MeV Dark Matter With Couplings To Neutrinos
Download
1 / 18

Dan Hooper Particle Astrophysics Center Fermi National Accelerator Laboratory dhooper@fnal - PowerPoint PPT Presentation


  • 148 Views
  • Uploaded on

MeV Dark Matter With Couplings To Neutrinos. Dan Hooper Particle Astrophysics Center Fermi National Accelerator Laboratory dhooper@fnal.gov. 2007 Pheno Symposium University of Wisconsin, Madison. 511 keV Emission from the Galactic Bulge.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Dan Hooper Particle Astrophysics Center Fermi National Accelerator Laboratory dhooper@fnal' - lam


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

MeV Dark Matter With Couplings To Neutrinos

Dan Hooper

Particle Astrophysics Center

Fermi National Accelerator Laboratory

dhooper@fnal.gov

2007 Pheno Symposium

University of Wisconsin, Madison


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

511 keV Emission from the Galactic Bulge

  • INTEGRAL/SPI has observed bright 511 keV emission from the bulge (1.3 x 1043 positrons injected per second)

  • Gaussian, spherically symmetric morphology (FWHM of 8˚)

  • The source of these positrons remains unknown

Dan Hooper - MeV Dark Matter With Couplings to Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

511 keV Emission from the Galactic Bulge

  • Type Ia supernovae are unable to generate the observed injection rate (too few escape)

  • Hypernovae (type Ic SNe) or Gamma Ray Bursts could potentially generate enough positrons if high estimates for rates are considered

  • Even if the injection rate is sufficient, a mechanism is required to transport from disk to bulge - appears difficult

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

511 keV Emission and MeV Dark Matter

  • The INTEGRAL morphology matches well that which would be generated through the annihilation (or decay) of dark matter

  • 1-10 MeV dark matter particles annihilating to e+e- could simultaneously generate the measured dark matter relic abundance, and the observed 511 keV emission

Boehm, Hooper, Silk, Casse, Paul, PRL, astro-ph/0309686

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

511 keV Emission and MeV Dark Matter

  • The INTEGRAL morphology matches well that which would be generated through the annihilation (or decay) of dark matter

  • 1-10 MeV dark matter particles annihilating to e+e- could simultaneously generate the measured dark matter relic abundance, and the observed 511 keV emission

Boehm, Hooper, Silk, Casse, Paul, PRL, astro-ph/0309686

The Mega-tron

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

511 keV Emission and MeV Dark Matter

  • A simple scalar dark matter particle (), annihilating via the s-channel exchange of a new gauge boson (U)

  • Light mediator, lack of Z-coupling avoids stringent LEP (and other) constraints

e-

e+

Boehm, Hooper, Silk, Casse, Paul, PRL, astro-ph/0309686; Boehm and Fayet, Nucl. Phys. B, hep-ph/0305261

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

Coupling to Neutrinos?

  • The U-neutrino-neutrino coupling is not determined by astrophysical or other considerations in this scenario

  • Neutrino-electron scattering experiments place the most stringent constraints

  • If the U coupling to neutrinos is comparable to its coupling to electrons, dark matter-neutrino scattering can be significant

Hooper, M. Kaplinghat, K. Zurek, L. Strigari, astro-ph/0704.2558

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

Kinetic Decoupling

  • Neutrino-dark matter elastic scattering keeps the dark matter in kinetic equlibrium well after the number density freezes out

  • Setting equal to H, yields:

2

Hooper, M. Kaplinghat, K. Zurek, L. Strigari, astro-ph/0704.2558

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

Kinetic Decoupling

  • The kinetic decoupling temperature can be used to estimate the cutoff in the scale scale power spectrum

  • Which in our MeV-dark matter scenario yields:

Hooper, M. Kaplinghat, K. Zurek, L. Strigari, astro-ph/0704.2558

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

MeV Dark Matter and Small Scale Power

  • The matter power spectrum in these scenarios resembles somewhat that found for warm dark matter

m=1 MeV, Tkd=1 keV, 10 keV

Warm DM limit (Ly-)

Hooper, M. Kaplinghat, K. Zurek, L. Strigari, astro-ph/0704.2558

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

MeV Dark Matter & Small Scale Structure

Excluded by (g-2)e

  • If we assume a common coupling to electrons and neutrinos, we find that power is cutoff below 104-107 solar masses

  • For comparison, EW-scale WIMPs feature cutoffs typically around 10-3-10-8 solar masses

Excluded by e scattering

Relic Density OK

Hooper, M. Kaplinghat, K. Zurek, L. Strigari, astro-ph/0704.2558

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

MeV Dark Matter & Small Scale Structure

Excluded by (g-2)e

  • If we assume a common coupling to electrons and neutrinos, we find that power is cutoff below 104-107 solar masses

  • For comparison, EW-scale WIMPs feature cutoffs typically around 10-3-10-8 solar masses

  • After all constraints and issues are considered, suppression of structure below 105-107 solar masses is expected

Excluded by e scattering

Relic Density OK

Fine Tuned

Hooper, M. Kaplinghat, K. Zurek, L. Strigari, astro-ph/0704.2558

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

Missing Satellites?

Excluded by (g-2)e

  • In the upper range of these estimates, suppression could appear in the number of observed Milky Way Satellites (ie. dwarf galaxies)

  • Possible solution to the so-called “missing satellites problem”

Excluded by e scattering

Relic Density OK

Fine Tuned

Hooper, M. Kaplinghat, K. Zurek, L. Strigari, astro-ph/0704.2558

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

High Energy Neutrino Absorption

  • New boson leads to resonant neutrino interactions with the cosmic neutrino background at:

  • For SM Z-boson, this corresponds to E~1021 eV (“Z-burst”)

  • For mU~MeV, E~ TeV

  • Energy redshift broadens the very narrow resonance

  • For couplings larger than ~10-5, efficient absorption occurs over the range: ER/(1+z) < E < ER

Hooper, hep-ph/0701194;

See also Weiler, Palomerez-Ruis, (in preparation)

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

The Neutrinos Are Coming!

  • To date, no (confirmed) sources of high or ultra-high energy neutrinos have been discovered

  • This is likely to change soon

  • Experimental sensitivity is rapidly approaching that needed to detect the first extra-galactic sources of high energy neutrinos

IceCube

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

Extragalactic Sources of High Energy Neutrinos

  • Cosmic ray spectrum of protons/nuclei extends to ~1020 eV

  • pp, p interactions generate neutrinos from cosmic ray sources

  • The flux of neutrinos produced can be tied to the cosmic ray spectrum

  • “Waxman-Bahcall” Argument:

Fraction of proton energy to pions

Accounts for source evolution, etc. (~1)

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

High Energy Neutrino Absorption

  • Observing an absorption feature in the high energy neutrino spectrum will be challenging

  • Requires good neutrino energy resolution (+shower)

  • Large volume, high resolution (small PMT spacing) experiment

  • Realistic goal for future designs

(log E)~0.1,

E2 dN/dE~ 10-7 GeV/cm2 s (high z),

10 km3 yr exposure

Hooper, hep-ph/0701194

Dan Hooper - MeV Dark Matter With Couplings To Neutrinos


Dan hooper particle astrophysics center fermi national accelerator laboratory dhooper fnal

Conclusions

  • The predictions for small scale structure can be very different in MeV dark matter scenarios than for ordinary CDM WIMPs

  • Power below 104-107 solar masses is suppressed

  • Presents a possible solution to the missing satellites problem

  • Scenario can be tested by searching for ~TeV absorption lines in the cosmic neutrino spectrum