Detection of the magnetar SGR J1745-2900 up to 291 GHz with evidence of polarized millimetre emission

Abstract

In Torne et al. (2015), we showed detections of SGR J1745-2900 up to 225 GHz (1.33 mm); at that time the highest radio frequency detection of pulsar emission. In this work, we present the results of new observations of the same magnetar with detections up to 291 GHz (1.03 mm), together with evidence of linear polarization in its millimetre emission. SGR J1745-2900 continues to show variability and is, on average, a factor $\sim$4 brighter in the millimetre band than in our observations of July 2014. The new measured spectrum is slightly inverted, with $⟨\alpha ⟩=+0.4\pm 0.2$ (for $S_{\nu }\propto {\nu }^{\alpha })$. However, the spectrum does not seem to be well described by a single power law, which might be due to the intrinsic variability of the source, or perhaps a turn-up somewhere between 8.35 and 87 GHz. These results may help us to improve our still incomplete model of pulsar emission and, in addition, they further support the search for and study of pulsars located at the Galactic Centre using millimetre wavelengths.

7 pages, 4 figures, 2 tables. Accepted for publication in MNRAS

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• The magnetar 1E 1547.0-5408: radio spectrum, polarimetry, and timing
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• Radio and X-ray observations of giant pulses from XTE J1810-197
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• An 86-GHz search for Pulsars in the Galactic Center with the Atacama Large Millimeter/submillimeter Array
• Searching for pulsars in the Galactic Centre at 3 and 2 mm
• ALMA and VLA observations of emission from the environment of Sgr A*
• Simultaneous 2.25/8.60 GHz observations of the newly discovered magnetar -- Swift J1818.0-1607
• Detection of the magnetar XTE J1810-197 at 150 and 260 GHz with the NIKA2 Kinetic Inductance Detector camera
• Submillimeter pulsations from the magnetar XTE J1810-197
• Observations of Radio Magnetars with the Deep Space Network
• Detection of a dense group of hyper-compact radio sources in the central parsec of the Galaxy
• The High Time Resolution Universe Pulsar Survey -- XVIII. The reprocessing of the HTRU-S Low Lat survey around the Galactic centre using a Fast Folding Algorithm pipeline for accelerated pulsars
• High Frequency Radio Observations of Two Magnetars, PSR J1622$-$4950 and 1E 1547.0$-$5408
• $4-8\mathrm{GHz}$ Spectro-temporal Emission from the Galactic Center Magnetar $\mathrm{PSR}J1745-2900$
• VLA Observations of Single Pulses from the Galactic Center Magnetar
• The Low Frequency Perspective on Fast Radio Bursts
• ALMA discovery of Punctum -- a highly polarized mm source in nuclear starburst galaxy NGC 4945
• Retuning radio astronomy for axion dark matter with neutron stars
• Tera-Hertz Counterparts to Fast Radio Bursts from Coherent Cherenkov Radiation by Tilted Bunches