HTRA Galway - June 2006 Dainis Dravins Lund Observatory

What information is contained in light? What is being observed ? What is not ? Quantum optics in astronomy?

BLACKBODY --- SCATTERED --- SYNCHROTRON --- LASER --- CHERENKOV --- COHERENT --- WAVELENGTH & POLARIZATION FILTERS OBSERVER

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

Intensity 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. 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. 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. III D.Dravins, ESO Messenger No. 78, 9

Quantum effects in cosmic light Examples of astrophysical lasers

Early thoughts about lasers in space D. Menzel : Physical Processes in Gaseous Nebulae. I, ApJ 85, 330 (1937)

J. Talbot Laser Action in Recombining Plasmas M.Sc. thesis, University of Ottawa (1995)

Quantum effects in cosmic light Hydrogen recombination lasers & masers in 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. Hollenbach Far-Infrared Hydrogen Lasers in the Peculiar Star MWC 349A Science 272, 1459 (1996)

Quantum Optics & Cosmology The First Masers in the Universe…

M. Spaans & C.A. Norman Hydrogen Recombination Line Masers at the Epochs of Recombination and Reionization ApJ 488, 27 (1997) FIRST MASERS IN THE UNIVERSE The black inner region denotes the evolution of the universe before decoupling. Arrows indicate maser emission from the epoch of recombination and reionization.

Quantum effects in cosmic light Emission-line lasers in Eta Carinae

Eta Carinae HST Visual magnitude ESO VLT

Model of a compact gas condensation near η Car with its Strömgren boundary between photoionized (H II) and neutral (H I) regions S. Johansson & V. S. Letokhov Laser Action in a Gas Condensation in the Vicinity of a Hot Star JETP Lett. 75, 495 (2002) = Pis’ma Zh.Eksp.Teor.Fiz. 75, 591 (2002)

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

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

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

Quantum effects in cosmic light Laser effects in Wolf-Rayet, symbiotic stars, & novae

Sketch of the symbiotic star RW Hydrae P. P. Sorokin & J. H. Glownia Lasers 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 objects A&A 384, 350 (2002)

Raman scattered emission bands in the symbiotic star V1016 Cyg H. M. Schmid Identification of the emission bands at λλ 6830, 7088 A&A 211, L31 (1989)

Quantum effects in cosmic light Emission from neutron stars, pulsars & magnetars

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

V.A. Soglasnov et al. Giant Pulses from PSR B with Widths ≤ 15 Nanoseconds and T b ≥ 5×10 39 K, the Highest Brightness Temperature Observed in the Universe, ApJ 616, 439 (2004) Longitudes of giant pulses compared to the average profile. Main pulse (top); Interpulse (bottom)

A. Shearer, B. Stappers, P. O'Connor, A. Golden, R. Strom, M. Redfern, O. Ryan Enhanced Optical Emission During Crab Giant Radio Pulses Science 301, 493 (2003) Mean optical “giant” pulse (with error bars) superimposed on the average pulse

Coherent emission from magnetars oPulsar magnetospheres emit in radio; higher plasma density shifts magnetar emission to visual & IR (= optical emission in anomalous X-ray pulsars?) oPhoton arrival statistics (high brightness temperature bursts; episodic sparking events?). Timescales down to nanoseconds suggested (Eichler et al. 2002)

Quantum effects in cosmic light CO 2 lasers on Venus, Mars & Earth

CO 2 lasers on Mars Spectra of Martian CO 2 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)

CO 2 lasers on Earth Vibrational energy states of CO 2 and N 2 associated with the natural 10.4 μ m CO 2 laser G.M. Shved, V. P. Ogibalov Natural population inversion for the CO 2 vibrational states in Earth's atmosphere J. Atmos. Solar-Terrestrial Phys. 62, 993 (2000)

”Random-laser” emission D.Wiersma, Nature,406, 132 (2000)

Letokhov, V. S. Astrophysical Lasers Quant. Electr. 32, 1065 (2002) = Kvant. Elektron. 32, 1065 (2002) Masers and lasers in the active medium particle-density vs. dimension diagram

Quantum Telescopes Detecting laser effects in astronomical radiation

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

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

Spectral resolution = 100,000,000 ! oTo resolve narrow optical laser emission (Δν  10 MHz) requires spectral resolution λ/Δλ  100,000,000 oAchievable by photon-correlation (“self-beating”) spectroscopy ! Resolved at delay time Δt  100 ns oMethod assumes Gaussian (thermal) photon statistics

Photon statistics of laser emission If(a) If the light is non-Gaussian, photon statistics will be closer to stable wave (such as in laboratory lasers) If(b) If the light has been randomized and is close to Gaussian (thermal), photon correlation spectroscopy will reveal the narrowness of the laser light emission

Photon correlation spectroscopy E.R.Pike, in R.A.Smith, ed. Very High Resolution Spectroscopy, p.51 (1976) LENGTH, TIME & FREQUENCY FOR TWO-MODE SPECTRUM

Photon correlation spectroscopy oAnalogous to spatial information from intensity interferometry, photon correlation spectroscopy does 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 stars Detection with RHESSI of High-Frequency X-Ray Oscillations in the Tail of the 2004 Hyperflare from SGR : Watts & Strohmayer, ApJ 637, L117 (2006) Power spectra after main flare (25–100 keV), at different rotational phases: QPO visible at 92.5 Hz. Possible identification: Toroidal vibration mode of neutron-star crust?

Rapid oscillations in neutron stars Detection with RHESSI of High-Frequency X-Ray Oscillations in the Tail of the 2004 Hyperflare from SGR : 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 star

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

Advantages of very large telescopes Telescope diameterIntensity Second-order correlation Fourth-order photon statistics 3.6 m m x 8.2 m , m19337,0001,385,000, m770595,000355,000,000,000

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