Related Experiment Video
Updated: Aug 3, 2026
10:39
Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
Published on: October 11, 2016
Redshift survey with multiple pencil beams at the galactic poles
A S Szalay1, T J Broadhurst, N Ellman
1Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA.
Summary
Multiple deep galaxy surveys reveal large-scale cosmic structures. Analysis of over 1200 galaxies confirms a significant peak in the power spectrum, indicating structures with substantial transverse size.
Area of Science:
- Cosmology
- Astrophysics
- Large-Scale Structure
Background:
- Cosmic structure observations suggest inhomogeneities on scales of 100h-1 to 150h-1 Mpc.
- Previous "pencil-beam" galaxy surveys indicated strong clustering and regularity at 128h-1 Mpc.
Purpose of the Study:
- To overcome statistical limitations of single pencil-beam surveys.
- To investigate the nature of large-scale cosmic structures using multiple deep probes.
- To confirm or refute the existence of structures responsible for the observed power spectrum peak.
Main Methods:
- Utilizing newly acquired data from multiple deep probes.
- Performing cross-correlations of multiple pencil-beam galaxy surveys.
- Analyzing data from over 1200 galaxies.
Main Results:
- Demonstrated that multiple deep probes mitigate statistical issues of single beams.
- Confirmed that the strong peak in the power spectrum arises from structures of large transverse size.
- Discussed the sensitivity of pencil-beam surveys to the topology of large-scale structures.
Conclusions:
- The observed clustering regularity is attributed to large transverse structures.
- Multiple pencil-beam surveys provide a more robust method for studying cosmic structure.
- Pencil-beam surveys are sensitive to the topology of the universe's large-scale structure.
More Related Videos
Related Concept Videos
02:39Emission Spectra
When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
01:19Magnetic Field Lines
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:
01:22Atomic Emission Spectroscopy: Instrumentation
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.
01:30Atomic Emission Spectroscopy: Interference
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,...