The episode touches on the wondrous journey a galaxy undergoes as it evolves through its life cycle. Angelo starts off the episode by asking the question, what's an early-type galaxy? Paolo Bonfini  explains that although you may think that early-type galaxies would be galaxies early in their evolution, they're not, they're galaxies a little later. They're the ultimate evolution of two galaxies coming together. 

Based on the topics touched on in Paolo's paper he then explains the role that supermassive black holes play in galaxy evolution. Paolo explains, "thanks to the recent development in gravitational-wave astronomy, which opened a completely new window of exploration because it's not based on electromagnetic waves, but on gravitational waves, which are a completely different thing. We are now able to explore black holes in more detail and we're able to study when supermassive black holes merged to create a bigger one."

Relating to the idea of bringing new technology forward, Angelo asks has any computer science techniques assisted you to be able to model this or put it together? Paolo explains, "there are a lot of computations involved in this process. People have in mind the romantic view of the astronomer who just looks through the scope of the telescope and notes things down on a piece of paper, but modern astronomy is completely digitalized. And recently it has been even automated by a lot of procedures that they track and scan the sky to create huge catalogs. Even the images themselves, they are captured on digital devices, like, the same as they appear in the phone, basically, the same technology, but just on a more refined scale. And the first process for which you will need a computer is to combine exposures. So you cannot expose a telescope on a specific direction in the sky for a very long time, for several reasons. The summary is that, in order to take an image of some patch in the sky, you will have to take multiple images and then combine them. Now the modern telescopes, they are extremely accurate. So when you combine them, you need to align the stars to a sub pixel resolution. That means that you have to find the center of the star and itself be positioned within a single individual pixel. And when you combine images, you have to align them by with the precision of, let's say, a third of a pixel, which sounds impossible because you're like, how can you do that? But, there are some techniques that allow you to do that. And of course you need a lot of computational power for that. It can take several minutes to do this even a half an hour, let's say, to combine and produce the image that you see on famous websites, like the Hubble. I mean, this is just the first step. You mentioned a thing you need to actually extract, in my case for the study I was doing, in order to assess the lack of stars at the center of a given galaxy you actually have to measure it. So what you have to do is, you have to trace the light profile, starting from the outskirts of the galaxy going gradually towards the center. In this way, you can draw a light curve if you want. It's not exact, it's more like a light profile. So you have some intensity at the edge of the galaxy, which would be low intensity because the light is very diffused and all the center it grows, grows, grows. And at some point you will see doesn't grow as much. That's where you meet the depleted core, but you also need to quantify this because you want to actually extract the information about the amount of depleted mass, like comments that you would expect it to be versus how many you actually measure. So, you have to fit the light profile. And this is done by, okay. In my case, I've been doing this with some kind of basic statistical technique, which is the chi squared fitting. So you have our model and you just fit the model to the observation and once you have the model, you can project only the other path towards the center and you compare it with the actual model that you fit. And from the difference between the two, you have the amount of stars that are missing. So you need to explore a lot of parameters and therefore you need to have this thing automated via computer technology. There is no chance you can get this information doing it by hand."

Referencing the famous space observatory, Hubble, Pablo explains what it was like to work with such a brilliant piece of machinery. He shares, "it's really amazing because the Hubble telescope was launched in the nineties and just to give you an idea is roughly the size of a bus. There is a replica of it you can visit at, I think it's the Aerospace Museum in Washington, so if you're curious. The main mirror is 2.3 meters in diameter, just to give you an idea, the larger the diameter, the higher the resolution you can achieve. On Earth, there are bigger telescopes. The biggest telescope we have on Earth is currently 10 meters. It's on the Canary Islands. On Earth you have the atmosphere on top of you and this makes everything flicker a little bit because you know, there is air moving, and these big masses of atmosphere move and this shifts the path of the light and this causes the images to be more confused. If you are instead outside the atmosphere, you don't have that problem and you really achieve the limiting resolution of your instrument. So the Hubble Space Telescope is particularly famous because of its resolution. It doesn't have a large collective area, it’s only two meters, let's say, so it doesn't collect a lot of light per second. So it doesn't have, let's say, the same contrast as ground-based telescopes, but it has extremely high resolution. So when you open an image and you're saying, okay, I want to look at this galaxy and I will work on this, which is at the center of the field of view because you pointed there. But, at the edges of it, you see a lot of tiny objects and if you zoom in you can see the structure. Maybe you see a lot of spiral galaxies around the merging objects in the background. And it's not at the center of your research. You're looking at the big galaxy at the center that you're studying. But, you know, it's like a small pleasure, small candy that you have for the eye. You're looking at these things around and you are like, well, man, this is incredible. There are so many things in the universe and I'm here focusing on these big galaxies at the center, but whatever else is happening in the background, and this is really the, I think it's the most impressive thing."

Angelo concludes the episode by discussing the ups and downs of crafting a research paper. Paolo touches on the rollercoaster of emotions one undergoes due to the sheer volume of work that needs to be done. to the most rewarding aspect of writing such a paper. He explains, "you know that you are at the forefront of this research, and I think this is when the reward comes when you're actually presenting and you see the people being curious and asking you directly at the conference, “What is this?” “How did you get there?” “It's very interesting. Let's work together.” “This is an idea to make it even better” and so on."

Our Guest - Thank you!:

Paolo Bonfini - https://www.linkedin.com/in/paolo-bonfini-phd-085a6a179/

Paolo's  Paper:

Connecting traces of galaxy evolution: the missing core mass-morphological fine structure relation

Our Team:

Host:Angelo Kastroulis

Executive Producer: Náture Kastroulis 

Producer: Albert Perrotta; 

Communications Strategist: Albert Perrotta;

Audio Engineer: Ryan Thompson

Music: All Things Grow by Oliver Worth

Host: Angelo Kastroulis

Executive Producer: Náture Kastroulis

Producer: Albert Perrotta

Communications Strategist: Albert Perrotta

Video/Audio Engineer: Ryan Thompson

Music: All Things Grow by Oliver Worth