Astrophysics and dark matter signals

Transcription

1 Astrophysics and dark matter signals Lorenzo Ubaldi

2 Maybe the axion is the dark matter candidate? 16th European White Dwarfs Workshop Journal of Physics: Conference Series 172 (2009) IOP Publishing doi: / /172/1/ Axions and the white dwarf luminosity function JIsern 1,2,SCatalán 1,2, E García Berro 2,3 and S Torres 2,3 1 Institut de Ciències de l Espai (CSIC), Facultat de Ciències, Campus UAB, Bellaterra, Spain 3 Institut d Estudis Espacials de Catalunya (IEEC), c/ Gran Capità 2 4, Barcelona, Spain 3 Departament de Física Aplicada, Escola Politècnica Superior de Castelldefels, Universitat Politècnica de Catalunya, Avda. del Canal Olímpic s/n, Castelldefels, Spain isern@ieec.cat, catalan@ieec.cat, garcia@fa.upc.edu, santi@fa.upc.edu Abstract. The evolution of white dwarfs can be described as a simple cooling process. Recently, it has been possible to determine with an unprecedented precision their luminosity function, that is, the number of stars per unit volume and luminosity interval. Since the shape of the bright branch of this function is only sensitive to the average cooling rate, we use this property to check the possible existence of axions, a proposed but not yet detected weakly interacting particle. We show here that the inclusion of the axion emissivity in the evolutionary models of white dwarfs noticeably improves the agreement between the theoretical calculations and the observational white dwarf luminosity function, thus providing the first positive indication that axions could exist. Our results indicate that the best fit is obtained for m a cos 2 β 2 6 mev, where m a is the mass of the axion and cos 2 β is a free parameter, and that values larger than 10 mev are clearly excluded.

3 Axion Bounds and Searches [GeV] f a m a kev ev mev ev nev Experiments Tele scope CAST Direct searches ADMX (Seattle & Yale) Too much hot dark matter Globular clusters (a coupling) String DW Too much CDM Too much cold dark matter (misalignment) (re alignment with i = 1) Anthropic Range SN 1987A Too many events Too much energy loss Globular clusters (He ignition), WD cooling (a e coupling) Axions with mev range masses? Dark matter Cooling of white dwarfs, neutron stars Diffuse axion background from SN emission Georg Raffelt, MPI Physics, Munich BLV 2013, MPIK Heidelberg, 9 11 April 2013

4 IceCube: neutrinos as a dark matter probe

5 Joakim Edsjo WIMP Capture ρ χ χ χ velocity distribution Sun ν interactions ν oscillations ν µ Earth σ scatt Γ χχ ann b b t t τ τ + W W + Z 0 Z 0 σ ann ν α ν α Silk, Olive and Srednicki H 85 ± W ± Gaisser, Steigman & Tilav 86 H 0 i Z0 Γ capture = = ν α Pythia Detector µ Freese 86 Krauss, Srednicki & Wilczek 86 Gaisser, Steigman & Tilav 86

6 MSSM incl. XENON (2012) ATLAS + CMS (2012) DAMA no channeling (2008) CDMS (2010) CDMS 2keV reanalyzed (2011) CoGENT (2010) XENON100 (2012) ) 2 log10 ( σ SI,p / cm (τ τ IceCube 2012 (bb ) - IceCube 2012 (W W ) 2 for m χ <m W = 80.4GeV/c ) log10 ( m / GeV c ) χ IceCube collaboration ) MSSM incl. XENON (2012) ATLAS + CMS (2012) DAMA no channeling (2008) COUPP (2012) Simple (2011) PICASSO (2012) SUPER-K (2011) (bb ) + SUPER-K (2011) (W W - ) 2 / cm log10 ( σ SD,p IceCube 2012 (bb ) - IceCube 2012 (W W ) 2 (τ + τ - for m χ <m W = 80.4GeV/c ) log10 ( m / GeV c ) χ

7 Neutrinos at IceCube from Heavy Decaying Dark Matter arxiv: v2 [hep-ph] 14 Jun 2013 Brian Feldstein (a), Alexander Kusenko (a,b), Shigeki Matsumoto (a),andtsutomu T. Yanagida (a) (a) Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa, Chiba , Japan (b) Department of Physics and Astronomy, University of California, Los Angeles, CA , USA Abstract Amonochromaticlineinthecosmicneutrinospectrumwouldbeasmoking gun signature of dark matter. It is intriguing that the IceCube experiment has recently reported two PeV neutrino events with energies that maybeequal up to experimental uncertainties, and which have a probability of being a background fluctuation estimated to be less than a percent. Here we explore prospects for these events to be the first indication of a monochromatic line signal from dark matter. While measurable annihilation signatures would seem to be impossible at such energies, we discuss the dark matter quantum numbers, effective operators, and lifetimes which could lead to an appropriate signal from dark matter decays. We will show that the set of possible decay operators is rather constrained, and will focus on several viable candidates which could explain the IceCube events; R-parity violating gravitinos, hidden sector gauge bosons, and singlet fermions in an extra dimension. In essentially all cases we find that a PeV neutrino line signal from dark matter would be accompanied by a potentially observable continuum spectrumofneutrinos rising towards lower energies. Wild speculations?

8 The Pamela saga is not over, it continues with AMS!! Figure'3:'A'comparison'of'AMS'results'with'recent'published'measurements.''With'its'magnet'and'precision'particle'detectors,'high'accuracy'and'statistics,' the'first'result'of'ams,'based'on'only'~10%'of'the'total'data'expected,'is'clearly'distinguished'from'earlier'experiments'(see'references).'!

9 Is the positron excess due to dark matter, pulsars, or none of them? AMS02 results support the secondary origin of cosmic ray positrons Kfir Blum, 1, Boaz Katz, 1, 2, and Eli Waxman 3, 1 Institute for Advanced Study, Princeton 08540, USA 2 Bahcall Fellow 3 Dept. of Part. Phys. & Astrophys., Weizmann Institute of Science, POB 26, Rehovot, Israel We show that the recent AMS02 positron fraction measurement is consistent with a secondary origin for positrons, and does not require additional primary sources such as pulsars or dark matter. The measured positron fraction at high energy saturates the previously predicted upper bound for secondary production [1], obtained by neglecting radiative losses. This coincidence, which will be further tested by upcoming AMS02 data at higher energy, is a compelling indication for a secondary source. Within the secondary model the AMS02 data imply a cosmic ray propagation time in the Galaxy of < 10 6 yr and an average traversed interstellar matter density of 1cm 3,comparable to the density of the Milky Way gaseous disk, at a rigidity of 300 GV secondary upper bound PAMELA (2009) PAMELA (2011) AMS02 (2013) e + /e ± 10 1 B/C extrapolation E [GeV]

10 A gamma-ray line is a smoking-gun dark matter signature. How compelling is the 130 GeV line? Should Fermi change its survey strategy as recommended by Weniger et al. in ?

11 Would anyone believe a dark matter signal coming solely from astrophysics? What if two or more independent astrophysical measurements point to the same kind of dark matter, but there are no direct detection and no collider signatures? Would anyone take it seriously?