Swift observations of Radio-quiet Fermi pulsars Swift and the Surprising Sky 24th-25th November 2011 In collaboration with Patrizia Caraveo and Andrea de Luca Martino Marelli

Fermi discovers PSRs The Fermi/LAT End of LEO: August 11, MeV-300GeV (100MeV-10GeV) - Very Large FOV (more than 2sr) and all-sky monitoring - Very high point source sensitivity (more than 1800 sources in 2 years) ~6μ - Very low deadtime (~65μs)

Fermi/LAT pulsar sample 101 (public) pulsar 66 radio-loud 39 classical 27 millisecond 34 discovered in BS (+Geminga), 32 “gamma-ray only” pulsars How can the X-ray band help the gamma-ray one? Why should we search for X-ray counterparts of pulsars?

The position is fundamental for BS! Gamma-ray data are sparse. Thousands of rotations may occur between detected gamma rays. Months (years) of analysis are necessary! The motions of the spacecraft and the Earth are significant compared to the time between pulses (msec to sec). Solution: do the timing analysis in an intertial reference system, not moving with respect to the pulsar.

Dormody et al., in preparation

With only 5 months of data and a bright pulsar.

The SWIFT fundamental contribution Compared with Chandra and XMM-Newton, high PSF (~15”), low spectral and timing resolutions BUT - rapidly re-pointed - useful for short observations - part of the SWIFT collaboration Counterparts of 4 RQ pulsars found (on 19 observed) few days after the Fermi discovery. For them, the gamma-ray light curve and positioning have been improved (see e.g. J )

X-ray spectrum: n H = *10 22 cm -2 p.i.= F = * erg/cm 2 s J P = 48.1ms τ = 43 ky E rot = 6.26*10 36 erg/s SWIFT first results Published on: Abdo et al., 2009, Science, 325, 840

J P = 290ms τ = 21 ky E rot = 3.58*10 35 erg/s SWIFT first results Published on: Abdo et al., 2009, Science, 325, 840

Are Swift observations useful also with no detection? YES! To obtain an upper limit X- ray flux, necessary for asking deeper observations (e.g. J0357) To study all nearby bright sources, necessary e.g. for Suzaku analysis (e.g. J1413) Low Nh, powerlaw spectrum => pulsar counterpart High Nh, powerlaw spectrum => pulsar counterpart? So that, Swift can also be useful in combination with other X-ray telescopes Papers in preparation: 2 nd Fermi pulsar catalog Marelli et al. 2012

When possible, taken from the 1 st pulsar catalogue ( Abdo et al. ApJ 2011, 193, 22 ): exponential cutoff and off-pulse tractation. Otherwise, pulsars' preliminary spectral analyses by the collaboration. If both the results were unavailable, I used the 2FGL catalogue's parameters. Gamma-raysX-rays - All the public Swift, Chandra and XMM- Newton data - Processed by using the standard analysis tools. Proton flares subtraction in XMM- Newton data where necessary - Only the appropriate event patterns and energies between 0.3 and 10 keV - Extraction regions in order to maximize the signal-to-noise ratio; a radial brillance profile has been producted where necessary - Spectra added by using ftools - XSPEC to simultaneously fit Chandra/ACIS, XMM-Newton (PN, MOS1,2) and Swift/XRT spectra (where available) by taking into account the different PSFs and cross-calibration studies. - Standard model: absorbed powerlaw. When statistically needed, I added (or used) a blackbody spectrum. Type 0 : no X-ray counterpart detection Type 1 : counterpart detection but spectral shape unknown Type 2 : PWN tractation, clear spectral results Assess the X-ray behaviour of Fermi psrs Marelli et al. 2011, ApJ, 733, 82

LogL x = logE rot χ 2 red =13 Distance Estimate? L=f*4πd 2 F, f dip α,ζ Pulsar geometrical factors? The X-ray luminosities - Marelli et al. 2011, ApJ, 733, 82

The γ-ray luminosities LogL γ = logE rot, E rot <4*10 35 erg/s LogL γ = logE rot, E rot >4*10 35 erg/s χ 2 red =7 - Marelli et al. 2011, ApJ, 733, 82

γ-to-X F γ /F x =L γ /L x *f x /f γ f x =f γ - Marelli et al. 2011, ApJ, 733, 82

High scatter Low scatter X-ray underluminous (f x >f γ ) Low scatter γ-to-X Radio-QuietMillisecond Radio-Loud - Marelli et al. 2011, ApJ, 733, 82

Assess the X-ray behaviour We can conclude that: - L x dip E rot with high scatter (distance or geometry?) - L γ dip E rot with little lower scatter (distance or geometry?) - X and γ-ray emissions are greatly dependent to geometry; moreover, they show no simple correlation good for each pulsar - RQ pulsars are undeluminous in the X band: a geometry different than RL ones could explain such behaviour - RL MS pulsars have a more uniform behaviour (geometry?) than RL ones (Our work is just a starting point)