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VIEWS: 3 PAGES: 15

									                         Damien Parent – Moriond, February 2009




     PSR J0205+6449, PSR J2229+6114,
and their cousins -- young & noisy gamma ray
                    pulsars


               Damien Parent
    on behalf of the Fermi LAT Collaboration
           parent@cenbg.in2p3.fr




                                                          1
                                                                       Damien Parent – Moriond, February 2009




  The context
     Before the launch of the Fermi Gamma-ray Space Telescope in 2008 June, we built a
      list of gamma-ray pulsar candidates based on their spin-down energy Edot.
     It seemed gamma-ray emitting electron-positron cascades occur for Edot > 3 x 1034
      erg s-1 (Thompson et al. 1999). We have selected pulsars with Edot > 1 x 1034 erg s-1.
      These pulsars are mainly young, energetic and exhibit rotational instabilities (« timing
      noise »).

Extract from the list of gamma-ray pulsar candidates (Smith et al. 2008)




                                                                                                        2
Discovery of pulsations from PSR
                                                           Damien Parent – Moriond, February 2009




J0205+6449 in SNR 3C 58 with Fermi




      Supernova remnant 3C 58. Optical(green), 1.466 GHz radio (red).
      Fesen et al. (2008)


                                                                                            3
                                                                                        Damien Parent – Moriond, February 2009

      PSR J0205+6449,
      the X-ray discovery in the SNR 3C 58
    ... suspected by Becker et al. in 1982.

X-ray Observations
     This young pulsar was discovered at X-ray wavelengths by the              X-ray
      Chandra X-ray Observatory with a pulsation period of 65.7 ms
      (Murray et al. 2002).
     RXTE data allowed a measurement of the spin-down rate of Pdot
      = 1.93 x 10-13 s s-1.
     The pulsed fraction for the folded light curve is ~ 21%.
     The pulsar has a spin-down energy Edot = 2.7 x 1037 erg s-1 (the
      third most energetic of the known Galactic pulsars).
      Edot = 4p² I Pdot/P3 (I: moment of inertia)


                                                                                             Pulsar Phase
3C 58
     Possible remnant of historical supernova SN 1181,
      in disagreement with the characteristic age t
      (=P/2Pdot) of the pulsar (5400 yrs)
     Similar to the comparably aged Crab nebula (a flat-
      spectrum radio nebula, non-thermal extended X-ray
      emission, point-like emission due to a pulsar) but
      differs both in luminosity and in size.
                                                                                                                             4
     Distance of ~ 3.2 kpc (Roberts et al. 1993)
                                                                 Image of 3C 58 at 1.4 GHz. The arrow marks the position of the pulsar.
                                                                           Damien Parent – Moriond, February 2009

      PSR J0205+6449,
      the radio observations

  Radio observations
  •   The radio discovery was made possible by the Chandra X-ray
      discovery (Camilo et al. 2002)
  •   Observed with a real weak signal of ~0.045 mJy at 1400 MHz
  •   One sharp pulse of width 2 ms
  •   The distance determined from the dispersion measures of
      ~141 cm-3 pc is 4.5 kpc.


  Timing irregularities
  •   Extremely high level of timing noise
  •   Two glitches have occured since its discovery



                                                                   Pulse profile of PSR J0205+6449
                                                                   displayed      as   a     function of
                                                                   time(bottom) and summed (top). Data
                                                                   at a center frequency of 1375 MHz.
« Giant » glitch comparable to the
glitches from the older Vela                                                                                5
pulsar.
                                                         Damien Parent – Moriond, February 2009

PSR J0205+6449,
the g-ray light curve
                 dfg-radio= 0.07   dfg= 0.49

                                                       The profile is very similar of the
                                                        Vela light curve:
                                                           with a radio delay ~ 0.1
                                                            cycles
                                                           a separation of the 0.4-0.5
                                                            cycles of the g-ray peaks

                                                       FWHM(P1)= 0.12 +/- 0.03 cycles
                                                       FWHM(P2)= 0.08 +/- 0.04 cycles

    Background                                         An evidence for an excess
                                                        between P1 and P2 appears with
                                                        a significance of ~ 6s.

                                                       Unpulsed emission defined
                                                        between 0.6 - 1.0 in phase
                                                        consistent with the background
                                                        estimated from regions around
                                                        the source.
                                                       9.0 x 10-9 cm-2 s-1 95% CL upper
                                                        limit on unpulsed emission
                                                        (PWN).


                                                                                          6

                                               Abdo et al. (2009) in preparation
                                             Damien Parent – Moriond, February 2009

PSR J0205+6449,
the light curves as a function of the energy

                          P1/P2 = 0.93 +/- 0.07
                                P1/P2 ratio decreases with energy
                                No significant change in gamma
                                 peak position and shape
                                Similar behavior as for Vela, Crab,
                                 Geminga and B1951+32.
                                The highest energy photon is in P2
                                 with an energy of 4 GeV.

                          P1/P2 = 0.81 +/- 0.08




                          P1/P2 = 0.22 +/- 0.08


                                                                              7
                                                                            Damien Parent – Moriond, February 2009

      PSR J0205+6449,
      the spectral energy distribution
                                                                         The young pulsars like Crab or
                                                                          B1509-58 have the maximum
                                                                          luminosity below 30 MeV.
                                                                         Lx/Lg larger than for older
                                                                          pulsars.




      We analysed the spectrum with a standard analysis tool
       for the collaboration « gtlike1 »
      The g-ray spectral analysis suggests an index G of 1.97 ±
       0.26 with an exponential (b = 1) cut-off Ec = 2.2 ± 1.1 GeV.
                                                      b
                        N(E)  N 0 E G e(E / Ec )


                                                                                                             8
(1) http://fermi.gsfc.nasa.gov/ssc/data/analysis/SAE_overview.html
          
Fermi LAT detection of pulsed g-rays
                                                             Damien Parent – Moriond, February 2009




from the Vela-like pulsar J2229+6114
... Halpern et al. (2001) report the detection of radio and X-ray
pulsations in the error box of the EGRET source 3EG J2227+6122

                                       0FGL J22290+6114 (see Jean Ballet’s talk)




       Radio pulse profile of PSR J2229+6114 at 1412 MHz (Discovery, Halpern
       et al. 2001).
                                                                                              9
                                                                 Damien Parent – Moriond, February 2009

    J2229+6114,
    the radio observation


Radio parameters
   Pulsations at a period of 51.6 ms,
    Pdot ~ 7.8 x 10-14 s s-1
   Edot = 2.2 x 10+37 erg s-1 (the fourth most
    energetic of the known Galactic pulsars)
   Characteristic age of ~ 10,500 yrs
   Surface magnetic flux density B ~ 2e+12 G
   The distance determined from the dispersion
    measures of ~200 cm-3 pc is ~ 7 kpc.

Pulse profile
   The radio profile consists of one peak with
    FWHM of 0.08 ± 0.02 cycles.
                                                  Radio pulse profile of PSR J2229+6114
                                                  at 1412 MHz. The phase-averaged flux
                                                  density is only ~ 0.25 mJy.

                                                                                                 10
                                                                                 Damien Parent – Moriond, February 2009

    J2229+6114,
    the X-ray observation
Association
   Associated with SNR G106.3+2.7 (shell morphology with an
    extremely flat radio spectrum)
   Distance of ~ 3 kpc estimated from the X-ray absorption

X-ray profile
   The pulsed fraction for the X-ray folded light curve is ~ 75%.




                                                                     A portion of the Chandra ACIS-I image
                                                                     showing PSR J2229+6114 and its associated
                                                                     PWN (greyscale) called the Boomerang
                                                                     PWN. The NVSS 20 cm map of the partial
                                                                     shell G106.65+2.96 is overlaid (contours).

    X-ray pulse profile of PSR J2229+6114 in the
    0.8-10 keV band from the ASCA GIS.                                                                           11
                                  Damien Parent – Moriond, February 2009

 PSR J2229+6114,
 the g-ray light curve
dfg-radio= 0.49+/- 0.01


                             The g-ray profile consists
                              of a single, asymmetric
                              peak.
                             FWHM(Peak)= 0.17 ± 0.03
                              cycles




                                                                  12
                                              Damien Parent – Moriond, February 2009

    PSR J2229+6114,
    the light curves as a function of the energy

   Evolution of the peak as a
    function of the energy
          Peak position is not stable
              0.1-0.3 GeV -> 0.5 +/- 0.01
              0.3-1.0 GeV -> 0.46 +/- 0.01
              1.0-3.0 GeV ->0.45 +/- 0.01
              > 3.0 GeV -> 0.42 +/- 0.04
          No significant change in gamma
           peak shape with energy
   The highest energy photon is
    observed with an energy of ~
    13.5 GeV in the peak.




                                                                              13
    Abdo et al. (2009) in preparation
                                                                                            Damien Parent – Moriond, February 2009




 Their cousins



                                  PSR J2021+3651, Kerr’s talk
PSR J0205+6449, this talk

                                                  Blind search pulsars, Giordano’s talk   Vela, Razzano’s talk




      PSR J2229+6114, this talk       J1833-1034, Caliandro’s talk                                          Crab, Grondin’s talk




                                                     MSP pulsars, Guillemot’s talk




                                                                                                                             14
                                                         Damien Parent – Moriond, February 2009




Summary
   The Fermi LAT Telescope has discovered two young pulsars in the
    Galactic plane, PSR J0205+6449 and PSR J2229+6449 and presents a
    new opportunity to study pulsar / PWN associations at high energies.
   The gamma-ray light curve for PSR J0205+6449 consists of two peaks
    for which the first peak trails the radio pulse by 0.07 and its amplitude
    decreases with increasing energy as for the known gamma-ray pulsars
    like Vela, Crab and Geminga.
   The Vela-like (comparable age) pulsar PSR J2229+6114 consists of one
    peak for which the location is variable as a function of the energy.
   Our gamma-ray pulsar candidates are becoming gamma-ray pulsar
    discoveries. We see what we expected (and more !). Our selection
    based on Edot isn’t so bad !



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