![]() In spite of the beam-widening expected at low radio frequencies, most of our nondetections can be explained by an unfavorable viewing geometry for the remaining observations, especially those of pulsars detected at higher frequencies, the nondetection is compatible with insufficient sensitivity. We also determine the pulsars' geometry from the gamma-ray profiles to see for which pulsars the low-frequency radio beam is expected to cross Earth.Ĭonclusions: This set of observations provides the most constraining upper limits on the flux density at 150 MHz for 27 radio-quiet gamma-ray pulsars. These nondetections are compatible with the upper limits derived from radio observations at other frequencies. Results: We do not detect radio pulsations from any of the 27 sources, and we establish stringent upper limits on their low-frequency radio fluxes. On average, we kept 9 h of observation per target after the removal of affected datasets, resulting in a sensitivity for pulse-averaged flux on the order of 1−10 mJy. Part of the data had to be discarded due to radio frequency interference. We used the LOFAR high band antenna band (110−190 MHz), with an average observing time of 13 h per target. However, pulsar radio fluxes increase rapidly. Most radio observations of gamma-ray pulsars have been performed at frequencies between 300 MHz and 2 GHz. In the population of nonrecycled gamma-ray pulsars, the fraction of radio-quiet pulsars is higher, about one half. About one quarter of these are labeled as radio-quiet. Methods: We have observed 27 Fermi-discovered gamma-ray pulsars with the international LOw Frequency ARray (LOFAR) station FR606 in single-station mode. The Fermi Large Area Telescope has detected over 260 gamma-ray pulsars. Our aim is to test this hypothesis with low-frequency radio observations. ![]() As a consequence, some of these pulsars might be detectable at low radio frequencies even when no radio flux is detected above 300 MHz. You will find yourself to get attracted by the sheer level of engagement of the radio. Radio Gamma 99.7 will entertain you in a very entertaining and engaging manner. However, pulsar radio fluxes increase rapidly with decreasing frequency, and their radio beams often broaden at low frequencies. If you don’t like some borng stuff a radio often presents one after one than Radio Gamma 99.7 could be the fresh content based radio you might be searching for. In the population of nonrecycled gamma-ray pulsars, the fraction of radio-quiet pulsars is higher, about one half.Īims: Most radio observations of gamma-ray pulsars have been performed at frequencies between 300 MHz and 2 GHz. About one quarter of these are labeled as radio-quiet, that is they either have radio flux densities < 30 μJy at 1400 MHz, or they are not detected at all in the radio domain. The Fermi Large Area Telescope has detected over 260 gamma-ray pulsars.
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