Multi-messenger astrophysics

In this episode, we discuss a significant new detection of the Geminga pulsar, a middle-aged, radio-quiet gamma-ray pulsar. The **Large-Sized Telescope (LST-1)**, the first of the Cherenkov Telescope Array Observatory (CTAO) Northern Array, has detected Geminga at energies down to 20 GeV. Key takeaways from the study: * The LST-1 detected the Geminga pulsar using 60 hours of data. * The **second e...

Astronomers have made a significant discovery, detecting X-ray emission from a rare type of cosmic object known as a **Long-Period Radio Transient (LPT)** for the very first time. The object, designated **ASKAP J1832−0911**, is extraordinarily bright in radio, reaching flux densities of 10–20 Jy. Crucially, it exhibits **coincident radio and X-ray emission**, both pulsing with a regular period of...

A recent study utilized **15 years of observations** from the **Fermi Large Area Telescope (LAT)** to analyze the gamma-ray emission from the Sun in its quiet state, meaning when it's not flaring. This is the first study to separately analyze the flux variation of the two distinct components of this quiet-state gamma-ray emission over solar cycles. According to theoretical understanding, the S...

The research investigates how supernovae exploding into dense circumstellar environments, specifically those with dense shells of material, can potentially accelerate particles to energies of a few PeV, thus acting as "PeVatrons" and contributing to the "knee" feature in the cosmic ray spectrum. Supernova remnants (SNRs) have long been considered prime candidates for the source...

The research presents **new observations of the gamma-ray binary system LS 5039 using the High Altitude Water Cherenkov (HAWC) observatory**, revealing significant insights into the nature of this high-energy source. One of the most striking findings is that **HAWC detected gamma rays from LS 5039 extending up to 200 TeV with no apparent spectral cutoff**. This is a crucial extension of previous o...

* EP241021a was discovered as a soft X-ray trigger but was not detected at gamma-ray frequencies. * The prompt soft X-ray emission spectrum is consistent with **non-thermal radiation**, suggesting a **mildly relativistic outflow with a bulk Lorentz factor Γ≳ 4**. * The optical and near-infrared light curve shows a **two-component behavior**: an initial fading component (∼ t⁻¹) followed by a **rapi...

**Introduction:** What are Fast Radio Bursts (FRBs)? These millisecond bursts from distant galaxies have astrophysicists intrigued. We explore repeating FRBs (R-FRBs) and theories about their origins, including magnetars. **AGILE's High-Energy Hunt:** The Italian AGILE satellite, with its SuperAGILE (18-60 keV), MCAL (0.35-100 MeV), and GRID (0.03-50 GeV) detectors, searched for X- and gamma-r...

Welcome to this episode about the **Einstein Telescope (ET)**, a planned **third-generation gravitational-wave observatory** [see source]. * **ET will revolutionize gravitational-wave astronomy** with **higher sensitivity** and a **broader frequency range** compared to current detectors [see source]. * This allows deeper insights into **Fundamental Physics** (tests of General Relativity, search fo...

* **Introduction:** Astronomers have discovered a new celestial object, PSR J0311+1402, a radio pulsar with an unusual spin period of **41 seconds**. This discovery bridges the gap between normal pulsars (millisecond to seconds) and long-period radio transients (LPTs) (minutes to hours). * **The Discovery:** PSR J0311+1402 was first detected by the **Australian Square Kilometre Array Pathfinder (A...

**Introduction** * The podcast discusses the search for **diffuse photons** with energies above tens of PeV, using data from the **Pierre Auger Observatory**. * These photons are produced by interactions between cosmic rays and interstellar matter or background radiation. * The measurement of a diffuse photon flux can help us understand the distribution of cosmic rays in the Galaxy and probe model...

**Introduction:** * This episode discusses the search for the sources of high-energy neutrinos using the example of the blazar B3 2247+381. * The IceCube Neutrino Observatory detects astrophysical neutrinos, and scientists are working to find their origins by looking for correlations between neutrino alerts and electromagnetic radiation from objects like blazars. **The IceCube Alert and B3 2247+38...

**Introduction:** * A recent ultra-high-energy neutrino event, named KM3-230213A, was detected by the KM3NeT/ARCA detector. * This event has sparked interest in the scientific community, as its origin is still unclear. * The neutrino's high energy suggests it may have come from a very powerful cosmic source. * The event was detected on February 13, 2023. * The podcast explores two potential or...

**Introduction** * A recent detection by the KM3NeT/ARCA telescope of an ultra-high-energy neutrino, named KM3-230213A, is discussed. This event has an estimated energy in the hundreds of PeV, surpassing previous observations by the IceCube Neutrino Observatory. * The observed neutrino's high energy suggests an astrophysical origin, as it's unlikely to be from atmospheric sources. **Key Co...

* **Introduction**: A recent groundbreaking discovery by the KM3NeT Collaboration has detected an exceptionally high-energy cosmic neutrino. This event, named KM3-230213A, is significant because its energy far exceeds any neutrino previously observed. * **What are Cosmic Neutrinos?**: Cosmic neutrinos are electrically neutral particles that travel vast distances without being deflected by magnetic...

The Mystery of ANITA: Investigating Anomalous Radio Pulses with the Pierre Auger Observatory * **Introduction**: The Antarctic Impulsive Transient Antenna (ANITA) has detected some unusual radio pulses that don't fit with the standard model of particle physics. These "anomalous" pulses, which appear to come from below the horizon, could potentially be caused by air showers developing...

* **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...