More Than Half A Million Galaxies Identified And Classified By The ALHAMBRA Project

The ALHAMBRA project, led by researchers from the Instituto de Astrofísica de Andalucía and in which the University of Valencia has participated, has identified and classified more than half a million galaxies, after seven years of close observation of the universe from the Observatory of Calar Alto (CAHA, Almería) and thanks to a technique that breaks the stars energy in their colors through astronomical filters.

In addition, this research has also allowed calculating the distances from these galaxies to us with unprecedented accuracy. ALHAMBRA (Advanced Large, Homogeneous Area Medium Band Redshift Astronomical survey) has a system of twenty filters covering all wavelengths in the optical and three filters in the infrared, which allows to accurately determine the energy emitted by galaxies and the distance of half a million galaxies with unprecedented depth for the sample size.

The ALHAMBRA mapping represents an ambitious scientific project that has mobilized scientists from sixteen research institutes. Led by Mariano Moles (CEFCA) and developed in the Instituto de Astrofísica de Andalucía (IAA-CSIC), it was tailored designed to trace the universe evolution during the last ten million years. “ALHAMBRA represents a decisive step to board pressing issues in cosmology and astrophysics through photometric mapping, that allow getting the accuracy required to the distance of the detected objects,” Moles says. Thus, “the unbiased character of these mappings allows obtaining relevant data for all cosmic scales and, in this sense, the ALHAMBRA project is a precursor of the new long-range mapping that is being proposed,” the researcher adds.

Professor in Astronomy and Astrophysics at the Astronomic Observatory at the University of Valencia, Vicent Martínez has been one of the members of ALHAMBRA and explains that it is a mapping project on an area of the universe in which the range of cosmic distances achieved is “impressive and, therefore, it allows to scan the cosmic evolution as, in Astronomy, looking away is to look at the past. We can get to know how galaxies were in early stages of the universe history.” “The research team have been able to coordinate themselves using the 3.5 meters telescope of Calar Alto to get spectacular results. Part of the data has already been made available to the community. Their analysis will still provide more surprising results in the next months,” the researcher of the University of Valencia adds.

Nowadays, astronomers have large area and shallow explorations or very deep samples of the sky, but that only contemplate and only and reduced region, which does not take into account what is known as cosmic variance, resulting from the fact that the universe has more or less dense regions of galaxies.

“In this sense, the ALHAMBRA project has allowed us to confirm that the COSMOS sampling, one of the most employed cosmological studies, is not representative of how galaxies are distributed in the universe because its area is limited in a space with overdensity of galaxies with regard to the average; the proximity makes the galaxies to evolve faster, so that the evolutionary studies generated by COSMOS have a local character,” Alberto Molino (IAA-CSIC) indicates.

From Red Orbit