Theoretical Cosmology and Theoretical Cosmology and Particle Astrophysics at Particle Astrophysics at

CaltechCaltech

Marc KamionkowskiJuly 21, 2004

HEP Experiment at Caltech:

People: Hitlin, Barish, Weinstein, Peck, Porter, Newman, Doug Michael....

NuclearPhysics at Caltech

HENP Theory at Caltech:• Strings •Phenomenology•Nuclear/Neutrino Physics•QFT/QC/QI

Active postdoc program (e.g., Rajagopal, Horava....)

Astronomy/Astrophysics at Caltech:

Also, SIRTF, GALEX, Hershel..... and everything at JPL. And Carnegie Observatories down the road....

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

Theoretical Astrophysics and Relativity:

Thorne, Sari, Phinney, Goldreich (part)

stellar astrophysics, relativity, gravitationalwaves, cosmology, high-energyastrophysics....

Strong postdoc program (Narayan, Tremaine, Bildsten, Hogan....)

Cosmology/ Particle/Nuclear Astrophysics Physics

•Dark matter•Dark energy•Inflation•Neutrino astrophysics•Ultrahigh-energy cosmic rays•Baryogenesis

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

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)

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)

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

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

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….

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

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.

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

Dipole dark matter (Sigurdson, Caldwell, Doran, Kurylov, MK, 2004)

Phenomenologicalinvestigation oflargest dark-matterelectric or magneticdipole momentconsistent withexperiments andobservations

II. The Cosmic Microwave II. The Cosmic Microwave Background (CMB) and Background (CMB) and

InflationInflation

Kesden, Cooray, MK, PRL 89, 011304 (2002)

Boomerang1998

Geometry Baryondensity

Hubbleconstant

Cosmologicalconstant

MK, Spergel, Sugiyama 1994

"Precision cosmology": Jungman, MK, Kosowsky, Spergel 1996

Results as of 2001:

CBI, May 2002

Archeops 2002

ACBAR, December 2002

(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....)

WHATNEXT???

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s???

10-43 secT~ 1019 GeV

10-36 secT~ 1016 GeV

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ng

??

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sym

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ng

??

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??

INFLATION

INFLATION

GEOMETRY SMOOTHNESS STRUCTUREFORMATION

What is Einfl?

STOCHASTIC GRAVITATIONAL-WAVE

BACKGROUND with amplitude µEinfl2

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)

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

Jaffe, Wang, MK 2000

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.

Kes

den,

Coo

ray,

MK

, PR

L 2

002

Possible solution: Use higher-order correlations in temperature map that measure stretching from cosmic shear as a function of position on sky

Hivon & MK, Science 296, 267 (2002)

Brief Aside: Large scale structure and inflation

ÛInflatonpotential

Matter powerspectrum

MK & Liddle, PRL 84, 4525 (2000)

Galactic substructuremay probe inflatonpotential nearend of inflation

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

III. Spin-dependentWIMPs in DAMA?

Ullio, MK, Vogel, JHEP 0107, 044 (2001)

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

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

Spin dependentWIMP-proton coupling

Spin dependentWIMP-neutron coupling

Ullio, MK, Vogel 2001

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

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".

One idea for dark energy: Quintessence, slowly-rolling

scalar field:V(f)

f

Pressure Energy density

w=p/r

SpintesseSpintessence! nce!

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?

Constraints to w (Wang et al. 2000):

"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.

What about w < -1?("phantom" energy)

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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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)

(More) Physics of "Phantom" Energy:

More possibilities:Braneworld models: (Sahni & Shtanov 2002)dS/CFT connections (McInnes 2002)

....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.

Summary: Particles/FieldsCosmology/AstrophysicsSpectacular recent advancesIntriguing ideasMore to come