Pulsed Detection on PSR J2021+4026 Collaborated with David Hui - PowerPoint PPT Presentation

Pulsed Detection on PSR J2021+4026 Collaborated with David Hui (CNU), Jason Wu (Max Planck), Chin-Ping Hu (NCU) and Trepl L.(FSU) Search for the Geminga-like pulsar Previously known Geminga-like pulsars i. Geminga ii. PSR J0007+7303 Pulsed detection of PSR J2021+4026 and its spectral features Other candidates of Geminga-like pulsars Summary Lupin Lin (China Medical Univ.) July 9th in HKU

1st Radio-quiet γ -ray Pulsar: Geminga Only 7 γ -ray pulsars were d e t e c t e d w i t h h i g h confidence level before 2000. 1991-2000 Many firsts of Geminga (Caraveo & Bignami 1997). !

Pulsed Features of Geminga (Malofeev & Malov; 1997 ) (Abdo et al., 2010) (D.J. Thompson et al, 1999)

Intrinsically or Geometircally Radio-quiet? Before the launch of Fermi observatory, Geminga is the only one radio-quiet γ -ray pulsar ( L 1400 <0.035 mJy kpc 2 =PSR J1907+0602). Two possible interpretations for a γ -ray pulsar to be radio-quiet: 1st: Geometrical: γ -ray beam is wider than the radio beam or they are in the different directions. Outer gap model: (Romani & Yadigaroglu 1995; Cheng & Zhang 1998) .Radio pulsed emission is directed along magnetic dipole axis. .Particle acceleration in outer gap (where Ω Ÿ B = 0) generates γ -rays Polar-cap model: (Radhakrishnan & Cooke 1969; Harding & Muslimov 1998) . γ -ray beam is concentric with radio beam which emitted within few stellar radii from surface. Polar-cap model » Slot Gap model (Arons 1983; Muslimov & Harding 2003)

Intrinsically or Geometircally Radio-quiet? Before the launch of Fermi observatory, Geminga is the only one radio-quiet γ -ray pulsar ( L 1400 <0.035 mJy kpc 2 =PSR J1907+0602). Two possible interpretations for a γ -ray pulsar to be radio-quiet: 1st: Geometrical: γ -ray beam is wider than the radio beam or they are in the different directions. µ Outer gap model: (Romani & Yadigaroglu 1995; Cheng & Zhang 1998) .Radio pulsed emission is directed along magnetic dipole axis. .Particle acceleration in outer gap (where Ω Ÿ B = 0) generates γ -rays Pair plasma Polar-cap model: (Radhakrishnan & Cooke 1969; Harding & Muslimov 1998) PFF . γ -ray beam is concentric with radio slot gap beam which emitted within few stellar radii from surface. Δξ SG Polar-cap model » Slot Gap model NS surface (Arons 1983; Muslimov & Harding 2003)

Intrinsically or Geometircally Radio-quiet? Two possible interpretations for a γ -ray pulsar to be radio-quiet: 2nd: Intrinsic: radio emission is weak or silent because of unfavour spin periods and magnetic strength. Magnificent Seven (PoPov et al., 2007)

Intrinsically or Geometircally Radio-quiet? Two possible interpretations for a γ -ray pulsar to be radio-quiet: 2nd: Intrinsic: radio emission is weak or silent because of unfavour spin periods and magnetic strength. Magnificent Seven (PoPov et al., 2007) Characteristic age :  = T P/2P year Spin-down energy:  P 46  = × E 4 10 erg/s 3 P Magnetic field: 19  × B  3.2 10 PP gauss Open field line voltage: − 20 3/2 1/2  Φ = × 4 10 P P volt open (Haberl 2007)

More and More Radio-quiet γ -ray Pulsars With the support of new techniques: 1. Weighting H-statistics (Kerr, 2011) 2. Sliding coherence window technique (Pletsch, 2011) More than 30 radio- quiet γ -ray pulsars we re d i s c ove re d through high energy γ - ra y p u l s at i o n s alone. Green beam: radio emission Pink area: γ -ray emission

Classification of Pulsars (Wavelength)+ (Morphology)+ Black Widow Pulsars Edited by Yang (2010)

Emission Mechanism of Geminga in X-rays and γ -rays The most frequent problem to be questioned is that are the emitting sites/ mechanisms of X-ray and γ -ray the same for a Geminga-like pular? Background subtracted folded light curves of Geminga. (Caraveo et al., 2004) Fig. Folded light curves of Geminga (Kargaltsev et al. 2005)

Emission Mechanism of Geminga in X-rays and γ -rays The most frequent problem to be questioned is that are the emitting sites/ mechanisms of X-ray and γ -ray the same for a Geminga-like pular? Background subtracted folded light curves of Geminga. Time-averaged spectral distribution of Geminga pulsar. (Caraveo et al., 2004) (Caraveo et al., 2004) Green dashed curve: Blackbody component with T bb =43±1 eV, covering a surface with 8.6±1 km radius. Red curve: Blackbody component with T bb =170±30 eV, covering a surface with 40±10 m radius. Fig. Folded light curves of Geminga Blue curve: Power-law component with photon index of 1.7±0.1. (Kargaltsev et al. 2005)

Pulsed detection of PSR J0007+7303 in X-rays and γ -rays How about the first radio-quiet γ -ray pulsar (PSR J0007+7303) detected by Fermi team? Fig. The Fermi LAT γ -ray source and its 95% error Fig. Contours of detection significance over a range region (small red circle), central PWN X-ray RX of period and period derivative within a region around J0007.0+7302 (black cross), and error of the RX J0007.0+7302 (Abdo et al.,2008). corresponding EGRET source 3EG J0010+7309 (blue circle) superimposed on 1 1420-MHz map of CTA 1. (Abdo et al.,2008).

Pulsed detection of PSR J0007+7303 in X-rays and γ -rays How about the first radio-quiet γ -ray pulsar (PSR J0007+7303) detected by Fermi team? Fig. (Lin et al., 2010) Fig. The Fermi LAT γ -ray source and its 95% error Fig. Contours of detection significance over a range Left panel: Spin-frequencies of PSR J0007+7303 detected from γ -ray (Fermi; labelled by squares) and X-ray (XMM; region (small red circle), central PWN X-ray RX of period and period derivative within a region around labelled by triangle). The plus sign marks the glitch of PSR J0007+7303 with df/f=5x10 -7 (Abdo et al., 2010) . The J0007.0+7302 (black cross), and error of the RX J0007.0+7302 (Abdo et al.,2008). circles and solid circles represent the spin frequencies detected by the Fermi data before and after the glitch, corresponding EGRET source 3EG J0010+7309 (blue respectively. circle) superimposed on 1 1420-MHz map of CTA 1. Right panel: Rayleigh test of X-ray (XMM) data around [3.114,3.218] Hz. The most significant signal corresponds to (Abdo et al.,2008). the spin frequency of PSR J0007+7303 at 3.165844 Hz.

Emission mechanism of PSR J0007+7303 in X-rays and γ -rays 0.2-2 keV 0.15-2 keV 2-12 keV Fig. (Caraveo et al., 2010) Upper panel: X-ray pulse profile of PSR J0007+7303. Gray Fig. Pulse profiles of PSR J0007+7303 shadow: on-pulse. Red shadow: off-pulse. in the different energy bands (Lin et al., Lower panel: X-ray spectrum (Black line: on-pulse; Red line: 2010) off-pulse) fitted with a three component model to a account for thermal emission (cyan symbols) of NS and non-thermal emission from pulsar (green dotted line) and PWN (blue dotted line). Cyan triangles present the thermal emission of on-pulse spectrum, while cyan squares present it of off-pulse one.

Emission mechanism of PSR J0007+7303 in X-rays and γ -rays 0.2-2 keV 0.15-2 keV 0.1-300 GeV 2-12 keV Fig. (Caraveo et al., 2010) Upper panel: X-ray pulse profile of PSR J0007+7303. Gray Fig. Pulse profiles of PSR J0007+7303 shadow: on-pulse. Red shadow: off-pulse. in the different energy bands (Lin et al., Lower panel: X-ray spectrum (Black line: on-pulse; Red line: 2010) off-pulse) fitted with a three component model to a account for thermal emission (cyan symbols) of NS and non-thermal emission from pulsar (green dotted line) and PWN (blue dotted line). Cyan triangles present the thermal emission of on-pulse spectrum, while cyan squares present it of off-pulse one.

Emission mechanism of PSR J0007+7303 in X-rays and γ -rays 0.2-2 keV 0.15-2 keV 0.1-300 GeV 2-12 keV Fig. (Caraveo et al., 2010) X-ray spectrum fitted with a single power-law Upper panel: X-ray pulse profile of PSR J0007+7303. Gray (PL), dual component of power-law Fig. Pulse profiles of PSR J0007+7303 shadow: on-pulse. Red shadow: off-pulse. +blackbody (PL+BB) and power-law in the different energy bands (Lin et al., Lower panel: X-ray spectrum (Black line: on-pulse; Red line: +magnetized neutron star atmosphere (PL 2010) off-pulse) fitted with a three component model to a account for +nsa). (Caraveo et al., 2004) thermal emission (cyan symbols) of NS and non-thermal emission from pulsar (green dotted line) and PWN (blue dotted line). Cyan triangles present the thermal emission of on-pulse spectrum, while cyan squares present it of off-pulse one.

A new Geminga-like pulsar candidate The EGRET and X-ray observations of the object show the steady flux, hard PL spec and high-energy cut-off that are known only among young pulsars (Merck et al. 1996) . The source is at the centre of a young SNR, which shows two opposing arcs on its rim. The F γ /F x for RX J2021.0+4026/2EG J2020+4026 is of order 6000, similar to value of Geminga. 2EG J2020+4026/3EG J2020+4017 ?? RX J2021.0+4026 ?? RX EFRET 95% error box ROSAT PSPC field around 3EG J2020+4017. The ROSAT PSPC image of γ -Cygni (G78.2+2.1), 68%, 95%, and 99% contour lines from 3EG EGRET summed from 6 individual observations. North is likelihood map and the ROSAT HRI sources are up and east is to the left. (Brazier et al., 1996) indicated. (Becker et al., 2004)