15 research outputs found
The TRAPUM L-band survey for pulsars in Fermi-LAT gamma-ray sources
More than 100 millisecond pulsars (MSPs) have been discovered in radio
observations of gamma-ray sources detected by the Fermi Large Area Telescope
(LAT), but hundreds of pulsar-like sources remain unidentified. Here we present
the first results from the targeted survey of Fermi-LAT sources being performed
by the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. We
observed 79 sources identified as possible gamma-ray pulsar candidates by a
Random Forest classification of unassociated sources from the 4FGL catalogue.
Each source was observed for 10 minutes on two separate epochs using MeerKAT's
L-band receiver (856-1712 MHz), with typical pulsed flux density sensitivities
of 100Jy. Nine new MSPs were discovered, eight of which are in
binary systems, including two eclipsing redbacks and one system, PSR
J15262744, that appears to have a white dwarf companion in an unusually
compact 5 hr orbit. We obtained phase-connected timing solutions for two of
these MSPs, enabling the detection of gamma-ray pulsations in the Fermi-LAT
data. A follow-up search for continuous gravitational waves from PSR
J15262744 in Advanced LIGO data using the resulting Fermi-LAT timing
ephemeris yielded no detection, but sets an upper limit on the neutron star
ellipticity of . We also detected X-ray emission from the
redback PSR J18036707 in data from the first eROSITA all-sky survey, likely
due to emission from an intra-binary shock.Comment: 17 pages, 8 figures, accepted for publication in MNRA
The TRAPUM L-band survey for pulsars in Fermi-LAT gamma-ray sources
More than 100 millisecond pulsars (MSPs) have been discovered in radioobservations of gamma-ray sources detected by the Fermi Large Area Telescope(LAT), but hundreds of pulsar-like sources remain unidentified. Here we presentthe first results from the targeted survey of Fermi-LAT sources being performedby the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. Weobserved 79 sources identified as possible gamma-ray pulsar candidates by aRandom Forest classification of unassociated sources from the 4FGL catalogue.Each source was observed for 10 minutes on two separate epochs using MeerKAT'sL-band receiver (856-1712 MHz), with typical pulsed flux density sensitivitiesof 100Jy. Nine new MSPs were discovered, eight of which are inbinary systems, including two eclipsing redbacks and one system, PSRJ15262744, that appears to have a white dwarf companion in an unusuallycompact 5 hr orbit. We obtained phase-connected timing solutions for two ofthese MSPs, enabling the detection of gamma-ray pulsations in the Fermi-LATdata. A follow-up search for continuous gravitational waves from PSRJ15262744 in Advanced LIGO data using the resulting Fermi-LAT timingephemeris yielded no detection, but sets an upper limit on the neutron starellipticity of . We also detected X-ray emission from theredback PSR J18036707 in data from the first eROSITA all-sky survey, likelydue to emission from an intra-binary shock.<br
Mass estimates from optical modelling of the new TRAPUM redback PSR J1910−5320
Spider pulsars continue to provide promising candidates for neutron star mass measurements. Here we present the discovery of PSR J1910−5320, a new millisecond pulsar discovered in a MeerKAT observation of an unidentified Fermi-LAT gamma-ray source. This pulsar is coincident with a recently identified candidate redback binary, independently discovered through its periodic optical flux and radial velocity. New multicolour optical light curves obtained with ULTRACAM/New Technology Telescope in combination with MeerKAT timing and updated SOAR/Goodman spectroscopic radial velocity measurements allow a mass constraint for PSR J1910−5320. icarus optical light curve modelling, with streamlined radial velocity fitting, constrains the orbital inclination and companion velocity, unlocking the binary mass function given the precise radio ephemeris. Our modelling aims to unite the photometric and spectroscopic measurements available by fitting each simultaneously to the same underlying physical model, ensuring self-consistency. This targets centre-of-light radial velocity corrections necessitated by the irradiation endemic to spider systems. Depending on the gravity darkening prescription used, we find a moderate neutron star mass of either 1.6 ± 0.2 or 1.4 ± 0.2 M⊙. The companion mass of either 0.45 ± 0.04 or M⊙ also further confirms PSR J1910−5320 as an irradiated redback spider pulsar
Chromosomal polymorphism in species of the Drosophila nasuta complex in East and South East Asia
Ultrastructural studies on Nicotiana benthamiana tissue following infection with a virus transmitted from mosaic-diseased Nigerian cassava
A targeted radio pulsar survey of redback candidates with MeerKAT
International audienceRedbacks are millisecond pulsar binaries with low mass, irradiated companions. These systems have a rich phenomenology that can be used to probe binary evolution models, pulsar wind physics, and the neutron star mass distribution. A number of high-confidence redback candidates have been identified through searches for variable optical and X-ray sources within the localisation regions of unidentified but pulsar-like Fermi-LAT gamma-ray sources. However, these candidates remain unconfirmed until pulsations are detected. As part of the TRAPUM project, we searched for radio pulsations from six of these redback candidates with MeerKAT. We discovered three new radio millisecond pulsars, PSRs J08382527, J09553947 and J23335526, confirming their redback nature. PSR J08382827 remained undetected for two years after our discovery despite repeated observations, likely due to evaporated material absorbing the radio emission for long periods of time. While, to our knowledge, this system has not undergone a transition to an accreting state, the disappearance, likely caused by extreme eclipses, illustrates the transient nature of spider pulsars and the heavy selection bias in uncovering their radio population. Radio timing enabled the detection of gamma-ray pulsations from all three pulsars, from which we obtained 15-year timing solutions. All of these sources exhibit complex orbital period variations consistent with gravitational quadrupole moment variations in the companion stars. These timing solutions also constrain the binary mass ratios, allowing us to narrow down the pulsar masses. We find that PSR J23335526 may have a neutron star mass in excess of 2 M