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