Visitors:• Robert Caldwell (sabbatical
visit from Dartmouth 2003-2004)
• Rashid Sunyaev (Moore distinguished scholar; 2003-4)
• Tsvi Piran (Moore distinguished scholar; 2004-5)
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Some Recent Alumni
Students:
• Mike Santos (PhD 2003; now postdoc at Cambridge)
• Catherine Cress (PhD 1999; (Columbia) Natal faculty)
• Alexandre Refregier (PhD 1998 (Columbia); CNRS faculty)
• Xuelei Chen (PhD 1999 (Columbia) KITP postdoc)
Postdocs:• Piero Ullio (1999-2000; SISSA
faculty)• Ken Nollett (2000-2002;
permanent member, Argonne nuclear theory group)
• Peng Oh (2000-2003; UCSB faculty)
• Andrew Benson (2000-2003; Roy Soc advanced fellow)
• Eric Agol (2000-2003; Washington faculty)
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Caltech is building in particle astrophysics:
Experiment:
Added Sunil Golwala (dark matter, dark energy, CMB) to faculty 2003
Theory:
Have just made tenured offer to Matias Zaldarriaga (CMB, inflation, dark energy….)
“Heart of Darkness” initiative will seek private fundingfor theoretical activity at string/particle/cosmology interface
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Our recent (~year) research topics
• Effects of dark-matter dipole moments, decays…• Variable fine-structure constant• Probes of dark matter at Galactic center• Dark energy, phantom energy, “Big Rip”• Galactic-halo merger rates• CMB tests of inflation• “Cooling” problem in galaxy clusters• Intergalactic medium• Supersymmetric dark matter• Large-scale structure, weak lensing, inflation, and dark energy• The first stars and reionization
~100 refereed publications over past 5 years
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Our work is relevant for
• SNAP/JDEM• CMB experiments (WMAP, Planck, CMBPOL…• GLAST/VERITAS/STACEE/….• Collider experiments (to some extent)• Neutrino experiments• CDMS, etc.• Super-K, IceCube….• LSST• SDSS/2dF….• AMS….
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Benefits of this program to DoE
• DoE funding heavily leveraged by Caltech• Maintains theoretical activity at major center for
experimental particle astrophysics and early-Universe cosmology
• Supports training of some of the best postdocs and students in the field
• Grad student support goes only to students in final year of research, when they are most productive
• “One-professor” budget supports theory program in exciting emerging area that competes with programs with larger faculty numbers
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Funding profile
• 1999-2003: ~$100K/year (PI summer salary plus student)
• 2003-2004: ~$150K/year (PI summer salary, student, plus 2nd student or 50% postdoc)
• Current request: continued funding at current level
Eventually, would like to be able to support 100% postdoc plus student from this Task.
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Science Menu
• Spintessence• Dipole dark matter• Galaxy-halo mergers• Cluster cooling• Phantom energy and Big Rip• CMB and inflation• Charged-particle decay and small-scale power• Dark clusters, dark energy, and weak lensing• WMAP, CBI, and the first stars• Dark matter at Galactic center
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Dipole dark matter (Sigurdson, Caldwell, Doran, Kurylov, MK, 2004)
Phenomenologicalinvestigation oflargest dark-matterelectric or magneticdipole momentconsistent withexperiments andobservations
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II. The Cosmic Microwave II. The Cosmic Microwave Background (CMB) and Background (CMB) and
InflationInflation
Kesden, Cooray, MK, PRL 89, 011304 (2002)
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Boomerang1998
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Geometry Baryondensity
Hubbleconstant
Cosmologicalconstant
MK, Spergel, Sugiyama 1994
"Precision cosmology": Jungman, MK, Kosowsky, Spergel 1996
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Results as of 2001:
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CBI, May 2002
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Archeops 2002
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ACBAR, December 2002
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(some of) What we have learned:
lpeak ~ 200 =1.00±0.03; the Universe is flat (MK, Spergel, Sugiyama '94) Structure grows from nearly scale invariant spectrum of primordial density perturbations on right track with inflation! (also, increasingly precise determinations of matter and baryon density, Hubble constant....)
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WHATNEXT???
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Th
e b
ig
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!!
tod
ay
1010 yrT~meV
Deco
up
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105 yrT~eV
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+p
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, D
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SecondsT~MeV
gala
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ark
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,p10-3 secT~100 MeV
ele
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weak
EM
,weak
10-9 secT~100 GeV
quan
tum
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vit
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stri
ng
s???
10-43 secT~ 1019 GeV
10-36 secT~ 1016 GeV
GU
T
Þele
ctro
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stro
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??
10-22 secT~ 1012 GeV
PQ
sym
metr
y b
reaki
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??
SU
SY b
reaki
ng
??
INFLATION
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INFLATION
GEOMETRY SMOOTHNESS STRUCTUREFORMATION
What is Einfl?
STOCHASTIC GRAVITATIONAL-WAVE
BACKGROUND with amplitude µEinfl2
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Detection of gravitational waves with CMB polarization
Temperature map:
Polarization Map:
Density perturbations have no handedness”
so they cannot produce a polarization with a curlGravitational waves do have a handedness, so they
can (and do) produce a curl
Model-independent probe of gravitational waves!
(MK, Kosowsky, Stebbins 1997; see also cover article of Jan 2001 Sci. Am, reprinted in Sci Am special edition 10/02)
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GWs Þ
Recall, GW amplitude is l2
GWs Þ unique polarization pattern. Is it detectable?
If E<<1015 GeV (e.g., if inflation from PQSB), then polarization far too small to ever be detected.
But, if E~1015-16 GeV (i.e., if inflation has something to do with GUTs), then polarization signal is conceivably detectable by Planck or realistic post-Planck experiment
And from COBEÞ
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Jaffe, Wang, MK 2000
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Problem: Weak gravitational lensing of CMB polarization by density perturbations along line of sight ("cosmic shear") turns part of curl-free polarization pattern into curl.
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Kes
den,
Coo
ray,
MK
, PR
L 2
002
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Possible solution: Use higher-order correlations in temperature map that measure stretching from cosmic shear as a function of position on sky
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Hivon & MK, Science 296, 267 (2002)
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Brief Aside: Large scale structure and inflation
ÛInflatonpotential
Matter powerspectrum
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MK & Liddle, PRL 84, 4525 (2000)
Galactic substructuremay probe inflatonpotential nearend of inflation
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Another possibility: suppression of small-scale power by decay of charged dark-matter particles
(Sigurdson-MK, 2004)
Decay of charged particle with lifetime 3.5 year to dark matter suppresses small-scale power
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III. Spin-dependentWIMPs in DAMA?
Ullio, MK, Vogel, JHEP 0107, 044 (2001)
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Earth
density
r
r0=8 kpc
core
radius
Velocity
distribution~ Maxwell-
BoltzmannWith <v2>1/2~270 km/sec
spherical halo:
0=0.3-0.6 GeV/cm3
If halo flattened,
0
The standard smooth halo model
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WIMPsWIMPsThe relic density of a massive particle is about:
Of Weak Interaction strength
the particle has to be coupled to SM particlesThere is chance for detection:
Detection
direct
indirect
Neutrinos
from sun/earth
anomalous
cosmic rays
WIMP candidate motivated by SUSY:Lightest Neutralino, LSP in SUSY extension of SM
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Spin dependentWIMP-proton coupling
Spin dependentWIMP-neutron coupling
Ullio, MK, Vogel 2001
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IV. Spintessence! And IV. Spintessence! And Phantom Energy: Some Phantom Energy: Some ideas for Dark Energyideas for Dark Energy
Boyle, Caldwell, MK, Phys Lett B 545, 17 (2002)
Caldwell, Weinberg, MK, in preparation
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Gravity with relativistic fluid:
So if p<-source forgravitational field is negative,and get repulsive gravity.Thus, 70% of critical densityis in form of negative-pressure "dark energy".
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One idea for dark energy: Quintessence, slowly-rolling
scalar field:V(f)
f
Pressure Energy density
w=p/r
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SpintesseSpintessence! nce!
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Spintessence! Connections:
Novel growth of perturbations CPT/Lorentz violation Baryogenesis/Q-balls Rotation of polarization of distant radio sources Spintessential inflational? Exponential potentials may address "why now?"
problem Non-circular orbits might reproduce oscillating
dark energy models Fuzzy dark matter=
Open question: potential that accelerates long enough?
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Constraints to w (Wang et al. 2000):
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"Deep" implications:
If w<-1/3, then Universe expands forever. However, scale factor grows more rapidly thanHubble distance. Therefore, Universe becomesexponentially colder, currently observable galaxiesdisappear. Extragalactic astronomy becomesless interesting, but Milky Way and local groupcontinue as usual.
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What about w < -1?("phantom" energy)
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Fire and Brimstone!!
If w<-1, get
Death by stretching!!Vacuum-energy density increases withscale factor a(t) as a-3(1+w). Scale factorand vacuum-energy density blow up infinite time.Horizon shrinks, and increasing vacuum-energy density ultimately tears boundobjects apart, roughly a dynamical timebefore the end of the Universe
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Big
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15 G
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10
43 s
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10
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Inflati
on
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tim
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t smas
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The Physics of "Phantom" Energy:
Is weird: violates "dominant-energy" condition; naively requires sound speed > c. Has increasing energy densityPossibilities:
"negative" kinetic term, as from supergravity or higher-derivative gravity (Caldwell 2002; Armendariz- Picon et al. 1999; Chiba et al. 2000)
"stringy" dark energy (related to Lorentz violation; Frampton 2002)
Nonminimal coupling (Faraoni 2002)
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(More) Physics of "Phantom" Energy:
More possibilities:Braneworld models: (Sahni & Shtanov 2002)dS/CFT connections (McInnes 2002)
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....just one more thing:
Nollett [Phys Rev D 66, 063507 (2002)] showedthat big bang nucleosynthesis restrictsfine structure constant to be within 10%of its current value ~minutes after thebig bang.
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