"If we can precisely measure the structures in the sky, then we can observe this struggle," says LMU astrophysicist Daniel Grun. Large-scale telescopic projects like the Dark Energy Survey and the Euclid satellite, with significant contributions from LMU scientists, aim to capture these celestial structures in detail.
Determining the distances of galaxies is crucial for understanding the universe's history, as distant galaxies provide a snapshot of the past. The color of a galaxy, observed through ground-based telescopes like Blanco or satellites like Euclid, offers vital information on its distance. A study led by Jamie McCullough and Daniel Grun, published in MNRAS, has analyzed the largest dataset to date, revealing what galaxy colors indicate about their true distances.
Spectroscopy, measuring the spectral lines of distant galaxies, helps determine their distances. As the universe expands, lightwaves from these galaxies stretch, causing a redshift that makes galaxies appear redder. This redshift is similar to the Doppler effect observed in sound.
Unique Galaxies and Their Distances
Jamie McCullough, a doctoral researcher at LMU and Stanford University, used spectroscopic data from the Dark Energy Spectroscopic Instrument (DESI) and the KiDS-VIKING survey. She analyzed data from 230,000 galaxies to determine the relationship between their distance, color, and brightness.
"If we can combine distance information with measurements of the shape of galaxies, we can infer large-scale structures from the light distortions," says Jamie McCullough. This study allows for statistically determining the true distances of galaxies observed by Euclid or the Dark Energy Survey.
Analyzing galaxy image distortions can reveal the behavior of cosmic structures and their evolutionary history. Observing structures at various distances allows scientists to understand the development of the universe without waiting billions of years. McCullough's study provides a model linking a galaxy's apparent color to its distance, crucial for this analysis.
Observing the Dark Matter and Dark Energy Contest
The primary goal of mapping galaxies at various distances is to understand the cosmic struggle between dark matter and dark energy. "To really see what's happening, you have to be able to observe the individual rounds of this match," says Grun. Dark energy may eventually halt the formation of larger cosmic structures. Understanding this interplay will help scientists discern the nature and ultimate influence of dark matter and dark energy.
Research Report:DESI complete calibration of the colour-redshift relation (DC3R2): results from early DESI data
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Understanding Time and Space
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