Using advanced radio telescopes, astronomers have made a significant discovery of 10 new pulsars in the dense globular cluster Terzan 5, located in the constellation Sagittarius.
These findings, resulting from a collaborative effort between the U.S. National Science Foundation's National Radio Astronomy Observatory (NSF NRAO) and the South African Radio Astronomy Observatory’s MeerKAT telescope, have been published in the journal Astronomy & Astrophysics.
This discovery not only increases the known pulsar population in this cluster but also provides deeper insights into the nature and behavior of these exotic objects.
New Neutron Stars in a Crowded Cluster
Terzan 5, situated towards the center of the Milky Way galaxy, is a bustling 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 exceptionally dense—millions or even billions of times denser than regular stars.
Prior to this discovery, astronomers had already identified 39 pulsars in Terzan 5. The addition of 10 more pulsars highlights the cluster's complexity and the unique conditions that allow such exotic objects to form and persist.
Scott Ransom, a scientist at the NSF NRAO, expressed his excitement about the discovery, saying, “It’s very unusual to find exotic new pulsars. But what’s really exciting is the wide variety of such weirdos in a single cluster.” This diversity underscores the unique evolutionary paths these pulsars have taken, shaped by their dense and dynamic environment. The crowded nature of Terzan 5 provides a rich hunting ground for pulsars, whose interactions and gravitational influences within the cluster lead to their varied and unusual characteristics.
Detailed Observations and Analysis
The MeerKAT telescope played a crucial role in pinpointing the locations and rotation rates of these pulsars, building on two decades of data from the NSF Green Bank Telescope (GBT). This collaboration allowed astronomers to map the pulsars' positions and track their orbits, revealing intricate details about their behavior and characteristics. The team utilized the precise measurements of pulsar timing to understand their rotational dynamics and orbital changes over time.
“Without the NSF Green Bank Telescope's archive, we wouldn't have been able to characterize these pulsars and understand their astrophysics,” Ransom added. The archival data from NSF GBT were essential in confirming the pulsars' identities and understanding their unique astrophysical properties. These observations have provided a clearer picture of the pulsars' locations within 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 likely neutron stars in a binary system. Out of the 3,600 known pulsars in the galaxy, only 20 have been identified as double neutron-star binaries. 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 double neutron-star system and the longest orbit of its kind.
Binary pulsar systems offer unique opportunities to study the effects of strong gravity and relativistic physics. When pulsars pair off in binaries, the gravitational interaction can transfer material and angular momentum from one star to the other, resulting in rapid rotation rates and complex orbital dynamics.
The current record holder for the fastest spinning pulsar already resides in Terzan 5, and this new discovery adds to the remarkable pulsar population within the cluster. “Future observations will reveal the truth,” Ransom noted, highlighting the need for continued monitoring to fully understand these systems.
Discovery of Spider Pulsars
In addition to the binary neutron stars, astronomers also observed three new rare binary systems known as spider pulsars. These systems, categorized as either "Redbacks" or "Black Widows" depending on their companion stars, feature a pulsar that gradually erodes its companion star through a web of plasma created by the pulsar's energy. These interactions provide valuable insights into the extreme environments and dynamics of such binary systems.
Spider pulsars are particularly interesting due to 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 rate and magnetic field. The discovery of these spider pulsars, along with the other new pulsars, enhances our understanding of the various categories of pulsars and the environments they inhabit. These findings also offer opportunities to test and expand upon existing theories of stellar evolution and neutron star behavior.
