The population of M dwarfs observed at low radio frequencies

Callingham, J. R.; Vedantham, H. K.; Shimwell, T. W.; Pope, Benjamin; Davis, Ivey; Best, P. N.; Hardcastle, Martin; Röttgering, H. J. A.; Sabater, J.; Tasse, C.; Weeren, R. J. van; Williams, W. L.; Zarka, Philippe; Gasperin, F. de; Drabent, A.

doi:10.1038/s41550-021-01483-0

Cited by 63 publications

(64 citation statements)

References 80 publications

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“…left or right handed) circular polarisation fraction. This is greater than the expected instrumental polarisation leakage (Callingham et al 2021) and also higher than many radio galaxies and blazars (e.g. Macquart & Fender 2004).…”

Section: Selection Of Pulsar Candidatesmentioning

confidence: 68%

“…However, other sources of polarised emission exist, including rare flare stars, star-planet interactions, ultracool dwarfs, radio galaxies, and blazars (e.g. O'Sullivan et al 2013;Vedantham et al 2020;Pritchard et al 2021;Callingham et al 2021). These linear and circularly polarised sources will be further discussed in O' Sullivan et al, in prep.…”

Section: Non-detection Of Other Polarised Sources As Pulsarsmentioning

confidence: 99%

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Searching for pulsars associated with polarised point sources using LOFAR: Initial discoveries from the TULIPP project

Sobey

Bassa

O’Sullivan

et al. 2022

A&A

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Discovering radio pulsars, particularly millisecond pulsars (MSPs), is important for a range of astrophysical applications, such as testing theories of gravity or probing the magneto-ionic interstellar medium. We aim to discover pulsars that may have been missed in previous pulsar searches by leveraging known pulsar observables (primarily polarisation) in the sensitive, low-frequency radio images from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS), and have commenced the Targeted search, using LoTSS images, for polarised pulsars (TULIPP) survey. For this survey, we identified linearly and circularly polarised point sources with flux densities brighter than 2 mJy in LoTSS images at a centre frequency of 144 MHz with a 48 MHz bandwidth. Over 40 known pulsars, half of which are MSPs, were detected as polarised sources in the LoTSS images and excluded from the survey. We have obtained beam-formed LOFAR observations of 30 candidates, which were searched for pulsations using coherent de-dispersion. Here, we present the results of the first year of the TULIPP survey. We discovered two pulsars, PSRs J1049+5822 and J1602+3901, with rotational periods of P = 0.73 s and 3.7 ms, respectively. We also detected a further five known pulsars (two slowly-rotating pulsars and three MSPs) for which accurate sky positions were not available to allow a unique cross-match with LoTSS sources. This targeted survey presents a relatively efficient method by which pulsars, particularly MSPs, may be discovered using the flexible observing modes of sensitive radio telescopes such as the Square Kilometre Array and its pathfinders/precursors, particularly since wide-area all-sky surveys using coherent de-dispersion are currently computationally infeasible.

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Section: Selection Of Pulsar Candidatesmentioning

confidence: 68%

Section: Non-detection Of Other Polarised Sources As Pulsarsmentioning

confidence: 99%

Searching for pulsars associated with polarised point sources using LOFAR: Initial discoveries from the TULIPP project

Sobey

Bassa

O’Sullivan

et al. 2022

A&A

Self Cite

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“…In that case, the emission is directly correlated with the strength of the planetary magnetic field. Coherent radio emission that could be associated with SPMI have been recently reported by Vedantham et al (2020); Turner et al (2021); Callingham et al (2021). If the radio signal shows a modulation with the orbital period of a known planet, or with the rotation period of the star, it could be furthermore possible to disambiguate the source of the detected radio emission (stellar or planetary magnetosphere, see e.g.…”

Section: Introductionmentioning

confidence: 83%

MOVES V. Modelling star-planet magnetic interactions of HD 189733

Strugarek,

Fares,

Bourrier

et al. 2022

Preprint

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Magnetic interactions between stars and close-in planets may lead to a detectable signal on the stellar disk. HD 189733 is one of the key exosystems thought to harbor magnetic interactions, which may have been detected in August 2013. We present a set of twelve wind models at that period, covering the possible coronal states and coronal topologies of HD 189733 at that time. We assess the power available for the magnetic interaction and predict its temporal modulation. By comparing the predicted signal with the observed signal, we find that some models could be compatible with an interpretation based on star-planet magnetic interactions. We also find that the observed signal can be explained only with a stretch-and-break interaction mechanism, while that the Alfvén wings scenario cannot deliver enough power. We finally demonstrate that the past observational cadence of HD 189733 leads to a detection rate of only between 12 to 23%, which could explain why star-planet interactions have been hard to detect in past campagins. We conclude that the firm confirmation of their detection will require dedicated spectroscopic observations covering densely the orbital and rotation period, combined with scarcer spectropolarimetric observations to assess the concomitant large-scale magnetic topology of the star.

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“…Cross-matching the archival information about that source on the sky would be helpful for early identification. By this means Pritchard et al (2021) identified 33 radio stars in the Rapid ASKAP Continuum Survey (RACS) and Callingham et al (2021) reported radio detection of 19 M dwarfs in LoTSS with ≈ 20% of the Northern sky processed. The catalog of brown dwarfs is far from complete in solar neighborhood so far, yet it will be greatly improved in future infrared surveys, e.g.…”

Section: Confirmation Of Flaring Ucd Candidatesmentioning

confidence: 95%

The Potential of Detecting Radio-flaring Ultracool Dwarfs at L band in the FAST Drift-scan Survey

Tang,

Tsai,

2022

Preprint

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The Five-hundred-meter Aperture Spherical radio Telescope (FAST) completed its commissioning and began the Commensal Radio Astronomy FasT Survey (CRAFTS), a multi-year survey to cover 60% of the sky, in 2020. We present predictions for the number of radio-flaring ultracool dwarfs (UCDs) that are likely to be detected by CRAFTS. Based on the observed flaring UCDs from a number of unbiased, targeted radio surveys in the literature, we derive a detection rate of ≥3%. Assuming a flat radio spectrum νL ν ∝ ν β+1 with β = -1.0 for UCD flares, we construct a flare luminosity function dN/dL ∝ L −1.96±0.45 (here L = νL ν ). CRAFTS is found to be sensitive enough for flares from UCDs up to ∼180 pc. Considering the Galactic thin disk, we carry out a 3D Monte Carlo simulation of the UCD population, which is then fed to mock CRAFTS observations. We estimate that ∼170 flaring UCDs would be detected through transient searches in circular polarization. Though only marginally sensitive to the scale height of UCDs, the results are very sensitive to the assumed spectral index β. For β from 0 to -2.5, the number of expected detections increases dramatically from ∼20 to ∼3460. We also contemplate the strategies for following up candidates of flaring UCDs, and discuss the implications of survey results for improving our knowledge of UCD behavior at L band and dynamos.

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The population of M dwarfs observed at low radio frequencies

Cited by 63 publications

References 80 publications

Searching for pulsars associated with polarised point sources using LOFAR: Initial discoveries from the TULIPP project

Searching for pulsars associated with polarised point sources using LOFAR: Initial discoveries from the TULIPP project

MOVES V. Modelling star-planet magnetic interactions of HD 189733

The Potential of Detecting Radio-flaring Ultracool Dwarfs at L band in the FAST Drift-scan Survey

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