LOFAR 144-MHz follow-up observations of GW170817
We present low-radio-frequency follow-up observations of AT 2017gfo, the electromagnetic counterpart of GW170817, which was the first binary neutron star merger to be detected by Advanced LIGO-Virgo. These data, with a central frequency of 144 MHz, were obtained with LOFAR, the Low-Frequency Array. The maximum elevation of the target is just 13.7 degrees when observed with LOFAR, making our observations particularly challenging to calibrate and significantly limiting the achievable sensitivity. On time-scales of 130-138 and 371-374 days after the merger event, we obtain 3$\sigma$ upper limits for the afterglow component of 6.6 and 19.5 mJy beam$^{-1}$, respectively. Using our best upper limit and previously published, contemporaneous higher-frequency radio data, we place a limit on any potential steepening of the radio spectrum between 610 and 144 MHz: the two-point spectral index $\alpha^{610}_{144} \gtrsim -2.5$. We also show that LOFAR can detect the afterglows of future binary neutron star merger events occurring at more favourable elevations.
Item Type | Article |
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Additional information | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 494, Issue 4, June 2020, Pages 5110–5117, ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords | astro-ph.he |
Date Deposited | 15 May 2025 14:20 |
Last Modified | 31 May 2025 00:25 |
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