The SuperNova Early Warning System (SNEWS) is a network of neutrino detectors designed to give early warning to astronomers in the event of a supernova in the Milky Way, our home galaxy, or in a nearby galaxy such as the Large Magellanic Cloud or the Canis Major Dwarf Galaxy.
As of March 2021 [update] , [1] SNEWS has not issued any supernova alerts. This is unsurprising, as supernovae appear to be rare: the most recent known supernova remnant in the Milky Way was around the turn of the 20th century, and the most recent Milky Way supernova confirmed to have been observed was Kepler's Supernova in 1604.
In June 2019 a "SNEWS 2.0" workshop was held at Laurentian University of Sudbury in Canada, focused on plans for an update of SNEWS. [1] [2] As the result, an upgraded system was devised under the name "SNEWS 2.0". [3] [4]
Powerful bursts of electron neutrinos (νe) with typical energies of the order of 10 MeV and duration of the order of 10 seconds are produced in the core of a red giant star as it collapses on itself via the "neutronization" reaction, i.e. fusion of protons and electrons into neutrons and neutrinos: p + e− → n + νe. It is expected that the neutrinos are emitted well before the light from the supernova peaks, so in principle neutrino detectors could give warning to astronomers that a supernova has occurred and may soon be visible. The neutrino pulse from supernova 1987A arrived 3 hours before the associated photons – but SNEWS was not yet active and it was not recognised as a supernova event until after the photons arrived.
Directional precision of approximately 5° is expected. [5] SNEWS is not able to give warning of a type Ia supernova, as they are not expected to produce significant numbers of neutrinos. Type Ia supernovae, caused by a runaway nuclear fusion reaction in a white dwarf star, are thought to account for roughly one-third of all supernovae. [6]
There are currently seven neutrino detector members of SNEWS: Borexino, Daya Bay, KamLAND, HALO, IceCube, LVD, and Super-Kamiokande. [7] SNEWS began operation prior to 2004, with three members (Super-Kamiokande, LVD, and SNO). The Sudbury Neutrino Observatory is no longer active as it is being upgraded to its successor program SNO+.
The detectors send reports of a possible supernova to a computer at Brookhaven National Laboratory to identify a supernova. If the SNEWS computer identifies signals from two detectors within 10 seconds, the computer will send a supernova alert to observatories around the world to study the supernova. [8] The SNEWS mailing list is open-subscription, and the general public is allowed to sign up; however, the SNEWS collaboration encourages amateur astronomers to instead use Sky and Telescope magazine's AstroAlert service, which is linked to SNEWS.
A neutrino is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero. The rest mass of the neutrino is much smaller than that of the other known elementary particles. The weak force has a very short range, the gravitational interaction is extremely weak due to the very small mass of the neutrino, and neutrinos do not participate in the electromagnetic interaction or the strong interaction. Thus, neutrinos typically pass through normal matter unimpeded and undetected.
A supernova is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
The Sudbury Neutrino Observatory (SNO) was a neutrino observatory located 2100 m underground in Vale's Creighton Mine in Sudbury, Ontario, Canada. The detector was designed to detect solar neutrinos through their interactions with a large tank of heavy water.
Super-Kamiokande is a neutrino observatory located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan. It is operated by the Institute for Cosmic Ray Research, University of Tokyo with the help of an international team. It is located 1,000 m (3,300 ft) underground in the Mozumi Mine in Hida's Kamioka area. The observatory was designed to detect high-energy neutrinos, to search for proton decay, study solar and atmospheric neutrinos, and keep watch for supernovae in the Milky Way Galaxy.
SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately 51.4 kiloparsecs from Earth and was the closest observed supernova since Kepler's Supernova in 1604. Light and neutrinos from the explosion reached Earth on February 23, 1987 and was designated "SN 1987A" as the first supernova discovered that year. Its brightness peaked in May of that year, with an apparent magnitude of about 3.
Neutrino astronomy is the branch of astronomy that gathers information about astronomical objects by observing and studying neutrinos emitted by them with the help of neutrino detectors in special Earth observatories. It is an emerging field in astroparticle physics providing insights into the high-energy and non-thermal processes in the universe.
A Type Ia supernova is a type of supernova that occurs in binary systems in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white dwarf.
A neutrino detector is a physics apparatus which is designed to study neutrinos. Because neutrinos only weakly interact with other particles of matter, neutrino detectors must be very large to detect a significant number of neutrinos. Neutrino detectors are often built underground, to isolate the detector from cosmic rays and other background radiation. The field of neutrino astronomy is still very much in its infancy – the only confirmed extraterrestrial sources as of 2018 are the Sun and the supernova 1987A in the nearby Large Magellanic Cloud. Another likely source is the blazar TXS 0506+056 about 3.7 billion light years away. Neutrino observatories will "give astronomers fresh eyes with which to study the universe".
T2K is a particle physics experiment studying the oscillations of the accelerator neutrinos. The experiment is conducted in Japan by the international cooperation of about 500 physicists and engineers with over 60 research institutions from several countries from Europe, Asia and North America and it is a recognized CERN experiment (RE13). T2K collected data within its first phase of operation from 2010 till 2021. The second phase of data taking is expected to start in 2023 and last until commencement of the successor of T2K – the Hyper-Kamiokande experiment in 2027.
The Large Volume Detector (LVD) is a particle physics experiment situated in the Gran Sasso laboratory in Italy and is operated by the Italian Institute of Nuclear Physics (INFN). It has been in operation since June 1992, and is a member of the Supernova Early Warning System. Among other work, the detector should be able to detect neutrinos from our galaxy and possibly nearby galaxies. The LVD uses 840 scintillator counters around a large tank of hydrocarbons. The detector can detect both charged current and neutral current interactions.
SNOLAB is a Canadian underground science laboratory specializing in neutrino and dark matter physics. Located 2 km below the surface in Vale's Creighton nickel mine near Sudbury, Ontario, SNOLAB is an expansion of the existing facilities constructed for the original Sudbury Neutrino Observatory (SNO) solar neutrino experiment.
The known history of supernova observation goes back to 1006 AD. All earlier proposals for supernova observations are speculations with many alternatives.
SNO+ is a physics experiment designed to search for neutrinoless double beta decay, with secondary measurements of proton–electron–proton (pep) solar neutrinos, geoneutrinos from radioactive decays in the Earth, and reactor neutrinos. It could also observe supernovae neutrinos if a supernova occurs in our galaxy. It is under construction using the underground equipment already installed for the former Sudbury Neutrino Observatory (SNO) experiment at SNOLAB.
The solar neutrino problem concerned a large discrepancy between the flux of solar neutrinos as predicted from the Sun's luminosity and as measured directly. The discrepancy was first observed in the mid-1960s and was resolved around 2002.
Multi-messenger astronomy is the coordinated observation and interpretation of multiple signals received from the same astronomical event. Many types of cosmological events involve complex interactions between a variety of astrophysical processes, each of which may independently emit signals of a characteristic "messenger" type: electromagnetic radiation, gravitational waves, neutrinos, and cosmic rays. When received on Earth, identifying that disparate observations were generated by the same source can allow for improved reconstruction or a better understanding of the event, and reveals more information about the source.
The Helium And Lead Observatory (HALO) is a neutrino detector at SNOLab for the Supernova Early Warning System (SNEWS). It began engineering operation on May 8, 2012, and joined as an operational part of SNEWS in October 2015.
Eugene William Beier is an American physicist.
The diffuse supernova neutrino background(DSNB) is a theoretical population of neutrinos (and anti-neutrinos) cumulatively originating from all core-collapse supernovae events throughout the history of the universe. Though it has not yet been directly detected, the DSNB is theorized to be isotropic and consists of neutrinos with typical energies on the scale of 107 eV. Current detection efforts are limited by the influence of background noise in the search for DSNB neutrinos and are therefore limited to placing limits on the parameters of the DSNB, namely the neutrino flux. Restrictions on these parameters have gotten more strict in recent years, but many researchers are looking to make direct observations in the near future with next generation detectors. The DSNB is not to be confused with the cosmic neutrino background (CNB), which is comprised by relic neutrinos that were produced during the Big Bang and have much lower energies (10−4 to 10−6 eV).
A hypernova is a very energetic supernova which is believed to result from an extreme core collapse scenario. In this case, a massive star collapses to form a rotating black hole emitting twin astrophysical jets and surrounded by an accretion disk. It is a type of stellar explosion that ejects material with an unusually high kinetic energy, an order of magnitude higher than most supernovae, with a luminosity at least 10 times greater. Hypernovae release such intense gamma rays that they often appear similar to a type Ic supernova, but with unusually broad spectral lines indicating an extremely high expansion velocity. Hypernovae are one of the mechanisms for producing long gamma ray bursts (GRBs), which range from 2 seconds to over a minute in duration. They have also been referred to as superluminous supernovae, though that classification also includes other types of extremely luminous stellar explosions that have different origins.
Supernova neutrinos are weakly interactive elementary particles produced during a core-collapse supernova explosion. A massive star collapses at the end of its life, emitting on the order of 1058 neutrinos and antineutrinos in all lepton flavors. The luminosity of different neutrino and antineutrino species are roughly the same. They carry away about 99% of the gravitational energy of the dying star as a burst lasting tens of seconds. The typical supernova neutrino energies are 10 to 20 MeV. Supernovae are considered the strongest and most frequent source of cosmic neutrinos in the MeV energy range.