Central Molecular Zone (CMZ): the Treasure House of H3+

Takeshi Oka

Thomas R. Geballe Gemini Observatory

Miwa Goto Max Planck Institute for Astronomy

Tomonori Usuda Subaru Telescope

Benjamin J. McCall University of Illinois, Urbana-Champaign

The Enrico Fermi Institute, the University of Chicago

Tetsuya Nagata Kyoto University

Tomoharu Oka University of Tokyo

Farhad Yusef-Zadeh Northwestern University

Harvey Liszt National Radio Astronomy Observatory

EFI mini-symposium April 20, 2007

H3+: the novel probe of the CMZ

Central Molecular Zone

Morris, Serabyn, ARA&A (1996)CMZ

OH, H2CO, CO, CS, NH3, HCN H3+

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

R(1, 1)u R(1, 0)

Geballe Phil. Trans. RSL A358, 2503 (2000)

the treasure house of H3+

Inferred face-on view of the CMZThe Expanding Molecular Ring

Oka, Hasegawa, Sato, Tsuboi, Miyazaki, ApJS 118, 455 (1998)Sawada, Hasegawa, Handa, Cohen, MNRAS 349, 1167 (2004)

Scoville, ApJ 175, L127 (1972)

145 km s-1

200 pc 130 pc

100 km s-1

EMR

Lazio & Cordes, ApJ 505, 715 (1998)

0.8 107 K

0.1 106 K 10 cm-3

0.1 102 K 104 cm-3

Gas in the CMZ : pre-H3+

160 pc × 30 pc

7 × 107 K

Suzaku Dec. 6, 2006

Koyama et al. PASJ 59, S245 (2007)

27° × 40°

The Galactic center

QuintupletArches

1° × 1° 140 pc × 140 pc

The Quituplet Stars

Central

Binary pinwheel nebula, Science (2006)

GCS 3-2

Telescope and spectrometer

UKIRT 3.8 m CGS4 8 km s-1 Mauna Kea 1982

Subaru 　 8.2 m IRCS 15 km s-1 Mauna Kea 2000

Gemini South 8 m Phoenix 5 km s-1 Cerro Pachon 2003

VLT 8 m CRIRES ≤3 km s-1 Cerro Paranal 2006

Breaking

Symmetry

Interstellar NH3 Oka, Shimizu, Shimizu, Watson, ApJ 165, L15 (1971)

Interstellar H3+ Pan, Oka, ApJ 305, 518 (1986)

Metastable

27.2 days

20.4 days

μ

Critical Density 200 cm-3

Ortho I = 3/2

Para I = 1/2J

KCollision H3

+ + H2 → (H5+)* → H3

+ + H2

16 hrs8 hrs

++ = uuu

The ideal rotational levels of H3+

(3,3)

(2,2)Unstable

(1,1)Ground

361 K

CO J = 1

(2,2) unstable

(3,3) metastable

(1,1) ground

Spectroscopy

Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

130 pc

100 km s-1

)2,2(

)3,3(

N

N

Discovery of high temperature (T ~ 250 K), low density (n ≤ 100 cm-3) clouds

)1,1(

)3,3(

N

N

Oka & Epp, ApJ 613,349 (2004)

Dimension of the discovered gas

ζL = 2 ke N(H3+) (nC/nH)SV RX / f

7.3 ×10-8 cm3/s 1.6 ×10-4 1

3.1 ×1015 cm-2 3 - 10

Sodroski et al ApJ 452, 262 (1995)

ζL = (2.5 – 8.4) ×105 cm/s

ζ (s-1) L (pc)

10-16 (0.8 - 2.1) k 10-15 80 - 210

COBE DIRBE

120 pc

100 km s-1

Harvey Liszt Phil. Trans. R. Soc. A 364, 3049 (2006)

ζ = 10-17s-1

ζ = 10-17s-1

Eight YSO’s within 30 pc of the GCSubaru Telescope

(2,2) densitometer

(3,3) thermometer

(1,1) ground level

(2,2) densitometer

(3,3) thermometer

(1,1) ground level

The warm and diffuse gas is ubiquitousand has a large volume filling factor

T = 220 K – 400 K n ≤ 100 cm-3 Lmin ~ 80 – 120 pc

RX = 3 - 10

Lazio & Cordes, ApJ 505, 715 (1998)

0.8 107 K

0.1 106 K 10 cm-3

0.1 102 K 104 cm-3

Gas in the CMZ : post-H3+

Warm and diffuse gas250 K 102 cm-3

0.01

??

Chandra 20 pc × 20 pc (0.5 – 8) keV Muno et al. ApJ 589, 225 (2003)

Warwick, Sakano Decourchelle (2006) Revnivtsev et al. (2006)

Hyperstrong Radio-wave Scattering in the Galactic Center. IIA Likelihood Analysis of Free Electrons in the Galactic Center

Lazio & Cordes, ApJ 505, 715 (1998)

0.8 107 K

0.1 106 K 10 cm-3

0.1 102 K 104 cm-3

Gas in the CMZ : post-H3+

Warm and diffuse gas250 K 102 cm-3

0.01

??

Folded Fields as the Source of Extreme Radio-wave Scattering in the Galactic CenterGoldreich and Sridhar, ApJ 640, L159 (2006)

Extragalactic H3+ in ULIRG

Geballe, Goto, Usuda, Oka, McCall ApJ 644, 907 (2006)

Z = 0.05821

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)

Linnott & Rawlings Dynamically evolving cloud A&A 448, 425 (2006)

The Infrared Pumping

10.2 ms

25.3 ms

3.75 hrs

V = 0

V2 = 1

(1, 0)

(3, 3)

(3, 0)

(2, 0)2

75.27 108

W A

A new estimate of the Galactic interstellar radiation field between 0.1 μm and 1000 μm T. A. Porter & A. W. Strong, Cosmic Ray Conference Pune (2005)

Pump rate (s-1) Infrared photon flux(cm-2 s-1 Hz-1)

Three Proton System

+

I = 3/2 ortho

I = 1/2 para

++ = uuup = uudn = udd

H – K’

AV = [(H-K’) + 0.097]/0.051

Cotera, Simpson, Erickson, Colgan, Burton, Allen, ApJS 129, 123 (2000)

Harvey Liszt Phil. Trans. R. Soc. A 364, 3049 (2006)

Cotera, Simpson, Erickson, Colgan, Burton, Allen, ApJS 129, 123 (2000)

The Quintuplet

Okuda et al. ApJ 351, 89 (1990)