PSR J2021+4026 IN THE GAMMA CYGNI REGION: THE FIRST VARIABLE γ-RAY PULSAR SEEN BY THE
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Allafort, A.; Baldini, Luca; Ballet, J.; Barbiellini, G.; Baring, Matthew G.; Bastieri, D.; Bellazzini, R.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; D’Ammando, F.; Palma, F. de; Digel, S. W.; Venere, L. Di; Drell, P. S.; Favuzzi, C.; Ferrara, E. C.; Franckowiak, A.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hayashida, M.; Hayashi, Katsuhiro; Hays, E.; Hewitt, John W.; Hill, A. B.; Horan, D.; Hou, X.; Jogler, T.; Johnson, A. S.; Johnson, T. J.; Kerr, M.; Knödlseder, J.; Kuss, M.; Landé, J.; Larsson, Stefan; Latronico, L.; Lemoine‐Goumard, M.; Longo, F.; Loparco, F.; Lubrano, P.; Malyshev, D.; Marelli, M.; Mayer, M.; Mazziotta, M. N.; Méhault, J.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paneque, D.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Ray, Paul S.; Razzano, M.; Reimer, O.; Reposeur, T.; Romani, Roger W.; Sartori, A.; Parkinson, P. M. Saz; Sgrò, C.; Siskind, E. J.; Smith, David A.; Spinelli, P.; Strong, A. W.; Takahashi, H.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Uchiyama, Y.; Usher, T.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello, G.; Vitale, V.; Winer, B. L.; Wood, K. S.

doi:10.1088/2041-8205/777/1/l2

Cited by 74 publications

(41 citation statements)

References 32 publications

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“…Similarly, the radio-quiet γ-ray pulsar PSRJ2021+4026, in the Gamma Cygni region, has also shown a sudden profile change accompanied by a spin-down rate change (Allafort et al 2013). Moding has never been seen in an RMSP or AMXP, nor is it believed to be associated with accretion.…”

Section: Mode Switchingmentioning

confidence: 99%

Timing Observations of PSR J1023+0038 During a Low-Mass X-Ray Binary State

Jaodand

Archibald

Hessels

et al. 2016

ApJ

146

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Transitional millisecond pulsars (tMSPs) switch, on roughly multi-year timescales, between rotation-powered radio millisecond pulsar (RMSP) and accretion-powered low-mass X-ray binary (LMXB) states. The tMSPs have raised several questions related to the nature of accretion flow in their LMXB state and the mechanism that causes the state switch. The discovery of coherent X-ray pulsations from PSRJ1023+0038 (while in the LMXB state) provides us withthe first opportunity to perform timing observationsand to compare the neutron star's spin variation during this state to the measured spin-down in the RMSP state. Whereas the X-ray pulsations in the LMXB state likely indicate that some material is accreting onto the neutron star's magnetic polar caps, radio continuum observations indicate thepresence of an outflow. The fraction of the inflowing material being ejected is not clear, but it may be much larger than that reaching the neutron star's surface. Timing observations can measure the total torque on the neutron star. We have phase-connected nine XMM-Newton observations of PSRJ1023 +0038over the last 2.5 years of the LMXB stateto establish a precise measurement of spin evolution. We find that the average spin-down rate as an LMXB is 26.8±0.4% faster than the rate (−2.39×10 −15 Hz s −1 ) determined during the RMSP state. This shows that negative angular momentum contributions (dipolar magnetic braking, andoutflow) exceed positive ones (accreted material), and suggests that the pulsar wind continues to operate at a largely unmodified level. We discuss implications of this tight observational constraint in the context of possible accretion models.

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Section: Mode Switchingmentioning

confidence: 99%

Timing Observations of PSR J1023+0038 During a Low-Mass X-Ray Binary State

Jaodand

Archibald

Hessels

et al. 2016

ApJ

146

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“…PSR B1931+24 has aν variation amplitude of 44.90%, but it is an intermittent pulsar with dramatic flux changes 22 . In October 2011, PSR J2021+4026 experienced a sudden change inν by 4% but no significant change in ν, and at the same time significant gamma-ray flux and profile variations were detected 23 , which are attributed to changes in the magnetosphere 23 . The SRT of PSR B0540-69 is similar to the timing instabilities of these pulsars, because they all show fast state transitions and appear to remain in the new states for months to years.…”

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confidence: 96%

The brightening of the pulsar wind nebula of PSR B0540−69 after its spin-down-rate transition

Yan

et al. 2019

Nat Astron

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It is believed that an isolated pulsar loses its rotational energy mainly through a relativistic wind consisting of electrons, positrons and possibly Poynting flux 1-3 . As it expands, this wind may eventually be terminated by a shock, where particles can be accelerated to energies of X-ray synchrotron emission, and a pulsar wind nebula (PWN) is usually detectable surrounding a young energetic pulsar 1-3 . However, the nature and/or energetics of these physical processes remain very uncertain, largely because they typically cannot be studied in a timeresolved fashion. Here we show that the X-ray PWN around the young pulsar PSR B0540-69 brightens gradually up to 32±8% over the mean previous flux, after a sudden spin-down rate (ν) transition (SRT) by ∼ 36% in December 2011, which has very different properties from a traditional pulsar glitch 4 . No evidence is seen for any change in the pulsed X-ray emission. We conclude that the SRT results from a sudden change in the pulsar magnetosphere that increases the pulsar wind power and hence the PWN X-ray emission. The X-ray light curve of the PWN suggests a mean life time of the particles of 397 ± 374 days, corresponding to a magnetic field strength of 0.78 +4.50 −0.28 mG in the PWN.

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“…The pulsar ephemeris we used was obtained from the Fermi -LAT data. Because PSR J2021+4026 is known to be variable , we selected an interval as close as possible to our observations (June 2008 to May 2009) and well before the "jump" which was observed by Allafort et al (2013) in October 2011. Given the AGILE pointing observing strategy, further addition of pointing data did not provide a significant improvement in the statistics and significance of the detection.…”

Section: Discussionmentioning

confidence: 99%

AGILE Study of the Gamma-Ray Emission from the SNR G78.2+2.1 (Gamma Cygni)

Piano

Cardillo

Pilia

et al. 2019

ApJ

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We present a study on the γ-ray emission detected by the AGILE-GRID from the region of the SNR G78.2+2.1 (Gamma Cygni). In order to investigate the possible presence of γ rays associated with the SNR below 1 GeV, it is necessary to analyze the γ-ray radiation underlying the strong emission from the pulsar PSR J2021+4026, which totally dominates the field. An "off-pulse" analysis has been carried out, by considering only the emission related to the pulsar off-pulse phase of the AGILE-GRID light curve. We found that the resulting off-pulsed emission in the region of the SNR -detected by the AGILE-GRID above 400 MeV -partially overlaps the radio shell boundary. By analyzing the averaged emission on the whole angular extent of the SNR, we found that a lepton-dominated double population scenario can account for the radio and γ-ray emission from the source. In particular, the MeV-GeV averaged emission can be explained mostly by Bremsstrahlung processes in a high density medium, whereas the GeV-TeV radiation by both Bremsstrahlung (E γ 250 GeV) and inverse Compton processes (E γ 250 GeV) in a lower density medium.

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PSR J2021+4026 IN THE GAMMA CYGNI REGION: THE FIRST VARIABLE γ-RAY PULSAR SEEN BY THE Fermi LAT

Cited by 74 publications

References 32 publications

Timing Observations of PSR J1023+0038 During a Low-Mass X-Ray Binary State

Timing Observations of PSR J1023+0038 During a Low-Mass X-Ray Binary State

The brightening of the pulsar wind nebula of PSR B0540−69 after its spin-down-rate transition

AGILE Study of the Gamma-Ray Emission from the SNR G78.2+2.1 (Gamma Cygni)

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