Two New Black Widow Millisecond Pulsars in M28

Douglas, Andrew J.; Padmanabh, P. V.; Ransom, S. M.; Ridolfi, A.; Freire, P. C. C.; Krishnan, V. Venkatraman; Barr, E. D.; Pallanca, Cristina; Cadelano, Mario; Possenti, A.; Stairs, I. H.; Hessels, J. W. T.; DeCesar, Megan E.; Lynch, R.; Bailes, M.; Burgay, M.; Champion, D. J.; Karuppusamy, R.; Krämer, M.; Stappers, B. W.; Calas, Laila Vleeschower

doi:10.3847/1538-4357/ac4744

Cited by 12 publications

(15 citation statements)

References 46 publications

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“…Indeed, for all pulsars except B their excess counts have a probability <10 −5 of being produced by background fluctuations (Cheng et al 2020). We did not detect the newly discovered pulsar N, but we were able to measure L X for the new MSP M28M (Douglas et al 2022). In Table 2, we give the wide range of net counts (18-13418) and count rates (6 × 10 −5 -4 × 10 −2 c s −1 ) for the NSs studied in this work.…”

Section: Resultsmentioning

confidence: 99%

“…For this paper we are primarily concerned with the more recent GUPPI observations, which we partially integrated both in time (by a factor of 4) and frequency (also by a factor of 4, dedispersing the channels incoherently) to give us 40.96 μs total-intensity samples in 128 frequency channels covering 800 MHz of radio bandwidth, of which ∼650 MHz was typically usable due to radio frequency interference. More information is available about the archival data and its processing in Douglas et al (2022). We present the radio positions of the 14 known pulsars in M28 in Table A1.…”

Section: Green Bank Telescopementioning

confidence: 99%

“…M's and Nʼs radio positions are taken from Douglas et al (2022). X-ray positions of I, L, and their positional uncertainties (68% c. l.) are taken from Becker et al (2003).…”

Section: New Faint and Variable X-ray Sourcesmentioning

confidence: 99%

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The Neutron Star Population in M28: A Joint Chandra/GBT Look at Pulsar Paradise

Vurgun

Linares

Ransom

et al. 2022

ApJ

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We present the results of a deep study of the neutron star (NS) population in the globular cluster M28 (NGC 6626), using the full 330 ks 2002–2015 ACIS data set from the Chandra X-ray Observatory and coordinated radio observations taken with the Green Bank Telescope (GBT) in 2015. We investigate the X-ray luminosity (L X ), spectrum, and orbital modulation of the seven known compact binary millisecond pulsars in the cluster. We report two simultaneous detections of the redback PSR J1824−2452I (M28I) and its X-ray counterpart at L X = [8.3 ± 0.9] × 1031 erg s−1. We discover a double-peaked X-ray orbital flux modulation in M28I during its pulsar state, centered around pulsar inferior conjunction. We analyze the spectrum of the quiescent NS low-mass X-ray binary to constrain its mass and radius. Using both hydrogen and helium NS atmosphere models, we find an NS radius of R = 9.2–11.5 km and R = 13.0–17.5 km, respectively, for an NS mass of 1.4 M ⊙ (68% confidence ranges). We also search for long-term variability in the 46 brightest X-ray sources and report the discovery of six new variable low-luminosity X-ray sources in M28.

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Section: Resultsmentioning

confidence: 99%

Section: Green Bank Telescopementioning

confidence: 99%

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The Neutron Star Population in M28: A Joint Chandra/GBT Look at Pulsar Paradise

Vurgun

Linares

Ransom

et al. 2022

ApJ

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“…About one-third of these (e.g. Ridolfi et al 2021;Douglas et al 2022;Ridolfi et al 2022;Vleeschower et al 2022;Abbate et al 2022), are found in various GCs, including 47 Tucanae (Chen et al, in prep. ), a cluster that has been searched for over 20 years.…”

Section: The Meerkat Surveymentioning

confidence: 99%

MeerKAT discovery of 13 new pulsars in Omega Centauri

Chen

Freire

Ridolfi

et al. 2023

Monthly Notices of the Royal Astronomical Society

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The most massive globular cluster in our Galaxy, Omega Centauri, is an interesting target for pulsar searches, because of its multiple stellar populations and the intriguing possibility that it was once the nucleus of a galaxy that was absorbed into the Milky Way. The recent discoveries of pulsars in this globular cluster and their association with known X-ray sources was a hint that, given the large number of known X-ray sources, there is a much larger undiscovered pulsar population. We used the superior sensitivity of the MeerKAT radio telescope to search for pulsars in Omega Centauri. In this paper, we present some of the first results of this survey, including the discovery of 13 new pulsars; the total number of known pulsars in this cluster currently stands at 18. At least half of them are in binary systems and preliminary orbital constraints suggest that most of the binaries have light companions. We also discuss the ratio between isolated and binaries pulsars and how they were formed in this cluster.

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“…These searches have proven to be fruitful with the discovery of 38 new pulsars in 11 different GCs so far 5 (e.g. Ridolfi et al 2021;Douglas et al 2022;Ridolfi et al 2022).…”

mentioning

confidence: 99%

Discoveries and Timing of Pulsars in NGC 6440

Vleeschower,

Stappers,

Bailes

et al. 2022

Preprint

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Using the MeerKAT radio telescope, a series of observations have been conducted to time the known pulsars and search for new pulsars in the globular cluster NGC 6440. As a result, two pulsars have been discovered, NGC 6440G and NGC 6440H, one of which is isolated and the other a non-eclipsing (at frequencies above 962 MHz) "Black Widow", with a very low mass companion (M c > 0.006 M ). It joins the other binary pulsars discovered so far in this cluster which all have low companion masses (M c < 0.30 M ). We present the results of long-term timing solutions obtained using data from both Green Bank and MeerKAT telescopes for these two new pulsars and an analysis of the pulsars NGC 6440C and NGC 6440D. For the isolated pulsar NGC 6440C, we searched for planets using a Markov Chain Monte Carlo technique. We find evidence for significant unmodelled variations but they cannot be well modelled as planets nor as part of a power-law red-noise process. Studies of the eclipses of the "Redback" pulsar NGC 6440D at two different frequency bands reveal a frequency dependence with longer and asymmetric eclipses at lower frequencies (962-1283 MHz).

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Two New Black Widow Millisecond Pulsars in M28

Cited by 12 publications

References 46 publications

The Neutron Star Population in M28: A Joint Chandra/GBT Look at Pulsar Paradise

The Neutron Star Population in M28: A Joint Chandra/GBT Look at Pulsar Paradise

MeerKAT discovery of 13 new pulsars in Omega Centauri

Discoveries and Timing of Pulsars in NGC 6440

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