High ionization rate and a vast amount of warm and diffuse gas

in the Central Molecular Zone

Takeshi OkaDepartment of Astronomy and Astrophysics

and Department of Chemistry The Enrico Fermi Institute, University of Chicago

The emerging, multi-wavelength picture of the Galactic center environments Max-Planck Haus, Heidelberg October 18, 2011

Tom Geballe Gemini ObservatoryMiwa Goto Max-Planck Institut für Astronomie

Infrared spectrum of H3+, the new probe for the GC

+

1951

19701973

1996

H

H2

H3+

92

10~

a

H2 → H2+ + e ζ ~ 10-17 – 10-14 s-1

H2+ + H2 → H + H3

+

Cosmic - ray

T. Oka, Phys. Rev. Lett. 45, 531 (1980)

p

T, n, ζ, L

(3,3) (2,2) (1,1)

(1,0)

Geballe and Oka, Nature, 384,334 (1996)

H3+ as thermometer and densitometer

Metastable

27.2 days

Ortho I = 3/2Para I = 1/2J

K

(3,3)

(2,2)

(1,1)

Pan and Oka, 1987, ApJ, 305, 518

(1,0)361 K

CO R(1)

(2,2) unstable

(3,3) metastable

(1,1) ground

T ~ 250 K

n ≤ 100 cm-3

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

T n

Spontaneous breakdown of symmetry

H3+ as dosimeter and yardstick

Destruction H3+ + e → H + H + H

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

103

104

105

106

n(X

)

10-1100101102103104105106

n(H)

Dense Clouds Diffuse Clouds

H2

HCO

C+H3

+

Production H2 → H2+ + e H2

+ + H2 →H + H3+

L = 2 ke N(H3+) (nC/nH)SV RX / f(H2)

1.1×10-7 cm3/s 1.6 ×10-4 < 1 ?

(1.8 ‒ 6.1) ×1015 cm-2 > 3

L > (2.0 – 6.5) ×105 cm/s

L

10-16 s-1 > 0.6 – 2.1 kpc 10-15 s-1 > 60 – 210 pc

dn(H3+)/dt = n(H2)

= ken(H3+)n(e)

L

α+

λε+ ε-η+

θ-

θ+

δ+

30 pc

Oka, Geballe, Goto, Usuda, McCall, 2005, ApJ, 632, 882GCS 3-2

Goto, Usuda, Nagata, Geballe, McCall, Indriolo,Suto, Henning, Morong, Oka, 2008, ApJ, 688, 306

, Geballe, Oka, 2010, ApJ, 709, L70

H3+ is ubiquitous

H3+ the most direct probe for soft cosmic ray

L N(H3+)

L = 2 ke N(H3+) (nC/nH)SV RC/H / f(H2)

L = 2 ke N(H3+) (nC/nH) / f(H2)

L = 2 kL N(H3+) (nC/nH)1.5

Dense clouds

Diffuse clouds

Galactic center

L = (0.6 – 2.3) 102 cm s-1

N(H3+)obs = (1.1 – 5.2) 1014 cm-2

N(H3+)obs = (0.21 – 2.4) 1014 cm-2

N(H3+)obs = (1.8 – 6.1) 1015 cm-2

L = (0.4 – 4.4) 104 cm s-1

L > (1.2 – 4.2) 105 cm s-1

Goto, Usuda, Nagata, Geballe, McCall, Indriolo, Suto, Henning, Morong, Oka, 2008, ApJ, 688, 306

Indriolo, Geballe, Oka, McCall, 2007, ApJ, 671,1736

= 3 10-17 s-1 L = (0.6 – 2.3) pc

= 2 10-15 s-1 L > (24 – 84) pc

= 4.5 10-16 s-1 L = (3 – 29) pc

RC/H 3 – 6.7

McCall, Geballe, Hinkle, Oka, 1999, ApJ, 522, 338

Rolleston et al. 2000, A&A, 363, 557Esteban et al. 2005, ApJ, 618, L95

RX 3 – 10, > 3Sodroski, et al. 1995, ApJ 452, 262Arima, Sofue, Tsujimoto, 1996, PASJ 48, 275

Lazio & Cordes, ApJ, 505, 715 (1998)

80% 107-8 K10% 104-6 K ne 10 cm-3

10% 50 K 104 cm-3

f

Previous concept drastically changed

T ~ 250 Kn ≤ 100 cm-3

L > 60 pc f > 30% > 2 × 1015 s-1

Enter a new category of molecular gas

GCDX GCPE

Much less dense gas in the CMZ 1

1.00

0.95

0.90

0.85

0.80

0.75

0.70

-200 -150 -100 -50 0 50 100

GCS 4

NHS 21

NHS 25

NHS 42

FMM 361

ι 68 pc East α 140 pc West

H3+ CO

Much less dense clouds in the CMZ 2

Schultheis et al. ApJ 495, 157 (2009)

T. Oka et al. ApJ. 493, 730 (1998)

Cotera et al. ApJ (2000)

Lazio & Cordes, ApJ, 505, 715 (1998)

80% 107-8 K10% 104-6 K ne 10 cm-3

10% 50 K 104 cm-3

f

Previous concept drastically changed

T ~ 250 Kn ≤ 100 cm-3

L > 60 pc f > 30% > 2 × 1015 s-1

Enter a new category of molecular gas

GCDX GCPE

1%

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

Much less GCDX and the ultra-hot plasma gas

α+

λε+ ε-η+

θ-

θ+

δ+

30 pc

Future 1 Increasing stars

Future 2: Using surrogates, OH+, H2O+, CH+ 1 Remarkable similarity of velocity profiles

Geballe & Oka, 2010, ApJ, 709, L70

H3+ R(1,1)l

H2O+ 111← 000

H2O+ 110← 101

E. Falgarone et al. 2011Schilke et al. 2011, A&A, 521, L11

H3+ f(H2) = 1 ?

H2O+ f(H2) = 0.1

17 pc

Future 2: 2 Herschel Proposal OA2

Molinari et al, 2011, ApJ, 735, L33

Double ring or single ring

Molinari et al, 2011, ApJ, 735, L33

Sawada et al. 2004

J. Kormendy & R. C. Kennicutt, 2004, ARA&A

Scoville, 1972

EMR

Rodríguez-Fernandez et al. 2006

Telescopes and spectrometersTelescope D Spectrom. λ/Δλ UKIRT 3.8 m CGS4 40,000 Mauna Kea 1982 Subaru 　 8.2 m IRCS 20,000 Mauna Kea 2000Gemini South 8 m Phoenix 60,000 Cerro Pachon 2003VLT 8.2 m CRIRES 100,000 Cerro Paranal 2006 Gemini North 8 m GENIRS 18,000 Mauna Kea 2011

Subaru UKIRTGemini South

VLT

Gemini North

Quintuplet Cluster

1° × 1° 140 pc × 140 pc

Super-massive clusters

GCS 3-2

Ubiquity of H3+

Sgr A* to 30 pc East

30 pc

1.00

0.95

0.90

0.85

0.80

0.75

0.70

-200 -150 -100 -50 0 50 100

GCS 4

NHS 21

NHS 25

NHS 42

FMM 361

Goto, et al. 2008, ApJ, 688, 306

Quintuplet Cluster

1° × 1° 140 pc × 140 pc

Super-massive clusters

GCS 3-2

Telescopes and spectrometersTelescope D Spectrom. λ/Δλ UKIRT 3.8 m CGS4 40,000 Mauna Kea 1982 Subaru 　 8.2 m IRCS 20,000 Mauna Kea 2000Gemini South 8 m Phoenix 60,000 Cerro Pachon 2003VLT 8.2 m CRIRES 100,000 Cerro Paranal 2006 Gemini North 8 m GENIRS 18,000 Mauna Kea 2011

Subaru UKIRTGemini South

VLT

Gemini North