Tag: 上海夜网龙凤网419论坛

Radio emission detected from a gammaray pulsar

No Comments

first_img Citation: Radio emission detected from a gamma-ray pulsar (2017, July 5) retrieved 18 August 2019 from https://phys.org/news/2017-07-radio-emission-gamma-ray-pulsar.html © 2017 Phys.org Astronomers discover bubble-like structure associated with the pulsar PSR J1015−5719 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Gamma-ray pulsars are rotating neutron stars emitting gamma-ray photons. Some of them also showcase radio emission that is often difficult to detect. This is most probably due to the fact that their narrow radio beams miss the sightline towards Earth.Located nearly 2,000 light years away from the Earth, J1732−3131 has a rotation period of about 196 milliseconds and is one such gamma-ray pulsar with hart-to-identify radio emission. The pulsar was found thanks to the data provided by the large area telescope (LAT) onboard NASA’s Fermi Gamma-ray Space Telescope. So far, only a faint radio signal from this pulsar was detected at 34 MHz in 2012.More recently, Maan’s team, motivated by previous faint detections, conducted follow-up observations of J1732−3131 between March 2014 and April 2015, using the Ooty radio telescope (ORT), located in Muthorai, India. This 530-meter-long and 30-meter-wide cylindrical paraboloid telescope allowed the researchers to observe the pulsar at 327 MHz, which resulted in detection of a faint periodic radio signal.”We report an extensive follow-up of the pulsar at 327 MHz with the Ooty radio telescope. Using the previously observed radio characteristics, and with an effective integration time of 60 hours, we present a detection of the pulsar at a confidence level of 99.82 percent,” the authors of the study wrote in the paper.The astronomers estimate that the 327 MHz mean flux density of J1732−3131 is between 0.5 and 0.8 mJy and the spectral index in the range from −2.4 to −3.0.More importantly, however, the 1,400 MHz pseudo-luminosity of the pulsar is only between 2.2 and 8.9 μJy kpc2, which suggests that J1732−3131 is one of the least luminous pulsars known to date.According to the scientists, their research provides new clues about gamma-ray pulsars in general, which could improve their understanding of these peculiar neutron stars. They noted that some of the radio-quiet gamma-ray pulsars might actually be very faint radio sources, and therefore not detectable in the radio searches using current generation telescopes. That is why the researchers call for more studies of such pulsars using more powerful radio telescopes.”The high sensitivity of upcoming radio telescopes like square kilometre array (SKA) and the 500-meter Aperture Spherical Telescope (FAST) will enable radio detection, and facilitate better studies of such pulsars,” the paper reads.SKA is a large, multi-radio telescope network being built in Australia and South Africa, which is expected to start initial observations in 2020. FAST is the world’s largest filled-aperture radio telescope, located in China. It achieved first light in September 2016, and is currently undergoing testing and commissioning. Explore further (Phys.org)—A team of astronomers led by Yogesh Maan of the Netherlands Institute for Radio Astronomy (ASTRON) has discovered radio emission from the gamma-ray pulsar known as J1732−3131. The study, presented in a paper published June 26 on arXiv.org, provides more details about J1732−3131, which was originally detected as a radio-quiet pulsar. Phase-aligned radio and gamma-ray profiles of J1732−3131. The continuous blue line shows the 327 MHz average profile from 2014 observations and the dashed-dotted-dashed red curve shows the gamma-ray profile. The horizontal extent of the grey shade on either side of the radio profile indicates the uncertainty in phase corresponding to 1σ error in DM. For clarity, both the profiles are duplicated and plotted over a range spanning two rotations of the pulsar. Credit: Maan et al., 2017. More information: Detection of radio emission from the gamma-ray pulsar J1732-3131 at 327 MHz, arXiv:1706.08613 [astro-ph.HE] arxiv.org/abs/1706.08613AbstractAlthough originally discovered as a radio-quiet gamma-ray pulsar, J1732-3131 has exhibited intriguing detections at decameter wavelengths. We report an extensive follow-up of the pulsar at 327 MHz with the Ooty radio telescope. Using the previously observed radio characteristics, and with an effective integration time of 60 hrs, we present a detection of the pulsar at a confidence level of 99.82%. The 327 MHz mean flux density is estimated to be 0.5-0.8 mJy, which establishes the pulsar to be a steep spectrum source and one of the least-luminous pulsars known to date. We also phase-aligned the radio and gamma-ray profiles of the pulsar, and measured the phase-offset between the main peaks in the two profiles to be 0.24±0.06. We discuss the observed phase-offset in the context of various trends exhibited by the radio-loud gamma-ray pulsar population, and suggest that the gamma-ray emission from J1732-3131 is best explained by outer magnetosphere models. Details of our analysis leading to the pulsar detection, and measurements of various parameters and their implications relevant to the pulsar’s emission mechanism are presented.last_img read more

In a realm of variations

No Comments

first_imgAll the art enthusiasts over the city can head on as Kala Mela 18 presents the group  exhibition titled Drishta that kick started yesterday. The show that exhibits paintings, sculptures, drawings and installations is curated by Sanchit Jain and is organised by Iqbal Krishan. The show was inaugurated by Yogendra Chandela, Mayor of North Delhi on 1 July  and the guest of honour was Meenakshi Lekhi. The aim of this event is to give a better platform to emerging artistes from all over India. Some of artistes exhibiting their  works  are Poonam Rana, Shuchi Khanna, Krupa Shah, Iqbal Krishan, Hemraj, Shridhaer Iyer, Manish Pushkale and Fida Khan, Mansa Bedi. Other participating artistes include  Santosh Kumar Sahni, Sanchit Jain, Ahish Kumar, Sadhna Tiwari, Anuja, Diksha Kain, Reena Choudhary, John Luis, Manoj Bhatti, Tarun Kumar, Seema, M Hosakoti, Rini Pant, Somnand Gadakari, Chirnjeev Panda, Sanjay Kr Biswal, Jyotika Nagar and Srinivasan Royal. Also Read – ‘Playing Jojo was emotionally exhausting’Kala Mela 18 has been organising fairs with painters to reawaken the appreciation for paintings among the people. These fairs comprise of different portrait works from contemporary artistes. Their motive is to bring renaissance in the realm of art and painting and invoke the lost interest for painting and art in masses. We reside in a society where aspiring painters are forced to switch profession because our vision has become shrouded with a thought that it is full of struggle and their lives get marred. Kala Mela 18 helps those artistes to come forth and show their talent. Till now it has successfully accomplished five of its fairs which boasts of works form more than 200 artistes from almost every state.When: On till 4 July Where: Visual Arts Gallery, India Habitat Centre, Lodhi RoadTiming: 10 am – 8 pmlast_img read more

Walk of life

No Comments

first_imgInspired by the stories, struggles, dreams and hopes of a motley group of teenagers, Walk! is a show born out of a 4 month intensive arts-for-social-change curriculum. 12 teenagers, cutting across barriers of caste, class, gender, religion, and nationality, have come together to teach each other about the social issues that affect them most deeply as well as the changes they dream of. Walk! is based on the lives and stories of the cast members; while no one plays their own part, the stories are all true. Facilitated by Tasawwur, a collective of artistes and educators, this show brings together song, choreography, tableaus, and stories to take the audience through the world these young people inhabit and the more inclusive world that they dream of.  Also Read – ‘Playing Jojo was emotionally exhausting’Tasawwur was started by Delhi based poet and educator, Aditi Rao. It  brings together a diverse group of teenagers in New Delhi to explore and transform some of the most complex social issues they grapple with. Using creative writing and the performing arts to support these young people on their explorations, Tasawwur helps them discover their unique voices and stories, while creating an atmosphere of care and respect for the voices and stories of others, and ultimately using their collective voice to effect positive change in the world.When: May 22 – 23Where: Studio Safdar Timing: 7 pmlast_img read more