Detection of the magnetar XTE J1810−197 at 150 and 260 GHz with the NIKA2 kinetic inductance detector camera

Abstract

Context. The investigation of pulsars between millimetre and optical wavelengths is challenging due to the faintness of the pulsar signals and the relative low sensitivity of the available facilities compared to 100 m class telescopes operating in the centimetre band. The kinetic inductance detector (KID) technology offers large instantaneous bandwidths and a high sensitivity that can help to increase the ability of existing observatories at short wavelengths substantially to detect pulsars and transient emission. Aims. To investigate whether pulsars can be detected with KIDs, we observed the anomalous X-ray pulsar XTE J1810−197 with the New IRAM KIDs Array-2 (NIKA2) camera installed at the IRAM 30 m telescope in Spain. Methods. Several short observations of XTE J1810−197 were made on 2019 March 25 under good weather conditions to verify the stability of the KIDs and to try to detect the expected broadband pulsations from the neutron star. Results. We detected the pulsations from the pulsar with NIKA2 at its two operating frequency bands, 150 and 260 GHz (λ = 2.0 and 1.15 mm, respectively). This is the first time that a pulsar is detected with a receiver based on KID technology in the millimetre band. In addition, this is the first report of short millimetre emission from XTE J1810−197 after its reactivation in December 2018, and it is the first time that the source is detected at 260 GHz, which gives us new insights into the radio emission process of the star. Conclusions. We demonstrate that KIDs can fulfil the technical requirements for detecting pulsed emission from neutron stars in the millimetre band. We show that the magnetar XTE J1810−197 is again emitting strong pulsations in the short millimetre band.

Multiwavelength Radio Observations of Two Repeating Fast Radio Burst Sources: FRB 121102 and FRB 180916.J0158+65

“…High-frequency radio emission is a hallmark feature of radio magnetars. Bright radio pulses have been detected from several radio magnetars in the Milky Way at record high frequencies, well above 100 GHz in some cases(e.g., see Camilo et al 2007;Torne et al 2017Torne et al , 2020, but no FRBsource has yet been detected at radio frequencies above 8 GHz. However, to date, very few searches for FRBs have been carried out at such high radio frequencies (Gajjar et al 2018;Majid et al 2020).…”

High-cadence observations and variable spin behaviour of magnetar Swift J1818.0−1607 after its outburst

“…Kramer et al 2003). The flatness of the radio spectrum has led to the detection of radio-loud magnetars up to a frequency of ∼300 GHz (Torne et al 2017(Torne et al , 2020, which is the highest radio frequency of any neutron star detection so far.…”

Multi-frequency radio observations of the radio-loud magnetar XTE J1810-197

“…The time gaps between observations are smaller than 24 hours if not simultaneous. Figure 5 shows five spectra between December 2018 and April 2019, with early results of precedent studies (Maan et al 2019;Dai et al 2019;Pearlman et al 2019Pearlman et al , 2020Torne et al 2020). Our upper limit at 0.3 GHz is marked as well.…”

“…Gotthelf et al (2019) reported an earlier increase of its Xray flux between MJDs 58442 and 58448, and confirmed X-ray outburst has preceded the radio burst. Many radio follow-up observations have reported the broad frequency range of its radio activity during this outburst, from 300 MHz (Maan et al 2019) to a few GHz (Levin et al 2019;Dai et al 2019;Johnston et al 2020), to 32 GHz (Pearlman et al 2019) and even up to 150 GHz and 260 GHz (Torne et al 2020).…”