The ASKAP-EMU Early Science Project: 888 MHz radio continuum survey of the Large Magellanic Cloud

Pennock, Clara M.; Loon, Jacco Th. van; Filipović, Miroslav; Andernach, H.; Haberl, F.; Kothes, R.; Lenc, E.; Rudnick, Lawrence; White, Sarah V.; Agliozzo, C.; Antón, Sonia; Bojičić, Ivan S.; Bomans, D. J.; Collier, Jordan D.; Crawford, E. J.; Hopkins, A. M.; Jeganathan, K.; Kavanagh, Patrick; Koribalski, B. S.; Leahy, D. A.; Maggi, Pierre; Maitra, Chandreyee; Marvil, J.; Michalowski, Michal; Norris, Ray; Oliveira, J. M.; Payne, Jeffrey L.; Sano, Hidetoshi; Sasaki, M.; Staveley‐Smith, L.; Vardoulaki, E.

doi:10.1093/mnras/stab1858

Cited by 32 publications

(28 citation statements)

References 134 publications

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“…We note that our result is further in close agreement with the positions of two additional objects: the spiral-shaped H region LHA 120-N 119 which has been considered to reside at the centre of the LMC, given its position and morphology (see, e.g. Pennock et al 2021) and the position of a tentative central black hole in the LMC. Based on MUSE data, Boyce et al (2017) analysed the kinematics of the central square degree of the LMC.…”

Section: Comparison With Previous Estimates From the Literaturesupporting

confidence: 86%

The VMC survey -- XLVI. Stellar proper motions in the centre of the Large Magellanic Cloud

Niederhofer,

Cioni,

Schmidt

et al. 2022

Preprint

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We present proper motion (PM) measurements within the central region of the Large Magellanic Cloud (LMC) using nearinfrared data from the VISTA survey of the Magellanic Cloud system (VMC). This work encompasses 18 VMC tiles covering a total sky area of ∼28 deg 2 . We computed absolute stellar PMs from multi-epoch observations in the 𝐾 𝑠 filter over time baselines between ∼12 and 47 months. Our final catalogue contains ∼6 322 000 likely LMC member stars with derived PMs. We employed a simple flat-rotating disc model to analyse and interpret the PM data. We found a stellar centre of rotation (𝛼 0 = 79.95 •+0.22 −0.23 , 𝛿 0 = −69.31 •+0.12 −0.11 ) that is in agreement with that resulting from Hubble Space Telescope data. The inferred viewing angles of the LMC disc (𝑖 = 33.5 •+1.2 −1.3 , Θ = 129.8 •+1.9 −1.9 ) are in good agreement with values from the literature but suggest a higher inclination of the central parts of the LMC. Our data confirm a higher rotation amplitude for the young ( 0.5 Gyr) stars compared to the intermediate-age/old ( 1 Gyr) population, which can be explained by asymmetric drift. We constructed spatially resolved velocity maps of the intermediate-age/old and young populations. Intermediate-age/old stars follow elongated orbits parallel to the bar's major axis, providing first observational evidence for 𝑥 1 orbits within the LMC bar. In the innermost regions, the motions show more chaotic structures. Young stars show motions along a central filamentary bar structure.

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Section: Comparison With Previous Estimates From the Literaturesupporting

confidence: 86%

The VMC survey -- XLVI. Stellar proper motions in the centre of the Large Magellanic Cloud

Niederhofer,

Cioni,

Schmidt

et al. 2022

Preprint

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“…They have been extensively studied in RC in both total power (For et al 2018;Klein et al 1989;Loiseau et al 1987;Haynes et al 1991;Joseph et al 2019;Pennock et al 2021) and polarization (Gaensler et al 2005;Mao et al 2008;Mao et al 2012;Klein et al 1993). The Herschel space observatory and the Spitzer space telescope have made major breakthroughs in studies of the dust and gas in the MCs (Gordon et al 2011;Meixner et al 2006Meixner et al , 2013Lakićević et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Role of Thermal and Non-thermal Processes in the ISM of Magellanic Clouds

Hassani,

Tabatabaei,

Hughes

et al. 2021

Preprint

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The radio continuum emission is a dust-unbiased tracer of both the thermal and non-thermal processes in the interstellar medium. We present new maps of the free-free and synchrotron emission in the Magellanic Clouds (MCs) at 0.166, 1.4, and 4.8 GHz with no prior assumption about the radio non-thermal spectrum. The maps were constructed using a de-reddened Hα map as a template for the thermal radio emission, which we subtract from maps of the total radio continuum emission. To de-redden the Hα emission, it is important to know the fraction of dust surface density that attenuates the Hα emission along the line-of-sight, f d . This fraction is obtained by comparing the dust opacity obtained through the infrared emission spectrum and the Balmer decrement method. In star-forming regions, the median f d is about 0.1 which is by a factor of 3 lower than that in diffuse regions. We obtain a global thermal radio fraction, f th , of 30 per cent (35 per cent) in the LMC (SMC) at 1.4 GHz. Furthermore, we present maps of the equipartition magnetic field strength with average values of 10.1 µG in the LMC and 5.5 µG in the SMC. The magnetic field is proportional to the star formation rate to a power of 0.24 and 0.20 for the LMC and SMC, respectively. This study shows that the non-thermal processes control the interstellar medium in the MCs.

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“…We also detected VAST J052348.6−712552 in archival radio observations including the Sydney University Molonglo Sky Survey (SUMSS; Mauch et al 2003) and an ASKAP commissioning observation (SB8532; Pennock et al 2021). We obtained a higher-time resolution lightcurve from the latter (by imaging 9 × 7 minutes scans separated by 1.2 hr) and found no significant variability within the 12 hr 40 minutes observation.…”

Section: Atca and Archival Radio Observationsmentioning

confidence: 76%

Discovery of PSR J0523-7125 as a Circularly Polarized Variable Radio Source in the Large Magellanic Cloud

Wang

Murphy

Kaplan

et al. 2022

ApJ

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We report the discovery of a highly circularly polarized, variable, steep-spectrum pulsar in the Australian Square Kilometre Array Pathfinder (ASKAP) Variables and Slow Transients (VAST) survey. The pulsar is located about 1° from the center of the Large Magellanic Cloud, and has a significant fractional circular polarization of ∼20%. We discovered pulsations with a period of 322.5 ms, dispersion measure (DM) of 157.5 pc cm−3, and rotation measure (RM) of +456 rad m−2 using observations from the MeerKAT and the Parkes telescopes. This DM firmly places the source, PSR J0523−7125, in the Large Magellanic Cloud (LMC). This RM is extreme compared to other pulsars in the LMC (more than twice that of the largest previously reported one). The average flux density of ∼1 mJy at 1400 MHz and ∼25 mJy at 400 MHz places it among the most luminous radio pulsars known. It likely evaded previous discovery because of its very steep radio spectrum (spectral index α ≈ −3, where S ν ∝ ν α ) and broad pulse profile (duty cycle ≳35%). We discuss implications for searches for unusual radio sources in continuum images, as well as extragalactic pulsars in the Magellanic Clouds and beyond. Our result highlighted the possibility of identifying pulsars, especially extreme pulsars, from radio continuum images. Future large-scale radio surveys will give us an unprecedented opportunity to discover more pulsars and potentially the most distant pulsars beyond the Magellanic Clouds.

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The ASKAP-EMU Early Science Project: 888 MHz radio continuum survey of the Large Magellanic Cloud

Cited by 32 publications

References 134 publications

The VMC survey -- XLVI. Stellar proper motions in the centre of the Large Magellanic Cloud

The VMC survey -- XLVI. Stellar proper motions in the centre of the Large Magellanic Cloud

Role of Thermal and Non-thermal Processes in the ISM of Magellanic Clouds

Discovery of PSR J0523-7125 as a Circularly Polarized Variable Radio Source in the Large Magellanic Cloud

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