Gamma-Ray Astronomy From Balloons

1. Gamma-Ray Astronomy From Balloons Jack Tueller Balloon Project Scientist SWRI Balloon Workshop Jack Tueller

2. Gamma Rays • Gamma rays are the highest energy photons. • Gamma rays do not penetrate to the ground. • Balloons can provide access to all energies >20 keV (Hard X-rays and Gamma Rays) SWRI Balloon Workshop Jack Tueller

3. What makes suborbital different? Different Risk Management Strategy • the payload is recovered • re-flights are inexpensive (<$1M for a balloon vs >$100M for a rocket) Higher Risk is the Best Strategy • lower cost • faster migration of new technology • smaller more focused efforts • training new workforce SWRI Balloon Workshop Jack Tueller

4. Gamma-Ray Astronomy from Balloons Boggs NCT ProtoEXIST HEFT GRIS InFOCuS GLAST • atmospheric cutoff is 20keV no soft x-rays • To get a high sensitivity gamma-ray payloads must be big and heavy • gamma-ray payloads work best at low latitudesmagnetic shielding low background • gamma-ray payloads must be pointed • real science is possible but we need LDB at low latitudes SWRI Balloon Workshop Jack Tueller

5. SN1987A • first nearby supernova in 400 years • every instrument possible was used • many new phenomena were discovered after before • balloons can provide quick access to space for timely measurements HST rings SWRI Balloon Workshop Jack Tueller

6. High Resolution Spectroscopy • In 1987 there were no high resolution germanium spectrometers in space like INTEGRAL • Gamma-ray lines yield nuclear yields and velocity distribution that cannot be determined at other wavelengths • Balloon experiments filled the gap GRIS, HEXAGONE, Lockheed Martin • balloon's success leads to INTEGRAL GRIS INTEGRAL SWRI Balloon Workshop Jack Tueller

7. SN1987A Lines • Gamma ray line profiles are not distorted by complicated effects such as resonant scattering. • Line profiles did not fit the standard models.Lines are red-shifted not blue-shifted. • But, they validate the detailed IR line profiles. • SN1987a was an asymmetric explosion! • future: 44Ti lines? SWRI Balloon Workshop Jack Tueller

8. Nuclear Lines • Nuclear lines are the unique signal of the production of new elements Boggs ACT Concept Study SWRI Balloon Workshop Jack Tueller

9. Type Ia Supernovae Explosion is driven by radioactive decay. Much Cosmology rests on using Type Ia's as a standard candle but the physics are not understood! Boggs ACT study SWRI Balloon Workshop Jack Tueller

10. Compton Scattering • GRIS worked with large detectors to capture all the energy and a thick collimator (800 lbs of NaI) to isolate the source. • Compton scattering is the dominant cross section between 200 keV and 2 MeV where most of the interesting gamma ray lines occur. • Localizing all the interactions allows accurate reconstruction of the source positions and spectra over a wide field SWRI Balloon Workshop Jack Tueller

11. Compton Telescopes Boggs NCT Development of an Advanced Compton Telescope • several technologies are possible • Si & Ge strip detectors • Si & CdZnTe strip detectors • thick Si • Liquid Xe • Gaseous Xe-LaBr3 • LaBr3 • All are now or are proposed balloon payloads ACT Concept SWRI Balloon Workshop Jack Tueller

12. High Energy Gamma Rays EGRET All-Sky >100 MeV GLAST • Technology for EGRET developed on HEBE balloon experiment • Go-no go test of GLAST technology on balloonsWould the background rejection work? CGRO/EGRET balloon test bed detector SWRI Balloon Workshop Jack Tueller

13. Understanding Supermassive Black Holes BAT XMM absorbed (52) unabsorbed (49) • How do black holes form and grow? • What stops the growth? • How do black holes effect galaxy formation? • Only in hard x-ray can you find all the sources and measure their luminosity. SWRI Balloon Workshop Jack Tueller

14. ProtoEXIST • A hard X-ray all-sky monitor can make great advances in variability studies of black holes. • A sensitive hard X-ray all-sky survey is the only way to find all the obscured sources. Swift/BAT Hard X-ray Survey >14 keV EXIST SWRI Balloon Workshop Jack Tueller

15. Hard X-ray Focusing Optics Launch Sep 16, 2004 Ft. Sumner NM • multilayer grazing incidence focusing optics • long focal lengths are required (InFOCuS is 8m) • CdZnTe focal plane is the other critical technology. (A Si focal plane would be 1 cm thick.) • Balloons can accommodate long focal lengths without costly mechanisms. 9m InFOCuS No mechanism was required to launch 9m truss. SWRI Balloon Workshop Jack Tueller

16. 3 Balloon Instruments HEFT InFOCuS HERO Three instruments are currently active: • HEFT-CIT Columbia • InFOCuS-GSFC Nagoya • HERO-MSFC Each of these instruments test alternative technology for hard x-ray focusing optics. Proposed for Con-X enhancement and SMEX-NuSTAR SWRI Balloon Workshop Jack Tueller

17. The Black Hole at the Galactic Center • A supermassive black hole lurks at the Galactic Center. • Like most black holes at the center of galaxies it is a very weak source at all wavelengths. • What is the accretion rate and why is it so low? • The GC is a very crowded area. • Only high resolution hard X-ray imaging can answer this question. INTEGRAL INTEGRAL imaging with >10 arcmin resolution is hopelessly confused. Soft X-ray imaging with Chandra sees 2000 sources <10 arcmin from the center. SWRI Balloon Workshop Jack Tueller

18. What is the future? How do we maintain strong balloon science in this field? • long duration flights at low latitude • super pressure balloon • trajectory modification system • long duration requires higher reliability - more cost and oversight • advanced designs:bigger and heavier payloads • secure and adequate funding SWRI Balloon Workshop Jack Tueller

19. Workforce Replenishment How are future instrument builders recruited and trained? BALLOONS! • fast enough for grad student to complete all phases of a project • small enough for the university researcher • open to hands-on student participation • pushing newest technology • produces significant science results SWRI Balloon Workshop Jack Tueller

20. Conclusions • Gamma-ray astronomy could have a bright future in ballooning. • Significant science can be achieved on balloons. • Balloons are crucial to the development of new missions. • Low cost ballooning can keep a field alive in hard times. • Ballooning is the natural way to recruit and train a workforce.NASA and gamma-ray astronomy need a vigorous balloon program SWRI Balloon Workshop Jack Tueller