Turbulent AU Structures Turbulent AU Structures RevealedRevealed by H by H22O and CHO and CH33OH MasersOH Masers

V. StrelnitskiV. StrelnitskiMaria Mitchell ObservatoryMaria Mitchell Observatory

In collaboration with: In collaboration with: J. Alexander, S. Gezari, B. Holder, J. Alexander, S. Gezari, B. Holder, N. Nezhdanova, J. Moran, M. Reed, V. N. Nezhdanova, J. Moran, M. Reed, V. ShishovShishov

SINS, Socorro, May 21-24, 2006SINS, Socorro, May 21-24, 2006

HH22O and CHO and CH33OH MasersOH Masersprovide information provide information on:on: Physics of natural masingPhysics of natural masing

Spatial and kinematical Spatial and kinematical structure of the surroundings structure of the surroundings of new-born starsof new-born stars

Physics of supersonic Physics of supersonic turbulence turbulence

CH3OH Masers in OMC-1

Johnston et al. 1997

Two Competing Interpretations:

• Maser “hot spots” are the result of a lucky coincidence of radial velocities in a homogeneous turbulent medium

• The “hot spots” are physical condensations with special conditions (density, temperature, abundances, etc)

Are H2O & H2CO Masers

or Things?

The Model (Holder The Model (Holder et al.et al. 2006):2006):

Random Kolmogorov velocity field in Random Kolmogorov velocity field in a 512a 51233 grid point box grid point box

Unsaturated and saturated maser Unsaturated and saturated maser amplificationamplification

I = I = II0 0 eeττ

I = II = I00ττ

Random fractalization of the medium Random fractalization of the medium ((d d = 1)= 1)

Does Supersonic Turbulence have

a Shock-Wave Dissipation Scale?

• Relevant parameters for dissipation:

ε = U3/L

cs

• Dissipation scale:

η = cs3 /ε = L / M3

• H2O Masers: L ~ 104 A.U.; M ~ 20 → η ~ 1 A.U.

Dimensional Approach

Physical Approach

uL= M cs

vs ~ cs

tl ~ l / ul

ts ~ l/cs

ul = uL (l / L)1/3

ts > tl as long as l > L/M3

η ~ L/M3

L

Conclusions• H2O masers are “things” and they may be ideal

probes of supersonic turbulence

• They point to: - High degree of intermittency of turbulence- Lack of energy dissipation at large scales

• They may be intimately connected with the shock-

wave dissipation scale of turbulence

• More computer simulations are needed to investigate the dependence of energy dissipation on scale for supersonic turbulence

pl = (η/l)3-d

Typical Model (Sobolev Typical Model (Sobolev et alet al. . 1998)1998)

Random Kolmogorov velocity field in a NRandom Kolmogorov velocity field in a N33 grid point grid point boxbox

Unsaturated (exponential) maser amplificationUnsaturated (exponential) maser amplificationI = I = II0 0 eeττ

Synthetic spectra and maps to be compared with Synthetic spectra and maps to be compared with observationsobservations

Result: Result: CHCH33OH hot spots may be an optical effectOH hot spots may be an optical effect

Unsaturated Amplification(Analytical Solution)

• Mean Intensity

<I> = C exp[<τ> + 0.5 <(Δτ)2>]

• The most probable realizations are within

<τ> ± [<(Δτ)2>]1/2

• If <(Δτ)2> >> 1, only a few bright spots

• Δτ τ

H2O:

T = T0 eτ ~ 1015 K τ ≈ 35

T0 ~ 1K

H2CO: τ ≈ 10

Required Maser Gains