DEPARTMENT OF PHYSICS AND ASTRONOMY 3671 Multiwavelength Astronomy

DEPARTMENT OF PHYSICS AND ASTRONOMY 3671: Multi-wavelength Astronomy Dr. Matthew Burleigh www. star. le. ac. uk/~mbu

The Electro-magnetic Spectrum 100 Me. V 100 ke. V 0. 1 ke. V 1000 A 5000 A 1 micron Gamma Ray Xray EUV UV Optical IR 1 cm Micro-wave Radio http: //imagine. gsfc. nasa. gov/docs/science/know_l 1/emspectrum. html Dr. Matt Burleigh 100 m

Multi-wavelength Astronomy Waveband Wavelength /Energy Temperature What can be studied Gamma rays 100 ke. V-100 Me. V >108 K accretion disks, gammaray bursts X-rays <1 -100 ke. V 106 -108 K Hot gas in clusters of galaxies, stellar coronae, accretion disks, Ultra-violet 900 -3000 A 104 -106 K Hot stars, white dwarfs, instellar gas Optical 3000 -10, 000 A 103 -104 K Sun-like stars. Infra-red 1 -100 micron 10 -103 K Dust, planets, brown dwarfs Microwave 1 cm <10 K Background radiation of the Universe (remnant of Big Bang) Radio >1 m <10 K Radiation from electrons moving in a magnetic field: pulsars Dr. Matt Burleigh

Wavelength scales • Rather annoyingly, astronomers use a variety of wavelength scales depending on the waveband involved (see diagram on last slide) – Radio astronomers use m and cm – Infra-red astronomers use microns – Optical and UV astronomers use Angstroms or nanometers – X-ray and gamma ray observers switch to an energy scale, i. e. in electron-Volts Dr. Matt Burleigh

Conversion factors • • • E = hn = hc/l in Joules 1 e. V = 1. 6 x 10 -19 J Wavelength l in Angstroms -> Energy in ke. V – ke. V = 12. 4/l • • • 1 Angstrom = 10 -10 m 1 nm = 10 -9 m 1 mm (micron) = 10 -6 m = 10, 000 A – Point at which optical becomes infra-red! Dr. Matt Burleigh

What is multi-wavelength astronomy? • Astronomers used to think of themselves as either ‘optical’, ‘radio’, ‘IR’ or ‘Xray’ • But modern astrophysics requires studying an object across the whole EM spectrum • Different physical processes can be studied at different wavelengths • Xray, gamma ray and radio astronomers need to identify their sources with optical counterparts http: //imagine. gsfc. nasa. gov/docs/science/know_l 1/multiwavelength. html Dr. Matt Burleigh

The Milky Way: Optical Stars, Dust lanes Dr. Matt Burleigh

The Milky Way: IR See through dust Dr. Matt Burleigh

The Milky Way: Xray Hot gas Dr. Matt Burleigh

Andromeda (M 31): Optical Dr. Matt Burleigh

Andromeda (M 31): IR Star forming regions in spiral arms Dr. Matt Burleigh

Andromeda (M 31): UV Young, hot stars in spiral arms Dr. Matt Burleigh

Andromeda (M 31): Xray binaries, supernova remnants, hot gas Dr. Matt Burleigh

Orion in the optical and xrays Optical Dr. Matt Burleigh Xrays

Multi-wavelength study of Xray sources Dr. Matt Burleigh

Binary stars: Sirius A & B Chandra: Xrays Optical photograph Dr. Matt Burleigh

Binary white dwarfs revealed in the ultra-violet HST Optical Dr. Matt Burleigh UV: white dwarf companion (star Ab)

Brown dwarfs & extra-solar planets in the infra-red HST IR image Gl 229: Red dwarf + brown dwarf companion Dr. Matt Burleigh

Brown dwarfs & extra-solar planets in the infra-red J band (IR) image from Gemini North of a nearby white dwarf Estimate a 10 Mjup planet would have a magnitude of J~20. 5 Dr. Matt Burleigh

Effect of atmosphere Band Gamma rays Xrays UV Optical Dr. Matt Burleigh Stopped by Observe from Balloon, space Ionisation, compton scattering Ionisation O 2, Space N 2 O 2, N 2, O 3 Space disassociation Clear! Ground Example

Effect of atmosphere Band Infra-red <10 microns Stopped by Observe from CO 2, H 2 O but clear bands mountain Infra-red >20 Molecular microns absorption Space, aircraft Sub mm Molecular absorption Mountain Radio Clear! Ground Dr. Matt Burleigh Example

Types of observation • Photometry – the brightness of an object in a certain waveband • Time-resolved photometry - Dr. Matt Burleigh

Types of observation • Spectroscopy - http: //imagine. gsfc. nasa. gov/docs/science/how_l 1/analysis. html Dr. Matt Burleigh

Course Outline • Overview: Today – The electro-magnetic spectrum – What is multi-wavelength astronomy? – Observing at different wavelengths Dr. Matt Burleigh

Course Outline • Basic physical processes: Tomorrow – Attenuation of radiation by matter • (important to IR, UV and X-ray) – BB radiation • (how to decide which waveband to observe in) • Emission processes Dr. Matt Burleigh

Optical astronomy • Telescopes – Modern telescope design – Diffraction limit, resolution – Seeing – Adaptive optics • Detectors – CCDs Dr. Matt Burleigh

Optical astronomy • Techniques – Spectroscopy: grating equation, resolution – Imaging: magnitude system, filters, colour Dr. Matt Burleigh

Infra-red Astronomy • Infra-red – Absorption by and emission from dust – Interstellar reddening – Detectors, telescopes and satellite missions Dr. Matt Burleigh

Ultraviolet Astronomy • Ultraviolet – Satellite Missions – Interstellar absorption – Curve of growth Dr. Matt Burleigh

Radio Astronomy • Radio astronomy – Differences between optical and radio – The radio telescope – Interferometers – Examples: Pulsars, radio galaxies, neutral H Dr. Matt Burleigh

The High-Energy Universe • X-ray astronomy – History – X-ray detectors – Absorption processes – X-ray emitting objects – Accretion onto compact objects – Black holes and the Eddington luminosity Dr. Matt Burleigh

Complimentary courses • • • 4326 Interaction radiation/matter – Wynn 3611. 2 Galaxies – O’Brien 3611. 1 Active Galaxies – Stewart 3631. 2 Interstellar Medium - Jameson 3631. 1 Binary stars – Wynn 3677 Life in the Universe – Raine/Sims/Burleigh • 4424 High Energy Astrophysics – Ward/Watson Dr. Matt Burleigh

Lecture timetable • Thursdays 10. 30 am LRB • Fridays 1. 30 pm LRB 3 rd Yr Support course TBD Dr. Matt Burleigh

Books • Modern Astrophysics – Carroll & Ostlie • High Energy Astrophysics – Longair (Cambridge University Press) ISBN 0 -52138873 -6 • Active Galactic Nuclei – Robson (Wiley) ISBN 0 -471 -96050 -0 • Active Galactic Nuclei – Peterson (Cambridge University Press) ISBN 0 -52147911 -8 • Observational Astronomy - Kitchin Dr. Matt Burleigh