What Is a Tidal Disruption Event Around a Black Hole?

Updated on August 13, 2018
1701TheOriginal profile image

Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly improve it.

Source

Black holes are likely the most interesting object in science. So much research has been done on their relativity aspects as well as their quantum implications. Sometimes it can be hard to relate to the physics around them and occasionally we may seek a more digestible option. So let’s talk about when a black hole eats a star by destroying it, also known as a tidal disruption event (TDE).

Source

Mechanics of the Event

The first work proposing these events occurred in the late 1970s when scientists realized that a star getting too close to a black hole could get torn apart as it crosses the Roche limit, with the star flinging around, undergoing spaghettification, and some material falling into the black hole and around as a brief accretion disc while other portions fly out into space. This all creates a rather luminous event as the in falling material can form jets that might point to a black hole unknown to us, then the brightness drops as the material disappears. Much of the data would come to us in high energy positions of the spectrum such as UV or X-rays. Unless something is present for a black hole to feed on, they will be (mostly) undetectable to us, so looking for a TDE can be a challenge, especially because of the close proximity the passing star needs to achieve a TDE. Based on stellar motions and statistics, a TDE should only happen in a galaxy once every 100,000 years, with a better chance near the center of galaxies because of the population density (Gezari, Strubble, Cenko 41-3).

Source

As the star is devoured by the black hole, energy is released around it as UV rays and X-rays, and as is the case for many black holes, dust surrounds them. The dust also comes into collision from actual star material being flung out of the event. The dust can absorb this flow of energy via collisions and then echo it out into space as infrared radiation at its perimeter. Evidence for this was gathered by Dr. Ning Jiang (University of Science and Technology in China) and Dr. Sjoert van Velze (John Hopkins University). The infrared readings came much later than the initial TDE and so by measuring this difference in time and using the speed of light, scientist can get a distance reading on the dust around those black holes (Gray, Cenko 42).

Source

Searching for the Event and Notable Examples

Many candidates were found in the 1990-91 search by ROSAT, and archival databases pointed to many more. How did scientists find them? The locations had no activity before or after the TDE, indicating a short-term event. Based on the number seen and the span of time they were spotted, it matched theoretical models for TDEs (Gezari).

The first one spotted at a previously known black hole was on May 31, 2010, when scientists at John Hopkins watched a star fall into a black hole and go through the TDE event. Dubbed PS1-10jh and located 2.7 billion light-years away, initial results were interpreted as a supernova or a quasar. But after the length of brightening didn’t wane down (in fact, it lasted until 2012), a TDE was the only possible explanation left. Lots of forewarning was sent out about the event at the time so observations in optical, X-rays, and radio were achieved. They found that the brightening (200 times more than normal) seen was not a result of an accretion disc based on the lack of such feature in prior readings, but jets did occur here just as a TDE would result in. The temperature was cooler than expected by a factor of 8 for accretion disc models, with a recorded temp of 30,000 C. Based on the lack of hydrogen but strength in He II lines in the spectrum, the star that fell in was likely a red giant with its outer hydrogen layer eaten by…a black hole, possibly the one that eventually ended its life. However, a mystery was left when the He II lines were found to be ionized. How did this happen? It is possible that dust between us and the TDE could have affected the light, but it’s unlikely and thus far unresolved. When examining prior observations with the brightness seen from the TDE, scientists were at least confident to conclude that the black hole is about 2 million solar masses (John Hopkins, Strubble, Cenko 44).

In a rare event, a TDE was spotted with high jet activity. Arp 299, about 146 million light-years away, was first spotted in January of 2005 by Mattila (University of Turku). As a galaxy collision, the infrared readings were high as temperatures rose but later that year the radio waves rose as well and after a decade jet features were present. This is a sign of a TDE, and scientists were able to study the shape and behavior of the jets in the hopes of uncovering more of these rare events, possibly 100-1000 times more so than a supernova (Carlson).

In November 2014, ASASSN-14li was spotted by Chandra, Swift, and XXM-Newton. Located 290 million light-years away, 14li was a post TDE observation, with the expected drop in light occurring as the observation progressed. Light spectrum readings indicate that the trailing material that was initially blown away is slowly falling back in to create a temporary accretion disc (NASA).

Source

TDEs as a Tool

TDEs have many useful theoretical properties including being a way to find the mass of a black hole. An important class of black holes that requires more evidence for their existence are intermediate black holes (IMBHs). They are important for black hole models but few (if any) have been seen. That is why events such as the one spotted in 6dFGS gJ215022.2-055059, a galaxy roughly 740 million light-years away, are critical. In that galaxy, a TDE was observed in the X-ray portion of the spectrum and based on the readings seen the only thing massive enough to produce it would be a black hole that is 50,000 solar masses - which can only be an IMBH (Jorgenson).

Works Cited

Carlson, Erika K. "Astronomers Catch a Black Hole Devouring Star." Astronomy.com. Kalmbach Publishing Co., 14 Jun. 2018. Web. 13 Aug. 2018.

Cenko, S. Bradley, and Neils Gerkess. “How to Swallow a Sun.” Scientific American Apr. 2017. Print. 41-4.

Gezari, Suvi. “The tidal disruption of stars by supermassive black holes.” Physicstoday.scitation.org. AIP Publishing, Vol.

Gray, Richard. “Echoes of a Stellar Massacre.” Dailymail.com. Daily Mail, 16 Sept. 2016. Web. 18 Jan. 2018.

Jorgenson, Amber. "Rare intermediate-mass black hole found tearing apart star." Astronomy.com. Kalmbach Publishing Co., 19 Jun. 2018. Web. 13 Aug. 2018.

NASA. “Tidal Disruption.” NASA.gov. NASA, 21 Oct. 2015. Web. 22 Jan. 2018.

Strubble, Linda E. “Insights into Tidal Disruption of Stars from PS1-10jh.” arXiv: 1509.04277v1.

© 2018 Leonard Kelley

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, owlcation.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://owlcation.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)