Related Experiment Video
Updated: Jan 21, 2026
10:05
Genome-wide Mapping of Drug-DNA Interactions in Cells with COSMIC Crosslinking of Small Molecules to Isolate Chromatin
Published on: January 20, 2016
8.6K
Stringent Limit on Primordial Magnetic Fields from the Cosmic Microwave Background Radiation
Karsten Jedamzik1, Andrey Saveliev2,3
1Laboratoire Univers et Particules de Montpellier, UMR5299-CNRS, Université de Montpellier, 34095 Montpellier, France.
Physical Review Letters
|August 7, 2019
Summary
Primordial magnetic fields (PMFs) before cosmic recombination create density fluctuations, altering cosmic microwave background (CMB) radiation. New analysis provides stringent limits on PMF strength, significantly improving upon previous constraints.
Area of Science:
- Cosmology
- Astrophysics
- Fundamental Physics
Background:
- Primordial magnetic fields (PMFs) predate cosmic recombination.
- PMFs induce baryonic density fluctuations, affecting recombination.
- These inhomogeneities alter cosmic microwave background (CMB) anisotropies.
Purpose of the Study:
- To derive stringent limits on the magnitude of PMFs.
- To account for the impact of inhomogeneous recombination on CMB anisotropies.
- To improve upon existing constraints on PMFs using observational data.
Main Methods:
- Numerical compressible magnetohydrodynamics (MHD) calculations.
- Monte Carlo Markov chain analysis.
- Comparison of calculated CMB anisotropies with WMAP and Planck satellite data.
Main Results:
- Derived new, stringent upper limits on present-day PMF strength.
- Established a limit of 47 pG for scale-invariant PMFs.
- Established a limit of 8.9 pG for violet Batchelor spectrum PMFs (95% confidence).
Conclusions:
- The derived limits are over an order of magnitude stronger than previous CMB-based constraints.
- This study highlights the importance of considering inhomogeneous recombination for PMF limits.
- The findings significantly refine our understanding of early universe magnetic fields.
Related Concept Videos
01:05Difference from Background: Limit of Detection
8.1K
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...
8.1K
01:27Magnetic Fields
7.1K
A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...
A magnetic field is defined by the force that a charged particle experiences...
7.1K
01:18Magnetic Field of a Solenoid
5.7K
A solenoid is a conducting wire coated with an insulating material, wound tightly in the form of a helical coil. The magnetic field due to a solenoid is the vector sum of the magnetic fields due to its individual turns. Therefore, for an ideal solenoid, the magnetic field within the solenoid is directly proportional to the number of turns per unit length and the current. Conversely, the magnetic field outside the solenoid is zero.
Consider a solenoid with 100 turns wrapped around a cylinder of...
Consider a solenoid with 100 turns wrapped around a cylinder of...
5.7K
01:19Magnetic Field Lines
5.5K
The representation of magnetic fields by magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. Each of the magnetic field lines forms a closed loop. The field lines emerge from the north pole (N), loop around to the south pole (S), and continue through the bar magnet back to the north pole.
Magnetic field lines follow several hard-and-fast rules:
Magnetic field lines follow several hard-and-fast rules:
5.5K
01:24Energy In A Magnetic Field
2.7K
If a magnetic field is sustained, there must be a current in a closed circuit or loop, implying some energy has been spent in creating the field. If this energy is not dissipated via the circuit's resistance, it is stored in the field.
Take an ideal inductor with zero resistance. Although it's practically impossible, assume that the coil's resistance is so small that it is practically negligible. The loss of the field's energy to dissipate thermal energy (or heat) is thus...
Take an ideal inductor with zero resistance. Although it's practically impossible, assume that the coil's resistance is so small that it is practically negligible. The loss of the field's energy to dissipate thermal energy (or heat) is thus...
2.7K
01:16Magnetic Field Of A Current Loop
6.3K
Consider a circular loop with a radius a, that carries a current I. The magnetic field due to the current at an arbitrary point P along the axis of the loop can be calculated using the Biot-Savart law.
6.3K