Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Dark Matter Search with the MAGIC Telescope: Analysis of the Unidentified EGRET Source 3EG J1835+5918 Candidato: Fabio Zandanel Relatore: Prof. Mosè Mariotti Correlatore: Dott. Michele Doro Summary The Dark Matter paradigm ● Detection of gamma rays from ground ● Data Analysis ● 3EG J1835+5918 Analysis ● Discussion ● 2 Universe content: Dark Matter Universe content: only about 4% is accounted of baryonic matter ~4% dark baryons ~0.4% luminous matter about 23% of the Universe energy matter density is accounted of nonbaryonic collisionless and dissipationfree (i.e. cold) dark matter ~73% dark energy 3 Universe content: Dark Matter Universe content: only about 4% is accounted of baryonic matter ~4% dark baryons ~0.4% luminous matter about 23% of the Universe energy matter density is accounted of nonbaryonic collisionless and dissipationfree (i.e. cold) dark matter Evidences for the dark matter existence: ~73% dark energy CMB anisotropies galaxies rotational curves “bullet” clustering 4 Universe content: Dark Matter Universe content: only about 4% is accounted of baryonic matter ~4% dark baryons ~0.4% luminous matter about 23% of the Universe energy matter density is accounted of nonbaryonic collisionless and dissipationfree (i.e. cold) dark matter Evidences for the dark matter existence: CMB anisotropies galaxies rotational curves “bullet” clustering ~73% dark energy two possible DM candidates: supersymmetric neutralino KaluzaKlein particle 5 Gamma rays from DM annihilation In many scenarios direct annihilation in two photons is severely suppressed, but a continuum gamma spectrum is expected from the decay of secondary neutral pions gamma rays flux from DM annihilation: E∝∫ 2 x dV 6 Gamma rays from DM annihilation In many scenarios direct annihilation in two photons is severely suppressed, but a continuum gamma spectrum is expected from the decay of secondary neutral pions gamma rays flux from DM annihilation: E∝∫ 2 x dV a detectable gamma rays flux is expected from regions where strong enhancements in the DM density are present, i.e. where strong gravitational field are present 7 Gamma rays from DM annihilation In many scenarios direct annihilation in two photons is severely suppressed, but a continuum gamma spectrum is expected from the decay of secondary neutral pions gamma rays flux from DM annihilation: E∝∫ 2 x dV a detectable gamma rays flux is expected from regions where strong enhancements in the DM density are present, i.e. where strong gravitational field are present Galactic Center Dwarf Spheroidal Intermediate Mass BlackHoles 8 The IMBHs Scenario Bertone, Zentner, Silk Phys.Rew.D 2005 “A New Signature of Dark Matter Annihilations: GammaRays from IntermediateMass Black Holes” During the evolution of halos, intermediate mass black holes formed at high redshift are found not to suffer merging and to grow adiabatically A number of them (1001000) can be remained wandering undisturbed in the Galactic Halo Onto them, DM could have had the time to accrete and produce very peaked distribution (“minispike”) The large density implies a large annihilation rate: they could be very bright gamma sources 9 Gamma rays flux from minispikes gamma spectrum prefactor dependence of per annihilation mass and particle physics radial profile central core 10 Gamma rays flux from minispikes gamma spectrum prefactor dependence of per annihilation mass and particle physics power low spectrum spectral index 1.5 exponential cutoff radial profile central core The flux final dependence from the particle physics parameters is: 2/ 7 −9/ 7 v m 11 Gamma rays flux from minispikes gamma spectrum prefactor dependence of per annihilation mass and particle physics power low spectrum spectral index 1.5 exponential cutoff radial profile central core The flux final dependence from the particle physics parameters is: 2/ 7 −9/ 7 v m Advantages with respect to other scenarios: IMBHs position: less background IMBHs do not suffer merging that could destroy the DM spike small dependence from particle physics parameters 12 Unidentified EGRET Sources After 10 years, still ~100 EGRET sources are unidentified Normal to search for IMBHs in Unidentified EGRET Sources Selection can be performed: – steady emission – spectral index compatible with 1.5 – high galactic latitude Different sources should have: same spectra same spectral index same cutoff at DM mass If observed, they would constitute a smoking gun signature for DM 13 Summary The Dark Matter paradigm ● Detection of gamma rays from ground ● Data Analysis ● 3EG J1835+5918 Analysis ● Discussion ● 14 Observation Technique Spaceborne experiments detect directly gamma rays gamma ray photons are only about 0.1% of the cosmic rays Ch er en Groundbased telescopes detect the Cherenkov light produced by air showers ko vl i gh t electromagnetic air shower ~ 1o ~ 10 km background hadronic showers ~ 120 m 15 Observation Technique Spaceborne experiments detect directly gamma rays gamma ray Ch er en Groundbased telescopes detect the Cherenkov light produced by air showers ko vl i gh t electromagnetic air shower ~ 1o ~ 10 km EGRET telescope supported by the CGRO satellite ~ 120 m 16 Observation Technique Groundbased telescopes detect the Cherenkov light produced by air showers gamma ray Ch er en Imaging Atmospheric Cherenkov Telescopes ko vl i gh t electromagnetic air shower ~ 120 m ~ 1o ~ 10 km Cherenkov photons focused on a pixelled camera typically elliptic images images analysis 17 Observation Technique Groundbased telescopes detect the Cherenkov light produced by air showers gamma ray Ch er en Imaging Atmospheric Cherenkov Telescopes ko vl i gh t electromagnetic air shower ~ 120 m ~ 1o ~ 10 km Image parametrization Hillas/Image parameters intensity orientation shape 18 The MAGIC Telescope La Palma (2225 m a.s.l.) Major Atmospheric Gammaray Imaging Cherenkov field of view: 3.5° angular resolution: 0.1° energy range: 60 GeV – 10 TeV energy resolution: 20 – 30% flux sensitivity: 2% Crab flux ~ 1o fast repositioning (< 40 sec) 17 m parabolic reflector multilevel trigger Largest singledish 577 PMTs camera 2 GHz MuX FADC Lowest energy threshold 19 Summary The Dark Matter paradigm ● Detection of gamma rays from ground ● Data Analysis ● 3EG J1835+5918 Analysis ● Discussion ● 20 Analysis Chain ON data OFF data Monte Carlo data Calibration: Data Sample reduction Signal detection Source Position reconstruction Flux/Upper Limits calculation charge number of photons Image “cleaning”: Hillas/Image parameters calculation: image Hillas parametrization parameters 21 Analysis Chain ON data OFF data Monte Carlo data Data Sample reduction Signal detection Source Position reconstruction Flux/Upper Limits calculation Background Rejection: gammahadron separation gamma hadrons Random Forest For each event a global parameter Hadronness: real number spanning from 0 to 1 0 gammalike event 1 hadronlike event Hadronness cut: rejection hadronlike events 22 Analysis Chain ON data OFF data Monte Carlo data Data Sample reduction Signal detection Source Position reconstruction Flux/Upper Limits calculation Alpha distribution: Hadronness cut Excess events gamma events are characterized by small Alpha values Background events hadronic events have a random Alpha distribution 23 Analysis Chain ON data OFF data Monte Carlo data Data Sample reduction Signal detection Source Position reconstruction Flux/Upper Limits calculation Alpha distribution: Hadronness cut Excess events gamma events are characterized by small Alpha values Background events hadronic events have a random Alpha distribution 24 Analysis Chain ON data OFF data Monte Carlo data Data Sample reduction Signal detection Source Position reconstruction Flux/Upper Limits calculation Alpha distribution: Hadronness cut a source is detected if the signal significance is greater then 5 25 Analysis Chain ON data OFF data Monte Carlo data Data Sample reduction Signal detection Source Position reconstruction Flux/Upper Limits calculation Source Position Reconstruction: bidimensional plot of the most probable source position in the sky If the source was correctly pointed, the excesses must be in the pointed position 26 Analysis Chain ON data OFF data Monte Carlo data SIGNAL NO SIGNAL Data Sample reduction Signal detection Source Position reconstruction Flux/Upper Limits calculation Differential Flux = F E Flux Upper Limit N E N E = excess events A eff T eff Teff = effective time N E min , E max 95 % f 0 〈 A eff E min , E max , 〉 T eff Aeff = effective area N95%: number of observable events (95% confidence level) 27 Summary The Dark Matter paradigm ● Detection of gamma rays from ground ● Data Analysis ● 3EG J1835+5918 Analysis ● Discussion ● 28 The source: 3EG J1835+5918 3EG J1835 was selected within the Unidentified EGRET Sources: no explanation for its emission “observed” in Xray but no association If there is a mini spike signal, it would become wellvisible within 30 hours of observation 29 3EG J1835+5918 Data Sample Observation Period: 22/06/2006 – 03/07/2006 Data Sample: 31.5 hours ON data 26 hours ON 5.5 hours OFF data 5.5 hours OFF exclusion of ~5 hours of ON data due to a mispointing (technical problem) Unfortunately operating conditions: ~5 hours of ON data lost few OFF hours bad background estimation technical trigger problem sensitivity loss 30 3EG J1835+5918 Data Sample Observation Period: 22/06/2006 – 03/07/2006 Data Sample: 31.5 hours ON data 26 hours ON 5.5 hours OFF data 5.5 hours OFF exclusion of ~5 hours of ON data due to a mispointing (technical problem) Unfortunately operating conditions: ~5 hours of ON data lost few OFF hours technical trigger problem the chips connecting the trigger levels convert the signal from 8 pixels 31 3EG J1835+5918 Data Sample Observation Period: 22/06/2006 – 03/07/2006 Data Sample: 31.5 hours ON data 26 hours ON 5.5 hours OFF data 5.5 hours OFF exclusion of ~5 hours of ON data due to a mispointing (technical problem) Unfortunately operating conditions: ~5 hours of ON data lost few OFF hours technical trigger problem the chips connecting the trigger levels convert the signal from 8 pixels overheating problem some chips burnt trigger region lost inhomogeneous events distribution 32 3EG J1835+5918 Data Inhomogeneity Center of Gravity events distribution distribution Expected: symmetric for rotations around the camera center and almost flat Expected: flat distribution 120300 GeV 33 3EG J1835+5918 Data Inhomogeneity Center of Gravity events distribution distribution Expected: symmetric for rotations around the camera center and almost flat Expected: flat distribution 120300 GeV 34 3EG J1835+5918 Data Inhomogeneity Center of Gravity events distribution distribution Expected: flat distribution Expected: symmetric for rotations around the camera center and almost flat the effect is less visible at higher energies 300700 GeV 35 3EG J1835+5918 Data Inhomogeneity The action was to take out the camera regions affected by the chipsburnt problem 30% camera lost 180°< <240° & 280°< <325° 36 Test Analysis on Crab Nebula Crab Nebula data sample: 2.5 hours ON data (04/01/2005) 2.7 hours OFF data (08/01/2005) taking in good operating conditions In order to test how a 30% of camera lost can affect the analysis two independent analysis normal Crab cut Crab: on which was applied the cut cut 37 Test Analysis on Crab Nebula Crab Nebula data sample: 2.5 hours ON data (04/01/2005) 2.7 hours OFF data (08/01/2005) taking in good operating conditions In order to test how a 30% of camera lost can affect the analysis two independent analysis normal Crab cut Crab: on which was applied the cut cut 38 Test Analysis on Crab Nebula Crab Nebula data sample: 2.5 hours ON data (04/01/2005) 2.7 hours OFF data (08/01/2005) taking in good operating conditions In order to test how a 30% of camera lost can affect the analysis two independent analysis normal Crab cut Crab: on which was applied the cut cut 39 Test Analysis on Crab Nebula Crab Nebula data sample: 2.5 hours ON data (04/01/2005) 2.7 hours OFF data (08/01/2005) taking in good operating conditions In order to test how a 30% of camera lost can affect the analysis two independent analysis normal Crab cut Crab: on which was applied the cut ~30% of excess events lost correct source position reconstruction correct flux estimation an analysis is possible according to these conclusions 40 Signal Detection No signal detection the significances were never greater then ~2 3EG J1835+5918 has not been observed with significant detection above 120 GeV 41 Source Position Reconstruction The source position reconstruction showed initially an astonishing result: above 300 GeV the “skyanalysis” showed an empty sky between 120 and 300 GeV, excesses offcenter were found [120300 GeV] excesses significances significances 42 Source Position Reconstruction The source position reconstruction showed initially an astonishing result: above 300 GeV the “skyanalysis” showed an empty sky between 120 and 300 GeV, excesses offcenter were found Crab Nebula Example [300700 GeV] excesses significances significances 43 Source Position Reconstruction The source position reconstruction showed initially an astonishing result: above 300 GeV the “skyanalysis” showed an empty sky between 120 and 300 GeV, excesses offcenter were found Sky Map [120300 GeV]: serendipity discovery? wrong EGRET source position? “fake source”? Image parameters recalculation with respect to the excesses position: no signal detection, significances never greater than ~1 , probably the analysis at these energies are dominated by systematic errors How it is possible? 44 Why a Fake Source? Great inhomogeneities could create fake sources: the 3EG J1835+5918 data sample have inhomogeneity problems at low energies these problems are very strong at energies above 300 GeV, the inhomogeneities are almost negligible 120300 GeV: very strong inhomogeneities in addition of the camera regions lost 45 Upper Limits Calculation Upper Limits on the 3EG J1835+5918 emission: f 0 [ 181 GeV ] =2.9∗10−10 ph cm−2 s −1 TeV −1 ⇒ 0.129 C.U. f 0 [ 403GeV ] =3.3∗10−12 ph cm−2 s−1 TeV −1 ⇒ 0.012 C.U. f 0 [ 1196 GeV ]=2.5∗10 −13 −2 ph cm s −3 f0 is given in “Crab Unit”: 1C.U.=1.5∗10 −1 E GeV TeV −2.58 −1 ⇒0.014 C.U. very high “good” ph cm−2 s −1 TeV −1 “the signal is below f0” “the signal presence above f0 probability is of 5%” “if there were a signal above f0, a detection would be possible” 46 Upper Limits Calculation Upper Limits on the 3EG J1835+5918 emission: −10 −2 −1 −1 f 0 [ 181 GeV ] =2.9∗10 ph cm s TeV ⇒ 0.129 C.U. −12 −2 −1 −1 f 0 [ 403GeV ] =3.3∗10 ph cm s TeV ⇒ 0.012 C.U. f 0 [ 1196 GeV ]=2.5∗10 −13 −2 ph cm s −1 TeV −1 ⇒0.014 C.U. very high “good” It is possible to set an upper limit on the dark matter mass 47 “DM Mass Upper Limit” Supposing the 3EG J1835 to be an IMBH: mDM< 800 GeV only a speculative result! 48 Summary The Dark Matter paradigm ● Detection of gamma rays from ground ● Data Analysis ● 3EG J1835+5918 Analysis ● Discussion ● 49 Discussion No signal detection was reached A fake signal was found at low energies [120300 GeV] due to the strong inhomogeneities, but: Important: as the inhomogeneities could be able to create a fake signal, they could also be able to board a true source with a faint signal!!! 3EG J1835+5918 was not observed, but in the energy range 120300 GeV this could be due to data peculiarities and another observation of this source is desirable! 50 Conclusions The 3EG J1835+5918 was not detected, but at energies below 300 GeV this could be do to data peculiarities software improvements: there is the necessity of a “skyanalysis” code that must be able to avoid fake results due to inhomogeneities another observation of the 3EG J1835+5918 is necessary other Unidentified EGRET Sources are good IMBH candidates waiting next generation spaceborn experiments results (AGILE, GLAST) waiting MAGIC II... 51 Outlook: the MAGIC TelescopeS MAGIC II a clone of the first telescope at 85 m of distance ~ 1o MAGIC II will be operating in early 2008 Stereoscopic view time coincidence constraints between two instruments lowering of the energy threshold (~30 GeV) increase in sensitivity of a factor 2 52 53 Gammas from DM Annihilation 0 Z gamma lines supersymmetric neutralino: f f bb continuum gammas from hadronization: 0 B 1 B 1 gamma lines KaluzaKlein particle: + B 1 B 1 l l and secondary gammas via cascading decays of final states and qq semihadronic decays of leptons gamma lines are severely suppressed or give a very low flux! 54 Gamma Spectrum per annihilation It is necessary to specify the gamma spectrum per annihilation dN/dE G.Bertone, A.R.Zentner & J.Silk, Phys.Rev. D72 (2005) 103517 55 IMBHs Main evidence for their existence Ultra Luminous Xray objects Two scenarios: remnants of Population collapse of primordial gas III or “first” stars in earlyforming halos gammas from mini spikes 56 Atmospheric Showers Electromagnetic Showers Hadronic Showers 57 Atmospheric Showers Electromagnetic Showers Hadronic Showers 58 Cherenkov Effect 1 cos= n 59 Cherenkov Radiation 60 IACT Technique Basic Idea: observe gamma rays studying the images formed on the telescope camera from the Cherenkov flashes (coming from air showers) when focused on a plane IACTs transform the arrival directions of Cherenkov photons in points that form a shower image on the focal (camera) plane Photons coming from the perpendicular direction with respect to the telescope plane are focused on the camera center Photons incident with an angle are focused on a distance ∝ 61 Detection Technique IACT (Imaging Atmospheric Cherenkov Telescopes) imaging Cherenkov technique Cherenkov photons ~ 1o image on telescope camera typical elliptic shape 62 Detection Technique IACT (Imaging Atmospheric Cherenkov Telescopes) imaging Cherenkov technique Cherenkov photons head ~ 1o image on telescope camera typical elliptic shape 63 Detection Technique IACT (Imaging Atmospheric Cherenkov Telescopes) imaging Cherenkov technique Cherenkov photons head ~ 1o tail image on telescope camera typical elliptic shape 64 Detection Technique IACT (Imaging Atmospheric Cherenkov Telescopes) imaging Cherenkov technique images analysis ~ 1o Intensity: primary particle energy 65 Detection Technique IACT (Imaging Atmospheric Cherenkov Telescopes) imaging Cherenkov technique gamma event images analysis image points toward the camera center ~ 1o Intensity: primary particle energy random events direction hadronic event Orientation: incoming direction 66 Detection Technique IACT (Imaging Atmospheric Cherenkov Telescopes) imaging Cherenkov technique gamma event images analysis elliptic shape very compact ~ 1o Intensity: primary particle energy Orientation: incoming direction roundish shape fragmentation hadronic event Shape: primary particle nature 67 Image Parameters images analysis images Hillas (1985) parametrization parameters image moments ~ 1o Main Image Parameters: Alpha: angle between major axis and the center of gravitycamera center direction Size: total number of collected photons 68 False Source Plot False Source Method: camera divided in N*N region for each region the image parameters are recalculated with respect to the center of the respective bin an Alpha plot is then obtained results plotted in a bidimensional plot 69 Source Position Reconstruction Skymap bidimensional plot of the most probable source position in the sky The Disp method: Disp: distance between the image center and the unknown source position (along the major axis) Source Position Reconstruction Skymap bidimensional plot of the most probable source position in the sky The Disp method: Disp: distance between the image center and the unknown source position (along the major axis) two possible solution Source Position Reconstruction Skymap bidimensional plot of the most probable source position in the sky The Disp method: Disp: distance between the image center and the unknown source position (along the major axis) two possible solution headtail discriminator Source Position Reconstruction Skymap bidimensional plot of the most probable source position in the sky The Disp method: Disp: distance between the image center and the unknown source position (along the major axis) two possible solution headtail discriminator Skymap and False Source Plot Skymap 120300 GeV False Source Plot 74 Skymap and False Source Plot Skymap 300700 GeV False Source Plot 75