Giant galaxies are built out of a patchwork of many smaller galaxies, drawn together by gravity. But the stars in these precursor galaxies are disimilar. How does this process of galactic assembly affect what we can infer about star formation?
Magnificent though they are, galaxies are in constant risk of death from their own members and the environment. Today, we look at a murder act staged by black holes and mergers.
How do galaxies grow? Today’s featured paper investigates the role of mergers between galaxies in assembling the most massive nearby galaxies.
Galaxy Zoo is a citizen science project that uses volunteers to classify galaxies from the Sloan Digitial Sky Survey as spiral or elliptical. Now the Galaxy Zoo 2 catalogue has gone public, with even more detailed classifications of galaxies, including bars, bulges, spiral arms, and round and squashed ellipticals.
Huang et al. dig up evidence that distant “red nugget” galaxies grew into the massive ellipticals we see today by consuming smaller, gas-poor galaxies.
Based on galactic rotation curves, we think that spiral galaxies are embedded in massive dark matter halos. Is the same true for elliptical galaxies? Magain and Chantry use gravitational lensing to measure the mass-to-light ratios in 15 elliptical galaxies, and the results might surprise you!