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Theoretical Cosmology and Particle Astrophysics at Caltech - Research Highlights and Funding Needs

Explore the latest research topics in theoretical cosmology and particle astrophysics at Caltech. Learn about dark matter, dark energy, inflation, and more. Discover how the program benefits from DoE funding and supports postdocs and students.

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Theoretical Cosmology and Particle Astrophysics at Caltech - Research Highlights and Funding Needs

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  1. Theoretical Cosmology and Particle Astrophysics at Caltech Marc Kamionkowski August 7, 2006

  2. Cosmology/ Û Particle/Nuclear Astrophysics Physics • Dark matter • Dark energy • Inflation • Neutrino astrophysics • Ultrahigh-energy cosmic rays • Baryogenesis

  3. Postdocs: Dan Babich (Moore prize scholar) Shin’ichiro Ando (Fairchild Fellow) Daisuke Nagai (Fairchild Fellow) Nicole Bell (Fairchild Fellow; just until January ‘07) Stefano Profumo (~60% Task B) Faculty: Marc Kamionkowski (Professor) Sean Carroll (Senior Research Associate [i.e., research professor]; Moore; are requesting DoE research funds for Sean) Andrew Benson (Senior Research Fellow [i.e., research asst prof]; Moore) Chris Hirata (assistant professor, arriving Fall 2007) People to be affiliated with Caltech theoretical cosmology and particle astrophysics 2006-2007

  4. Graduate Students: Jonathon Pritchard (5th year; DoE/NASA) Tristan Smith (4th year; TA) Anthony Pullen (3rd year; NSF Fellow) Adrienne Erickcek (3rd year; NSF Fellow) Dan Grin (3rd year; Moore Fellow) Martin Springer (3rd year; Oxford student with Benson) People to be affiliated with Caltech theoretical cosmology and particle astrophysics 2006-2007 • Visiting Associates: • Asantha Cooray (UC, Irvine) • Kris Gorski (JPL) • Elena Pierpaoli (USC) • Visitors: • Robert Caldwell (Dartmouth; 2 months; fall 2006) • Orfeu Bertolami (Lisbon; 6 months)

  5. Students: None graduating this year Postdocs/SRFs: Steven Furlanetto (assistant professor, Yale) Elena Pierpaoli (assistant professor, USC) Milos Milosavljevic (assistant professor, UT Austin) Nicole Bell (assistant professor, Adelaide) This past year’s graduates:

  6. Theory: Added Sean Carroll and Andrew Benson to research faculty (Moore). Chris Hirata will start as assistant professor fall 2007 Caltech is building in theoretical particle astrophysics: Recently funded (10-year grant) Moore Center for Theoretical Cosmology and Physics pays salaries for Benson, Carroll, two prize postdoctoral scholars, and some visitors

  7. Our recent (~year) research topics • Substructure in SUSY dark-matter halos • Tests of equivalence principle for dark matter • Probes of inflationary gravitational waves • New upper limit to gravitational-wave background • Galactic-halo merger rates • Search for dark-matter-annihilation radiation • Search for axion decay lines • Intergalactic medium • Supersymmetric dark matter • Neutrino astrophysics • The first stars and reionization ~100 refereed publications over past 5 years

  8. 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….

  9. 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 advanced students, when they are most productive

  10. 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) • 2004-2005; ~$140K/year • 2005-2006; ~$150K/year • Current request: continued funding at current level plus $50K/year supplement to provide research expenses for new faculty member (Sean Carroll) in theoretical particle astrophysics

  11. Journal articles completed over past 12 months under Task B ``Galilean Equivalence for Galactic Dark Matter,'' M. Kesden and M. Kamionkowski, astro-ph/0606566. ``Cosmological Bounds on Dark-Matter--Neutrino Interactions,'' G. Mangano, A. Melchiorri, P. Serra, A. Cooray, and M. Kamionkowski, astro-ph/0606190. ``21-cm fluctations from inhomogeneous x-ray heating before reionization,'' J. R. Pritchard and S. R. Furlanetto, astro-ph/0607234. ``The scattering of Lyman-Series Photons in the Intergalactic Medium,'' J. R. Pritchard and S. R. Furlanetto, astro-ph/0605680.

  12. ``Supermassive Black Hole Merger Rates: Uncertainties from Halo Merger Theory,'' A. L. Erickcek, M. Kamionkowski and A. J. Benson, astro-ph/0604281. To appear in MNRAS. ``Galaxy surveys, inhomogeneous reionization, and dark energy,'' J. R. Pritchard, S. R. Furlanetto and M.~Kamionkowski, ``A new cosmic microwave background constraint to primordial gravitational waves,'' T. L. Smith, E. Pierpaoli and M. Kamionkowski, Phys. Rev. Lett. 97, 021301 (2006). ``What mass are the smallest protohalos?'' S. Profumo, K. Sigurdson, and M. Kamionkowski, Phys. Rev. Lett. 97, 031301 (2006). ``Detecting dark matter WIMPs in the Draco dwarf: A multi-wavelength perspective,'' S. Colafrancesco, S. Profumo, P. Ullio, astro-ph/0607073.

  13. ``Mixed higgsino dark matter from a reduced SU(3) gaugino mass: Consequences for dark matter and collider searches,'' H. Baer, A. Mustafayev, E. K. Park, S. Profumo and X. Tata, JHEP 0604, 041 (2006). ``Baryogenesis, electric dipole moments and dark matter in the MSSM,'' V. Cirigliano, S. Profumo and M. J. Ramsey-Musolf, JHEP 0607, 002 (2006). ``Dark matter and the CACTUS gamma-ray excess from Draco,'' S. Profumo and M. Kamionkowski, JCAP 0603, 003 (2006). ``Cluster magnetic fields from large-scale-structure and galaxy-cluster shocks,'' M. V. Medvedev, L. O. Silva and M. Kamionkowski, Astrophys. J. 642, L1 (2006). ``Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization,'' M. McQuinn, O. Zahn, M. Zaldarriaga, L. Hernquist and S. R. Furlanetto, astro-ph/0512263. ``Have We Detected Patchy Reionization in Quasar Spectra?,'' A. Lidz, S. P. Oh and S. R. Furlanetto, Astrophys. J. 639, L47 (2006).

  14. ``Exploring the BWCA (Bino-Wino co-annihilation) scenario for neutralino dark matter,'' H. Baer, T. Krupovnickas, A. Mustafayev, E. K. Park, S. Profumo and X. Tata, arXiv:hep-ph/0511034. ``Low energy antideuterons: Shedding light on dark matter,'' H.~Baer and S.~Profumo, JCAP 0512, 008 (2005). ``The Evidence of Absence: Galaxy Voids in the Excursion Set Formalism,'' S. Furlanetto and T. Piran, MNRAS 366, 467 (2006). ``Cluster Merger Variance and the Luminosity Gap Statistic,'' M. Milosavljevic, C. J. Miller, S. R. Furlanetto and A. Cooray, Astrophys. J. 637, L9 (2006). ``Descending from on high: Lyman series cascades and spin-kinetic temperature coupling in the 21 cm line,'' J. R. Pritchard and S. R. Furlanetto, MNRAS 367, 1057 (2006).

  15. Big News: Sean Carroll joins Caltech faculty • Senior theorist with interests/expertise spanning string theory, particle theory, QFT, tests of Lorentz symmetry, general relativity, dark energy, and physical cosmology. • Has been DoE supported investigator at U Chicago (as asst prof). • Doubles Caltech faculty associated with Task B • Strengthens Caltech’s effort in exploring theoretical ideas for cosmic acceleration and dark energy • Enhances connection between cosmological phenomenology, particle theory, and string theory

  16. Some Recent Research

  17. New probe of primordial GWsSmith, Pierpaoli, MK, PRL 2006 “Conventional” way to probe them: 1) low-l plateau versus peaks 2) curl mode polarization New approach: Small-wavelength GWs behave as massless particles. They contribute to the energy density of the Universe and affect CMB fluctuationsand large-scale structure.

  18. New limits on gravitational-wave energy density at frequencies 10-16-10-11 Hz. At higher frequencies, constraints now comparable, and in future, stronger, than BBN , constraints Smith, Pierpaoli, MK (PRL 2006)

  19. Galilean equivalence for Galactic dark matterKesden and MK, 2006 • Does dark matter fall the same way in a gravitational field as ordinary matter? • Models that couple dark matter and dark energy may lead to additional 1/r2 force law that mimics a Newton’s constant G that is different for dark matter. • We thus consider force law for dark matter that is bigger by factor (1+2).

  20. Tidal Disruptions • Galaxies form hierarchically; smaller satellites are tidally disrupted in the haloes of larger hosts • Several stellar streams have been found in the MW, e.g. the Sgr dwarf at 24 kpc • disrupted stars retain similar orbits to satellite; trail/lead with gain/loss in energy

  21. Stellar Streams of Sgr Dwarf

  22. Tidal Streams Probe “Fifth” Force

  23. Conclusions • A coupling between dark matter and dark energy naturally leads to a “fifth” force that acts effectively as a violation of the equivalence principle for dark matter • Tidally disrupting galaxies provide perfect test; core is DM-dominated but not streams • Attractive DM-force sweeps core ahead; leading-to-trailing ratio suppressed. • Current data show roughly equally populated tidal streams; already suggests Newton constant for dark matter differs by no more than 10% from ordinary matter. • More detailed analysis of current data should be sensitive at the ~ 1% level

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