Observation of Pulsars and Plerions with MAGIC The Crab Nebula in X-rays (Chandra) Nepomuk Otte for the MAGIC collaboration

Outline the pulsar wind complex pulsar pulsar wind nebula the MAGIC telescope Observations: Crab / PSR B1951+32 Conclusions Max-Planck-Institut für Physik / Humboldt Universität Berlin

The Pulsar Wind Nebula Complex magnetized, spinning neutron star powerful source of energy particle acceleration in: magnetosphere shock front pulsar powerful source of energy VHE gamma-rays expected from various sites up to now only the nebula detected in VHE gamma rays (at least that is what people believe) one ofter the other relativistic particles emit VHE-γ-rays γ-rays are messengers of non-thermal processes Max-Planck-Institut für Physik / Humboldt Universität Berlin

Gamma-Ray Emission from the Pulsar Crab pulsar in optical three different sites favored for particle acceleration emission appears pulsed lighthouse model Max-Planck-Institut für Physik / Humboldt Universität Berlin

Pulsar: Broadband Emission MAGIC spectroscopy >10GeV needed strong cutoff exponential or even stronger Thompson et al. 1999 HE-emission processes synchrotron radiation curvature radiation inverse Compton scattering no pulsar detected above ~100GeV Max-Planck-Institut für Physik / Humboldt Universität Berlin

The Pulsar Wind Nebula Complex shock front acceleration up to 1016 eV synchrotron emission inverse Compton scattering SSC model electrons stream out in uniform flow from the pulsar accelerated at standig reverse shock, randomized in pitch angle cooled by synchrotron radiation VHE-gamma rays due to IC scattering of thermal photons or synchrotron photons. Max-Planck-Institut für Physik / Humboldt Universität Berlin

PWN: Broadband Emission MAGIC Synchrotron Spectrum well described in MHD model calculations Above 1GeV inverse Compton scattering dominates observational gap between 10GeV and ~400GeV Aharonian & Atoyan (1998) Max-Planck-Institut für Physik / Humboldt Universität Berlin

Crab and PSR B1951+32 Pulsar Crab PSR B1951+32 Age ~103 yrs ~105 yrs Energy loss rate 1038 erg sec-1 4x1036 erg sec-1 Maximum detected energy ~10 GeV ~20 GeV Spectral shape ~2.2 ~1.8 Indication of cutoff yes no pulsar space velocity 140±8 km sec-1 240±40 km sec-1 PWN in Gamma rays detected not detected Pulsar young vs. middle aged similar gamma ray luminosities at 10GeV no cutoff in prs1951  prime candidate for observation pwn should be detectable with MAGIC according to predictions but first for the pulsar case Max-Planck-Institut für Physik / Humboldt Universität Berlin

The MAGIC Telescope largest Air Cherenkov Telescope lowest energy threshold ~50GeV highest sensitivity >200GeV ~2% Crab in 50 hours γ-PSF ~ 0.1° energy resolution: ~30% at 100 GeV ~20% > 300 GeV Max-Planck-Institut für Physik / Humboldt Universität Berlin

Crab Pulsar preliminary ~65 GeV no pulsed emission detected cutoff <30 GeV Max-Planck-Institut für Physik / Humboldt Universität Berlin

PSR B1951+32 Pulsar no pulsed emission detected strong constrain on the cutoff energy <30GeV constrain predicted IC at TeV previous observations compare note for experts; polar cap more favorable than outer gap predicted IC flux higher than in Crab not detectedunfavorable magnetic field configuration at the light cylinder überleitung auf nebel Max-Planck-Institut für Physik / Humboldt Universität Berlin

The Crab Nebula preliminary gamma-ray emission detected over two decades of energy 60 GeV – 9 TeV preliminary power-law behavior disfavored Max-Planck-Institut für Physik / Humboldt Universität Berlin

Crab Nebula: Broad Band Emisision good agreement with other experiments >400GeV data well described in SSC framework just above the expected IC-peak preliminary Spectral energy density Max-Planck-Institut für Physik / Humboldt Universität Berlin

Crab Nebula: Change of Photon Index clear change of photon index with energy nicely reproduced by model calculations preliminary Max-Planck-Institut für Physik / Humboldt Universität Berlin

Crab Nebula: Variability no variability detected on several time scales: minutes days months preliminary preliminary 10 minute binning flux steady within experimental resolution Max-Planck-Institut für Physik / Humboldt Universität Berlin

CTB80 / PSR B1951+32 no detection of gamma-ray emission Max-Planck-Institut für Physik / Humboldt Universität Berlin

CTB80 / PSR B1951+32 model calculation do not take pulsar motion into account emission smeared over a larger volume? magnetic field larger than assumed  wind not particle dominated? emission smeared  reduced sensitivity propto 1/sqrt(area) Max-Planck-Institut für Physik / Humboldt Universität Berlin

Conclusions no pulsed gamma-ray emission from Crab and PSR B1951+32 (a prime candidate to search for pulsed emission) need to lower the threshold below 50 GeV  MAGIC II / CTA, better photon detectors (see e.g. T 604.4) no steady emission from CTB80/PSR B1951+32 (< few %Crab) motion of pulsar has to be taken into account in models pulsar wind particle dominated (σ>1)? Crab nebula emission detected down to 60 GeV good agreement with SSC model no variability detected consistent with a point source Max-Planck-Institut für Physik / Humboldt Universität Berlin

80 GeV to 100 GeV (estimated energy) Max-Planck-Institut für Physik / Humboldt Universität Berlin

Crab Nebula: Morphology gamma-ray source is pointlike for MAGIC down to 100 GeV expect increasing source size with decreasing energy preliminary ~250 GeV emission: center of gravity upper limit on the emission region <2.3’ Max-Planck-Institut für Physik / Humboldt Universität Berlin