Gamma-ray bursts (GRBs) are some of the most violent occurrences in the universe. They can unleash energy equivalent to all the stars we can observe, primarily in the gamma-ray spectrum. Yet, our understanding of GRBs remains limited. A recent paper in The Astrophysical Journal, authored by a global team of researchers, introduces a new theory about how at least one type of GRB occurs – through the collapse and formation of a black hole in a binary system of specific stars.
To grasp this theory, it’s essential to start with the basics. GRBs are broadly categorized as “short” (lasting seconds) and “long” (lasting minutes). Short GRBs are believed to result from the collision of massive objects like black holes or neutron stars. On the other hand, long GRBs have been linked to the catastrophic collapse of exceptionally massive stars, those with more than 30 times the mass of our sun.
Traditionally, the formation of a new black hole through a star’s collapse has been the accepted explanation for hypernovae, a type of extraordinarily powerful supernova. However, the interdisciplinary research team led by Yerlan Aimuratov of the Fesenkov Astrophysical Institute in Kazakhstan challenges this notion. They propose that long GRBs are triggered not by a single star’s collapse but by a binary system consisting of a Carbon-oxygen (CO) star and a neutron star (NS). When the core of the CO star starts to collapse, it sets off a hypernova and the birth of a new neutron star, resulting in a binary system comprising two neutron stars.
Crucially, during the hypernova, a substantial amount of material is ejected from the newly formed neutron star. This material is then captured by its companion, the binary neutron star. The addition of this material can push the star beyond a critical mass, causing it to collapse into a black hole. This process emits the radiation observed as a gamma-ray burst.
The paper delves into the intricate details of this process, including the impact of the binary system’s rotational period, and provides a comprehensive historical background on the scientific journey that led to this theory, tracing back to Newton’s Principia Mathematica.
The researchers also commend the telescopes that aided them in observing GRBs and testing their theory, notably the BeppoSAX satellite, launched nearly three decades ago. Additionally, NASA’s SWIFT telescope and the Lick observatory detected two GRBs, GRB090618 and GRB090423, which exhibited characteristics consistent with binary star systems, offering tangible support for the proposed theory.
Nevertheless, the astrophysics community is likely to engage in ongoing debates regarding the exact causes of these immensely destructive phenomena. The urgency of this inquiry is magnified because such events could potentially occur nearby, posing a threat to life on Earth. Consequently, the ability to predict and understand systems, whether binary or solitary, where such events might transpire in our vicinity is crucial, and this paper advances our comprehension in that direction.
Source: Universe Today