Powering the Universe with Supermassive Black Holes. Steve Ehlert and Paul Simeon

Transcription

1 Powering the Universe with Supermassive Black Holes Steve Ehlert and Paul Simeon

2 Overview Introduction to Galactic Nuclei Galactic Nuclear Activity Input and output energies. The aftermath of AGN flares.

3 But First... A brief primer of structure in the universe.

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13 Our Own Galaxy Our story of AGN begins in our own galaxy, the Milky Way. In particular, it begins with observations at the center of our galaxy. This is in the direction of the Sagittarius constellation. Easier to observe from the Southern Hemisphere. Radio source defined as galactic center known as Sagittarius A*.

14 Sagittarius A* Image is a combination of infrared observations.

15 Sagittarius A* X-ray emission: Red 1-3 kev, Green 3-5 kev, Blue 5-8 kev

16 What is Sagittarius A*? Careful experiments show more than a dozen stars orbiting the galactic center. Central object must have mass of ~ 4 million solar within region smaller than the orbit of Uranus. This all but certainly is a super-massive black hole!

17 Tracing Stellar Orbits

18 Data Suggests a Point Source!

19 Supermassive Black Holes Black holes like the one at Sagittarius A* are observed at the center of most every galaxy. Supermassive black holes can either be Active or Inactive. Active galactic nuclei have a central region that is brighter than normal in some frequency range. Active Galaxies are among the brightest objects in the universe.

20 The Inactive Sombrero Galaxy

21 The Active Galaxy Centaurus A

22 The AGN Zoo Huge # of classifications for AGN. Based on observational history. Seyfert I/II galaxies Radio galaxy Quasi-stellar objects (Quasars) Blazars BL Lacs Optical Violently Variable (OVV)

23 Defining an AGN Key aspects spanning many different classifications: Variable emission Jets Continuum radio emission Emission lines in optical and infrared Non-thermal high energy emission Different types of AGN have different combinations of these signatures.

24 Emission at Many Frequencies ~100,000 light years across! Blue is X-ray, green is optical, and red is infrared

25 Not all to scale!

26 Outstanding Questions Does the zoo of AGN types have a common origin? If there is a common cause, why such different effects? What is the origin of such spectacular emission? Where does it originate? What are the limits to what an AGN can do? How do AGN help answer other big questions in astrophysics?

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34 Mass and Angular Momentum

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41 AGN & Galaxy Formation There appears to be a very strong correlation between black hole properties and galaxy properties. Any complete galaxy formation model needs to acknowledge the influence of the AGN. The theory of supermassive black hole formation is incomplete Where are the intermediate-mass black holes

42 AGN Feedback in Galaxy Clusters In larger scale structures known as galaxy clusters, a particularly large galaxy known as a cd found at the center. A very massive galaxy means a very massive black hole and emission power. The local medium of the galaxy cluster (ICM) can be disrupted by the central AGN. The ICM is best observed in X-rays.

43 M87 in Optical, X-Ray, and Radio Jet of M87 Blue X-ray, yellow optical, and red radio

44 Temperature Map Around M87

45 Pressure Map Around M87

46 Interpreting M87 The AGN is uplifting cool gas from the center of the cluster to larger radii. We can even measure multi-temperature structure in the arms. The rings of high pressure are indicative of shocks. The nature of the jets can be constrained by the effects on the surrounding medium.

47 Inflating Cavities These jets can also inflate 'bubbles' in the local cluster medium. These bubbles have very little X-ray gas, but instead filled with radio plasma. Huge amounts of energy can go into inflating these cavities.

48 A More Powerful AGN Outburst Blue: X-ray Pink: Radio ~500,000 light years!

49 Conclusions Safe to say that super-massive black holes reside at the center of every galaxy. When an accretion disk is present, fireworks ensue. AGN directly influence the formation of large structures like galaxies and galaxy clusters. Many of the unanswered questions about AGN are being pursued by a number of people here at KIPAC.