The X-Ray Universe. The X-Ray Universe

Size: px

Start display at page:

Download "The X-Ray Universe. The X-Ray Universe"

Tracey Hodge
6 years ago
Views:

The X-Ray Universe The X-Ray Universe Potsdam University Dr. Lidia Oskinova Wintersemester 2013-2014 lida@astro.physik.

1 The X-Ray Universe The X-Ray Universe Potsdam University Dr. Lidia Oskinova Wintersemester astro.physik.uni-potsdam.de/~lida/x-ray.html Chandra X-ray, HST optical, Spitzer IR NGC602 in the SMC d=60pc

2 Clusters of galaxies 01

02 Coma cluster CXO: 17 arcmin wide The baryons in the ICM thermalize to > 10 6 K making clusters strong X-ray

3 Coma cluster HST: 9 arcmin wide 02 X-rays from Clusters of Galaxies Clusters of galaxies are selfgravitating accumulations of dark matter which have trapped barions: ICM and galaxies. 02 Coma cluster CXO: 17 arcmin wide The baryons in the ICM thermalize to > 10 6 K making clusters strong X-ray sources. Most of the baryons are in the hot ICM plasma - only 10-20% are in the galaxies. NASA/CXC/SAO/A.Vikhlinin et al. Lets rememeber what is bremsstrahlung

03 X-ray measurments 03 From the spectrum we can measure a mean temperature, a redshift, and abundances of the most common elements (heavier than He).

4 03 X-ray measurments 03 From the spectrum we can measure a mean temperature, a redshift, and abundances of the most common elements (heavier than He). With good S/N we can determine whether the spectrum is consistent with a single temperature or is a sum of emission from plasma at different temperatures. Using symmetry assumptions the X-ray surface brightness can be converted to a measure of the ICM density.

5 04 Cosmology from cluster evolution (Vikhlinin et al. 2003) Independent on other methods -- New surveys are underway

6 05 Sunyaev-Zeldovich effect 05 Interaction between Cosmic Microwave Background Radiation (CMB) and hot gas in the galaxy clusters. CMB photons passing through the hot ICM have a ~1 per cent chance of inverse Compton scattering off the energetic electrons, causing a small (~1 mk) distortion of the CMB spectrum: the Sunyaev-Zeldovich effect. The ICM emits X-rays primarily through thermal bremsstrahlung. The SZE is a function of the integrated pressure, T n e T e dl, the integration is along the line of sight. The X-ray emission: S X n 2 eλdl, Λ is the cooling function. The different dependences on density, along with a model of the cluster gas, enables a direct distance determination to the galaxy cluster.

7 Clusters of galaxies: Physics 06

8 07 Central regions of galaxy clusters 07 Basic model: Clusters are spherically symmetric balls of plasma that evolved in isolation. Gas density is highest at the center. ε~n 2, cooling time is smaller than the cluster age Gas must lose energy by radiating X-rays Pressure drops, gas gets compressed by garvitational well Density and ε increase leading to a steady cooling inflow of plasma cooling flow. The X-ray spectra are expected to show evidence for a range of temperatures from the ambient for the cluster down to zero. But! They don t! little cooling gas is found cooling flow-problem

9 Bonamente etal

10 09

11 10 High-Resolution X-Ray Spectroscopy of CFs Peterson etal If the blobs of plasma cool in thermal isolation at constant pressure, and the dominant energy loss mechanism is via X- radiation, then the luminosity radiated per unit temperature interval, must be proportional to the mass deposition rate dl X dt = 5 2 Ṁk µm p The only free parmeter is Ṁ - mass deposition. Can be estimated the density distribution inferred from the X-ray image. Then a cluster spectrum has two components: (1) the coolingflow spectrum, as described above, and (2) an isothermal spectrum evaluated at the temperature of the background cluster gas.

From Peterson etal 2003, ApJ 590:207 11 observed, model, best fit Model is

12 From Peterson etal 2003, ApJ 590: observed, model, best fit Model is inconsistent with observations when temperature is about 1/3 of the ambient value

13 12

14 13 Hydra A: key to the CF problem? 13 Chandra Image NASA/CXC/SAO

15 14 AGN feedback - a key to the CF problem? 14 NASA/CXC/SAO/NRAO Chandra + Radio Image

15 Bubbles in Abell 2597 15 Chandra X-ray image Ghost cavities are 100 millionyear-old relics of an ancient eruption that originated around a massive black hole in the core of a

16 15 Bubbles in Abell Chandra X-ray image Ghost cavities are 100 millionyear-old relics of an ancient eruption that originated around a massive black hole in the core of a centrally located galaxy. Bubbles are hot gas, magnetized, high-energy particles enough to support surrownding pressure. Multiple events deposit into the ICM energy NASA/CXC/SAO/NRAO

17 16 Sound Waves in Perseus A 16 Sound waves from explosive events In the AGN in the central galaxy Dissipation of sound waves heating of ICM Cavities are radio sources, filled with high-energy particles and magnetic fields. NASA/CXC/SAO/ see annimation

18 17 Chemical evolution of the Universe 17 What is the origin of the metals in the ICM and when were they injected? What is the origin of the entropy of the ICM?

19 18

19 Summary Hot ICM in the potential well of galaxy cluster 19 Most barions in the cluster are in the hot ICM gas Measuring X-ray flux and temperature profiles across cluster density and temperature

20 19 Summary Hot ICM in the potential well of galaxy cluster 19 Most barions in the cluster are in the hot ICM gas Measuring X-ray flux and temperature profiles across cluster density and temperature distribution barionic mass Clusters are weakly selfsimilar (z-dependence) Can help to contstarin cosmological models NASA/CXC/SAO/NRAO MS : Gravitational potnetial traces dark matter AGN feedback keeps central cluster regions hot

21 Galaxies 20 M31 NASA/CXC

22 Milky Way Center 21 National Geographic

23 Artist impression 22

24 Radio image 23

25 Radio image 24

26 Radio image 25

27 VLT adaptive optics Sgr A* 26

28 2.2 micron image 27

29 Mass of the Black Hole 2.2 micron animation of the stellar orbits in the central parsec 28 Use Kepler s III Law to determine the mass of the BH: a 3 =M BH P 2 For this one needs to determine for many stars: a) the period P b) the size of the orbit s semimajor axis a Current best estimate M BH =7.2 millions M

30 Composite image of Galactic Center in near IR (HST) and X-ray (Chandra) 29 X-ray luminosity of Sgr A* is ~10 32 erg/s

31 Activity of our Black Hole 30 see flare at SINFONI VLT image

32 Fermi Bubbles: evidence of previous activity 31

The X-Ray Universe. The X-Ray Universe

The X-Ray Universe. The X-Ray Universe The X-Ray Universe The X-Ray Universe Potsdam University Dr. Lidia Oskinova Sommersemester 2017 lida@astro.physik.uni-potsdam.de astro.physik.uni-potsdam.de ~lida/vorlesungxrayso17.html Chandra X-ray,