Support ATel At Patreon

[ Previous | Next | ADS ]

Detection of pulsed radio emission from bursting Magnetar XTE1810-197 below 750 MHz with the uGMRT

ATel #12312; Bhal Chandra Joshi (NCRA-TIFR, Pune, India), Yogesh Maan (ASTRON, Netherlands), Mayuresh P Surnis(WVU, USA), Manjari Bagchi(IMSc-HBNI, Chennai, India), P. K. Manoharan(RAC, Ooty, India)
on 20 Dec 2018; 10:49 UT
Credential Certification: Bhal Chandra Joshi (bcj@ncra.tifr.res.in)

Subjects: Radio, Neutron Star, Soft Gamma-ray Repeater, Star, Pulsar, Magnetar

Referred to by ATel #: 12323, 12353, 12372

Intense radio emission from the magnetar XTE J1810-197 (Gotthelf et al. 2003, Ibrahim et al. 2004) has recently been reported in monitoring observations with the Lovell radio telescope (Lyne et al. 2018, ATEL #12284). These observations have been at higher frequencies and subsequent follow-up have detected pulsation at frequencies above 835 MHz (Lyne et al. 2018, ATEL #12284; Desvignes et al. 2018, ATEL #12285; Lower et al. 2018, ATEL #12288). Although the source is near Sun, enhanced high energy emission is also indicated in follow up observations (Mihara et al. 2018, ATel #12291; Gotthelf et al. 2018, ATEL #12297). This is only second such outburst accompanied by radio emission from this unique magnetar in last 10 years, during which the source was in quiescence state (Camilo et al. 2006; Camilo et al. 2016)

We observed this source for about 40 minutes with the upgraded GMRT (Gupta et al. 2018) using a phased array of 19 antennas at Band 4 between 550-750 MHz. We recorded the data with 4096 channels across 200 MHz bandwidth with a sampling time of 1.3 ms. Intense single pulses were detected with 35 to 70 signal-to-noise ratio (S/N). Our best estimate of the period and DM are 5.54156(7) s and 181(5) respectively. The average profile with very high S/N of about 700 shows two distinct components with a large and narrow trailing component following a smaller and wider leading component. The emission was seen across the whole band from 550 to 750 MHz. The profile evolves across the band with the ratio of peak of trailing component to leading component varying from 2.7 to 3 from 550 to 750 MHz. Our preliminary estimate of the source flux density averaged over the full bandwidth is 17(7) mJy. We also notice a significant evolution of the flux density across the observed bandwidth.

Plot of the detection can be found at XTE J1810-197 . The individual profiles for four sub-bands across 200 MHz bandwidth can be seen in this sub-band plot . The time and frequency variations with phase are in this summary plot .

Further observations at even lower frequencies (300-500 MHz) as well as the same band are scheduled. We will continue to monitor the source at frequencies 300-750 MHz using the uGMRT.

We thank the GMRT staff members for making these observations possible at short notice. We are also thankful for a prompt allocation of Director's discretionary time for these observations.