Related Experiment Video
Updated: Dec 25, 2025
06:28
Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera
Published on: January 30, 2020
13.1K
Detection of Cross-Correlation between Gravitational Lensing and γ Rays
S Ammazzalorso1,2, D Gruen3,4, M Regis1,2
1Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, 10125 Torino, Italy.
Physical Review Letters
|March 29, 2020
Summary
Scientists found a connection between gamma rays and cosmic mass distribution using weak gravitational lensing. This discovery helps study faint cosmic emissions and potential dark matter signals.
Area of Science:
- Astrophysics
- Cosmology
Background:
- Many gamma-ray sources are known, but faint emissions remain unstudied.
- Cross-correlation with gravitational tracers is a promising method to probe faint signals.
Purpose of the Study:
- To identify the cross-correlation signal between gamma rays and the Universe's mass distribution.
- To investigate the origin and implications of this signal.
Main Methods:
- Utilized data from the Dark Energy Survey Y1 weak lensing survey.
- Analyzed 9-year gamma-ray data from the Fermi Large Area Telescope.
- Performed cross-correlation analysis between gamma-ray and mass distribution data.
Main Results:
- First identification of a cross-correlation signal between gamma rays and mass distribution, with a signal-to-noise ratio of 5.3.
- Signal predominantly observed at small angular scales and high gamma-ray energies.
- Hint of correlation detected at extended separations.
Conclusions:
- The small-scale signal is likely from blazar emissions.
- The large-scale component warrants further investigation for astrophysical sources and particle dark matter.
- This method opens new avenues for studying the Universe's faint emission components.
Related Concept Videos
01:10Detection of Black Holes
2.5K
Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
2.5K
01:30Atomic Emission Spectroscopy: Interference
525
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,...
525
01:05Difference from Background: Limit of Detection
8.0K
The limit of detection (LOD) is the smallest amount of analyte that can be distinguished from the background noise. The LOD value corresponds to the concentration at which the analyte signal is three times larger than the standard deviation of the blank signal. Below this value, the analyte signal cannot be differentiated from the background noise. It is calculated by dividing the calibration slope by 3 times the standard deviation of the blank signals.
The LOD indicates the presence or absence...
The LOD indicates the presence or absence...
8.0K
01:24X-ray Imaging
9.6K
German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible "ray" would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an "X-ray" image (as it came to be called) of his wife’s hand. Scientists worldwide quickly began their own experiments with...
9.6K
02:18Interference and Diffraction
51.3K
Interference is a characteristic phenomenon exhibited by waves. When two electromagnetic waves interact with their peaks and troughs coinciding, a resulting wave with enhanced amplitude is produced. This is known as constructive interference. In this case, the two waves interacting are in phase with each other.
51.3K
01:11Atomic Nuclei: Larmor Precession Frequency
2.5K
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,...
2.5K