skip to main content

DOE PAGESDOE PAGES

Title: A Search for Transitions between States in Redbacks and Black Widows Using Seven Years of Fermi-LAT Observations

Considering about seven years of Fermi-Large Area Telescope (LAT) data, we present a systematic search for variability that is possibly related to transitions between states in redbacks and black widow systems. In addition, the transitions are characterized by sudden and significant changes in the gamma-ray flux that persist on a timescale that is much larger than the orbital period. This phenomenology was already detected in the case of two redback systems, PSR J1023+0038 and PSR J1227-4853, which we present here. We show the existence of only one transition for each of these systems over the past seven years. We determine their spectra, establishing high-energy cutoffs at a few GeV for the high gamma-ray state of PSR J1023+0038, and for both states of PSR J1227-4853. The surveying capability of the Fermi-LAT allows further study of whether similar phenomenology has occurred in other sources. Although we have not found any evidence of a state transition for most of the studied pulsars, we note two black-widow systems, PSR J2234+0944 and PSR J1446-4701, whose apparent variabilities are reminiscent of the transitions in PSR J1023+0038 and PSR J1227-4853. Finally, for the other systems, we set limits on potential transitions in their measured gamma-ray light curves.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ;  [4] ; ORCiD logo [5] ;  [4] ;  [6]
  1. Institute of Space Sciences (IEEC-CSIC), Campus UAB, Barcelona (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA), Barcelona (Spain)
  2. Chinese Academy of Sciences (CAS), Beijing (China). Key Laboratory for Particle Astrophysics, Institute of High Energy Physics; Institut fur Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics (Germany)
  3. Institute of Space Sciences (IEEC-CSIC), Campus UAB, Barcelona (Spain)
  4. INAF-Osservatorio Astronomico di Roma (Italy)
  5. Institute of Space Sciences (IEEC-CSIC), Campus UAB, Barcelona (Spain); University of Amsterdam (The Netherlands). Anton Pannekoek Institute
  6. Chinese Academy of Sciences (CAS), Beijing (China). Key Laboratory for Particle Astrophysics, Institute of High Energy Physics
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 836; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Contributing Orgs:
Fermi LAT Collaboration
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gamma-ray: observations; pulsars: individual (PSR J1023+0038, PSR J1227−4853)
OSTI Identifier:
1355738