Lyman- Emission from The Intergalactic Medium

Juna A. Kollmeier

Theorsts:Zheng Zheng (IAS), David H. Weinberg (OSU), Jordi Miralda-Escudé (ICREEA), Romeel Davé (Steward) Neal Katz (U.Mass)Observers:Kurt Adelberger (McKenzie), Joe Hennawi (UCB), Jason Prochaska (UCSC), Chuck Steidel (Caltech)

Precision Cosmology

Courtesy M. Tegmark

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Hinshaw et al. 2003

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Viel et al. 2006 WMAP team

Precision Galaxy Formation?

Galaxy formation is far more complicated than

cosmology!

The Formation of Structure

Courtesy of A. Kravtsov

The IGM: Absorption

Courtesy of W. Sargent

Lyman- forest powerful tool: traces mass and can be connected to cosmology!

The IGM: Absorption

1d-Skewers 3d IGM

Why Lyman- emission?• Look at the universe in Lyman- eyes:

FULL 3D INFORMATION!

• Ionizations lead to recombinations:

--> emission of Lyman- photon

2P

1S

Cosmic web in emission --> Galaxy/IGM connection!

DETECTIONS!

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Reuland et al. 2003

Steidel et al. 2000

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Nilsson et al. 2007 QuickTime™ and a

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Weidinger et al. 2004

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Francis et al. 2006

Sources of Ly Emission

• Fluorescence from uniform UVB• Fluorescence from local sources (internal and external)• Cooling radiation • Stars and quasars

Predictions for these phenomena require Radiative Transfer!

Frequency Diffusion

Zheng & Miralda-Escude 2002, ApJ, 578

Flu

x

Frequency Shift

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Monte Carlo Radiative Transfer of Resonant Line Radiation

Zheng & Miralda-Escude 2002, ApJ, 578

From Simple Structures: Structures predicted by CDM:

Monte Carlo Radiative Transfer of Resonant Line Radiation

• Select observation direction• Select photon’s initial position in gas

according to emissivity• Scatter photon according to velocity,

temperature, density field • At each scattering, accumulate

image/spectrum

Observation Direction

P(esc)

P(esc)P(esc)

A 2.5 Mpc region From z=2 SPH Simulation

GAS DENSITY GAS TEMPERATURE

Predicted Image + 2D Spectra

From Kollmeier et al. in prep

Fluorescence by Local Sources

• Optically thick patches of IGM can be near bright sources (stars, QSOs)

• The density combined with the high photoionization rate increases recombination rate

• Careful balance!

Effect of Quasar on X

1D distribution of neutral fraction in the plane of the QSO

y=0

Case I: Transverse

From Adelberger, Steidel, Kollmeier, Reddy, ApJ, 2006, 637, 745

Detection?

From Adelberger, Steidel, Kollmeier, Reddy, ApJ, 2006, 637, 745

To Quasar

40’’

Model Predictions

Match?

• Simultaneous match of high surface brightness and large absorber size not successful

• Improvements to model? Add heating from QSO does increase SB (but why would this not evaporate the cloud). Ly not from QSO (but why such good agreement with “mirror”)?

• Something else?

Case II: Line of Sight

Detection?

From Hennawi, Prochaska, Kollmeier & Zheng in prep

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Model Predictions

QSO Behind DLA

Total Flux (predicted) = 5.33 x 10-20 erg/s/cm2

Total Flux (observed) = 4.3 x 10-16 erg/s/cm2

For the Future

Integral field units on big telescopes could produce this:

Once you have 1 Lyman Limit System you have many!

Summary• IGM is rife with information on structure formation!• Monte Carlo radiative transfer of Ly now included in

cosmological simulations Many applications for studying galaxy formation at high and low redshift– fluorescence of Lyman limit systems by UVB– fluorescence of DLAs by local sources– cooling radiation from galaxy formation in action– Ly emitters– sources of reionization

• Required to interpret programs underway• Helpful for designing future surveys