Using advanced radio telescopes, astronomers have made the significant discovery of 10 new pulsars in the dense globular cluster Terzan 5, located in the constellation Sagittarius.
These findings, the result of a collaborative effort between the US National Science Foundation’s National Radio Astronomy Observatory (NSF NRAO) and the South African Radio Astronomy Observatory’s MeerKAT telescope, are published in the journal Astronomy and astrophysics.
This discovery not only increases the known population of pulsars in this cluster, but also provides deeper insight into the nature and behavior of these exotic objects.
New neutron stars in a crowded cluster
Terzan 5, located towards the center of the Milky Way galaxy, is a lively globular cluster, home to hundreds of thousands of stars. Pulsars, which are rapidly spinning neutron stars emitting bright pulses of light from their magnetic fields, are extremely dense—millions or even billions of times denser than ordinary stars.
Before this discovery, astronomers had already identified 39 pulsars in the Terzan 5. The addition of 10 more pulsars underscores the complexity of the cluster and the unique conditions that allow such exotic objects to form and exist.
Scott Ransomscientist in FNI NRAO, expressed his excitement at the discovery, saying, “It is very unusual to discover exotic new pulsars. But what’s really exciting is the wide variety of such freaks in one cluster. This diversity highlights the unique evolutionary paths these pulsars have taken, shaped by their dense and dynamic environments. The overcrowded nature of Terzan 5 provides a rich hunting ground for pulsars whose interactions and gravitational influences within the cluster give rise to their diverse and unusual characteristics.
Detailed observations and analyses
The MeerKAT telescope played a crucial role in determining the locations and rotation rates of these pulsarsbuilding on data from two decades of NSF Green Bank Telescope (GBT). This collaboration allowed astronomers to map the positions of pulsars and track their orbits, revealing intricate details about their behavior and characteristics. The team used the precise timing measurements of the pulsars to understand their rotational dynamics and orbital changes over time.
“Without the NSF Green Bank telescope archive, we would not have been able to characterize these pulsars and understand their astrophysics,” Ransom added. The archive data from NSF GBT were essential in confirming the identity of pulsars and understanding their unique astrophysical properties. These observations provided a clearer picture of the location of the pulsars in the cluster and how their orbits evolve, contributing to a deeper understanding of their formation and evolution.
Discovery of binary neutron stars
Among the newly discovered pulsars, astronomers identified two probable ones neutron stars in binary system. Of the 3,600 known pulsars in the galaxy, only 20 have been identified as binary binary neutron stars. These binary systems are particularly fascinating because the gravitational pull between the stars can cause one to spin even faster, becoming a millisecond pulsar. This newly discovered pair could potentially set a record for the fastest spinning pulsar in a binary neutron star system and the longest orbit of its kind.
Double pulsar systems offer unique opportunities to study the effects of strong gravity and relativistic physics. When pulsars pair up in binary systems, the gravitational interaction can transfer material and angular momentum from one star to the other, leading to fast rotation rates and complex orbital dynamics.
The current record holder for the fastest spinning pulsar now resides in the Terzan 5and this new discovery adds to the remarkable population of pulsars in the cluster. “Future observations will reveal the truth,” Ransom noted, stressing the need for continued monitoring to fully understand these systems.
Discovery of spider pulsars
In addition to binary neutron stars, astronomers also observed three new rare binary systems known as spider pulsars. These systems, categorized as “Redbacks” or “Black Widows” depending on their companion stars, include a pulsar that gradually eats away at its companion star through a web of plasma created by the pulsar’s energy. These interactions provide valuable insight into the extreme environments and dynamics of such binary systems.
Spider pulsars are particularly interesting because of their complex interactions with their companion stars. The energy emitted by the pulsar can strip material from the companion, creating a plasma cloud that envelops both stars. This process can lead to dramatic changes in the pulsar’s rotation velocity and magnetic field. The discovery of these spider pulsars, along with the other new pulsars, improves our understanding of the different categories of pulsars and the environments they inhabit. These findings also offer opportunities to test and extend existing theories of stellar evolution and the behavior of neutron stars.
