Sagittarius A* at the Center of Our Galaxy

A black hole called Sagittarius A* (pronounced A-star) lies at the center of our Milky Way Galaxy, only 27,000 light-years away. Its mass is roughly 4 million times the mass of the Sun. Our galaxy’s black hole is mild-mannered compared to the central black holes in some other galaxies, much more calmly consuming material around it. However, it does sometimes flare-up. An flareup lasting several hours is documented in this series of X-ray images from the orbiting Nuclear Spectroscopic Telescope Array (NuSTAR). NuSTAR is the first instrument to provide focused views of the area surrounding Sgr A* at X-ray energies higher than those accessible to the Chandra and XMM observatories. The flare sequence is shown in the panels on the right. The images cover a two-day span. X-rays are generated in material heated to over 100 million C and traveling at nearly the speed of light as it falls into the black hole. The center X-ray image spans about 100 light-years. Its bright white region is the hottest material closest to the black hole; the pinkish cloud probably belongs to the remnant of a nearby supernova. Click the picture to embiggen it.

Sgr A* is monitored on a daily basis by the X-ray telescope of the Swift satellite. I made contributions to the design of the power and thermal control systems of the Burst Alert Telescope instrument on Swift.

Image Credit: NASA

Mergers and Acquisitions

Galaxy clusters are the largest objects in the universe held together by gravity. They can contain hundreds or thousands of galaxies held together in vast clouds of multi-million-degree gas glowing in X-rays.

The system known as Abell 2384 is the result of the collision of a pair galaxy cluster hundreds of millions of years ago. This composite image was put together using x-ray data from the Chandra X-ray Observatory and XMM-Newton (blue) and radio data from the Giant Metrewave Radio Telescope in India (red). It shows the superheated bridge of gas running through Abell 2384 and reveals the effects of a jet from a supermassive black hole in the center of a galaxy in one of the clusters. The jet is so powerful that it bends the shape of the 3 million light-year long gas bridge which has the mass of about 6 trillion Suns.

Image Credit: NASA

An X-Ray View of the Universe

ESA’s XMM-Newton satellite produced this map of x-ray sources. Its shows the 30 000 sources in the 84% of the sky it covers. The plot is color-coded. Lower energy x-ray sources are red, and higher energy sources are blue. The brighter the source, the larger it appears on the map.

Image Credit: ESA

The Heart of the Crab

Here’s NASA’s description of this video—

This video starts with a composite image of the Crab Nebula, a supernova remnant that was assembled by combining data from five telescopes spanning nearly the entire breadth of the electromagnetic spectrum: the Very Large Array, the Spitzer Space Telescope, the Hubble Space Telescope, the XMM-Newton Observatory, and the Chandra X-ray Observatory.

The video dissolves to the red-colored radio-light view that shows how a neutron star’s fierce “wind” of charged particles from the central neutron star energized the nebula, causing it to emit the radio waves. The yellow-colored infrared image includes the glow of dust particles absorbing ultraviolet and visible light. The green-colored Hubble visible-light image offers a very sharp view of hot filamentary structures that permeate this nebula. The blue-colored ultraviolet image and the purple-colored X-ray image shows the effect of an energetic cloud of electrons driven by a rapidly rotating neutron star at the center of the nebula.

Video Credit: NASA, ESA, J. DePasquale (STScI)