Related Experiment Video
Updated: Mar 21, 2026
08:53
Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures
Published on: October 9, 2012
18.3K
Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope
M Ajello1, A Albert2, B Anderson3,4
1Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, South Carolina 29634-0978, USA.
Physical Review Letters
|May 7, 2016
Summary
Researchers searched for axionlike particles (ALPs) in NGC 1275
Area of Science:
- Astrophysics
- Particle Physics
Background:
- Axionlike particles (ALPs) are hypothetical particles that could mediate interactions between photons and affect astrophysical observations.
- The galaxy NGC 1275 in the Perseus cluster is a potential source for detecting such particles due to its high-energy emissions.
Purpose of the Study:
- To search for spectral irregularities in the gamma-ray spectrum of NGC 1275, indicative of photon-ALP oscillations.
- To constrain the properties of axionlike particles, specifically their mass and coupling strength.
Main Methods:
- Analysis of 6 years of Fermi Large Area Telescope gamma-ray data from NGC 1275.
- Searching for deviations from expected spectral shapes that could signal the presence of ALPs.
Main Results:
- No evidence for axionlike particles was found in the gamma-ray spectrum of NGC 1275.
- Couplings above 5×10⁻¹² GeV⁻¹ were excluded for ALP masses between 0.5 and 5 neV at 95% confidence.
Conclusions:
- The study sets stringent limits on ALP properties, competitive with future laboratory experiments.
- These findings, combined with other constraints, significantly limit the possibility of ALPs reducing the universe's gamma-ray opacity.
Related Concept Videos
01:30Atomic Emission Spectroscopy: Interference
735
In atomic emission spectroscopy (AES), high-temperature atomizers excite a broad range of elements and molecules that generate complex emissions from sources such as oxides, hydroxides, and flame combustion products in the flame or plasma. Several strategies can be employed to minimize spectral interferences caused by overlapping emission lines or bands. These include increasing instrument resolution, choosing alternative emission lines, optimally placing the detector in low-background regions,...
735
01:12Fermi Level Dynamics
950
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
950
01:22Atomic Emission Spectroscopy: Instrumentation
1.5K
The instrumentation of atomic emission spectrometry (AES) involves various components, including atomization devices that convert samples into gas-phase atoms and ions. There are two main types of atomization devices: continuous and discrete atomizers. Continuous atomizers, like plasmas and flames, introduce samples in a constant stream, while discrete atomizers inject individual samples using syringes or autosamplers. The most common discrete atomizer is the electrothermal atomizer.
1.5K
01:20Atomic Emission Spectroscopy: Overview
4.2K
Atomic emission spectroscopy (AES) is an analytical technique used to determine the elemental composition of a sample by analyzing the light emitted from excited atoms. In AES, atoms in a sample are excited to higher energy levels by thermal energy from high-temperature sources, such as plasma, arcs, or sparks. When these excited atoms return to lower energy states, they emit light at specific wavelengths characteristic of each element. The resulting atomic emission spectrum, which consists of...
4.2K
01:11Atomic Nuclei: Larmor Precession Frequency
3.5K
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession,...
3.5K
01:24IR Spectroscopy: Molecular Vibration Overview
5.9K
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
5.9K