1. 3K background radiation by Roman Werpachowski and Peter Holrick

2. Structure Overview and Background Aim and how to reach it COBE –Technical Information –Interpretation of maps –Maps Other projects in the future

3. What we will look at? Source: Rod Nave, HyperPhysics, http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

4. What we will look at? Source: Rod Nave, HyperPhysics, http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

5. What is detected? Microwave Background Radiation (MBR): wavelength=mm to cm In terms of photons, or packets of light, there are quite a few of them in the microwave background -- about 400 per cubic centimeter. Travelling at the speed of light Our eyes can‘t see it TV waves are similar to 3k radiation => on terrestic TVs few percent of the snow is CMB (Cosmic microwave background) Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.htmlhttp://background.uchicago.edu/~whu/beginners/introduction.html

6. What do we see? By looking in the sky, we actually look backwards in time Light from more distant objects takes longer to reach us We can see back a few billion years MBR is from an 300 000 year old universe: Soup of fundamental particles like electrons, protons, helium nuclei, neutrinos Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.htmlhttp://background.uchicago.edu/~whu/beginners/introduction.html

7. Why 2,73° K? Because of the expansion, the microwave background is very cold now - 3 degrees above absolute zero. It's wavelength has been stretched out of the visible and into the microwave regime of millimeters to centimeters. Temperature is almost constant. Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.htmlhttp://background.uchicago.edu/~whu/beginners/introduction.html Rod Nave, HyperPhysics, http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

8. Temperature anisotropies Small variations in the temperature of the background radiation from point to point on the sky are called anisotropies. These anisotropies were first detected for the whole sky by the COBE satellite in 1989. They produced a map of the sky: Source:Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.html colors represent temp- erature on the sky

9. Structure Overview and Background Aim and how to reach it COBE –Technical Information –Interpretation of maps –Maps Other projects in the future

10. Aim: To understand how the universe went from a smooth particle soup to a complex system of galaxies Using the surface of the soup in the microwave back- ground to help understand and solve this question Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.htmlhttp://background.uchicago.edu/~whu/beginners/introduction.html

11. The data analysis pipline Source:Source: Max Tegmark, CMB data analysis center, http://www.hep.upenn.edu/~max/cmb/pipeline.htmlhttp://www.hep.upenn.edu/~max/cmb/pipeline.html Parameter estimates Sky Measurement Raw data Cleaning Mapmaking Time- ordered data Multi- Frequency maps Foreground removal Sky map Power estimation Power spectrum Model Testing

12. Why power spectrum estimation? If the statistical properties of the CMB fluctuations are isotropic and Gaussian (which they are in the standard inflationary models), then all the cosmological information in a sky map is contained in its power spectrum This means that all the information from even a giant data set (say a map with n=10^7 pixels) can be reduced to just a couple of thousand numbers, greatly facilitating parameter estimation It allows a model-independent comparison between different experiments one-to-one correspondence between visible features in the power spectrum and the physical processes one is studying Source: Max Tegmark, CMB data analysis center, http://www.hep.upenn.edu/~max/cmb/pipeline.htmlhttp://www.hep.upenn.edu/~max/cmb/pipeline.html

13. Angular power spectrum of CMB anisotropies Source:Source: Max Tegmark, CMB data analysis center, http://www.hep.upenn.edu/~max/cmb/experiments.htmlhttp://www.hep.upenn.edu/~max/cmb/experiments.html Experiments: Satellites COBE MAP Planck (COBRAS/SAMBA)Planck Balloon-born FIRS, ARGO, MAX, MSAM, BAM, QMAP (Princeton, Penn, QMASK data), BOOMERanG, MAXIMA, Top Hat, HACME, ACE, Archeops, BEASTFIRSARGOMAXMSAM BAMPrincetonPenn QMASK dataBOOMERanG MAXIMATop HatHACME ACEArcheopsBEAST Ground-based Tenerife, South Pole, Saskatoon, Python, and many more (>20)Tenerife South Pole Saskatoon Python multipole space

14. Structure Overview and Background Aim and how to reach it COBE –Technical Information –Interpretation of maps –Maps Other projects in the future

15. COBE - Cosmic Background Explorer The COBE satellite was developed by NASA's Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe to the limits set by our astrophysical environment. launched November 18, 1989 3 instruments: –Far Infrared Absolute Spectrophotometer (FIRAS) to compare the spectrum of the cosmic microwave background radiation with a precise blackbody,Far Infrared Absolute Spectrophotometer (FIRAS) –Differential Microwave Radiometer (DMR) to map the cosmic radiation sensitively, andDifferential Microwave Radiometer (DMR) –Diffuse Infrared Background Experiment (DIRBE) to search for the cosmic infrared background radiation.Diffuse Infrared Background Experiment (DIRBE) Source: The COBE Home Page, http://space.gsfc.nasa.gov/astro/cobe/http://space.gsfc.nasa.gov/astro/cobe/ The COBE datasets were developed by the NASA Goddard Space Flight Center under the guidance of the COBE Science Working Group and were provided by the NSSDC.NASA Goddard Space Flight CenterCOBE Science Working Group NSSDC

16. COBE - Cosmic Background Explorer

17. FIRAS: Principle Far Infrared Absolute Spectrophotometer (FIRAS) Should measure precisely the spectrum of the cosmic microwave background radiation over the wavelength range from 0.1 to 10 mm 7 degree field of view polarizing Michelson interferometer with bolometer detectors to determine the intensity of the incoming light at a large number of wavelengths (i.e., a spectrum) simultaneously.

18. Cosmological discovery: FIRAS The cosmic microwave background (CMB) spectrum is that of a nearly perfect blackbody with a temperature of 2.725 +/- 0.002 K. This observation matches the predictions of the hot Big Bang theory extraordinarily well It indicates that nearly all of the radiant energy of the Universe was released within the first year after the Big Bang. Far Infrared Absolute Spectrophotometer (FIRAS)

19. Should detect anisotropy 2 antenna for each wavelengt: 3.3, 5.7 and 9.6mm Antennas are 60 degrees apart Antenna are switched to ensure difference comes from the sky and not from differences in the antennas 7 degree field of view DMR Differential Microwave Radiometer (DMR)

20. Cosmological discovery: DMR The CMB was found to have intrinsic "anisotropy" for the first time, at a level of a part in 100,000. These tiny variations in the intensity of the CMB over the sky show how matter and energy was distributed when the Universe was still very young. Later, through a process still poorly understood, the early structures seen by DMR developed into galaxies, galaxy clusters, and the large scale structure that we see in the Universe today. Differential Microwave Radiometer (DMR)

21. DIRBE Diffuse Infrared Background Experiment (DIRBE) Should minimize response to objects outside the desire 0.7 degrees view Internal temperature comparison Ten wavelengths (1.25 to 240μm) Polarisation at three shortest wavelengths

22. Cosmological discovery: DIRBE Infrared absolute sky brightness maps in the wavelength range 1.25 to 240 microns were obtained to carry out a search for the cosmic infrared background (CIB). The CIB was originally detected in the two longest DIRBE wavelength bands, 140 and 240 microns, and in the short-wavelength end of the FIRAS spectrum. Subsequent analyses have yielded detections of the CIB in the near-infrared DIRBE sky maps. The CIB represents a "core sample" of the Universe; it contains the cumulative emissions of stars and galaxies dating back to the epoch when these objects first began to form. Diffuse Infrared Background Experiment (DIRBE)

23. Interpretation of COBE-maps Theoretical map, if COBE looked down 2 dimensional representation of the 3 dimensional surface of the earth Source:Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.html

24. Interpretation of COBE-maps COBE has rather blurry vision and can only see large features corresponding to 7 degree separations on the sky Source:Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.html Result:

25. Interpretation of COBE-maps COBE also has noise in its detectors like you would have with bad reception on your TV Source:Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.html Result:

26. Interpretation of COBE-maps To get rid of the noise, maps can be smoothed. This brings out the large features like continents but fine details are lost in the map Source:Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.html Result:

27. Interpretation of COBE-maps Similarly COBE's map of the background radiation only shows you the large features in the sky and all finer details are lost. Source:Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.html

28. Example maps Maps based on observations made with the DMR over the entire 4-year mission, at each of the three measured frequencies, following dipole subtraction. the red and blue spots correspond to regions of greater or lesser density in the early universe. Differential Microwave Radiometer (DMR)

29. Example maps Maps based on 53 GHz (5.7 mm wavelength) observations made with the DMR over the entire 4 year mission (top) on a scale from 0 - 4 K, showing the near-uniformity of the CMB brightness, (middle) on a scale intended to enhance the contrast, and (bottom) following subtraction of the dipole component. Emission from the Milky Way Galaxy is evident in the bottom image.

30. Example maps This image combines data from the DIRBE obtained at infrared wavelengths of 25, 60 and 100 µm. The sky brightness at these wavelengths is represented respectively by blue, green, and red colors in the image. The image is dominated by the thermal emission from interstellar dust in the Milky Way. Large and Small Magellanic Clouds Orion molecular clouds, which are active "stellar nurseries" in our Galaxy structured, warmer emission from interplanetary dust

31. Example maps This image combines data from the DIRBE obtained at infrared wavelengths of 100, 140 and 240 µm. The sky brightness at these wavelengths is represented respectively by blue, green, and red colors in the image. The image is dominated by the thermal emission from interstellar dust in the Milky Way. Large and Small Magellanic Clouds Orion molecular clouds, which are active "stellar nurseries" in our Galaxy structured, warmer emission from interplanetary dust

32. Structure Overview and Background Aim and how to reach it COBE –Technical Information –Interpretation of maps –Maps Other projects in the future

33. Microwave Anisotropy Probe The Microwave Anisotropy Probe (MAP) will make a map of the temperature fluctuations of the CMB radiation with much higher resolution, sensitivity, and accuracy than COBE. MAP is the first mission to use an L2 orbit as its permanent observing station. L2 is a semi-stable region of gravity that is about 4 times further than the Moon, following the Earth around the Sun. June 30, 2001: MAP Launch Oct. 1, 2001: MAP Arrives at L2 One full sky scan last 6 months Jan. 2003: First Data Release Source: http://map.gsfc.nasa.gov/m_mm/ms_status.htmlhttp://map.gsfc.nasa.gov/m_mm/ms_status.html

34. Microwave Anisotropy Probe Source: http://map.gsfc.nasa.gov/m_mm/ms_status.htmlhttp://map.gsfc.nasa.gov/m_mm/ms_status.html

35. PLANCK Source:Source: http://astro.estec.esa.nl/SA-general/Projects/Planck/http://astro.estec.esa.nl/SA-general/Projects/Planck/ To be launched in the first quarter of 2007 By European Space Agency Better and more instruments L2 orbit

36. Aim: To understand how the universe went from a smooth particle soup to a complex system of galaxies Using the surface of the soup in the microwave back- ground to help understand and solve this question Source: Wayne Hu, An Introduction to the Cosmic Microwave Background, http://background.uchicago.edu/~whu/beginners/introduction.htmlhttp://background.uchicago.edu/~whu/beginners/introduction.html

38. Degree Angular Scale Interferometer (DASI) Polarization of CMB supports current models of the universe