Radio nebula discovered around the pulsar PSR J0855–4644

March 21, 2018 by Tomasz Nowakowski, report
Radio nebula discovered around the pulsar PSR J0855–4644
A zoomed in view showing the radio nebula and the shell structure. The red cross marks the position of the pulsar as reported in Kramer et al. 2003. Credit: Maitra et al., 2018.

Using the Giant Metrewave Radio Telescope (GMRT) in India, an international team of astronomers has detected a diffuse radio emission forming a nebula around the pulsar PSR J0855–4644. The finding is reported March 9 in a paper published on the arXiv pre-print repository.

Discovered in 2003, PSR J0855–46444 is a young and energetic pulsar located some 3,000 light years away in the Vela region. Although the presence of an X-ray surrounding this pulsar was detected by previous observations using NASA's Chandra X-ray observatory and ESA's XMM Newton spacecraft, there is an ongoing search for its radio counterpart.

Finding such X-ray and radio could be key for our understanding of the so-called pulsar wind nebulae (PWNe). Astronomers believe that pulsars lose a significant part of their energy via relativistic winds which, upon interactions with the ambient medium, produce a synchrotron powered nebula emitting from radio to beyond the X-ray bands.

In January 2017, a group of researchers led by Chandreyee Maitra of the Max Planck Institute for Extraterrestrial Physics in Germany, conducted observations of PSR J0855–46444 with the upgraded GMRT (uGMRT). In result, they found a radio counterpart of the PWN surrounding this pulsar.

"We report the discovery of a diffuse radio emission around PSR J0855–4644 using an upgraded GMRT (uGMRT) observation at 1.35 GHz. The radio emission is spatially coincident with the diffuse X-ray pulsar wind nebula (PWN) seen with XMM-Newton but is much larger in extent compared to the compact axisymmetric PWN seen with Chandra," the researchers wrote in the paper.

The astronomers noted that the spatial coincidence of the radio emission with the diffuse X-ray emission suggests that it is the radio counterpart of the PWN.

According to the study, the newly identified radio nebula has an estimated physical size of about 1.43 light years. Therefore, it turns out to be much larger than the compact axisymmetric X-ray nebula spotted by the Chandra spacecraft. However, the radio nebula is similar in size to the diffuse X-ray nebula observed with the XMM-Newton telescope.

"Since the higher energy X-ray electrons cool faster, the number of X-ray emitting particles decrease rapidly with increasing distance from the leading to a smaller size of the X-ray nebula compared to the radio counterpart," the scientists explained.

GMRT observations revealed that a central ring-like feature surrounds PSR J0855–46444, which is brightened at the southeast region. Furthermore, the researchers found that two tail-like features extend in the north-west direction and a faint diffuse emission fills the whole feature.

The authors of the paper assume that the morphology of the emission is reminiscent of a bow shock nebula.

"The PWN morphology strongly resembles a bow shock nebula and the radius of the termination shock indicates a velocity of 100 km/s through the ambient medium," the paper reads.

Explore further: Astronomers discover bubble-like structure associated with the pulsar PSR J1015−5719

More information: Discovery of a radio nebula around PSR J0855-4644, arXiv:1803.03592 [astro-ph.HE]

We report the discovery of a diffuse radio emission around PSR J0855—4644 using an upgraded GMRT (uGMRT) observation at 1.35 GHz. The radio emission is spatially coincident with the diffuse X-ray pulsar wind nebula (PWN) seen with XMM but is much larger in extent compared to the compact axisymmetric PWN seen with Chandra. The morphology of the emission, with a bright partial ring-like structure and two faint tail-like features strongly resembles a bow shock nebula, and indicates a velocity of 100 km/s through the ambient medium. We conclude that the emission is most likely to be associated with the radio PWN of PSR J0855-4644. From the integrated flux density, we estimate the energetics of the PWN.

Related Stories

Pulsar wind nebulae

November 7, 2016

Neutron stars are the detritus of supernova explosions, with masses between one and several suns and diameters only tens of kilometers across. A pulsar is a spinning neutron star with a strong magnetic field; charged particles ...

Lyman-alpha emission detected around quasar J1605-0112

February 20, 2018

Using the Multi Unit Spectroscopic Explorer (MUSE) instrument astronomers have discovered an extended and broad Lyman-alpha emission in the form of a nebula around the quasar J1605-0112. The finding is reported February 9 ...

Crab Nebula: A crab walks through time

March 14, 2018

Next year marks the 20th anniversary of NASA's Chandra X-ray Observatory launch into space. The Crab Nebula was one of the first objects that Chandra examined with its sharp X-ray vision, and it has been a frequent target ...

Radio emission detected from a gamma-ray pulsar

July 5, 2017

(—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 ...

Recommended for you

Unconfirmed near-Earth objects

June 22, 2018

Near-Earth objects (NEOs) are small solar system bodies whose orbits sometimes bring them close to the Earth, potentially threatening a collision. NEOs are tracers of the composition, dynamics and environmental conditions ...

HESS J1943+213 is an extreme blazar, study finds

June 21, 2018

An international group of astronomers have carried out multi-wavelength observations of HESS J1943+213 and found evidence supporting the hypothesis that this gamma-ray source is an extreme blazar. The finding is reported ...

'Red nuggets' are galactic gold for astronomers

June 21, 2018

About a decade ago, astronomers discovered a population of small, but massive galaxies called "red nuggets." A new study using NASA's Chandra X-ray Observatory indicates that black holes have squelched star formation in these ...

The Rosetta stone of active galactic nuclei deciphered

June 21, 2018

A galaxy with at least one active supermassive black hole – named OJ 287 – has caused many irritations and questions in the past. The emitted radiation of this object spans a wide range – from the radio up to the highest ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.