The (3, 3) metastable rotational level of H3+

Takeshi Oka

Department of Chemistry and Department of Astronomy and Astrophysics

The Enrico Fermi Institute, The University of Chicago

New Horizon of Astrochemistry and Laboratory SpectroscopyMarch 16, 9 am, 2006

I am looking for a postdoc, Laboratory or Observatory

Metastable rotational levels

0 1 2 30

1

2

3

J

K

NH3

Lifetime of the Universe ?

Metastable rotational levels

0 1 2 30

1

2

3

J

K

NH3

Breakdown of symmetry

ΔK = 0 ΔK = 3

GeometryC3

Permutation(123)

selection rules

Metastable rotational levels

0

1

2

3

JNH3

μ

T. Oka, F. O. Shimizu, T. Shimizu, J. K. G. Watson, ApJ 165, L15 (1971)

50 years人生五十年

Δk = 3 200 ye

ars

F. Y. Chu, T. Oka, J. Chem. Phys. 60, 4612 (1974) PH3 AsH3

H3+ is simpler

0

1

2

3

J

Δk = 3

H3+

Non-polar

No inversion

J

K32.9 K

361 K

(J, K)

The ideal energy levels of H3+

(3, 3) metastable level

(1, 1) ground level

Δk = ± 3 forbidden transitions

27.2 days(2, 2) unstable level

(1, 0)

0 ±1 ±2 ±3 k

Ncrit ~ 200 cm-3

H3+ + H2 → (H5

+)* → H3+ + H2

Pan, Oka, ApJ 305, 518 (1986)

Discovery of metastable interstellar H3+

Goto, McCall, Geballe, Usuda,Kobayashi, Terada, OkaPASJ, 54, 951 (2002)

(3, 3) metastable

Subaru telescope

(1, 1) ground level

Sightline toward the Galactic center

The Central Molecular Zone

J

K32.9 K

361 K

(J, K)

Thermalization of H3+

(3, 3) metastable level

(1, 1) ground level

27.2 days(2, 2) unstable level

(1, 0)

0 ±1 ±2 ±3 k

Ncrit ~ 200 cm-3

H3+ + H2 → (H5

+)* → H3+ + H2

Radiation Collision Reaction

Rigorous Selection Rules Approximate Rules Random

ortho para ΔI = 0 ortho para ΔI = 0 ΔItotal = 0

A

A

B

B

C

A

D

B

Ψ’

ψ

Trad 3 K « Tkin

Elementary processes

Rate Equations

1' ' ' '2

' '

( ) exp( )2

J K JK JK J KJK JK

J K

g E Ek Cg kT

2

' '' '

' '

' '' '

' '

( ) ( ) ( )

( ' ') ( )

( ' ') ( )

( ) ( ) ( ) ( )

J K JKJK J K

J K

J K JKJK J K

J K

e XX

dn JK n H f JKdtA n J K A n JK

k n J K k n JK

k n e n JK k n X n JK

Production

Spontaneous emission 4 10-7 s-

1

Collision n(H2) 100 cm-3 10-7 s-1

Destruction 10-9 s-1

10-17 s-1

10-7 cm3 s-1 10-9 cm3 s-1

' '' '

' ' ' '

exp( )J KJK JK JK J KJKJ K J K

k g E Ek g kT

H3+ + H2 (H5

+)* H3+ + H2

Detailed balance

Cosmic ray ionization

Dissociative recombination Proton hop reaction

0 =

Steady State

Oka, Epp ApJ, 613, 349 (2004)

)2,2()3,3(

NN

Discovery of hot and diffuse clouds

)1,1()3,3(

NN

Oka, Epp, ApJ 613,349 (2004)Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

(1, 1) ground levelCMZ and spiral arms

(3, 3) metastable level All CMZ

(2, 2) unstable level Neither

CO Mostly spiral arms

High temperature

Low density

Enter Gemini South Observatory

The Expanding Molecular RingKaifu, Kato, Iguchi, Nature (1972)Scoville, ApJ (1972)

Whiteoak, Gardner, MNRAS (1979)

The central 30 pc of the CMZ

Yusef-Zadeh, Morris, AJ (1987)Nagata et al. (1990)Okuda et al. (1990)

The Quituplet

Oka, Geballe, Goto, Usuda, McCall, ApJ (2005)

Other stars

Controversies

T. Oka No hot gas in the Expanding Molecular Ring

F. Le Petit Diffuse gas cannot be that hot

J. Black Infrared pumping

(1, 0)

(3, 0)

(2, 0)

(3, 3)

F. Yusef-Zadeh 4 categories of gases ApJ 637, L101 (2006)

The Galactic centerThe Central Molecular Zone (CMZ)

The treasure house of H3+

Discovery of metastable H3

+Revelation of warm and diffuse gas

Cold30 K>104 cm-3

Hot104 K~102 cm-3

Ultrahot107-8 K~0.3 cm-3

Warm250 K~102 cm-3

CO, CS X-rayH3+ Radio diffraction

Volume filling factor f

0.1 0.5 - 1 ~ 0.5 «10.01

Extragalactic H3+

Geballe, Goto, Usuda, Oka, McCall ApJ in press

Z = 0.05821

The (3, 3) metastable rotational level of H3+

Takeshi Oka

Department of Chemistry and Department of Astronomy and Astrophysics

The Enrico Fermi Institute, The University of Chicago

New Horizon of Astrochemistry and Laboratory SpectroscopyMarch 16, 9 am, 2006

I am looking for a postdoc, Laboratory or Observatory

6

5

4

3

2

1

0

H3+ C

olum

n D

ensi

ty (1

014cm

-2)

50403020100

E(B-V) (mag)

AFGL2136

W33A

MonR2 IRS 3

AFGL961E

AFGL490

AFGL2591

8

6

4

2

0

H3+ C

olum

n D

ensi

ty (1

014cm

-2)

6543210

E(B-V) (mag)

OphP Cygni

HD 183143

WR 118

Cyg OB2 12

WR 104

Cyg OB2 5

WR 121

HD 168607

HD 194279

GC IRS 3

2 Ori

HD 20041

Dense clouds

McCall, Geballe, HinkleOka, ApJ 522,338(1999)

Diffuse clouds

McCall, Hinkle, Geballe, Moriarty-Schieven, Evans,Kawaguchi, Takano, Smith, Oka, ApJ 567, 391 (2002)

Per

Surprise!! H3+ more abundant in diffuse clouds!!

N(H3+) ~ 3.6 ×1012 cm-2 AV

N(H3+) ~ 4.4 ×1013 cm-2 AV

Central Molecular Zone, the treasure house of H3+

M ~ 5 ×107 M⊙Dominantly molecularDense clouds, n(H2) > 104 cm-4

Volume filling factor 0.1Hot gas T ~ 300 KHigh velocity dispersionLow dust temperature T ~ 20-30 K

Mezger, Duschl, Zylka, A&A Rev. (1996)

Morris, Serabyn, ARA&A (1996)

CMZ

Sightlines toward the CMZ

Extraordinary radio emission

• Radio Arc– Arched filaments– Nonthermal filaments

• Sgr A* Yusef-Zadeh, Morris, AJ (1987)