Using the Atacama Large Millimetre/submillimetre Array (ALMA), a team of astronomers has delved remarkably deep into the heart of a nearby elliptical galaxy to study the motion of a disc of gas encircling the supermassive black hole at its centre. These observations provide one of the most accurate mass measurements to date for a black hole outside of our galaxy.
Subtle distortions hidden in a stunning Atacama Large Millimetre/submillimetre Array (ALMA) image of the gravitational lens SDP.81 are telltale signs that a dwarf dark galaxy is lurking in the halo of a much larger galaxy nearly 4 billion light-years away. This discovery could help astronomers address important questions on the nature of dark matter.
There are about two dozen so-called hypervelocity stars known to be escaping our Milky Way galaxy, but PB 3877 is the first wide binary star found to travel at such a high speed. The results of a new study challenge the commonly accepted scenario that hypervelocity stars are accelerated by the supermassive black hole at the galactic centre.
This new image from the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile captures a spectacular concentration of galaxies known as the Fornax Cluster, which can be found in the Southern Hemisphere constellation of Fornax (The Furnace). The cluster plays host to a menagerie of galaxies of all shapes and sizes, some of which are hiding secrets.
This striking NASA/ESA Hubble Space Telescope image depicts the low surface brightness (LSB) galaxy known as UGC 477, located just over 110 million light-years away in the constellation of Pisces. LSB galaxies appear to be dominated by dark matter, making them excellent objects to study to further our understanding of this elusive substance.
Atoms or their constituents account for a mere 4.9 percent of the universe. The rest is dark matter, so understanding this ubiquitous yet mysterious substance is a prime goal of modern astrophysics. By studying the spatial distribution of gamma-ray emission in the Milky Way, astronomers believe they have now identified a signature of dark matter annihilation.
At first glance, this cosmic kaleidoscope of purple, blue and pink offers a strikingly beautiful — and serene — snapshot of the cosmos. However, this multi-coloured haze actually marks the site of two colliding galaxy clusters, forming a single object known as MACS J0416.1-2403 (or MACS J0416 for short), 4.3 billion light-years away from Earth.
Indisputable physical calculations state that approximately 27 percent of the universe is dark matter, but there are indications that we might never see it. Now researchers in Denmark turn this somehow depressing scenario into an advantage and propose a new model for what dark matter might be — and how to test it.
Galaxy clusters are enormous collections of hundreds or even thousands of galaxies and vast reservoirs of hot gas embedded in massive clouds of dark matter. To learn more about clusters, including how they grow via collisions, astronomers have used some of the world’s most powerful X-ray, optical and radio telescopes. The name for this galaxy cluster project is the “Frontier Fields”.
Astronomers have used computer simulations based on theoretical models to explain massive star formation observed in dwarf galaxies. Researchers in the US and the Netherlands found that during a dark matter satellite’s closest approach to a dwarf galaxy, through gravity it compresses the gas in the dwarf, triggering significant episodes of starbursts.
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