Class notes
ASTRO 101: Black Holes Module 9
- Course
- Institution
Notes for ASTRO 101 based on the official Coursera videos for the class. Covers Module 9.
[Show more]
Seller
Follow
valladaressasha
Content preview
Module 9Black Hole Observations
● History & Motivation:
○ Astronomers have studied black holes since 1963.
○ Despite decades of research, many mysteries remain unsolved.
○ Continued funding for advanced telescopes is needed to probe deeper into
black hole physics.
● Unanswered Questions:
○ What more can be learned about black holes?
○ Why haven't astronomers fully understood black holes after 50+ years?
● Black Hole Binaries:
○ Key systems for research: black holes paired with companion stars.
○ Companion stars send mass toward the black hole.
■ Mass travels through a disk and corona or is ejected via jets.
● Observation Techniques:
○ Visible light alone is insufficient for detailed study.
○ Multi-wavelength observations (radio, infrared, ultraviolet, X-ray) provide a
fuller picture.
○ Different wavelengths reveal the physics of binary components.
● Changing Properties of Black Holes:
○ Black hole properties evolve over time.
○ Brightness depends on feeding activity ("eating").
■ Feeding rates vary: slow (like tea) vs. rapid (like a pie-eating contest).
○ These feeding dynamics influence observations across wavelengths.
Black Hole Feeding and Observation
● Feeding Behavior:
○ Black holes alternate between feeding (active) and resting (inactive).
○ Brightness and emission wavelengths depend on feeding activity.
● How Black Holes Feed:
○ Material (e.g., stars, gas clouds, dust, even astronauts) drawn too close is
pulled into the accretion disk.
○ Feeding generates emissions across the electromagnetic spectrum (radio to
gamma rays).
, ● Scientific Insights from Feeding Black Holes:
○ Actively accreting black holes allow astronomers to study:
■ The type of material being consumed.
■ Physics of feeding processes and tests of general relativity in
extreme gravity.
○ Doppler shift from the rotating accretion disk provides information:
■ Blueshifted light (disk side moving toward us).
■ Redshifted light (disk side moving away).
● Models Explaining Black Hole Behavior:
○ Corona models:
■ "Lamp Post Model" vs. "Sandwich Model."
○ Jets have two types (flavors) that require further observation to understand.
● Challenges of Non-Feeding Black Holes:
○ Hungry black holes drifting through space are nearly invisible due to the
lack of emitted light.
○ Isolated black holes are detected via gravitational lensing:
■ Their strong gravitational field curves spacetime, warping light from
distant stars or galaxies.
● Wide vs. Close Binary Systems:
○ Wide Binary Systems:
■ Easier to study; black hole's mass and size can be determined from
the distinct light of the companion star and accretion disk.
○ Close Binary Systems:
■ Material from the companion gets so bright that it outshines the
star, making it harder to distinguish light sources.
■ Analogy: Like spotting a firefly above a campfire across a dark field.
Stellar-Mass Black Holes and X-Ray Binaries
Stellar-Mass Black Hole Identification
● Companion Stars:
○ Black holes are easier to locate when they have companion stars due to
gravitational effects.
○ X-ray binaries (low mass and high mass) are key systems for identifying
black holes.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller valladaressasha. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.14. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
51683 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 15 years now