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

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. The context.

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

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  1. 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

  2. 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)

  3. Discovery of pulsations from PSR J0205+6449 in SNR 3C 58 with Fermi Supernova remnant 3C 58. Optical(green), 1.466 GHz radio (red).Fesen et al. (2008)

  4. X-ray Pulsar Phase Image of 3C 58 at 1.4 GHz. The arrow marks the position of the pulsar. 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 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) 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. • Distance of ~ 3.2 kpc (Roberts et al. 1993)

  5. 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 pulsar.

  6. PRELIMINARY Background PSR J0205+6449,the g-ray light curve dfg= 0.49 dfg-radio= 0.07 • 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 • 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). Abdo et al. (2009) in preparation

  7. PSR J0205+6449,the light curves as a function of the energy • 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 = 0.93 +/- 0.07 PRELIMINARY P1/P2 = 0.81 +/- 0.08 P1/P2 = 0.22 +/- 0.08

  8. 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. PRELIMINARY • 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. (1) http://fermi.gsfc.nasa.gov/ssc/data/analysis/SAE_overview.html

  9. Fermi LAT detection of pulsed g-rays 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).

  10. 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.

  11. 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.

  12. PRELIMINARY 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

  13. 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. PRELIMINARY Abdo et al. (2009) in preparation

  14. 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

  15. 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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