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The Hubble Space Telescope has a lot to show in this week\u2019s\u00a0Picture of the Week. Its view here is studded with stars, many of which appear particularly large and bright thanks to their nearby locations in our own galaxy, and which feature the characteristic\u00a0diffraction patterns\u00a0caused by Hubble\u2019s optics. Much further away \u2014 around 240 million light-years distant, in fact, in the southern constellation Telescopium \u2014 is the\u00a0spiral galaxy\u00a0IC 4709. Its swirling disc filled with stars and dust bands is beautifully captured, as is the faint halo surrounding it. The compact region at its core might be the most remarkable sight, however: this is an\u00a0active galactic nucleus\u00a0(AGN).<\/p>\n
If IC 4709\u2019s core were just filled with stars, it would not be nearly so bright. Instead it hosts a gargantuan\u00a0black hole, 65 million times the mass of our Sun. A disc of gas spirals around and eventually into this black hole, with the gas crashing together and heating up as it spins. It reaches such high temperatures that it emits vast quantities of\u00a0electromagnetic radiation, from infrared to visible to ultraviolet light and beyond \u2014 in this case including X-rays. The AGN in IC 4709 is obscured by a lane of dark dust, just visible at the centre of the galaxy in this image, which blocks any\u00a0optical emission\u00a0from the nucleus itself. Hubble\u2019s spectacular resolution, however, gives astronomers a detailed view of the interaction between the quite small AGN and its host galaxy. This is essential to understanding supermassive black holes in galaxies much more distant than IC 4709, where resolving such fine details is not possible.<\/p>\n
This image incorporates data from two Hubble surveys of nearby AGNs that were identified by the Swift X-ray\/UV telescope, as does the\u00a0image from last week. Swift will collect new data on these galaxies \u2014 with an X-ray telescope, it\u2019s possible to directly see the X-rays from IC 4709\u2019s AGN breaking through the obscuring dust.\u00a0ESA\u2019s Euclid telescope\u00a0\u2014 currently surveying the dark Universe in optical and infrared light \u2014 will also image IC 4709 and other local AGNs. The complementary use of space telescopes across the electromagnetic spectrum is key to fully researching black holes and their impact on their host galaxies.<\/p>\n
[Image Description:<\/i>\u00a0A spiral galaxy is situated right of centre. It has a white, brightly-shining core, a glowing disc which is thick with swirling patterns of dark dust, and a faint halo around the disc. It is on a black background with some small, distant galaxies and some foreground stars around it. Six stars along the left side appear particularly large and bright, with two opposing sets of spikes surrounding each one.]<\/p>\n<\/p><\/div>\n<\/p><\/div>\n