Multi-messenger astrophysics

* **Introduction:** This episode discusses the search for extremely-high-energy neutrinos (EHEν) using 12.6 years of data from the IceCube Neutrino Observatory. EHEνs are unique messengers from the distant universe, traveling without being deflected by magnetic fields or attenuated by interactions with background photons. * **IceCube Detector:** The IceCube detector, located at the South Pole, con...

**Article Reference:** * Thakore, B., et al. (2024). "High-Significance Detection of Correlation Between the Unresolved Gamma-Ray Background and the Large Scale Cosmic Structure." **Introduction:** * The universe is filled with a mysterious glow of gamma rays, known as the **unresolved gamma-ray background (UGRB)**. This background could contain clues about the faintest gamma-ray sources and the n...

Introduction: This episode discusses the groundbreaking discovery of AT2019pim, the first spectroscopically confirmed afterglow of a relativistic explosion with no observed high-energy gamma-ray emission. This event challenges our understanding of gamma-ray bursts (GRBs) and suggests the existence of "orphan afterglows," which are afterglows not associated with typical GRB prompt emissio...

**Reference:** Patel et al., "Direct evidence for r-process nucleosynthesis in delayed MeV emission from the SGR 1806-20 magnetar giant flare" (2025) * **Introduction:** * The origin of heavy elements, specifically those formed through the rapid neutron-capture process (**r-process**), has been a long-standing mystery in astrophysics. * While neutron star mergers have been considered a p...

* **Introduction:** * The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) will soon produce an unprecedented amount of transient astronomical data, with around 10 million alerts every night. * This data deluge requires intelligent tools to prioritize the most scientifically valuable events for follow-up, especially spectroscopic observations. * This podcast discusses AAS2RTO, a...

* **Introduction**: * This episode discusses the search for continuous gravitational waves (CWs) emitted by neutron stars, specifically known pulsars, using data from the LIGO-Virgo-KAGRA (LVK) collaboration's fourth observing run (O4a). * CWs are distinct from transient gravitational waves (GWs) like those from black hole mergers; they are nearly monochromatic signals with small variations ov...

**Introduction:** * This episode discusses the **Markarian Multiwavelength Data Center (MMDC)**, a new web-based tool designed to access and model multiwavelength data from blazar observations. * MMDC is designed to enhance blazar research by providing a comprehensive framework for data accessibility, analysis, and theoretical interpretation. * The tool integrates archival data, optical data from...

* This study uses data from the IceCube Neutrino Observatory, a massive detector at the South Pole, to study cosmic rays. * The IceCube detector is primarily designed to detect high-energy neutrinos. However, it also collects a large amount of data on cosmic-ray muons. * Muons are created when cosmic rays collide with the Earth's atmosphere. * By studying the arrival directions of these muons, sci...

* Orphan gamma-ray burst (GRB) afterglows occur when the gamma-ray emission from a GRB is not directed towards Earth, making the initial burst invisible. However, the afterglow, produced by the interaction of the GRB's blast wave with surrounding material, can be observed. * Studying orphan afterglows provides valuable insights into GRB physics and their progenitors, and can enhance multi-messenge...

Fast Radio Bursts (FRBs) are brief, powerful pulses of radio waves originating from distant galaxies. Their origins are still a mystery, with one leading theory pointing to magnetars, highly magnetized neutron stars, as the source. Astronomers have identified a small number of FRBs that emit repeated bursts, termed repeating FRBs (rFRBs). A subset of rFRBs have a persistent radio source (PRS) asso...

The discovery of a new ultra-high-energy gamma-ray source, 1LHAASO J1857+0203u, by the Large High Altitude Air Shower Observatory (LHAASO) suggests the presence of a PeVatron, a cosmic accelerator capable of boosting particles to peta-electron volt energies. This source is particularly interesting because it is located in a region with complex multi-wavelength features, including the supernova rem...

The TAIGA-HiSCORE Cherenkov array, located in Siberia, is a unique instrument designed to study cosmic rays and gamma rays. However, scientists have realized that it can also be used to search for a variety of fascinating astronomical phenomena, including nanosecond optical transients . What are nanosecond optical transients? These are extremely short bursts of light that last for only a few nanos...

Kilonovae (KNe) are bright, rapidly fading astronomical events believed to be caused by the radioactive decay of heavy elements produced during the merger of neutron stars or a neutron star and a black hole. While there are several candidate KNe events observed in association with short gamma-ray bursts (GRBs), there is only one confirmed KN associated with a gravitational wave (GW) event, AT2017g...

In this episode, we explore the fascinating world of diffuse gamma rays emanating from the Galactic plane. A new study using the Large High Altitude Air Shower Observatory's Water Cherenkov Detector Array (LHAASO-WCDA) has provided unprecedented insights into these mysterious emissions. What are diffuse gamma rays? These high-energy photons are produced when cosmic rays, energetic particles that c...

Publication: arXiv:2411.06996 Acknowledements: Podcast prepared with Google/NotebookLM. Illustration credits: Y. Xing et al. (arXiv:2411.06996)

IACTs (Imaging Atmospheric Cherenkov Telescopes) are typically used for gamma-ray astronomy. Muons are produced in hadronic showers and IACTs can detect these muons, which are normally considered background noise. The information from these muons can be used to study cosmic ray showers. One way to study cosmic rays is by observing the muon lateral distribution , which is the muon density as a func...

Ultra-high-energy cosmic rays (UHECRs) are the most energetic particles ever detected, with energies exceeding 10^18 eV. Their origin remains a mystery, as their paths are deflected by magnetic fields in space, making it difficult to trace them back to their sources. Scientists use models of the Galactic magnetic field (GMF) to account for these deflections and try to pinpoint the sources of UHECR...

Swift's New Capability: Continuous Commanding A new capability of the Neil Gehrels Swift Observatory, called "continuous commanding", allows Swift to respond to targets of opportunity within 10 seconds. This capability allows Swift to receive commands in real-time because the spacecraft is now constantly in contact with the ground. This capability was developed to allow Swift to respond to early w...

The Pierre Auger Observatory, situated in Argentina, is designed to detect UHE cosmic rays. The observatory is also sensitive to UHE photons and has been used to search for photons from various sources. This study looked for coincidences between UHE photon events and a selection of GW events detected by the LIGO/Virgo observatories. No UHE photon events were observed in coincidence with any of the...

Astronomers discovered a new long-period (21-minute) radio transient called GPM J1839–10, with the Murchison Widefield Array (MWA). Follow-up observations were done using other telescopes, including the Australia Telescope Compact Array (ATCA), Parkes/Murriyang radio telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), and MeerKAT. The pulses from GPM J1839–10 vary in brightness, l...

Microquasars, like V4641 Sgr, are binary star systems with a black hole that pulls material from a companion star. They are fascinating objects for astronomers because they can produce jets of relativistic particles. The High-Altitude Water Cherenkov (HAWC) Observatory observed TeV gamma-ray emissions from V4641 Sgr. These observations suggest that the microquasar is accelerating particles far fro...

Astronomers using LOFAR detected a short, coherent radio flash at 144 MHz, 76.6 minutes after observing a short gamma-ray burst (GRB) called GRB 201006A . The probability of finding an unrelated transient is less than 1 in a million and it is thus likely the radio counterpart to GRB 201006A. The discovery of this radio flash suggests that searches for similar emissions could be helpful for multi-m...

The paper examines the " Matthew Effect " in science, where more well-known scientists or institutions tend to receive a disproportionate amount of credit for discoveries, even in collaborative efforts. This effect extends to large research collaborations, as demonstrated by the case of the LIGO, Virgo, and KAGRA collaborations . While LIGO, Virgo, and KAGRA have been working together since 2007 a...

Ultra-high-energy cosmic rays (UHECRs) are a mystery. Scientists still don’t know where or how they are created. A new study combines three kinds of data measured at the Auger Observatory : the energy spectrum, shower maximum depth distributions, and arrival directions of UHECRs. Publication : A.A. Halim et al., "Constraining models for the origin of ultra-high-energy cosmic rays with a novel comb...

GRB 201216C , a long GRB, was observed by numerous instruments, including Swift-BAT, Fermi-GBM, and the MAGIC telescopes. MAGIC detected GRB 201216C at a redshift of z = 1.1 , making it the farthest known source detected at VHE gamma rays. Modeling of GRB 201216C's multiwavelength data, including the MAGIC observations, favors a scenario where the GRB jet is expanding into a wind-like medium shape...