In Extensive Sky Survey, Hundreds of Deceased Stars Found Emitting Gamma Rays Pulses

The catalog of gamma-ray pulsars observed by the Fermi Large Area Telescope has been significantly expanded with the addition of 294 previously unidentified stars. This brings the total number of objects in the catalog to over 340, marking a substantial increase since the telescope began its observations in 2008, when only a handful of such pulsars were known.

The newly released Third Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars is a valuable source of information that will contribute to our understanding of these mysterious celestial bodies.

According to astrophysicist David Smith from the Bordeaux Astrophysics Laboratory, which is affiliated with the French National Center for Scientific Research (CNRS), pulsars are of great interest in various fields of astrophysics research, including cosmic rays, stellar evolution, gravitational wave detection, and the study of dark matter.

This comprehensive catalog provides detailed information on all known gamma-ray pulsars, aiming to inspire new avenues of exploration.Pulsars are some of the most extreme objects in the Universe. They belong to the category of neutron stars, which are the remnants of massive stars that have collapsed but not into black holes due to insufficient mass.The key characteristic that sets pulsars apart from regular neutron stars is their pulsating nature. Pulsars emit powerful beams of radiation from their poles, resembling spotlights piercing through space.

Additionally, pulsars exhibit rapid rotation, often spinning at incredibly high speeds. Some of these stars, known as millisecond pulsars (MSPs), can complete a full rotation in just 10 milliseconds.

The fastest known pulsar rotates 716 times per second in fact. Here’s a bunch of pulsar pulses transcribed into sound, for an idea of what that means.

These beams, as they rotate, have the ability to pass by Earth, resembling the actions of a celestial beacon.

There is a current understanding of approximately 3,400 pulsars. Among these, the emissions they produce typically fall within the radio wavelength range. However, a small subset of pulsars possess the capability to emit the most potent form of radiation known to exist in the Universe – gamma rays. These gamma-ray pulsars possess magnetic fields of immense strength, which enable them to accelerate particles to extraordinarily high energies, resulting in bursts of powerful yet invisible light.

Based on the recently compiled catalog, it has been determined that approximately 10 percent of the known pulsars are now identified as gamma-ray emitters. While it is important to acknowledge that our ability to detect these emissions may be influenced by certain selection biases, such as technological limitations, this sample size is significant enough to discern the factors that differentiate a pulsar as a gamma emitter in comparison to the radio-emitting population.

Furthermore, the new population of pulsars serves other purposes as well. Pulsars, particularly those with rotation rates measured in milliseconds, exhibit remarkable precision in their timing. The catalog includes 144 such pulsars. This precision makes them valuable for applications like space navigation, which becomes increasingly crucial as more space missions are undertaken.

Additionally, these pulsars can be utilized to detect gravitational waves by analyzing anomalies in the timing of their signals. These anomalies can indicate expansions and contractions in the fabric of space-time caused by the passage of a gravitational wave resulting from a significant cosmic event. Moreover, they can be employed to conduct tests of relativity.

Astronomer Lucas Guillemot from the Laboratory of Physics and Chemistry of the Environment and Space and the University of Orleans in France states that prior to Fermi, there was uncertainty regarding the visibility of MSPs at high energies. However, it has been discovered that they predominantly emit gamma rays, and now they constitute half of our catalog. Additionally, a significant number of the newly discovered pulsars, around 45, are referred to as ‘spider’ pulsars, as they consume material from a binary companion star.

Astronomer Megan DeCesar from George Mason University and the US Naval Research Laboratory explains that spider pulsars are named after arachnids that consume their smaller mates. She further elaborates that a similar phenomenon occurs when a neutron star and its binary companion are in close proximity, resulting in an intense radiation and particle wind from the pulsar eroding the surface of the other star, creating a puffball of evaporated material. The researchers anticipate that Fermi’s discoveries are not yet complete, as the possibility of identifying another 100 gamma-ray pulsars exists, with several more tens being likely.

Astronomer Elizabeth Hays from NASA’s Goddard Space Flight Center emphasizes that even after 15 years since its launch, Fermi continues to be an extraordinary instrument for discovery, with pulsars and their neutron star counterparts leading the way. The catalog containing these findings has been published in The Astrophysical Journal.

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