htra galway - june 2006 dainis dravins lund observatory

HTRA Galway - June 2006HTRA Galway - June 2006

Dainis Dravins

Lund Observatory

What information is contained in light?

What is being observed ? What is not ?

Quantum optics in astronomy?Quantum optics in astronomy?

BLACKBODY ---

SCATTERED ---

SYNCHROTRON ---

LASER ---

CHERENKOV ---

COHERENT ---

WAVELE

NG

TH

& P

OLA

RIZ

ATIO

N F

ILTERS

OBSERVER

Intensity interferometryIntensity interferometry

Narrabri stellar intensity interferomer circa 1970 (R.Hanbury Brown, R.Q.Twiss et al., University of Sydney)

Intensity interferometryIntensity interferometry

R.Hanbury Brown, J.Davis, L.R.Allen, MNRAS 137, 375 (1967)

Roy Glauber

Nobel prize in physics

Stockholm, December 2005

Roy Glauber in Lund, December 2005

Information content of light. IInformation content of light. I

D.Dravins, ESO Messenger No. 78, 9

Galileo’s telescopes (1609)

Instruments measuring first-order spatial coherence

Hubble Space Telescope (1990)

HARPS (2003)

Fraunhofer’s spectroscope (1814)

Instruments measuring first-order temporal coherence

“COMPLEX” RADIATION SOURCES

What can a [radio] telescope detect?

What can it not?

Information content of light. IIInformation content of light. II

D.Dravins, ESO Messenger No. 78, 9

R. Loudon The

Quantum Theory of

Light (2000)

PHOTON STATISTICS

Semi-classical model of light: (a) Constant classical intensity produces photo-electrons with Poisson statistics; (b) Thermal light results in a compound

Poisson process with a Bose-Einstein distribution, and ‘bunching’ of the photo-electrons (J.C.Dainty)

Information content of light. IIIInformation content of light. III

D.Dravins, ESO Messenger No. 78, 9

Quantum effects in cosmic light

Quantum effects in cosmic light

Examples ofastrophysical

lasers

Early thoughts about lasers in space

Early thoughts about lasers in space

D. Menzel : Physical Processes in Gaseous Nebulae. I , ApJ 85, 330 (1937)

J. TalbotLaser Action in Recombining PlasmasM.Sc. thesis, University of Ottawa (1995)

Quantum effects in cosmic light

Quantum effects in cosmic light

Hydrogen recombinationlasers & masersin MWC 349 A

Hydrogen recombination lasers & masers in MWC 349A

Circumstellar disk surrounding the hot star.Maser emissions occur in outer regions while lasers operate nearer to the central

star.

V. Strelnitski; M.R. Haas; H.A. Smith; E.F. Erickson; S.W. Colgan; D.J. HollenbachFar-Infrared Hydrogen Lasers in the Peculiar Star MWC 349A Science 272, 1459 (1996)

Quantum Optics & CosmologyQuantum Optics & Cosmology

The First Masersin the Universe…

M. Spaans & C.A. NormanHydrogen Recombination Line Masers at the Epochs of Recombination and ReionizationApJ 488, 27 (1997)

FIRSTMASERSIN THE

UNIVERSE

The black inner regiondenotes the evolutionof the universe before

decoupling.

Arrows indicate maseremission from the epoch

of recombination andreionization.

Quantum effects in cosmic light

Quantum effects in cosmic light

Emission-line lasersin Eta Carinae

Eta Carinae

HST

Visual magnitude

ESO VLT

Model of a compact gas condensation near η Car with its Strömgren boundarybetween photoionized (H II) and neutral (H I) regions

S. Johansson & V. S. LetokhovLaser Action in a Gas Condensation in the Vicinity of a Hot StarJETP Lett. 75, 495 (2002) = Pis’ma Zh.Eksp.Teor.Fiz. 75, 591 (2002)

S. Johansson & V.S. LetokhovAstrophysical lasers operating in optical Fe II lines in stellar ejecta of Eta CarinaeA&A 428, 497 (2004)

S. Johansson & V.S. LetokhovAstrophysical lasers operating in optical Fe II lines in stellar ejecta of Eta CarinaeA&A 428, 497 (2004)

S. Johansson & V.S. LetokhovAstrophysical lasers operating in optical Fe II lines in stellar ejecta of Eta CarinaeA&A 428, 497 (2004)

Quantum effects in cosmic light

Quantum effects in cosmic light

Laser effects inWolf-Rayet,

symbiotic stars,& novae

Sketch of the symbiotic star RW Hydrae

P. P. Sorokin & J. H. GlowniaLasers without inversion (LWI) in Space: A possible explanation for intense, narrow-band, emissions that dominate the visible and/or far-UV (FUV) spectra of certain astronomical objectsA&A 384, 350 (2002)

Raman scattered emission bands in the symbiotic star V1016 Cyg

H. M. SchmidIdentification of the emission bands at λλ 6830, 7088A&A 211, L31 (1989)

Quantum effects in cosmic light

Quantum effects in cosmic light

Emission fromneutron stars,

pulsars & magnetars

T.H. Hankins, J.S. Kern, J.C. Weatherall, J.A. EilekNanosecond radio bursts from strong plasma turbulence in the Crab pulsarNature 422, 141 (2003)

V.A. Soglasnov et al.Giant Pulses from PSR B1937+21 with Widths ≤ 15 Nanoseconds and Tb ≥ 5×1039 K, the Highest Brightness Temperature Observed in the Universe, ApJ 616, 439 (2004)

Longitudes of giantpulses comparedto the average

profile.Main pulse (top);

Interpulse (bottom)

A. Shearer, B. Stappers, P. O'Connor, A. Golden, R. Strom, M. Redfern, O. RyanEnhanced Optical Emission During Crab Giant Radio PulsesScience 301, 493 (2003)

Mean optical “giant” pulse (with error bars) superimposed on the average pulse

Coherent emission from magnetars

Coherent emission from magnetars

o Pulsar magnetospheres emit in radio;higher plasma density shifts magnetar emission to visual & IR (= optical emission in anomalous X-ray pulsars?)

o Photon arrival statistics (high brightness temperature bursts; episodic sparking events?). Timescales down to nanoseconds suggested (Eichler et al. 2002)

Quantum effects in cosmic light

Quantum effects in cosmic light

CO2 lasers onVenus, Mars & Earth

CO2 lasers on Mars

Spectra of Martian CO2 emission line as a function of frequency difference from line center (in MHz). Blue profile is the total emergent intensity in the absence of laser emission. Red profile

is Gaussian fit to laser emission line. Radiation is from a 1.7 arc second beam (half-power width) centered on Chryse Planitia. The emission peak is visible at resolutions R > 1,000,000.

(Mumma et al., 1981)

CO2 lasers on Earth

Vibrational energy states of CO2 and N2 associated with the natural 10.4 μm CO2 laserG.M. Shved, V. P. Ogibalov

Natural population inversion for the CO2 vibrational states in Earth's atmosphereJ. Atmos. Solar-Terrestrial Phys. 62, 993 (2000)

”Random-laser” emission”Random-laser” emission

D.Wiersma, Nature,406, 132 (2000)

Letokhov, V. S.Astrophysical LasersQuant. Electr. 32, 1065 (2002) = Kvant. Elektron. 32, 1065 (2002)

Masers and lasers in the active medium particle-density vs. dimension diagram

Quantum Optics @ TelescopesQuantum Optics @ Telescopes

Detectinglaser effects in

astronomical radiation

Intensity interferometryIntensity interferometry

Narrabri stellar intensity interferomer circa 1970 (R.Hanbury Brown, R.Q.Twiss et al., University of Sydney)

S.Johansson & V.S.LetokhovPossibility of Measuring the Width of Narrow Fe II Astrophysical Laser Lines in the Vicinity ofEta Carinae by means of Brown-Twiss-Townes Heterodyne Correlation Interferometryastro-ph/0501246, New Astron. 10, 361 (2005)

Spectral resolution = 100,000,000 !

Spectral resolution = 100,000,000 !

o To resolve narrow optical laser emission (Δν 10 MHz) requires spectral resolution λ/Δλ 100,000,000

o Achievable by photon-correlation (“self-beating”) spectroscopy ! Resolved at delay time Δt 100 ns

o Method assumes Gaussian (thermal) photon statistics

Photon statistics of laser emissionPhoton statistics of laser emission

• (a) IfIf the light is non-Gaussian, photon statistics will be closer to stable wave(such as in laboratory lasers)

• (b) IfIf the light has been randomized andis close to Gaussian (thermal), photon correlation spectroscopy will reveal the narrowness of the laser light emission

Photon correlation spectroscopyPhoton correlation spectroscopy

E.R.Pike, in R.A.Smith, ed. Very High Resolution Spectroscopy, p.51 (1976)

LENGTH,TIME &FREQUENCYFORTWO-MODESPECTRUM

Photon correlation spectroscopyPhoton correlation spectroscopy

o Analogous to spatial informationfrom intensity interferometry,photon correlation spectroscopydoes not reconstruct the shape of

the source spectrum, but “only” gives linewidth information

D. Dravins 1, C. Barbieri

2

V. Da Deppo 3, D. Faria

1, S. Fornasier 2

R. A. E. Fosbury 4, L. Lindegren

1

G. Naletto 3, R. Nilsson

1, T. Occhipinti 3

F. Tamburini

2, H. Uthas 1, L. Zampieri

5

(1) Lund Observatory(2) Dept. of Astronomy, Univ. of Padova

(3) Dept. of Information Engineering, Univ. of Padova(4) ST-ECF, ESO Garching

(5) Astronomical Observatory of Padova

HIGHEST TIME RESOLUTION, REACHING QUANTUM OPTICS

• Other instruments cover seconds and milliseconds

• QuantEYE will cover milli-, micro-, and nanoseconds, down to the quantum limit !

MILLI-, MICRO- & NANOSECONDS

• Millisecond pulsars ?• Variability near black holes ?• Surface convection on white dwarfs ?• Non-radial oscillations in neutron stars ?• Surface structures on neutron-stars ?• Photon bubbles in accretion flows ?• Free-electron lasers around magnetars ? • Astrophysical laser-line emission ?• Spectral resolutions reaching R = 100

million ?• Quantum statistics of photon arrival

times ?

John M. Blondin

(North Carolina State University)

Hydrodynamics on supercomputers:

Interacting Binary Stars

Photon Bubble

Oscillations in Accretion

Klein, Arons, Jernigan & Hsu ApJ 457, L85

(1996)

Fluctuations of Pulsar Emission

with Sub-Microsecond Time-Scales

J. Gil, ApSS 110, 293 (1985)

Rapid oscillations in neutron starsDetection with RHESSI of High-Frequency X-Ray Oscillations in the Tail of the 2004 Hyperflare from SGR 1806-20: Watts & Strohmayer, ApJ 637, L117

(2006)

Power spectra after mainflare (25–100 keV), atdifferent rotational phases:QPO visible at 92.5 Hz.

Possible identification:Toroidal vibration modeof neutron-star crust?

Rapid oscillations in neutron starsDetection with RHESSI of High-Frequency X-Ray Oscillations in the Tail of the 2004 Hyperflare from SGR 1806-20: Watts & Strohmayer, ApJ 637, L117

(2006)

Surface patterns for torsional modes that may have been excited by the hyperflare.Colors and arrows indicate the magnitude of the vibrations.

(Max Planck Institute for Astrophysics)

p-mode oscillating neutron starp-mode oscillating neutron star

1215Y

Non-radial oscillations in neutron starsMcDermott, Van Horn & Hansen, ApJ 325, 725 (1988)

Advantages of very large telescopes

Advantages of very large telescopes

Telescope diameter

Intensity <I> Second-order  correlation  <I2>

Fourth-order photon  statistics  <I4>

3.6 m 1 1 1

8.2 m 5 27 720

4 x 8.2 m 21 430 185,000

50 m 193 37,000 1,385,000,000

100 m 770 595,000 355,000,000,000

. . .