{"id":8999,"date":"2020-06-22T18:00:00","date_gmt":"2020-06-22T09:00:00","guid":{"rendered":"https:\/\/www.icrr.u-tokyo.ac.jp\/?post_type=news&p=8999"},"modified":"2020-06-22T16:45:12","modified_gmt":"2020-06-22T07:45:12","slug":"cta%e5%a4%a7%e5%8f%a3%e5%be%84%e6%9c%9b%e9%81%a0%e9%8f%a11%e5%8f%b7%e6%a9%9f%e3%80%80%e3%81%8b%e3%81%ab%e6%98%9f%e9%9b%b2%e3%83%91%e3%83%ab%e3%82%b5%e3%83%bc%e3%81%8b%e3%82%89%e3%81%ae%e4%bf%a1-2","status":"publish","type":"news","link":"https:\/\/www.icrr.u-tokyo.ac.jp\/en\/news\/8999\/","title":{"rendered":"CTA Prototype LST-\uff11 Detects Very High-Energy Emission from the Crab Pulsar"},"content":{"rendered":"\n

La Palma, Canary Islands, Spain<\/strong> \u2013Between January and February 2020, the prototype Large-Sized Telescope (LST), the LST-\uff11, observed the Crab Pulsar, the neutron star at the centre of the Crab Nebula. The telescope, which is being commissioned on the CTA-North site on the island of La Palma in the Canary Islands, was conducting engineering runs to verify the telescope performance and adjust operating parameters.<\/p>\n\n\n\n

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Figure 1. Multiwavelength view of the Crab Nebula and the Crab pulsar \u2013 the bright spot at the centre of the image. Credit: NASA, ESA, G. Dubner (IAFE, CONICET-University of Buenos Aires) et al.; A. Loll et al.; T. Temim et al.; F. Seward et al.; VLA\/NRAO\/AUI\/ NSF; Chandra\/ CXC; Spitzer\/JPL-Caltech; XMM-Newton\/ESA; Hubble\/STScI<\/figcaption><\/figure>\n\n\n\n

Pulsars are very rapid rotating and strongly magnetized neutron stars that emit light in the form of two beams, which can be observed from Earth only when passing our line of sight. While detecting the strong and steady emission or outbursts of gamma-ray sources with Imaging Atmospheric Cherenkov Telescopes (IACTs) has become routine, pulsars are much more challenging to detect due to their weak signals and the typical dominance of the foreground gamma-ray signal from the surrounding nebulae. Despite hundreds of observations hours by IACTs around the globe, only four pulsars emitting signals in the very high-energy gamma-ray regime have been discovered, so far. Now that the LST-\uff11 has shown that it can detect the Crab pulsar, it joins the field of telescopes capable of detecting gamma-ray pulsars, validating the timestamping\u00a0system and the low-energy performance of the telescope.<\/p>\n\n\n\n

“This milestone shows us that the LST-\uff11 is already performing at an extraordinary level, detecting a challenging source in record time,” says Masahiro Teshima, Director of Max-Planck-Institute for physics in Munich and Principal Investigator of LST. “Pulsars are one of the key scientific targets of the LSTs, and it’s exciting to imagine what we’ll be able to achieve when the telescope is fully commissioned and operational.\u201d<\/p>\n\n\n\n

The data set collected includes 11.4 hours from eight observation nights. Figure\uff12 shows the resulting phasogram, plotting the gamma-ray events as a function of the pulsar rotation phase. The flat background is a mixture of gamma-like isotropic cosmic rays and dominant irreducible steady emission from the Crab pulsar wind nebula. In the phase regions marked P1 and P2, one expects to see more gamma rays in these time intervals as gamma rays from the Crab pulsar are emitted towards the Earth. The signal detected with the LST-\uff11 is undeniably significant for phase P2, while the signal during P1 is still marginal. The animation in Figure\uff13 highlights the pulse behavior of the source during the different phases.<\/p>\n\n\n\n

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Figure 2: Phasogram of Crab Pulsar as measured by the LST-\uff11. The pulsar is known to emit pulses of gamma rays during phases P1 and P2. The shown significance is calculated considering source emission from those phases (in red) and background events from phases (in grey). Credit: LST Collaboration<\/figcaption><\/figure>\n\n\n\n