Search for transitions between states in redbacks and black widows using seven years of Fermi-LAT observations

Abstract

Considering about seven years of Fermi-Large Area Telescope (LAT) data, we present a systematic search for variability possibly related to transitions between states in redbacks and black widow systems. Transitions are characterized by sudden and significant changes in the gamma-ray flux that persist on a timescale 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, for which we present here a dedicated study. 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 studying whether similar phenomenology has occurred in other sources. Although we have not found any hint for a state transition for most of the studied pulsars, we note two black-widow systems, PSR J2234+0944 and PSR J1446-4701, whose apparent variability is reminiscent of the transitions in PSR J1023+0038 and PSR J1227-4853. For the other systems we set limits on potential transitions in their measured gamma-ray light curves.

20 pages, 3 figures, 2 tables. Accepted for publication in ApJ

References in corpus (6)

• A Radio Pulsar/X-ray Binary Link
• Discovery of PSR J1227-4853: A transition from a low-mass X-ray binary to a redback millisecond pulsar
• Identification of the High-Energy Gamma-Ray Source 3FGL J1544.6-1125 as a Transitional Millisecond Pulsar Binary in an Accreting State
• Spin frequency distributions of binary millisecond pulsars
• Evidence for gamma-ray emission from the low-mass X-ray binary system FIRST J102347.6+003841
• Discovery of Gamma-ray Pulsations from the Transitional Redback PSR J1227-4853

Cited by in corpus (9)

• Prolonged sub-luminous state of the new transitional pulsar candidate CXOU J110926.4-650224
• Precise optical timing of PSR J1023+0038, the first millisecond pulsar detected with Aqueye+ in Asiago
• High-Energy Variability of PSR J1311-3430
• The permanent ellipticity of the neutron star in PSR J1023+0038
• The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars
• NuSTAR and Parkes observations of the transitional millisecond pulsar binary XSS J12270-4859 in the rotation-powered state
• 4FGL J1120.0-2204: A Unique Gamma-ray Bright Neutron Star Binary with an Extremely Low Mass Proto-White Dwarf
• A Multi-wavelength search for Black Widows and Redbacks counterparts of candidate $\gamma$-ray millisecond pulsars
• Investigation of the Millisecond Pulsar Origins by their Spin Periods at the Wavebands of Radio, X-Ray, and γ-Ray