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Title: PSR J2021+4026 in the gamma Cygni region: The first variable γ-ray pulsar seen by the Fermi LAT

Abstract

Here, long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The "jump" was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33 ± 0.08) × 10–10 erg cm–2 s–1 to (6.86 ± 0.13) × 10–10 erg cm–2 s–1. Simultaneously, the frequency spindown rate increased from (7.8 ± 0.1) × 10–13 Hz s–1 to (8.1 ± 0.1) × 10–13 Hz s–1. Significant (>5σ) changes in the pulse profile and marginal (<3σ) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at γ-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. Furthermore, we argue that the change in pulsed γ-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.

Authors:
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Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1356554
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 777; Journal Issue: 1; Journal ID: ISSN 2041-8205
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gamma rays: stars; pulsars: individual (PSR J2021+4026); stars: neutron

Citation Formats

Allafort, A., Baldini, L., Ballet, J., Barbiellini, G., Baring, M. 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., de Palma, F., Digel, S. W., Di Venere, L., 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, K., Hays, E., Hewitt, J., Hill, A. B., Horan, D., Hou, X., Jogler, T., Johnson, A. S., Johnson, T. J., Kerr, M., Knödlseder, J., Kuss, M., Lande, J., Larsson, S., Latronico, L., Lemoine-Goumard, M., Longo, F., Loparco, F., Lubrano, P., Malyshev, D., Marelli, M., Mayer, M., Mazziotta, M. N., Mehault, 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, P. S., Razzano, M., Reimer, O., Reposeur, T., Romani, R. W., Sartori, A., Saz Parkinson, P. M., Sgrò, C., Siskind, E. J., Smith, D. 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. L., Vandenbroucke, J., Vasileiou, V., Venter, C., Vianello, G., Vitale, V., Winer, B. L., and Wood, K. S. PSR J2021+4026 in the gamma Cygni region: The first variable γ-ray pulsar seen by the Fermi LAT. United States: N. p., 2013. Web. doi:10.1088/2041-8205/777/1/L2.
Allafort, A., Baldini, L., Ballet, J., Barbiellini, G., Baring, M. 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., de Palma, F., Digel, S. W., Di Venere, L., 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, K., Hays, E., Hewitt, J., Hill, A. B., Horan, D., Hou, X., Jogler, T., Johnson, A. S., Johnson, T. J., Kerr, M., Knödlseder, J., Kuss, M., Lande, J., Larsson, S., Latronico, L., Lemoine-Goumard, M., Longo, F., Loparco, F., Lubrano, P., Malyshev, D., Marelli, M., Mayer, M., Mazziotta, M. N., Mehault, 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, P. S., Razzano, M., Reimer, O., Reposeur, T., Romani, R. W., Sartori, A., Saz Parkinson, P. M., Sgrò, C., Siskind, E. J., Smith, D. 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. L., Vandenbroucke, J., Vasileiou, V., Venter, C., Vianello, G., Vitale, V., Winer, B. L., & Wood, K. S. PSR J2021+4026 in the gamma Cygni region: The first variable γ-ray pulsar seen by the Fermi LAT. United States. doi:10.1088/2041-8205/777/1/L2.
Allafort, A., Baldini, L., Ballet, J., Barbiellini, G., Baring, M. 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., de Palma, F., Digel, S. W., Di Venere, L., 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, K., Hays, E., Hewitt, J., Hill, A. B., Horan, D., Hou, X., Jogler, T., Johnson, A. S., Johnson, T. J., Kerr, M., Knödlseder, J., Kuss, M., Lande, J., Larsson, S., Latronico, L., Lemoine-Goumard, M., Longo, F., Loparco, F., Lubrano, P., Malyshev, D., Marelli, M., Mayer, M., Mazziotta, M. N., Mehault, 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, P. S., Razzano, M., Reimer, O., Reposeur, T., Romani, R. W., Sartori, A., Saz Parkinson, P. M., Sgrò, C., Siskind, E. J., Smith, D. 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. L., Vandenbroucke, J., Vasileiou, V., Venter, C., Vianello, G., Vitale, V., Winer, B. L., and Wood, K. S. Wed . "PSR J2021+4026 in the gamma Cygni region: The first variable γ-ray pulsar seen by the Fermi LAT". United States. doi:10.1088/2041-8205/777/1/L2. https://www.osti.gov/servlets/purl/1356554.
@article{osti_1356554,
title = {PSR J2021+4026 in the gamma Cygni region: The first variable γ-ray pulsar seen by the Fermi LAT},
author = {Allafort, A. and Baldini, L. and Ballet, J. and Barbiellini, G. and Baring, M. G. and Bastieri, D. and Bellazzini, R. and Bonamente, E. and Bottacini, E. and Brandt, T. J. and Bregeon, J. and Bruel, P. and Buehler, R. and Buson, S. and Caliandro, G. A. and Cameron, R. A. and Caraveo, P. A. and Cecchi, C. and Chaves, R. C. G. and Chekhtman, A. and Chiang, J. and Chiaro, G. and Ciprini, S. and Claus, R. and D'Ammando, F. and de Palma, F. and Digel, S. W. and Di Venere, L. and Drell, P. S. and Favuzzi, C. and Ferrara, E. C. and Franckowiak, A. and Fusco, P. and Gargano, F. and Gasparrini, D. and Giglietto, N. and Giroletti, M. and Glanzman, T. and Godfrey, G. and Grenier, I. A. and Guiriec, S. and Hadasch, D. and Harding, A. K. and Hayashida, M. and Hayashi, K. and Hays, E. and Hewitt, J. and Hill, A. B. and Horan, D. and Hou, X. and Jogler, T. and Johnson, A. S. and Johnson, T. J. and Kerr, M. and Knödlseder, J. and Kuss, M. and Lande, J. and Larsson, S. and Latronico, L. and Lemoine-Goumard, M. and Longo, F. and Loparco, F. and Lubrano, P. and Malyshev, D. and Marelli, M. and Mayer, M. and Mazziotta, M. N. and Mehault, J. and Mizuno, T. and Monzani, M. E. and Morselli, A. and Murgia, S. and Nemmen, R. and Nuss, E. and Ohsugi, T. and Omodei, N. and Orienti, M. and Orlando, E. and Paneque, D. and Pesce-Rollins, M. and Pierbattista, M. and Piron, F. and Pivato, G. and Porter, T. A. and Rainò, S. and Rando, R. and Ray, P. S. and Razzano, M. and Reimer, O. and Reposeur, T. and Romani, R. W. and Sartori, A. and Saz Parkinson, P. M. and Sgrò, C. and Siskind, E. J. and Smith, D. A. and Spinelli, P. and Strong, A. W. and Takahashi, H. and Thayer, J. B. and Thompson, D. J. and Tibaldo, L. and Tinivella, M. and Torres, D. F. and Tosti, G. and Uchiyama, Y. and Usher, T. L. and Vandenbroucke, J. and Vasileiou, V. and Venter, C. and Vianello, G. and Vitale, V. and Winer, B. L. and Wood, K. S.},
abstractNote = {Here, long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The "jump" was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33 ± 0.08) × 10–10 erg cm–2 s–1 to (6.86 ± 0.13) × 10–10 erg cm–2 s–1. Simultaneously, the frequency spindown rate increased from (7.8 ± 0.1) × 10–13 Hz s–1 to (8.1 ± 0.1) × 10–13 Hz s–1. Significant (>5σ) changes in the pulse profile and marginal (<3σ) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at γ-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. Furthermore, we argue that the change in pulsed γ-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.},
doi = {10.1088/2041-8205/777/1/L2},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 777,
place = {United States},
year = {2013},
month = {10}
}

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Works referenced in this record:

Detection of 16 Gamma-Ray Pulsars Through Blind Frequency Searches Using the Fermi LAT
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THE VELA PULSAR: RESULTS FROM THE FIRST YEAR OF FERMI LAT OBSERVATIONS
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THE FERMI ALL-SKY VARIABILITY ANALYSIS: A LIST OF FLARING GAMMA-RAY SOURCES AND THE SEARCH FOR TRANSIENTS IN OUR GALAXY
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A Cocoon of Freshly Accelerated Cosmic Rays Detected by Fermi in the Cygnus Superbubble
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The Imprint of the Extragalactic Background Light in the Gamma-Ray Spectra of Blazars
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Phase-Resolved Spectroscopy of Geminga Shows Rotating Hot Spot(s)
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Study of the γ -ray source 1AGL J2022+4032 in the Cygnus region
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Two‐Pole Caustic Model for High‐Energy Light Curves of Pulsars
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Change in the high-energy radiation from the Crab
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Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere
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DISCOVERY OF NINE GAMMA-RAY PULSARS IN FERMI LARGE AREA TELESCOPE DATA USING A NEW BLIND SEARCH METHOD
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PRECISE γ-RAY TIMING AND RADIO OBSERVATIONS OF 17 FERMI γ-RAY PULSARS
journal, April 2011


Constraining Pulsar Magnetosphere Geometry with γ-Ray Light Curves
journal, April 2010


Multiwavelength properties of a new Geminga-like pulsar: PSR J2021+4026
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The Identification of the X-Ray Counterpart to psr J2021+4026
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    Works referencing / citing this record:

    Pulsar gamma-rays - Spectra, luminosities, and efficiencies
    journal, April 1981

    • Harding, A. K.
    • The Astrophysical Journal, Vol. 245
    • DOI: 10.1086/158807

    A study of 315 glitches in the rotation of 102 pulsars: A study of 315 glitches in 102 pulsars
    journal, April 2011


    THE LARGE AREA TELESCOPE ON THE FERMI GAMMA-RAY SPACE TELESCOPE MISSION
    journal, May 2009


    The Imprint of the Extragalactic Background Light in the Gamma-Ray Spectra of Blazars
    journal, November 2012


    JPL pulsar timing observations. III - Pulsar rotation fluctuations
    journal, November 1985

    • Cordes, J. M.; Downs, G. S.
    • The Astrophysical Journal Supplement Series, Vol. 59
    • DOI: 10.1086/191076

    THE FERMI LARGE AREA TELESCOPE ON ORBIT: EVENT CLASSIFICATION, INSTRUMENT RESPONSE FUNCTIONS, AND CALIBRATION
    journal, October 2012

    • Ackermann, M.; Ajello, M.; Albert, A.
    • The Astrophysical Journal Supplement Series, Vol. 203, Issue 1
    • DOI: 10.1088/0067-0049/203/1/4

    Vortex creep and the internal temperature of neutron stars. I - General theory
    journal, January 1984

    • Alpar, M. A.; Pines, D.; Anderson, P. W.
    • The Astrophysical Journal, Vol. 276
    • DOI: 10.1086/161616

    Detection of 16 Gamma-Ray Pulsars Through Blind Frequency Searches Using the Fermi LAT
    journal, July 2009


    Pulsars as tools for fundamental physics & astrophysics
    journal, December 2004


    Switched Magnetospheric Regulation of Pulsar Spin-Down
    journal, June 2010


    Multiwavelength properties of a new Geminga-like pulsar: PSR J2021+4026
    journal, April 2010


    DISCOVERY OF NINE GAMMA-RAY PULSARS IN FERMI LARGE AREA TELESCOPE DATA USING A NEW BLIND SEARCH METHOD
    journal, December 2011


    FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG
    journal, March 2012

    • Nolan, P. L.; Abdo, A. A.; Ackermann, M.
    • The Astrophysical Journal Supplement Series, Vol. 199, Issue 2
    • DOI: 10.1088/0067-0049/199/2/31

    Variability of EGRET Gamma‐Ray Sources
    journal, November 2003

    • Nolan, P. L.; Tompkins, W. F.; Grenier, I. A.
    • The Astrophysical Journal, Vol. 597, Issue 1
    • DOI: 10.1086/378353

    A Cocoon of Freshly Accelerated Cosmic Rays Detected by Fermi in the Cygnus Superbubble
    journal, November 2011


    New perspectives on the supernova remnant G78.2+2.1
    journal, August 2008


    Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere
    journal, January 2013


    tempo2, a new pulsar-timing package - I. An overview: tempo2, a new pulsar-timing package - I. Overview
    journal, May 2006


    Study of the γ -ray source 1AGL J2022+4032 in the Cygnus region
    journal, November 2010


    PSR J2021+4026 IN THE GAMMA CYGNI REGION: THE FIRST VARIABLE γ-RAY PULSAR SEEN BY THE Fermi LAT
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    • DOI: 10.1086/380486

    THE FERMI ALL-SKY VARIABILITY ANALYSIS: A LIST OF FLARING GAMMA-RAY SOURCES AND THE SEARCH FOR TRANSIENTS IN OUR GALAXY
    journal, June 2013


    Discovery of X-Ray Pulsation from the Geminga-Like Pulsar psr J2021+4026
    journal, May 2013


    PRECISE γ-RAY TIMING AND RADIO OBSERVATIONS OF 17 FERMI γ-RAY PULSARS
    journal, April 2011


    Pulsar state switching, timing noise and free precession: State switching, timing noise and precession
    journal, January 2012


    Constraining Pulsar Magnetosphere Geometry with γ-Ray Light Curves
    journal, April 2010


    THE VELA PULSAR: RESULTS FROM THE FIRST YEAR OF FERMI LAT OBSERVATIONS
    journal, March 2010


    Phase-Resolved Spectroscopy of Geminga Shows Rotating Hot Spot(s)
    journal, July 2004


    Second AGILE catalogue of gamma-ray sources
    journal, June 2019


    SEARCH FOR SPATIALLY EXTENDED FERMI LARGE AREA TELESCOPE SOURCES USING TWO YEARS OF DATA
    journal, August 2012


    Two‐Pole Caustic Model for High‐Energy Light Curves of Pulsars
    journal, December 2003

    • Dyks, J.; Rudak, B.
    • The Astrophysical Journal, Vol. 598, Issue 2
    • DOI: 10.1086/379052

    The Identification of the X-Ray Counterpart to psr J2021+4026
    journal, November 2011

    • Weisskopf, Martin C.; Romani, Roger W.; Razzano, Massimiliano
    • The Astrophysical Journal, Vol. 743, Issue 1
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    Change in the high-energy radiation from the Crab
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    • The Astrophysical Journal, Vol. 197
    • DOI: 10.1086/153532

    Second AGILE catalogue of gamma-ray sources
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    The brightening of the pulsar wind nebula of PSR B0540−69 after its spin-down-rate transition
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    Fermi Large Area Telescope Fourth Source Catalog
    journal, March 2020

    • Abdollahi, S.; Acero, F.; Ackermann, M.
    • The Astrophysical Journal Supplement Series, Vol. 247, Issue 1
    • DOI: 10.3847/1538-4365/ab6bcb