LOFAR Deep Fields: probing a broader population of polarized radio galaxies in ELAIS-N1

Ruiz, N. Herrera; O’Sullivan, S. P.; Vacca, V.; Jelić, Vibor; Nikiel-Wroczyński, B.; Bourke, S.; Sabater, J.; Dettmar, R.‐J.; Heald, G.; Horellou, C.; Piras, S.; Sobey, C.; Shimwell, T. W.; Tasse, C.; Hardcastle, M. J.; Kondapally, R.; Chyży, K. T.; Iacobelli, M.; Best, P. N.; Brüggen, M.; Carretti, E.; Prandoni, I.

doi:10.1051/0004-6361/202038896

Cited by 11 publications

(5 citation statements)

References 87 publications

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“…This facilitates a range of science goals aimed at investigating magnetic fields (e.g. Heald et al 2020;O'Sullivan et al 2020;Herrera Ruiz et al 2021;Hutschenreuter et al 2022). Despite the high Galactic latitudes of the observations (b ∼ −33 • & 70 • ), this catalogue contains over 30 known pulsars, over 50% of which are MSPs (O'Sullivan et al, in prep.).…”

Section: Introductionmentioning

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

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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: Introductionmentioning

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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“…However, thanks to improving instruments and observational techniques we have started to detect polarised low-frequency emission as well [77]. Furthermore, there have been attempts to apply the stacking technique to polarised low-frequency emission [29,78].…”

Section: Measuring Magnetic Fields and Cosmic Raysmentioning

confidence: 99%

Cosmic-Ray Acceleration and Magnetic Fields in Galaxy Clusters and Beyond: Insights from Radio Observations

Wittor

2023

Universe

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The discovery of diffuse radio emission in galaxy clusters proved the existence of energetic cosmic-ray electrons and cosmic magnetic fields on Mpc-scales in the Universe. Furthermore, both magnetic fields and cosmic-ray electrons are predicted to exist beyond galaxy clusters, namely, in the filaments and voids of the cosmic web. Recent detection of diffuse radio emission in intercluster bridges—the region between two merging clusters—strengthens the theory that both cosmic magnetic fields and cosmic-ray electrons exist on these large scales. Radio observations are our most powerful tool to study cosmic magnetic fields and cosmic-ray electrons in the Universe. The recent improvements in radio astronomy, including the exploration of the low-frequency radio sky, have led to the discovery of countless new radio sources, and hence a new understanding of the origin and evolution of cosmic magnetic fields and cosmic-ray electrons. In this contribution, we summarise the newest discoveries in the field. Furthermore, we discuss what these new radio observations teach us about cosmic magnetic fields and cosmic rays in galaxy clusters and beyond.

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“…We used the catalogue of the polarised sources provided by Herrera Ruiz et al (2021) to check how many of them we detect in our final stacked Faraday cube. The purpose of this comparison is only to verify our stacking method on very low-resolution data.…”

Section: Cross-checking the Detection Of The Radio Sourcesmentioning

confidence: 99%

“…Herrera Ruiz et al (2021) did an initial analysis of polarised radio sources in the LoTSS Deep Fields using six eight-hour observations of the ELAIS-N1 field. They used low-resolution (20 ) polarimetric images (Sabater et al 2021) and successfully demonstrated the feasibility of stacking LOFAR data.…”

Section: Introductionmentioning

confidence: 99%

LOFAR Deep Fields: Probing faint Galactic polarised emission in ELAIS-N1

Šnidarić¹,

Jelić²,

Mevius³

et al. 2023

Preprint

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We present the first deep polarimetric study of Galactic synchrotron emission at low radio frequencies. Our study is based on 21 observations of the European Large Area Infrared Space Observatory Survey-North 1 (ELAIS-N1) field using the Low-Frequency Array (LOFAR) at frequencies from 114.9 to 177.4 MHz. These data are a part of the LOFAR Two-metre Sky Survey Deep Fields Data Release 1. We used very low-resolution (4.3 ) Stokes QU data cubes of this release. We applied rotation measure (RM) synthesis to decompose the distribution of polarised structures in Faraday depth, and cross-correlation RM synthesis to align different observations in Faraday depth. We stacked images of about 150 hours of the ELAIS-N1 observations to produce the deepest Faraday cube at low radio frequencies to date, tailored to studies of Galactic synchrotron emission and the intervening magneto-ionic interstellar medium. This Faraday cube covers ∼ 36 deg 2 of the sky and has a noise of 27 µJy PSF −1 RMSF −1 in polarised intensity. This is an improvement in noise by a factor of approximately the square root of the number of stacked data cubes (∼ √ 20), as expected, compared to the one in a single data cube based on five-to-eight-hour observations. We detect a faint component of diffuse polarised emission in the stacked cube, which was not detected previously. Additionally, we verify the reliability of the ionospheric Faraday rotation corrections estimated from the satellite-based total electron content measurements to be of ∼ 0.05 rad m −2 . We also demonstrate that diffuse polarised emission itself can be used to account for the relative ionospheric Faraday rotation corrections with respect to a reference observation.

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LOFAR Deep Fields: probing a broader population of polarized radio galaxies in ELAIS-N1

Cited by 11 publications

References 87 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

Cosmic-Ray Acceleration and Magnetic Fields in Galaxy Clusters and Beyond: Insights from Radio Observations

LOFAR Deep Fields: Probing faint Galactic polarised emission in ELAIS-N1

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