Supernova Remnants and Pulsar Wind Nebulae observed in TeV γ … › ... ›...

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Kathrin Valerius Erlangen Centre for Astroparticle Physics Univ. Erlangen-Nürnberg KCETA Karlsruhe Institute of Technology Supernova Remnants and Pulsar Wind Nebulae observed in TeV γ rays NOW 2014 Conca Specchiulla, Sept 7-14, 2014
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  • Kathrin ValeriusErlangen Centre for Astroparticle PhysicsUniv. Erlangen-NürnbergKCETAKarlsruhe Institute of Technology

    Supernova Remnants and Pulsar Wind Nebulaeobserved in TeV γ rays

    NOW 2014Conca Specchiulla, Sept 7-14, 2014

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 2

    Particle acceleration by stellar remnants

    Gamma-ray astronomy at energies ~100 MeV to ~10 TeV:rich evidence of particle acceleration in ...

    … supernova remnants … pulsar wind nebulae … young and “rejuvenated” pulsars

    Crab Nebula → talk by F. CaloreSN 1006

    Powered by

    Acceleration at

    Time scale after death of star

    explosion energy pulsar rotation strong EM fields; accretion

    shock front shocked wind polar cap, slot gap?

    few kyr few 10 kyr few 100 kyr – Myr

    Adapted from F. Acero

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 3

    Particle acceleration by stellar remnants

    Gamma-ray astronomy at energies ~100 MeV to ~10 TeV:rich evidence of particle acceleration in ...

    … supernova remnants … pulsar wind nebulae … young and “rejuvenated” pulsars

    Crab Nebula → talk by F. CaloreSN 1006

    Major Galactic TeV γ-ray source classes:5 shell-type, 9 interacting SNRs, 33 PWNe● Flux and composition (hadr./e± ?)● Max. energy (~1 PeV ?)

    of accelerated particles ?

    Important Fermi source class● Release & acceleration?● Contribution to

    diffuse γ flux?

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 4

    Supernova remnants W2835-150 kyr

    Young SNRs Older SNRs● Hadronic

    scenariofavoured

    ● Electronaccelerationless efficient

    ● π0 → 2γenhanced bymol. clouds:

    - interactionw/ shellor - illuminationby escapingCR flux

    H.E.S.S. coll.,Acero et al. (2010)

    ● Efficient particle acceleration in the shell● Spectral features well reproduced by

    mixed hadr./lept. models

    SN 10061 kyr

    Multi-band X-ray image(Chandra; F. Winkler 2013)

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 5

    Pulsar wind nebulae: synopsis“A bubble of shockedrelativistic particles,produced when apulsar's relativistic wind interacts withits environment“(Gaensler & Slane, 2006)

    Crab Nebula

    (infrared, optical, X-rays) radio vis X γ VHE γIR

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 6

    “A bubble of shockedrelativistic particles,produced when apulsar's relativistic wind interacts withits environment“(Gaensler & Slane, 2006)

    Crab Nebula

    (infrared, optical, X-rays)

    RL ~ 106 m pulsar windmagnetized outflow

    wind termination shock

    e± e±

    Rwind ~ 0.1 pc

    non-thermalnebula

    RPWN ~ several pc

    Synchrotron Inv. Compton

    Pulsar wind nebulae: synopsis

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 7

    Pulsar wind nebulae: evolution

    2-6 kyr 20-100 kyr?

    I. Free expansion II. Reverse shock interaction III. Relic phase

    pulsar

    PWN

    SNR

    ● Simplest phase● R ~ t6/5● Well studied, e.g. via Crab

    Kennel & Coroniti 1964,Martín++ 2012, ...

    ● Even more influenced by SNR evolution, surroundings

    ● R ~ ??● Only case-by-case studies

    ● Depends on SNR development● Oscillatory reverberations● Analytically: R ~ t0.3● Only over-idealized and/or

    numerical modelse.g. Swaluw++ 2001, 2004, ...

    Adapted from S. Klepser

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 8

    Pulsar wind nebulae in TeV γ rays

    H.E.S.S. coll.,Aharonian et al. (2006)

    Funk et al. (2008)

    pulsar

    ● Middle-aged (τc~21 kyr, r~35 pc)● “Crushed” shape

    (asymmetry, displacement)● Synchr. burn-off of high-E particles

    ~25 pc

    3C 58

    MAGIC coll.,Aleksić et al. (2014)

    ● Weakest TeV PWN ever detected:L >1TeV ~0.65% Crab, ~10-5 Ė

    ● Probably young (τc~5 kyr)● TeV source coincides with pulsar,

    size not resolved (r < 4 pc)NEW !

    exce

    ss/b

    ackg

    rd

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 9

    PWN population study: aims

    ● Link between properties of pulsarand TeV PWN?

    ● Benchmark common perceptionsof PWN evolution

    ● Uniform analysis of TeV sources,selection and evaluation of candidates

    ● Upper limits for non-detections

    Observational data Interpretation

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 10

    PWN population study: ingredients

    (1) H.E.S.S. Galactic Plane Survey~2800 h obs. of the inner Galaxy (2004-13)better than 2% Crab sensitivitydiscovery of ~60 new sources→ Position, size, F(1-10 TeV)

    (2)

    > 2000 pulsars (radio, X, γ)→ Position, P, Pdot, Edot, τc, d

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 11

    PWN population study: methods

    HGPS+ ATNFcatalogs

    (w/o SNR, GCBinaries, AGN)

    TeVCatonline catalogof ~150 VHEγ-ray sources

    Previouslyassociated

    New candidates

    Externals

    known PWNe

    not in HGPS, from TeVCat

    Pulsars for limits

    Association & selection of candidates

    no TeV detection

    HGPS source + matching PSR

    ● Uniform analysis of TeV sources,selection and evaluation of candidates

    ● Upper limits for non-detections

    ● Link between properties of pulsarand TeV PWN?

    ● Benchmark common perceptionsof PWN evolution

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 12

    HGPS+ ATNFcatalogs

    (w/o SNR, GCBinaries, AGN)

    TeVCatonline catalogof ~150 VHEγ-ray sources

    Previouslyassociated

    New candidates

    Externals

    known PWNe

    not in HGPS, from TeVCat

    Pulsars for limits

    Association & selection of candidates

    no TeV detection

    HGPS source + matching PSR

    Population plotsrelating PSR to TeV properties

    ● Common trends?● Theory expectations?

    Simple leptonic modeling● Plausibility of candidates

    PWN population study: methods

    ● Uniform analysis of TeV sources,selection and evaluation of candidates

    ● Upper limits for non-detections

    ● Link between properties of pulsarand TeV PWN?

    ● Benchmark common perceptionsof PWN evolution

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 13

    Correlation of TeV sources and pulsars

    (b) angular separation criterion(a) energy-dep. detection fraction

    Klepser et al., arXiv:1307.7905Carrigan et al., arXiv:0709.4094

    High-Edot pulsars:TeV signal within ~0.5°

    candidate selection

    log10 (Ė)

    Nde

    tect

    ed/N

    all

    cand

    idat

    e se

    lect

    ion

    No correlation beyond chancecoincidences below ~1035 erg/s

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 14

    Preliminary

    Selection of PWN candidatesS. Klepser et al., arXiv:1307:7905

    ● Most PWNe likely in reverseshock interaction phase

    ● Candidates: more evolved

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 15

    ● PWNe trace close-byspiral arms

    ● Average distance: ~5 kpc● Exposure covers ~1/4 of

    the Milky Way

    How far can we reach out?

    Graphic: C. Deil, S. Klepser

    1% 10%of Crab luminosity > 1 TeVPreliminary

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 16

    Evolutionary trends

    ● RPWN ~t0.3 as a rough guideline, butlarge scatter due to surrounding mediumor SNR interaction

    ● Good for evaluating candidates

    ● Compares accumulated e± populationwith momentary energy output of pulsar

    ● Time-dependent one-zone model basedon M. Mayer et al., arXiv:1202:1455 (added free expansion phase)

    Size RPWN EfficiencyL1-10TeV/Ė

    S. Klepser et al., arXiv:1307:7905

    http://arxiv.org/abs/1202.1455

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 17

    Evolutionary trends

    ● RPWN ~t0.3 as a rough guideline, butlarge scatter due to surrounding mediumor SNR interaction

    ● Good for evaluating candidates

    ● Compares accumulated e± populationwith momentary energy output of pulsar

    ● Time-dependent one-zone model basedon M. Mayer et al., arXiv:1202:1455 (added free expansion phase)

    Size RPWN EfficiencyL1-10TeV/Ė

    S. Klepser et al., arXiv:1307:7905

    Upperlimits

    http://arxiv.org/abs/1202.1455

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 18

    ● VHE γ-rays allow to study mostpowerful particle acceleratorsin the Galaxy

    ● Data quality & quantity supportscumulative studies: SNRs, PWNe

    ● PWN population: biggest(& rather diverse) Galacticsource class

    ● Many UNID sourcesmight be ageing PWNe

    ● Modeling: need betterunderstanding of evolvedPWNe …

    Summary & outlook

    … in particular for the leap ahead with CTA

    UNID

    PWN SNR (shell)SNR (int.)

    binaryclu

    ster

    Composition of Gal. TeV sourcestevcat.uchicago.edu

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 19

    References

    Selection of recent reports on progress of Galactic TeV survey & source census:

    ● H.E.S.S. Galactic Plane Survey● Carrigan et al., Charting the TeV Milky Way, arXiv:1307.4868 ● Carrigan et al., The H.E.S.S. Galactic Plane Survey, arXiv:1307.4690

    ● PWN population study● Klepser et al., A population of Teraelectronvolt Pulsar Wind Nebulae in the H.E.S.S. Galactic Plane Survey,

    arXiv:1307.7905

    ● SNR population study● Fernandez et al., Study of the Very High Energy emission from Supernova Remnants with H.E.S.S.,

    arXiv:1307.6347

    ● Future perspectives: 'CTA special edition', Astrop. Phys. 43 (2013)● Aharonian, Gamma rays from supernova remnants, p. 71● Acero et al., Gamma-ray signatures of cosmic-ray acceleration, propagation, and confinement in the era of

    CTA, p. 276● de Ona Wilhelmi et al., Prospects for observations of pulsars and pulsar wind nebulae with CTA, p. 287

    http://arxiv.org/abs/1307.4868v2http://arxiv.org/abs/1307.4690v3http://arxiv.org/abs/1307.7905http://arxiv.org/pdf/1307.6347v1.pdf

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 20

    Supplementary slides

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 21

    Galactic Sources of VHE γ rays

    ~90 sources of VHE γ rays (E > 100 GeV) in the Milky Way known today*:

    *) tevcat.uchicago.edu, Aug. 2014

    335 5

    11

    926

    Dominantsource class

    How manyare ancientPWNe?

    Differentorigin ofγ-ray emission

    http://tevcat.uchicago.edu/

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 22

    The TeV gamma-ray sky today

    Http://tevcat.uchicago.edu

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 23

    Mattana et al. (2009)

    Old PWNe as unidentified VHE γ-ray sources?

    M. J. Mayer, J. Brucker, I. Jung, KV, C. Stegmann, arXiv:1202.1455

    Comparison of X-ray and VHE γ-rayluminosities for several identified PWNe

    Time-dependent leptonic model of broad-band emission for a generic PWN

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 24

    PWN population study: potential selection bias

    S. Klepser et al., ICRC'13

    Closer objects tend to have larger lower efficiencies and smaller extensions● Far away sources need to be more efficient in order to get detected● Clipping of large, nearby sources due to limited field of view ?● Far, small sources cannot be resolved → upper limits on extension

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 25

    ● We can learn something about …

    – the pulsar: spin-down characteristics/history, proper motion, …

    – the pulsar wind: composition, energetics, geometry, termination shock, …

    – the ambient medium: local density/homogeneity, magnetic field, …

    ● Increasing sample of detected PWNe allows to

    – identify general properties

    – investigate various evolutionary stages

    Why study (multi-wavelength) properties of PWNe?

    Multi-wavelengthobservational data +Detailed modeling

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 26

    Imaging Atmospheric Cherenkov Technique

    ~ 10 kmParticle shower

    ~ 10 km

    Photon

    Cher

    enko

    v ligh

    t

    Air shower observed simultaneously by multiple telescopes

    ~ 120 m

    Shower image:Intensity → energyOrientation → directionShape → primary particle

    for ground-based gamma-ray detection (Eγ ~ 100 GeV … 10 TeV)

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 27

    Aharonian, Bogovalov & Khangulyan (2012)http://www.nature.com/nature/journal/v482/n7386/images/nature10793-f2.2.jpg

    What is a Pulsar Wind Nebula?

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 28

    Pulsar Wind Nebulae: Overview

    Hydrodynamical simulations, Van der Swaluw, Downes & Keegan (2004)

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 29

    Time-dependent leptonic modelof non-thermal emission from PWNe

    Cooling processes (see Zhang et al., 2008):

    PWN evolution (Gaensler & Slane, 2006):

    Time evolution of energy output and magn. field (see Zhang et al., 2008):

    Characteristic age and spin-down timescale

    free expansion

    after RS interaction

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 30

    Dissecting the broad-band SED into contributions from different epochs

    Generic middle-aged PWN:

    P0 = 30 ms, P = 100 msB0 = 50 µGĖ = 2.8·1036 erg/s

    Mayer, Brucker, Holler, Jung, KV, Stegmann: Predicting the X-ray flux of evolved pulsarwind nebulae based on VHE gamma-ray observations, arXiv:1202:1455

    http://arxiv.org/abs/1202.1455

  • K. Valerius . NOW 2014 . Supernova Remnants and Pulsar Wind Nebulae 31

    Supernova Remnants● Paradigm of galactic cosmic rays (E ≤ 1015 eV):

    young SNRs as acceleration sites ('PeVatrons' ?)● Both high-energy hadrons (p, nuclei) and leptons (e±)

    can be present → VHE γ-ray production via π0 decay or inverse Compton scattering

    Multi-band X-ray image(Chandra; F. Winkler 2013)

    SN 1006

    H.E.S.S. coll.,Acero et al. (2010)

    ● TeV γ-rays coincidentwith non-thermal X-raysfrom the shell

    ● Spectral energydistribution wellreproduced by mixedhadronic-leptonic model

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