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Damien Parent – Moriond, February 2009

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

pulsars

Damien ParentDamien Parent on behalf of the Fermi LAT Collaboration

parent@cenbg.in2p3.fr

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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)

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Damien Parent – Moriond, February 2009

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)

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Damien Parent – Moriond, February 2009

PSR J0205+6449, the X-ray discovery in the SNR 3C 58

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 = 4² I Pdot/P3 (I: moment of inertia)

3C 58 Possible remnant of historical supernova SN 1181,

in disagreement with the characteristic age (=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)

... suspected by Becker et al. in 1982.

Image of 3C 58 at 1.4 GHz. The arrow marks the position of the pulsar.

Pulsar Phase

X-ray

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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

« Giant » glitch comparable to the glitches from the older Vela pulsar.

Pulse profile of PSR J0205+6449 displayed as a function of time(bottom) and summed (top). Data at a center frequency of 1375 MHz.

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Damien Parent – Moriond, February 2009

Background

PRELIMIN

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PSR J0205+6449,the -ray light curve

-radio= 0.07 = 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 -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 ~ 6.

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

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Damien Parent – Moriond, February 2009

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

P1/P2 = 0.81 +/- 0.08

P1/P2 = 0.22 +/- 0.08

PRELIMIN

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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/L larger than for older pulsars.

We analysed the spectrum with a standard analysis tool for the collaboration « gtlike1 »

The -ray spectral analysis suggests an index of 1.97 ± 0.26 with an exponential (b = 1) cut-off Ec = 2.2 ± 1.1 GeV.

N(E)N0E e (E /Ec )

b

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

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Damien Parent – Moriond, February 2009

Fermi LAT detection of pulsed -rays from the Vela-like pulsar J2229+6114

Radio pulse profile of PSR J2229+6114 at 1412 MHz (Discovery, Halpern et al. 2001).

... 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)

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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.

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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%.

X-ray pulse profile of PSR J2229+6114 in the 0.8-10 keV band from the ASCA GIS.

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).

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Damien Parent – Moriond, February 2009

PRELIMINARY

PSR J2229+6114,the -ray light curve

The -ray profile consists of a single, asymmetric peak.

FWHM(Peak)= 0.17 ± 0.03 cycles

-radio= 0.49+/- 0.01

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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.

PRELIMIN

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Abdo et al. (2009) in preparation

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Damien Parent – Moriond, February 2009

Their cousins

PSR J0205+6449, this talk

PSR J2229+6114, this talk

PSR J2021+3651, Kerr’s talk

MSP pulsars, Guillemot’s talk

Vela, Razzano’s talk

J1833-1034, Caliandro’s talk

Blind search pulsars, Giordano’s talk

Crab, Grondin’s talk

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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 !