Today, ESA's Gaia mission releases a goldmine of knowledge about our galaxy and beyond in its 'focused product release'. Among other findings, the star surveyor identifies 381 possible cosmic lenses: elusive and exciting objects that hold clues to some of humanity’s biggest questions about the cosmos.
Gaia researchers found that some of the objects we see in the skies around us aren’t simply stars, even though they look like them. They are actually very distant lensed quasars – extremely bright, energetic galactic cores powered by black holes. The researchers present 381 solid candidates for lensed quasars, including 50 deemed highly likely: the largest set of candidates ever released at once.
The team identified the candidates from an extensive list of 3 760 032 possible quasars (including those identified as part of Gaia DR3). Five of the possible lenses are potential Einstein crosses, rare lensed systems with four different image components shaped like a cross.
The upper-left graphic shows the phenomenon of gravitational lensing in a little more depth. This occurs when the image of a faraway object becomes warped by a disturbing mass – a star or galaxy, for instance – sitting between us and the object. This intermediate mass acts as a giant magnifying glass, or lens, that can amplify the brightness of light and cast multiple images of the faraway source onto the sky. These curious and rare configurations are visually intriguing and hold immense scientific value, revealing unique clues about the very earliest days and inhabitants of the Universe.
The six lensed systems shown to the right were identified in Gaia DR3, and shown as seen by the Dark Energy Spectroscopic Instrument (DESI) and PanSTARRS.
Alt-text: This infographic has three main parts: a visual describing how gravitational lensing works (top left), six images of lensed systems identified in Gaia DR3 (top right), and some key facts about Gaia's discovery of new lensed quasars (bottom). The visual on gravitational lensing illustrates how light travels from a distant quasar to Gaia, bending around a foreground mass (a galaxy) as it travels, and shows how this causes the telescope to see multiple images of the quasar on the sky.
Acknowledgments: Based on the paper “Gaia Focused Product Release: A catalogue of sources around quasars to search for strongly lensed quasars” by Gaia Collaboration, A. Krone-Martins et al.; Graphic produced by ATG under contract to ESA.