Not too long ago, astronomers figured out that most large galaxies – including our own – have a supermassive black hole (an enormous object which can be billions of times the Sun’s mass) right in its core. Along with this astonishing finding, an unsettling question was raised: Which came first, galaxies or the supermassive black holes in their cores?
The cosmic chicken-and-the-egg problem
Scientists know that there is an intrinsic relationship between the galaxy and its black hole. It’s believed that black holes and galaxies grow together, in a kind of partnership. As the black hole swallows the material in the surrounding area, it becomes more and more massive, and the more massive a black hole is, the more radiation it blasts out. This powerful radiation heats up the clouds of gas in the galaxy, but it’s still unclear whether this radiation boosts or prevents the formation of new stars.
By studying the nearby galaxies, astronomers also figured out that there is an elegant relation between the mass of the supermassive black holes and the giant cloud of stars and gas in the core of their galaxies (nicknamed “bulge”): no matter how big is the galaxy, the black hole is always about 700 times more massive than the bulge. Although this suggests that galaxies and their black holes evolve together, scientists weren’t sure whether this rule was obeyed in the early universe.
Looking back in time
In order to see the first black holes, astronomers need to look as deep into space as possible. The problem is that it’s not easy to observe an ancient galaxies in details, mainly because of their high redshift. The most easily seen galaxies in higher redshifts are quasars, due to their extreme brightness. Nevertheless, separating the radiation emitted by the supermassive black hole from the glare of the quasar is a tough challenge.
To calculate the size of the Milky Way’s supermassive black hole – as we cannot actually “see” it, – astronomers needed to measure the speed of the stars orbiting in the heart of the galaxy: the faster the stars move around the black hole, the more massive it is. Measuring the size of a supermassive black hole hosted in another galaxy is an even more complex task: the scientists need to analyse the infrared light coming from the centre of the galaxy. Moreover, the data needs to be carefully filtered, in order to separate the radiation emitted by the black hole from the light coming from other objects in the galaxy.
Using powerful radio telescopes, such as the Very Large Array (VLA) in U.S. and the Atacama Large Millimeter/sub-millimeter Array (ALMA) in Chile, along with image-filtering processes, astronomers were finally able to get accurate measurements of the mass of these early black holes and had a big surprise.
In the galaxies observed during the studies, the black holes were only 30 times less massive than the bulge of their host galaxy, breaking the rule we see in the modern galaxies. It appears to solve the chicken-and-the-egg mystery, indicating that black holes actually came first.
Despite this major discovery, the origins of the supermassive black holes remains one of the most hotly debated topics in astronomy. Many undergoing projects are trying to pile up evidences to either underpin or contest this theory, and better explain when and how this mysterious relation came about.
Today on the Young Astronomers we bring you an interview with the amazing astrophotographer Ken Crawford, so without further ado let’s begin:
What is an astrophotographer?
Astrophotographers come in two basic types. Solar System astrophotography are images of the Sun, Moon, and Planets. These types of images are normally taken with special video cameras to capture many pictures of the object. Because the objects are bright, the pictures are taken very quickly. You then remove any blurred images and keep the good ones
Deep sky astrophotography captures the light from very faint and distant objects like nebulae, galaxies, and star clusters. These pictures are taken with very long exposures over several hours and the combined together for the final result.
What first attracted you to astrophotography? Did anyone inspire you to take it up?
I have always been interested in astronomy and built my first telescope in 8th grade. I became interested in astrophotography because it is a technical art form. The technical part is that you assemble different imaging tools together like the telescope, mount, and camera and make them work together. Then you need to be able to learn to use the software that controls the telescope and camera and the assembling of the images. The art form is the presentation of the colors, contrast, and details in their most beautiful form possible. The amazing thing is that amateurs can produce very professional results with modest equipment, dark skies, and lots of practice.
I was inspired by some of the pioneers of astrophotography like David Malin, Rob Gendler, and Tony Hallas. I also had the support of my wife of over 34 years which is a huge plus.
What is/are your favourite object(s) to photograph?
My favourite objects are distant island universes (Galaxies) and star forming regions (Nebulae).
Does astrophotography require any special equipment, or is a standard digital camera suitable?
You can do what is called wide field low resolution work with standard DSLR cameras but the better work comes from astronomical cameras with monochrome (greyscale) CCD with color filters in front. Here is a picture of my imaging train.
A = main CCD Camera – cooled to -25c
B = Filter wheel with 10 color filters
C= Off axis pick-off mirror to send starlight to the guider camera.
D= Guider Camera
E = Rotator to rotate the complete image train to any position
Do any resources exist for beginners?
Some, online forums, books, and online telescope rentals can help. Some astronomy clubs can help out if they have Astrophotographers as members. I am president of the Advanced Imaging Conference and we have once a year seminars and classes. The online forum called Cloudy Nights has a beginner section.
Is the any advice you could pass on to any of our readers interested in starting astrophotography as a hobby?
The hobby can be expensive but you can start out very easily with just a DSLR camera and a small tracking tripod. You can capture nice images of the constellations and other large celestial objects. You can use an inexpensive webcam to capture images of the moon and bright planets. But first, join the online forums or find someone who is doing astrophotography and ask for help.
We would once again like to thank Ken for his participation with the interview and giving up his time to answer our questions!
The ESA’s Mars Express orbiter has captured this fantastic image of the Ladon Basin, specifically of this spectacular double impact crater:
The pair are named Sigli and Shambe and are believed to have been formed by a single object that broke into two larch fragments just before impacting the surface of Mars.
The shape and shallow nature of the impact crater suggest that it was formed when an asteroid or comet hits a planet at a reasonably shallow angle.
This particular pair is 16km across and shows significant fracturing of the crater floor. The pair also show signs of being partially filled with sedimentary material at some point after their formation. This implies that they may well have been lakes, as such material is only deposited under water, hinting once more of Mars’ more environmentally pleasant past.
You can read more about this image here
In around eight hours at 06:31 am, (I’m not counting, honest) the Mars Curiosity Rover will begin her descent into the Martian atmosphere and, if all of the many stages of descent and landing go perfectly, begin her mission.
The mission itself is to find out if the past – or present – environment on mars was suitable for microbial life to inhabit the soil. The mission will last as long as Curiosity does, her plutonium power source will give her enough power to be our interplanetary geologist for at least 687 days; a Martian year.
As of an hour ago Curiosity was just 142,783 km away from Mars, less than a third of the distance Earth is from the Moon. If you’d like to know plenty more snippets like this I suggest following @MSL_101 on twitter or the official NASA account, @MarsCuriosity.
I also had to share this brilliant NASA Jet Propulsion Lab video describing the challenges faced during descent. Unsurprisingly it’s described as ‘the seven minutes of terror’:
You can find a good summary of the mission here!
It has certainly been a long while since Hannah and myself produced a podcast episode though we hope to bring you a few episodes over the next couple of weeks.
To kick us back off, here is the next section of our interview with Professor Bill Keel. In this segment we take a look at Voorwerpjes along with Hanny’s Voorwerp.
Hannah and I will also be returning to these topics in more detail in our next Podcast.
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