TY - JOUR
T1 - A Search for Transitions between States in Redbacks and Black Widows Using Seven Years of Fermi-LAT Observations
AU - Torres, Diego F.
AU - Ji, Long
AU - Li, Jian
AU - Papitto, Alessandro
AU - Rea, Nanda
AU - Wilhelmi, Emma De Oña
AU - Zhang, Shu
PY - 2017/2/10
Y1 - 2017/2/10
N2 - © 2017. The American Astronomical Society. All rights reserved.. 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. 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. For the other systems, we set limits on potential transitions in their measured gamma-ray light curves.
AB - © 2017. The American Astronomical Society. All rights reserved.. 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. 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. For the other systems, we set limits on potential transitions in their measured gamma-ray light curves.
KW - gamma-rays: stars
KW - pulsars: individual (PSR J1023+0038, PSR J1227-4853)
U2 - 10.3847/1538-4357/836/1/68
DO - 10.3847/1538-4357/836/1/68
M3 - Article
VL - 836
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 68
ER -