Astrophysics from Space Lecture 1: Introduction

1. Astrophysics from Space Lecture 1: Introduction Prof. Dr. M. Baes (UGent) Prof. Dr. C. Waelkens (KUL) Academic year 2013-2014

2. The electromagnetic spectrum radio infrared optical high-energy Ch. 8 Ch. 4 & 5 Ch. 2 & 3 Ch. 6 & 7

3. The goal of this course Discuss the history, benefits, possibilities, limitations and (some) major accomplishments of astrophysics space missions in the optical, infrared, high-energy and radio wavelength regimes.

4. Why different wavelength regimes ? Theoretically: no fundamental difference between radiation in the different wavelength regimes • Practically, there is a huge difference: • difference in atmospheric properties • difference in telescope/detector properties • difference in physical processes dominating the emission Each wavelength range contains information that we usually cannot obtain from observations in other wavelength regimes.

5. Radiation processes: blackbody radiation Planck radiation law Three important things - continuum radiation - Wien’s displacement law - Stefan-Boltzmann law

6. Radiation processes: line radiation • Line radiation can be used in many ways • chemistry: each element has different lines • temperature, ionization…: from line ratios • kinematics: from Doppler shift • magnetic fields: from Zeeman effect

7. Example: hydrogen atom NIR radio (21 cm) optical Even hydrogen, the most abundant and most simple element, has different lines in the UV, optical, near-infrared and radio regimes. UV

8. Radiation processes: there are more… Bremsstrahlung Synchrotron radiation

9. Multiwavelength view of Cen A Optical radiation is dominated by emission from normal stars… Significant obscuration by interstellar dust.

10. Multiwavelength view of Cen A NIR radiation is dominated by emission from cooler stars… Bright central condensation of stars. Obscuration by dust is much less pronounced

11. Multiwavelength view of Cen A UV radiation is dominated by emission from hot and young stars… Bulge disappears and young stellar disc appears. Obscuration by dust is dramatic !

12. Multiwavelength view of Cen A Mid-infrared emission is dominated by thermal emission from warm dust (reprocessed energy). FIR image would trace the cooler dust (not in star-forming regions).

13. Multiwavelength view of Cen A X-ray image shows synchrotron radiation from the jet, coming from the supermassive black hole in the centre. Isolated X-ray sources are neutron stars or background sources.

14. Multiwavelength view of Cen A 6 cm radio image is similar to X-ray image: dominated by synchrotron emission from jets linked to the supermassive black hole.

15. Main driver for astrophysics from space A solid understanding of the Universe requires a multi-wavelength view. The only way to do this is observations from space. Note: this is not the only reason why we want to go to space…

16. Europe in space: ESA 20 member states Annual budget (2012) ~ 4.02 G€

17. ESA budget

18. ESA integrated science program 1983-1984: Horizon 2000 1994-1995: Horizon 2000+ (Cosmic Vision 2005-2015) 2004-2005: Cosmic Vision 2015-2025 • Integrated long-term plans identifying the major scientific questions to be addressed by ESA’s future science missions • astrophysics, exploration and fundamental physics • intense collaboration between ESA and community • Cosmic Vision: combination of S, M and L missions http://sci.esa.int/science-e/www/area/index.cfm?fareaid=100

19. Cosmic Vision 2015-2025 • S-class missions (<50 M€) • S1: CHEOPS (selected in 2012, launch in 2017) • M-class missions (<470 M€) • M1: Solar Orbiter (selected in 2011, launch in 2017) • M2: Euclid (selected in 2011, launch in 2020) • M3: 5 candidates still in the running… • M4: call expected in 2014… • L-class missions (<900 M€) • L1: JUICE (selected in 2012, launch in 2022) • L2 and L3: themes decided in Nov 2013

20. Europe in space: national agencies 1.3 G€ 1 G€ 1.7 G€ Belgium: has not developed a purely national large space program (deliberately chosen the European route) http://www.esa.int/esapub/hsr/HSR_29.pdf

21. NASA • Remarkable: NASA budget ~ 17.8 billion USD • US has enormous history in space exploration since 1950s • Dramatic cuts in 1970s • Significant disasters have shaken NASA (with repercussions on the science program) 1986 2003

22. NASA Science NASA Science focuses on four broad themes - better understanding of Earth itself - Solar System exploration - heliophysics - astrophysics http://science.nasa.gov/

23. NASA Great Observatories Series of four large space missions - each in a different wavelength region - each of similar size and cost (at program outset) - synergy to increase the science output HST (1990-)CGRO (1991-2000) Chandra (1999-) Spitzer (2003-)

24. NASA Origins theme

25. Japan: JAXA Important player in space astrophysics - launched its first satellite in 1970 - stress on X-ray and infrared astronomy - pioneer in radio astronomy from space Collaboration between JAXA and ESA/NASA for several missions Akari Suzaku

26. USSR and Russia USSR was the first space power with many firsts Striking: almost no involvement in astrophysics programs Russian space program is focusedon launching and space station.

27. Other countries Countries with manned space programmes

28. Other countries Countries with space launch capabilities

29. Other countries Many countries have space agencies and plans for space programs in the near future. Modest involvement in astrophysics (so far). Countries with national space agencies