DEPARTMENT OF PHYSICS AND ASTRONOMY

3671: Multi-wavelength Astronomy3671: Multi-wavelength Astronomy

Dr. Matthew BurleighDr. Matthew Burleigh

www.star.le.ac.uk/~mbuwww.star.le.ac.uk/~mbu

Dr. Matt Burleigh

Gamma Ray Xray EUV UV Optical IR Micro-wave Radio

100MeV 100keV 0.1keV 1000A 5000A 1micron 1cm 100m

The Electro-magnetic Spectrum

http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html

Dr. Matt Burleigh

Multi-wavelength AstronomyMulti-wavelength AstronomyWavebandWaveband WavelengthWavelength

/Energy/EnergyTemperatureTemperature What can be What can be

studiedstudied

Gamma raysGamma rays 100keV-100MeV100keV-100MeV >10>1088KK accretion disks, gamma-accretion disks, gamma-ray burstsray bursts

X-raysX-rays <1-100keV<1-100keV 101066-10-1088KK Hot gas in clusters of Hot gas in clusters of galaxies, stellar coronae, galaxies, stellar coronae, accretion disks, accretion disks,

Ultra-violetUltra-violet 900-3000A900-3000A 101044-10-1066KK Hot stars, white dwarfs, Hot stars, white dwarfs, instellar gasinstellar gas

OpticalOptical 3000-10,000A3000-10,000A 101033-10-1044KK Sun-like stars. Sun-like stars.

Infra-redInfra-red 1-100 micron1-100 micron 10-1010-1033KK Dust, planets, brown Dust, planets, brown dwarfsdwarfs

MicrowaveMicrowave 1cm1cm <10K<10K Background radiation of Background radiation of the Universe (remnant of the Universe (remnant of Big Bang)Big Bang)

RadioRadio >1m>1m <10K<10K Radiation from electrons Radiation from electrons moving in a magnetic moving in a magnetic field: pulsarsfield: pulsars

Dr. Matt Burleigh

Wavelength scalesWavelength scales

• Rather annoyingly, astronomers use a variety of Rather annoyingly, astronomers use a variety of wavelength scales depending on the waveband wavelength scales depending on the waveband involved (see diagram on last slide) involved (see diagram on last slide) – Radio astronomers use m and cmRadio astronomers use m and cm– Infra-red astronomers use micronsInfra-red astronomers use microns– Optical and UV astronomers use Angstroms or nano-Optical and UV astronomers use Angstroms or nano-

metersmeters– X-ray and gamma ray observers switch to an energy X-ray and gamma ray observers switch to an energy

scale, i.e. in electron-Voltsscale, i.e. in electron-Volts

Dr. Matt Burleigh

Conversion factorsConversion factors

• E = hE = h= hc/= hc/in Joulesin Joules• 1eV = 1.6x101eV = 1.6x10-19-19JJ• Wavelength Wavelength in Angstroms -> Energy in keVin Angstroms -> Energy in keV

– keV = 12.4/keV = 12.4/• 1Angstrom = 101Angstrom = 10-10-10mm• 1 nm = 101 nm = 10-9-9mm• 11m (micron) = 10m (micron) = 10-6-6m = 10,000Am = 10,000A

– Point at which optical becomes infra-red!Point at which optical becomes infra-red!

Dr. Matt Burleigh

What is multi-wavelength astronomy?What is multi-wavelength astronomy?

• Astronomers used to think of themselves as Astronomers used to think of themselves as either ‘optical’, ‘radio’, ‘IR’ or ‘Xray’either ‘optical’, ‘radio’, ‘IR’ or ‘Xray’

• But modern astrophysics requires studying an But modern astrophysics requires studying an object across the whole EM spectrum object across the whole EM spectrum

• Different physical processes can be studied at Different physical processes can be studied at different wavelengths different wavelengths

• Xray, gamma ray and radio astronomers need Xray, gamma ray and radio astronomers need to identify their sources with optical to identify their sources with optical counterpartscounterparts

http://imagine.gsfc.nasa.gov/docs/science/know_l1/multiwavelength.html

Dr. Matt Burleigh

The Milky Way: OpticalThe Milky Way: Optical

Stars, Dust lanes

Dr. Matt Burleigh

The Milky Way: IRThe Milky Way: IR

See through dust

Dr. Matt Burleigh

The Milky Way: XrayThe Milky Way: Xray

Hot gas

Dr. Matt Burleigh

Andromeda (M31): OpticalAndromeda (M31): Optical

Dr. Matt Burleigh

Andromeda (M31): IRAndromeda (M31): IR

Star forming regions in spiral arms

Dr. Matt Burleigh

Andromeda (M31): UVAndromeda (M31): UV

Young, hot stars in spiral arms

Dr. Matt Burleigh

Andromeda (M31): XrayAndromeda (M31): Xray

Xray binaries, supernova remnants, hot gas

Dr. Matt Burleigh

Orion in the optical and xrays Orion in the optical and xrays

Optical Xrays

Dr. Matt Burleigh

Multi-wavelength study of Xray sourcesMulti-wavelength study of Xray sources

Dr. Matt Burleigh

Binary stars: Sirius A & BBinary stars: Sirius A & B

Chandra: XraysOptical photograph

Dr. Matt Burleigh

Binary white dwarfs revealed in the Binary white dwarfs revealed in the ultra-violetultra-violet

Optical UV: white dwarf companion (star Ab)

HST

Dr. Matt Burleigh

Brown dwarfs & extra-solar planets in Brown dwarfs & extra-solar planets in the infra-redthe infra-red

Gl 229:

Red dwarf + brown dwarf companion

HST IR image

Dr. Matt Burleigh

Brown dwarfs & extra-solar planets in Brown dwarfs & extra-solar planets in the infra-redthe infra-red

J band (IR) image from Gemini North of a nearby white dwarf

Estimate a 10Mjup planet would have a magnitude of J~20.5

Dr. Matt Burleigh

Effect of atmosphereEffect of atmosphereBandBand Stopped byStopped by Observe Observe

fromfromExampleExample

Gamma raysGamma rays Ionisation, Ionisation, compton compton scatteringscattering

Balloon, Balloon, spacespace

XraysXrays Ionisation OIonisation O22, , NN22

SpaceSpace

UVUV OO22, N, N2, 2, OO3 3

disassociationdisassociationSpaceSpace

OpticalOptical Clear!Clear! GroundGround

Dr. Matt Burleigh

Effect of atmosphereEffect of atmosphereBandBand Stopped byStopped by Observe Observe

fromfromExampleExample

Infra-red Infra-red <10microns<10microns

COCO22, H, H22O O but clear but clear bandsbands

mountainmountain

Infra-red >20 Infra-red >20 micronsmicrons

Molecular Molecular absorptionabsorption

Space, Space, aircraftaircraft

Sub mmSub mm Molecular Molecular absorptionabsorption

MountainMountain

RadioRadio Clear!Clear! GroundGround

Dr. Matt Burleigh

Types of observationTypes of observation• Photometry – the brightness of an object in a certain waveband

• Time-resolved photometry -

Dr. Matt Burleigh

Types of observationTypes of observation

• Spectroscopy -

http://imagine.gsfc.nasa.gov/docs/science/how_l1/analysis.html

Dr. Matt Burleigh

Course OutlineCourse Outline• Overview: Today

– The electro-magnetic spectrum– What is multi-wavelength astronomy?– Observing at different wavelengths

Dr. Matt Burleigh

Course OutlineCourse 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 Optical astronomy • TelescopesTelescopes

– Modern telescope designModern telescope design– Diffraction limit, resolutionDiffraction limit, resolution– SeeingSeeing– Adaptive opticsAdaptive optics

• DetectorsDetectors– CCDsCCDs

Dr. Matt Burleigh

Optical astronomy Optical astronomy • TechniquesTechniques

– Spectroscopy: grating equation, resolutionSpectroscopy: grating equation, resolution

– Imaging: magnitude system, filters, colourImaging: magnitude system, filters, colour

Dr. Matt Burleigh

Infra-red Astronomy Infra-red Astronomy

• Infra-redInfra-red– Absorption by and emission from dustAbsorption by and emission from dust– Interstellar reddeningInterstellar reddening– Detectors, telescopes and satellite Detectors, telescopes and satellite

missionsmissions

Dr. Matt Burleigh

Ultraviolet Astronomy Ultraviolet Astronomy

• UltravioletUltraviolet– Satellite MissionsSatellite Missions– Interstellar absorptionInterstellar absorption– Curve of growthCurve of growth

Dr. Matt Burleigh

Radio Astronomy Radio Astronomy

• Radio astronomyRadio astronomy– Differences between optical and radioDifferences between optical and radio– The radio telescopeThe radio telescope– InterferometersInterferometers– Examples: Pulsars, radio galaxies, neutral HExamples: Pulsars, radio galaxies, neutral H

Dr. Matt Burleigh

The High-Energy Universe The High-Energy Universe

• X-ray astronomyX-ray astronomy– HistoryHistory– X-ray detectorsX-ray detectors– Absorption processesAbsorption processes– X-ray emitting objectsX-ray emitting objects– Accretion onto compact objectsAccretion onto compact objects– Black holes and the Eddington luminosityBlack holes and the Eddington luminosity

Dr. Matt Burleigh

Complimentary coursesComplimentary courses

• 4326 Interaction radiation/matter – Wynn4326 Interaction radiation/matter – Wynn• 3611.2 Galaxies – O’Brien3611.2 Galaxies – O’Brien• 3611.1 Active Galaxies – Stewart3611.1 Active Galaxies – Stewart• 3631.2 Interstellar Medium - Jameson3631.2 Interstellar Medium - Jameson• 3631.1 Binary stars – Wynn3631.1 Binary stars – Wynn• 3677 Life in the Universe – 3677 Life in the Universe –

Raine/Sims/BurleighRaine/Sims/Burleigh• 4424 High Energy Astrophysics – 4424 High Energy Astrophysics –

Ward/WatsonWard/Watson

Dr. Matt Burleigh

Lecture timetableLecture timetable

• Thursdays 10.30am LRBThursdays 10.30am LRB• Fridays 1.30pm LRBFridays 1.30pm LRB

3rd Yr Support course TBD

Dr. Matt Burleigh

BooksBooks

• Modern AstrophysicsModern Astrophysics – Carroll & Ostlie – Carroll & Ostlie• High Energy AstrophysicsHigh Energy Astrophysics – Longair – Longair

(Cambridge University Press) ISBN 0-521-38873-6(Cambridge University Press) ISBN 0-521-38873-6• Active Galactic NucleiActive Galactic Nuclei – Robson – Robson

(Wiley)(Wiley) ISBN 0-471-96050-0ISBN 0-471-96050-0• Active Galactic NucleiActive Galactic Nuclei – Peterson – Peterson

(Cambridge University Press) ISBN 0-521-47911-8(Cambridge University Press) ISBN 0-521-47911-8• Observational AstronomyObservational Astronomy - Kitchin - Kitchin