Discovery of an Extremely Intermittent Periodic Radio Source

International audienceWe report the serendipitous discovery of an extremely intermittent radio pulsar, PSR J1710-3452, with a relatively long spin period of 10.4 s. The object was discovered through the detection of 97 bright radio pulses in only one out of 66 epochs of observations spanning almost three years. The bright pulses have allowed the source to be localised to a precision of 0.5" through radio imaging. We observed the source location with the Swift X-ray telescope but did not detect any significant X-ray emission. We did not identify any high-energy bursts or multi-frequency counterparts for this object. The solitary epoch of detection hinders the calculation of the surface magnetic field strength, but the long period and the microstructure in the single-pulses resembles the emission of radio-loud magnetars. If this is indeed a magnetar, it is located at a relatively high Galactic latitude (2.9 degree), making it potentially one of the oldest and the most intermittent magnetars known in the Galaxy. The very short activity window of this object is unique and may point towards a yet undetected population of long period, highly transient radio emitting neutron stars

A sample of Fast Radio Bursts discovered and localised with MeerTRAP at the MeerKAT telescope

International audienceWe present a sample of well-localised Fast Radio Bursts (FRBs) discovered by the MeerTRAP project at the MeerKAT telescope in South Africa. We discovered the three FRBs in single coherent tied-array beams and localised them to an area of ~1 arcmin$^2$. We investigate their burst properties, scattering, repetition rates, and localisations in a multi-wavelength context. FRB 20201211A shows hints of scatter broadening but is otherwise consistent with instrumental dispersion smearing. For FRB 20210202D, we discovered a faint post-cursor burst separated by ~200 ms, suggesting a distinct burst component or a repeat pulse. We attempt to associate the FRBs with host galaxy candidates. For FRB 20210408H, we tentatively (0.35 - 0.53 probability) identify a compatible host at a redshift ~0.5. Additionally, we analyse the MeerTRAP survey properties, such as the survey coverage, fluence completeness, and their implications for the FRB population. Based on the entire sample of 11 MeerTRAP FRBs discovered by the end of 2021, we estimate the FRB all-sky rates and their scaling with the fluence threshold. The inferred FRB all-sky rates at 1.28 GHz are $4.4_{-2.5}^{+4.3}$ and $2.1_{-1.1}^{+1.8} \times 10^3$ sky$^{-1}$ d$^{-1}$ above 0.66 and 3.44 Jy ms for the coherent and incoherent surveys, respectively. The scaling between the MeerTRAP rates is flatter than at higher fluences at the 95 per cent confidence level. There seems to be a deficit of low-fluence FRBs, suggesting a break or turn-over in the rate versus fluence relation below 2 Jy ms. We speculate on cosmological or progenitor-intrinsic origins. The cumulative source counts within our surveys appear consistent with the Euclidean scaling

A MeerKAT, e-MERLIN, HESS, and Swift search for persistent and transient emission associated with three localized FRBs

We report on a search for persistent radio emission from the one-off fast radio burst (FRB) 20190714A, as well as from two repeating FRBs, 20190711A and 20171019A, using the MeerKAT radio telescope. For FRB 20171019A, we also conducted simultaneous observations with the High-Energy Stereoscopic System (H.E.S.S.) in very high-energy gamma rays and searched for signals in the ultraviolet, optical, and X-ray bands. For this FRB, we obtain a UV flux upper limit of 1 . 39 ×10 −16 erg cm −2 s −1 Å−1 , X-ray limit of ∼6 . 6 ×10 −14 erg cm −2 s −1 and a limit on the very high energy gamma-ray flux Φ ( E > 120 GeV ) < 1 . 7 ×10 −12 erg cm −2 s −1 . We obtain a radio upper limit of ∼15 μJy beam −1 for persistent emission at the locations of both FRBs 20190711A and 20171019A with MeerKAT. Ho we ver, we detected an almost unresolved (ratio of integrated flux to peak flux is ∼1.7 beam) radio emission, where the synthesized beam size was ∼8 arcsec size with a peak brightness of ∼53 μJy beam −1 at MeerKAT and ∼86 μJy beam −1 at e-MERLIN, possibly associated with FRB 20190714A at z = 0.2365. This represents the first detection of persistent continuum radio emission potentially associated with a (as-yet) non-repeating FRB. If the association is confirmed, one of the strongest remaining distinction between repeaters and non-repeaters would no longer be applicable. A parallel search for repeat bursts from these FRBs revealed no new detections down to a fluence of 0.08 Jy ms for a 1 ms duration burst.J. O. Chibueze, M. Caleb, L. Spitler, H. Ashkar, F. Sch, ussler, B. W. Stappers, C. Venter, I. Heywood, A. M. S. Richards, D. R. A. Williams, M. Kramer, R. Beswick, M. C. Bezuidenhout, R. P. Breton, L. N. Driessen, F. Jankowski, E. F. Keane, M. Malenta, M. Mickaliger, V. Morello, H. Qiu, K. Rajwade, S. Sanidas, M. Surnis, T. W. Scragg, C. R. H. Walker, N. Wrigley, H.E.S.S. Collaboration, F. Aharonian, F. Ait Benkhali, E. O. Ang, uner, M. Backes, V. Baghmanyan, V. Barbosa Martins, R. Batzofin, Y. Becherini, D. Berge, M. B, ottcher, C. Boisson, J. Bolmont, M. de Bony de Lavergne, M. Breuhaus, R. Brose, F. Brun, T. Bulik, F. Cangemi, S. Caroff, S. Casanova, J. Catalano, M. Cerruti, T. Chand, A. Chen, O. U. Chibueze, G. Cotter, P. Cristofari, J. Damascene Mbarubuc ye ye, J. Devin, A. Djannati-Ata, ı, A. Dmytriiev, K. Egberts, J.-P. Ernenwein, A. Fiasson, G. Fichet de Clairfontaine, G. Fontaine, S. Funk, S. Gabici, S. Ghafourizadeh, G. Giavitto, D. Glawion, M.-H. Grondin, M. H, orbe, C. Hoischen, T. L. Holch, Zhiqiu Huang, M. Jamrozy, F. Jankowsky, V. Joshi, I. Jung-Richardt, E. Kasai, K. Katarzy, nski, U. Katz, B. Kh, elifi, W. Klu, zniak, Nu. Komin, K. Kosack, D. Kostunin, A. Lemi, ere, J.-P. Lenain, F. Leuschner, T. Lohse, A. Luashvili, I. Lypova, J. Mackey, D. Malyshev, V. Marandon, P. Marchegiani, A. Marcowith, G. Mart, ı-Devesa, R. Marx, A. Mitchell, R. Moderski, L. Mohrmann, E. Moulin, J. Muller, K. Nakashima, M. de Naurois, A. Nayerhoda, J. Niemiec, A. Priyana Noel, P. O, Brien, S. Ohm, L. Olivera-Nieto, E. de Ona Wilhelmi, M. Ostrowski, S. P ann y, R. D. P arsons, S. Pita, V. Poireau, D. A. Prokhorov, H. Prokoph, G. P, uhlhofer, A. Quirrenbach, P. Reichherzer, A. Reimer, O. Reimer, G. Rowell, B. Rudak, E. Ruiz-Velasco, V. Sahakian, S. Sailer, H. Salzmann, D. A. Sanchez, A. Santangelo, M. Sasaki, H. M. Schutte, U. Schw ank e, J. N. S. Shapopi, A. Specovius, S. Spencer, R. Steenkamp, S. Steinmassl, T . Takahashi, T . Tanaka, C. Thorpe-Morgan, N. Tsuji, C. van Eldik, J. Veh, J. Vink, S. J. Wagner, A. Wierzcholska, Yu Wun Wong, A. Yusafzai, M. Zacharias, D. Zargaryan, A. A. Zdziarski, A. Zech, S. J. Zhu, S. Zouari, and N., Zywuck

A study of two FRBs with low polarization fractions localized with the MeerTRAP transient buffer system

International audienceLocalisation of fast radio bursts (FRBs) to arcsecond and sub-arcsecond precision maximizes their potential as cosmological probes. To that end, FRB detection instruments are deploying triggered complex-voltage capture systems to localize FRBs, identify their host galaxy and measure a redshift. Here, we report the discovery and localisation of two FRBs (20220717A and 20220905A) that were captured by the transient buffer system deployed by the MeerTRAP instrument at the MeerKAT telescope in South Africa. We were able to localize the FRBs to a precision of $\sim$1 arc-second that allowed us to unambiguously identify the host galaxy for FRB 20220717A (posterior probability$\sim$0.97). FRB 20220905A lies in a crowded region of the sky with a tentative identification of a host galaxy but the faintness and the difficulty in obtaining an optical spectrum preclude a conclusive association. The bursts show low linear polarization fractions (10--17$\%$) that conform to the large diversity in the polarization fraction observed in apparently non-repeating FRBs akin to single pulses from neutron stars. We also show that the host galaxy of FRB 20220717A contributes roughly 15$\%$ of the total dispersion measure (DM), indicating that it is located in a plasma-rich part of the host galaxy which can explain the large rotation measure. The scattering in FRB 20220717A can be mostly attributed to the host galaxy and the intervening medium and is consistent with what is seen in the wider FRB population