One Star Could Answer Many Unsolved Questions About Black Holes – Universe Today
[ad_1]
A supermassive black hole (SMBH) likely resides at the center of the Milky Way, and in the centers of other galaxies like it. It’s never been seen though. It was discovered by watching a cluster of stars near the galactic center, called S stars.
S stars’ motions indicated the presence of a massive object in the Milky Way’s center and the scientific community mostly agreed that it must be an SMBH. It’s named Sagittarius A*.
But some scientists wonder if it really is a black hole. And one of the S stars could answer that question and a few others about black holes.
Scientists have been monitoring and studying the S stars for over 20 years. They’ve gathered precise astrometric data for the group of stars, and the measurements of the stars’ positions and movements around the galactic center have shown that there’s a massive object there. One particular star in the group—named S2 (or S0-2)—could help astronomers determine more clearly the nature of that massive object.
A new research letter is taking a close look at S2’s behaviour and asking a potentially uncomfortable question. The study is titled “What does lie at the Milky Way centre? Insights from the S2 star orbit precession.” It’s available on the pre-print site arxiv.org. The first author is C. R. Argüelles from the Fac. de Ciencias Astron. y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque.
The question of what’s at the Milky Way’s Center has largely been settled. The 2020 Nobel Prize in Physics was awarded to three scientists. Two of them, Andrea Ghez and Reinhard Genzel, received it for their research into the object at the center of the galaxy. The press release from the Nobel Prize Organization reads “Reinhard Genzel and Andrea Ghez discovered that an invisible and extremely heavy object governs the orbits of stars at the centre of our galaxy. A supermassive black hole is the only currently known explanation.”
Now there’s some uncertainty.
It’s possible that the massive object at the center of our galaxy is actually dark matter. In this case, fermionic dark matter. According to the authors, “It has been recently demonstrated that both, a classical Schwarzschild black hole (BH), and a dense concentration of self-gravitating fermionic dark matter (DM) placed at the Galaxy centre, can explain the precise astrometric data (positions and radial velocities) of the S-stars orbiting Sgr A*.”
There’s another cosmic actor playing a role in this question. It’s not a star, but a cloud of gas called G2. In 2014 G2 passed close by the Milky Way’s center. Astronomers think it came to within 36 light hours of Sgr A*. Prior to its closest approach, astronomers simulated what the encounter might look like. They thought that the black hole would tear gas from the cloud, leading to a pronounced brightening from Sgr A* as it accreted mass from G2. But it never happened.
Why weren’t there any fireworks when G2 passed so close to Sgr A*? As it turns out, G2 may not have been a gas cloud. Instead, G2 is made up of two components: a cold cloud of low-mass gas, and a dusty stellar object. So G2’s close passage by Sgr A* didn’t end up shedding much light on the nature of the object in the galactic center.
Back to S2.
As the authors outline, there are two competing models that can explain the nature of the massive object. And they differ in one important way. “While the Schwarzschild BH scenario predicts a unique prograde precession for S2, in the DM scenario it can be either retrograde or prograde…” they write. Whether S2’s precession is either prograde or retrograde depends on the amount of DM mass inside S2’s orbit.
The authors point out that even with all the observations of the S2 star and all of the publicly available data, researchers are still unable to determine which of the models are correct. But there’s an opportunity to observe S2 coming up that should determine if the Milky Way’s center is inhabited by a black hole or dark matter. “… upcoming S2 astrometry close to next apocentre passage could potentially establish if Sgr A* is governed by a classical BH or by a quantum DM system,” they write.
Most of the matter in the Universe is dark matter, not baryonic matter. So should we register surprise when some of the most massive objects around may be made of dark matter rather than regular matter? Definitely. Because confirming that Sgr A* is not a black hole but a mass of dark matter would be a huge deal.
But we’ll have to wait and see. S2 has an orbital period of 16 years, and the last closest approach to Sgr A* was in 2018. The next best opportunity to observe S2 as it passes by Sgr A* is in 2034.
More:
[ad_2]
Original Post
I was wondering if you ever thought of changing the page layout of your website? Its very well written; I love what youve got to say. But maybe you could a little more in the way of content so people could connect with it better. Youve got an awful lot of text for only having 1 or two pictures. Maybe you could space it out better?
I carry on listening to the news update speak about getting boundless online grant applications so I have been looking around for the best site to get one. Could you tell me please, where could i find some?
Hey there I am so happy I found your webpage, I really found you by error, while I was searching on Aol for something else, Anyways I am here now and would just like to say thanks a lot for a fantastic post and a all round entertaining blog (I also love the theme/design), I don’t have time to read it all at the moment but I have bookmarked it and also added in your RSS feeds, so when I have time I will be back to read much more, Please do keep up the fantastic job.
Howdy! I could have sworn I’ve been to this blog before but after reading through some of the post I realized it’s new to me. Nonetheless, I’m definitely happy I found it and I’ll be book-marking and checking back often!
I appreciate, cause I found exactly what I was looking for. You have ended my four day long hunt! God Bless you man. Have a nice day. Bye
Enjoyed reading through this, very good stuff, thankyou.
Hello my loved one! I want to say that this post is amazing, great written and come with almost all vital infos. I would like to see extra posts like this .
It is best to participate in a contest for among the finest blogs on the web. I will advocate this website!
You are a very capable individual!
Lovely just what I was looking for.Thanks to the author for taking his time on this one.
I adore gathering useful information , this post has got me even more info! .
We are a group of volunteers and opening a new scheme in our community. Your web site provided us with valuable information to work on. You’ve done a formidable job and our whole community will be thankful to you.
Great post. I am facing a couple of these problems.
It’s the best time to make a few plans for the longer term and it is time to be happy. I have read this put up and if I may I wish to counsel you few interesting issues or suggestions. Perhaps you could write next articles regarding this article. I desire to read even more issues approximately it!
I was looking through some of your blog posts on this internet site and I believe this web site is really informative! Retain putting up.
I just could not leave your web site prior to suggesting that I extremely loved the standard info an individual supply for your visitors? Is gonna be back steadily in order to inspect new posts
Greetings from Colorado! I’m bored to death at work so I decided to check out your website on my iphone during lunch break. I really like the knowledge you provide here and can’t wait to take a look when I get home. I’m shocked at how quick your blog loaded on my mobile .. I’m not even using WIFI, just 3G .. Anyhow, awesome blog!
Woah! I’m really digging the template/theme of this blog. It’s simple, yet effective. A lot of times it’s very difficult to get that “perfect balance” between superb usability and visual appearance. I must say that you’ve done a superb job with this. Additionally, the blog loads super fast for me on Chrome. Exceptional Blog!
Oh my goodness! an amazing article dude. Thanks Nonetheless I’m experiencing challenge with ur rss . Don’t know why Unable to subscribe to it. Is there anybody getting identical rss downside? Anybody who is aware of kindly respond. Thnkx
My brother suggested I might like this blog. He was once totally right. This post truly made my day. You cann’t imagine simply how much time I had spent for this information! Thank you!
Somebody essentially help to make significantly posts I might state. That is the first time I frequented your web page and to this point? I amazed with the research you made to make this particular publish extraordinary. Fantastic job!
As a Newbie, I am continuously browsing online for articles that can benefit me. Thank you
Thank you for the sensible critique. Me and my neighbor were just preparing to do a little research on this. We got a grab a book from our area library but I think I learned more from this post. I’m very glad to see such fantastic information being shared freely out there.
Write more, thats all I have to say. Literally, it seems as though you relied on the video to make your point. You clearly know what youre talking about, why waste your intelligence on just posting videos to your weblog when you could be giving us something informative to read?
I got good info from your blog
You made certain fine points there. I did a search on the issue and found nearly all persons will agree with your blog.
Spot on with this write-up, I truly assume this web site needs much more consideration. I’ll in all probability be once more to read much more, thanks for that info.
Valuable info. Lucky me I found your website by accident, and I’m shocked why this accident did not happened earlier! I bookmarked it.
you will have a terrific weblog here! would you wish to make some invite posts on my weblog?
It’s actually a great and useful piece of info. I’m satisfied that you just shared this useful information with us. Please stay us up to date like this. Thank you for sharing.