Gravitational lensing is the deflection of the trajectory of a photon by gravity, and it is a natural consequence of the theory of General Relativity. Lensing distorts the shapes and orientations of galaxies and in today’s post, we discuss a new method to reconstruct dark matter maps of our Universe using the position angles of galaxies.
New results from stacked weak lensing measurements of over a hundred thousand galaxies show that, on large scales, light from stars appears to trace the dark matter distribution of the Universe remarkably well.
NASA is looking for a new mission for the damaged Kepler space telescope. Here are some ideas.
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!
In today’s astrobite, we continue our overview of the papers from the Planck 2013 release. This time, we review papers XVII and XXIII, which discuss weak gravitational lensing of the Cosmic Microwave Background, and the isotropy of the Universe at the time this background radiation was emitted.
What were astronomers reading and talking about in their research last year? Check out figures from the top 12 most-cited astronomy papers from 2012 (so far) and find out what researchers were up to and why!
The Canada-France Hawaii Telescope weak gravitational lensing survey (CFHTLens), recently released new results to help constrain our cosmological models. While still in its early stages, weak lensing will ultimately be a powerful tool to discover the nature of the mysterious dark energy.
I recently attended a two-week crash course in the “Astrophysical Applications of Gravitational Lensing”. In this post, I overview a few of the ways astronomers employ lensing to study the Universe, from extrasolar planets to distant quasars and large-scale structure.
Throughout much of the 20th century, it was an open question in astronomy as to what the universe looked like on the largest observable scales. Were galaxies and galaxy clusters distributed uniformly throughout space, or was there a pattern? Thanks to galaxy surveys we know that, on large scales, the matter distribution of the universe is clumpy instead of smooth. Through these surveys we observe directly the distribution of luminous matter like stars, gas, and galaxies. However, luminous matter comprises only a small fraction of the matter in the universe (17%), the rest is dark matter which interacts via gravity but does not absorb and emit electromagnetic radiation like normal matter. Theoretical simulations of dark matter cosmologies firmly predict that there is a dark matter backbone to the cosmic web, with filaments of dark matter stretching between clusters of galaxies, though has not yet been a robust detection of a dark matter filament, until now.