Three new millisecond pulsars discovered in Terzan 5 globular cluster

February 6, 2018 by Tomasz Nowakowski, report
Top panels: Averaged pulse profiles of the best detections of Ter5aj (on the left), Ter5ak (in the middle) and Ter5al (on the right). Bottom panel: Intensity of the signal (gray scale) as a function of the rotational phase and time for each MSP. Credit: Cadelano et al., 2018.

An international team of astronomers has found three new millisecond pulsars (MSPs) in a Milky Way globular cluster called Terzan 5. The new discovery increases the number of identified pulsars in Terzan 5 to 37 and makes this cluster the most efficient factory of MSPs in the galaxy known to date. The finding is reported January 30 in a paper published on

Millisecond pulsars spin rapidly, at hundreds of times per second. Astronomers searching for new MSPs focus their observations on (GCs), as such gravitationally bound collections of stars are ideal factories for the formation of a large variety of astronomical objects, including pulsars. So far, 146 MSPs were detected in 28 globular clusters, but it is believed that a very large population of several thousand millisecond pulsars is still to be uncovered.

Now, a team of scientists led by Mario Cadelano of the University of Bologna, Italy, has replenished the list of known MSPs in GCs by finding three new objects of this type in the Terzan 5 globular . Residing in the bulge of the Milky Way galaxy, Terzan 5 is most likely a heavily obscured globular cluster. However some studies have found that it is probably not a genuine GC, but could be a pristine remnant of a building block of the galactic bulge. All in all, Terzan 5 is perceived by astronomers as a prolific MSP factory as previous observations have detected 34 such pulsars in this cluster.

Cadelano's team has analyzed the archival observational data of Terzan 5 obtained by the 100-m Robert C. Byrd Green Bank Telescope (GBT) in Green Bank, West Virginia, for over five years—between August 2010 and October 2015. As a result, they identified three previously unknown MSPs in the inner regions of this cluster, designated: J1748−2446aj, J1748−2446ak and J1748−2446al.

"We report on the discovery of three new millisecond pulsars (namely J1748−2446aj, J1748−2446ak and J1748−2446al) in the inner regions of the dense stellar system Terzan 5. These pulsars have been discovered thanks to a method, alternative to the classical search routines, that exploited the large set of archival observations of Terzan 5 acquired with the Green Bank Telescope over 5 years (from 2010 to 2015)," the astronomers wrote in the paper.

According to the research, J1748−2446aj, J1748−2446ak and J1748−2446al are isolated MSPs with spin periods of 2.96, 1.89 and 5.95 milliseconds. Therefore, J1748−2446ak turns out to be the fourth fastest MSP in Terzan 5 and the fifth fastest among all the known pulsars in globular clusters.

Moreover, the researchers estimated the intrinsic spin-down rates for J1748−2446aj and J1748−2446ak, which are consistent with those typically measured for MSPs in globular clusters. In general, the new discovery increases the number of known MSPs in Terzan 5 to 37, which now hosts one-fourth of the entire population detected so far in globular clusters.

Explore further: Pulsar jackpot reveals globular cluster's inner structure

More information: Discovery of three new millisecond pulsars in Terzan 5, arXiv:1801.09929 [astro-ph.HE]

We report on the discovery of three new millisecond pulsars (namely J1748-2446aj, J1748-2446ak and J1748-2446al) in the inner regions of the dense stellar system Terzan 5. These pulsars have been discovered thanks to a method, alternative to the classical search routines, that exploited the large set of archival observations of Terzan 5 acquired with the Green Bank Telescope over 5 years (from 2010 to 2015). This technique allowed the analysis of stacked power spectra obtained by combining ~206 hours of observation. J1748-2446aj has a spin period of ~2.96 ms, J1748-2446ak of ~1.89 ms (thus it is the fourth fastest pulsar in the cluster) and J1748-2446al of ~5.95 ms. All the three millisecond pulsars are isolated and currently we have timing solutions only for J1748-2446aj and J1748-2446ak. For these two systems, we evaluated the contribution to the measured spin-down rate of the acceleration due to the cluster potential field, thus estimating the intrinsic spin-down rates, which are in agreement with those typically measured for millisecond pulsars in globular clusters. Our results increase to 37 the number of pulsars known in Terzan 5, which now hosts 25% of the entire pulsar population identified, so far, in globular clusters.

Related Stories

Pulsar jackpot reveals globular cluster's inner structure

September 13, 2017

The Milky Way is chock full of star clusters. Some contain just a few tens-to-hundreds of young stars. Others, known as globular clusters, are among the oldest objects in the Universe and contain up to a million ancient stars.

Image: Hubble looks into Terzan 7

February 17, 2014

Named after its discoverer, the French-Armenian astronomer Agop Terzan, this is the globular cluster Terzan 7—a densely packed ball of stars bound together by gravity. It lies just over 75,000 light-years away from us on ...

Image: Hubble checks out a home for old stars

December 21, 2015

This image, taken with the Wide Field Planetary Camera 2 on board the NASA/ESA Hubble Space Telescope, shows the globular cluster Terzan 1. Lying around 20,000 light-years from us in the constellation of Scorpius (The Scorpion), ...

Millisecond pulsars

October 3, 2016

When a star with a mass of roughly ten solar masses finishes its life, it explodes as a supernova, leaving behind a neutron star as remnant "ash." Neutron stars have masses of one-to-several suns but they are tiny in diameter, ...

Hubble discovers rare fossil relic of early Milky Way

September 7, 2016

A fossilised remnant of the early Milky Way harbouring stars of hugely different ages has been revealed by an international team of astronomers. This stellar system resembles a globular cluster, but is like no other cluster ...

Image: Hubble's standout stars bound together by gravity

January 29, 2018

This image from the NASA/ESA Hubble Space Telescope reveals a glistening and ancient globular cluster named NGC 3201—a gathering of hundreds of thousands of stars bound together by gravity. NGC 3201 was discovered in 1826 ...

Recommended for you

Comprehensive model captures entire life cycle of solar flares

January 15, 2019

A team of scientists has, for the first time, used a single, cohesive computer model to simulate the entire life cycle of a solar flare: from the buildup of energy thousands of kilometers below the solar surface, to the emergence ...

Team discovers new way supermassive black holes are 'fed'

January 14, 2019

Supermassive black holes weigh millions to billions times more than our sun and lie at the center of most galaxies. A supermassive black hole several million times the mass of the sun is situated in the heart of our very ...

The orderly chaos of black holes

January 14, 2019

During the formation of a black hole, a bright burst of very energetic light in the form of gamma rays is produced, these events are called gamma ray bursts. The physics behind this phenomenon includes many of the least understood ...


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.