Microlensing of Lensed Supernovae

Given the number of recently discovered galaxy-galaxy lens systems, we anticipate that a gravitationally lensed supernova will be observed within the next few years. We explore the possibility that stars in the lens galaxy will produce observable microlensing fluctuations in lensed supernova light curves. For typical parameters, we predict that ~70% of lensed SNe will show microlensing fluctuations > 0.5 mag, while ~25% will have fluctuations > 1 mag. Thus microlensing of lensed supernova will be both ubiquitous and observable. Additionally, we show that microlensing fluctuations will complicate measurements of time delays from multiply imaged supernovae: time delays accurate to better than a few days will be difficult to obtain. We also consider prospects for extracting the lens galaxy's stellar mass fraction and mass function from microlensing fluctuations via a new statistical measure, the time-weighted light curve derivative.Comment: 13 pages, emulateapj format; accepted in ApJ; expanded discussion of time delay uncertaintie

A Last Look at the Microwave Haze/Bubbles with WMAP

The microwave "haze" was first discovered with the initial release of the full sky data from the Wilkinson Microwave Anisotropy Probe. It is diffuse emission towards the center of our Galaxy with spectral behavior that makes it difficult to categorize as any of the previously known emission mechanisms at those wavelengths. With now seven years of WMAP data publicly available, we have learned much about the nature of the haze, and with the release of data from the Fermi Gamma-Ray Space Telescope and the discovery of the gamma-ray haze/bubbles, we have had a spectacular confirmation of its existence at other wavelengths. As the WMAP mission winds down and the Planck mission prepares to release data, I take a last look at what WMAP has to tell us about the origin of this unique Galactic feature. Much like the gamma-rays, the microwave haze/bubbles is elongated in latitude with respect to longitude by a factor of roughly two, and at high latitudes, the microwave emission cuts off sharply above ~35 degrees (compared to ~50 degrees in the gammas). The hard spectrum of electrons required to generate the microwave synchrotron is consistent with that required to generate the gamma-ray emission via inverse Compton scattering, though it is likely that these signals result from distinct regions of the spectrum (~10 GeV for the microwaves, ~1 TeV for the gammas). While there is no evidence for significant haze polarization in the 7-year WMAP data, I demonstrate explicitly that it is unlikely such a signal would be detectable above the noise.Comment: 9 pages, 6 figures; accepted in ApJ; matches published version with significantly enhanced figure

Identification of Spinning Dust in Halpha-Correlated Microwave Emission

CMB experiments commonly use maps of Halpha intensity as a spatial template for Galactic free-free emission, assuming a power law I_nu \propto nu^-0.15 for the spectrum. Any departure from the assumed free-free spectrum could have a detrimental effect on determination of the primary CMB anisotropy. We show that the Halpha-correlated emission spectrum in the diffuse warm ionized medium (WIM) is not the expected free-free spectrum at WMAP frequencies. Instead, there is a broad bump in the spectrum at ~50 GHz which is consistent with emission from spinning dust grains. Spectra from both the full sky and smaller regions of interest are well fit by a superposition of a free-free and WIM Draine & Lazarian (1998) spinning dust model, shifted in frequency. The spinning dust emission is ~5 times weaker than the free-free component at 50 GHz, with the null hypothesis that the Halpha-correlated spectrum is pure free-free, ruled out at >8 sigma in all regions and >100 sigma for the full sky fit.Comment: 8 pages, 5 figures; submitted to ApJ; LaTeX modified slightly to reveal missing Figure

Evidence Of Dark Matter Annihilations In The WMAP Haze

The WMAP experiment has revealed an excess of microwave emission from the region around the center of our Galaxy. It has been suggested that this signal, known as the ``WMAP Haze'', could be synchrotron emission from relativistic electrons and positrons generated in dark matter annihilations. In this letter, we revisit this possibility. We find that the angular distribution of the WMAP Haze matches the prediction for dark matter annihilations with a cusped density profile, $\rho(r) \propto r^{-1.2}$ in the inner kiloparsecs. Comparing the intensity in different WMAP frequency bands, we find that a wide range of possible WIMP annihilation modes are consistent with the spectrum of the haze for a WIMP with a mass in the 100 GeV to multi-TeV range. Most interestingly, we find that to generate the observed intensity of the haze, the dark matter annihilation cross section is required to be approximately equal to the value needed for a thermal relic, $\sigma v \sim 3 \times 10^{-26}$ cm$^3$/s. No boost factors are required. If dark matter annihilations are in fact responsible for the WMAP Haze, and the slope of the halo profile continues into the inner Galaxy, GLAST is expected to detect gamma rays from the dark matter annihilations in the Galactic Center if the WIMP mass is less than several hundred GeV.Comment: 4 pages, 3 figure

Prospects For Detecting Dark Matter With GLAST In Light Of The WMAP Haze

Observations by the WMAP experiment have identified an excess of microwave emission from the center of the Milky Way. It has previously been shown that this "WMAP Haze" could be synchrotron emission from relativistic electrons and positrons produced in the annihilations of dark matter particles. In particular, the intensity, spectrum and angular distribution of the WMAP Haze is consistent with an electroweak scale dark matter particle (such as a supersymmetric neutralino or Kaluza-Klein dark matter in models with universal extra dimensions) annihilating with a cross section on the order of sigma v~3x10^-26 cm^3/s and distributed with a cusped halo profile. No further exotic astrophysical or annihilation boost factors are required. If dark matter annihilations are in fact responsible for the observed Haze, then other annihilation products will also be produced, including gamma rays. In this article, we study the prospects for the GLAST satellite to detect gamma rays from dark matter annihilations in the Galactic Center region in this scenario. We find that by studying only the inner 0.1 degrees around the Galactic Center, GLAST will be able to detect dark matter annihilating to heavy quarks or gauge bosons over astrophysical backgrounds with 5sigma (3sigma) significance if they are lighter than approximately 320-500 GeV (500-750 GeV). If the angular window is broadened to study the dark matter halo profile's angular extension (while simultaneously reducing the astrophysical backgrounds), WIMPs as heavy as several TeV can be identified by GLAST with high significance. Only if the dark matter particles annihilate mostly to electrons or muons will GLAST be unable to identify the gamma ray spectrum associated with the WMAP Haze.Comment: 10 pages, 6 figure

The Case for a 700+ GeV WIMP: Cosmic Ray Spectra from PAMELA, Fermi and ATIC

Multiple lines of evidence indicate an anomalous injection of high-energy e+- in the Galactic halo. The recent $e^+$ fraction spectrum from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) shows a sharp rise up to 100 GeV. The Fermi Gamma-ray Space Telescope has found a significant hardening of the e+e- cosmic ray spectrum above 100 GeV, with a break, confirmed by HESS at around 1 TeV. The Advanced Thin Ionization Calorimeter (ATIC) has also detected detected a similar excess, falling back to the expected spectrum at 1 TeV and above. Excess microwaves towards the galactic center in the WMAP data are consistent with hard synchrotron radiation from a population of 10-100 GeV e+- (the WMAP ``Haze''). We argue that dark matter annihilations can provide a consistent explanation of all of these data, focusing on dominantly leptonic modes, either directly or through a new light boson. Normalizing the signal to the highest energy evidence (Fermi and HESS), we find that similar cross sections provide good fits to PAMELA and the Haze, and that both the required cross section and annihilation modes are achievable in models with Sommerfeld-enhanced annihilation. These models naturally predict significant production of gamma rays in the galactic center via a variety of mechanisms. Most notably, there is a robust inverse-Compton scattered (ICS) gamma-ray signal arising from the energetic electrons and positrons, detectable at Fermi/GLAST energies, which should provide smoking gun evidence for this production.Comment: 28 pages; v2 plots corrected, references added; v3 included Fermi electron data at reviewer request, references adde