Limits on Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

ORAL

Abstract

We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) of Arkani-Hamed, Dimopoulos, and Dvali. We use 11-months of Fermi-LAT data to set $\gamma$-ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED, we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein graviton ($G_{KK}$) production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The decays $G_{KK}\to\gamma\gamma$ should contribute to the flux from NSs. For $n=2,3,...,7$ LED of the same size in the context of the HR model, we use MC techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our MC differential flux to the experimental differential flux using maximum likelihood techniques, and obtain limits on LED that are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than collider limits for 3 or fewer LED. If the effective Planck scale is around a TeV, then with $n=2,3$, the LED topology is non-toroidal.

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Authors

  • Bijan Berenji

    SLAC National Accelerator Laboratory/Stanford University/KIPAC

  • G.V. Brown

    Department of Physics at CSU, Fresno, Lawrence Livermore National Laboratory, Stanford University, Advanced Light Source, Lawrence Berkeley National Lab, Nanoelectronics Research Institute, Japan Atomic Energy Agency, University of Tokyo, Cornell University, Tokyo Institute of Technology, Suranaree University of Technology, Shandong University, Stanford Synchrotron Radiation Lightsource, UC Davis, CSU Dominguez Hills, Thomas Jefferson National Accelerator Facility, UC Berkeley, ANL, UChicago/ANL, UManitoba, Northwestern U/ANL, LLNL, UCB/LLNL, McGill U, McGill U/ANL, University of Nevada, Reno, Hitachi Global Storage Technology, Advanced Light Source, Stanford Synchrotron Radiation Laboratory, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Materials Science and Engineering, Stanford University, Radiation Oncology, Stanford University School of Medicine, Missouri University of Science and Technology, International Institute of Physics, University of Missouri, University of Notre Dame du Lac, Department of Physics, California State University, Fresno, California, California State University Long Beach, BNL, IWF Dresden, Department of Physics, University of California, Davis, CA 95616, USA, University of California, Merced, Laboratoire Univers et Particules de Montpellier, IN2P3 (France), SLAC National Accelerator Laboratory/Stanford University/KIPAC, University of Perugia, University of Washington, CEA/Saclay, UNR, UNM, UCSD, RAL, ILE, MIT, LANL, LLE, NRL, SLAC National Accelerator Laboratory, Technische Universitaet Berlin, Max Born Institut, Hiroshima University, Western Michigan University, MPIK

  • G.V. Brown

    Department of Physics at CSU, Fresno, Lawrence Livermore National Laboratory, Stanford University, Advanced Light Source, Lawrence Berkeley National Lab, Nanoelectronics Research Institute, Japan Atomic Energy Agency, University of Tokyo, Cornell University, Tokyo Institute of Technology, Suranaree University of Technology, Shandong University, Stanford Synchrotron Radiation Lightsource, UC Davis, CSU Dominguez Hills, Thomas Jefferson National Accelerator Facility, UC Berkeley, ANL, UChicago/ANL, UManitoba, Northwestern U/ANL, LLNL, UCB/LLNL, McGill U, McGill U/ANL, University of Nevada, Reno, Hitachi Global Storage Technology, Advanced Light Source, Stanford Synchrotron Radiation Laboratory, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Materials Science and Engineering, Stanford University, Radiation Oncology, Stanford University School of Medicine, Missouri University of Science and Technology, International Institute of Physics, University of Missouri, University of Notre Dame du Lac, Department of Physics, California State University, Fresno, California, California State University Long Beach, BNL, IWF Dresden, Department of Physics, University of California, Davis, CA 95616, USA, University of California, Merced, Laboratoire Univers et Particules de Montpellier, IN2P3 (France), SLAC National Accelerator Laboratory/Stanford University/KIPAC, University of Perugia, University of Washington, CEA/Saclay, UNR, UNM, UCSD, RAL, ILE, MIT, LANL, LLE, NRL, SLAC National Accelerator Laboratory, Technische Universitaet Berlin, Max Born Institut, Hiroshima University, Western Michigan University, MPIK