h3+h3+. h 3 +, a new astrophysical probe: revelation of warm and diffuse gas near the galactic...
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H3+, a new astrophysical probe:
Revelation of warm and diffuse gas near the Galactic center
Takeshi OkaDepartment of Astronomy and Astrophysics and
Department of Chemistry, The Enrico Fermi InstituteThe University of Chicago
Thomas R. Geballe Gemini Observatory
Miwa Goto Max Planck Institute for Astronomy
Tomonori Usuda Subaru Telescope
Benjamin J. McCall University of Illinois, Urbana-Champaign
Tetsuya Nagata Kyoto UniversityTomoharu Oka University of TokyoFarhad Yusef-Zadeh Northwestern UniversityHarvey Liszt National Radio Astronomy Observatory
June 27, 2007 CSO
Thumbnail sketch of H3+
+
1951
1970
1996
H
H2
H3+
Simplest polyatomic molecule
CO
Simple chemistry H2 → H2+ + e H2
+ + H2 → H + H3+
c.r.
p
Initiator of interstellar chemistry H3+ + O → H2 + OH+
H 2
H 2+
C H 3+
C H 5+
C H 4
C H2 3+
C H2 2
C H3+
C H3 3+
C Hm n
C H+
C H 2+
N H2
+
H C O+
O H+
H O2+
H O3
+H O2
O H
C H C N H2 5
+
C H C N H3+
C H N H3 2+
H C N2
+
H C N
C H N H3 2
C H N H2
C H C N3
C H C N2 5
C H
C H C O3
+
C H O H3 2
+
C H C O2
C H O H3
H C OC H O H
C H O C H
2
2 5
3 3
C H2 5
+C H2 4
H C O2 3
+C O3
C H2
H C N3 3
+H C N3
H C N5
H C N7
H C N9
H C N11
C H3
C 4
+
C H4+
C H4 2+
C H4 3+
C H4
C H3 2
cosm ic ray
H 2N 2
C OO
H 2
H 2
e
e
e
ee
e
e
N
N H 3
H C N
C H C N3
e
C O
H O2
C H O H , e3
C
H 2
H 2
H 2
e
e
C H 3
+e
e eH C N
C+
e
C+
H 2
e eC
+
H 2H 2
e
C O
C
H
+
e
e
p
Powerful informant of:
Cosmic ray ionization rate ζ Temperature T density n
Radial length of clouds L
X(H3+)diffuse ~ 10X(H3
+)dense
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
)
10-1
100
101
102
103
104
105
106
n(H)
Dense Clouds Diffuse Clouds
H2
HCO
C+H3
+
ζL = 2 ke N(H3+) (nC/nH)
2005 Hot and Diffuse Clouds near GC Probed by Metastable H3
+
Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882
Progress of H3+ observation
1980 Oka, PRL. 45, 531Laboratory Spectrum
1996 Geballe, Oka, Nature 384, 334Interstellar H3+, Discovery
1989 - 95
2002 Metastable H3+, Discovery Goto, McCall, Geballe, Usuda,
Kobayashi, Terada, Oka PASJ, 54, 951
1998 – 2002 Ubiquity, Dense and Diffuse Clouds McCall, Geballe, Hinkle, Oka
ζdiffuse ~ !0 ζdense
1975
Inferred face-on view of the Central Molecular Zone
Sawada, Hasegawa, Handa, Cohen, MNRAS 349, 1167 (2004)Oka, Hasegawa, Sato, Tsuboi, Miyazaki, ApJS 118, 455 (1998)
130 pc
100 km s-1
Quintuplet
GCS3-2
130 pc
100 km s-1
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 2000Gemini South 8 m Phoenix 5 km s-1 Cerro Pachon 2003VLT 8.2 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)
Oka, Epp, ApJ 613, 349 (2004)
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
The ideal rotational levels of H3+
(3,3)
(2,2)Unstable
(1,1)Ground
361 K
Central Molecular Zone is the Treasure House
of H3+
R(1, 1)u R(1, 0)
Geballe Phil. Trans. RSL A358, 2503 (2000)
N(H3+) = 3.8 × 1014 cm-2
L = 21 pc
N(H3+) = 4.4 × 1015 cm-2
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
T = 250 K
n ≤ 100 cm-3
Dimension of the discovered gas
ζL = 2 ke N(H3+) (nC/nH)SV RX
7.3 ×10-8 cm3/s 1.6 ×10-4
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
130 pc
100 km s-1
Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)
(2,2) densitometer
(3,3) thermometer
(1,1) ground level
(2,2) densitometer
(3,3) thermometer
(1,1) ground level
8 stars within 30 pc from GC
T = 220 - 400 Kn ≤ 100 cm-3
All show high T and low n
All stars: high N(H3+) and hence high ζL
N(H3+) = (2.3 - 4.5) × 1015 cm-2
R(2, 2)l
R(1, 1)l
Q(1, 0)Q(1, 1)R(3, 3)l
R(1, 0)+R(1, 1)u
R(2, 2)l
R(1, 1)l
Q(1, 0)Q(1, 1)R(3, 3)l
R(1, 0)+R(1, 1)u
L ≥ 60 – 120 pc for RX = 3 and ζ = 10-15 s-1
Lazio & Cordes, ApJ 505, 715 (1998)
0.8 107 K
0.1 106 K 10 cm-3
0.1 102 K 104 cm-3
Enter a new category of gas in the CMZ
Warm and diffuse gas250 K 102 cm-3
??
that is incompatible with two other gases
Chandra 20 pc × 20 pc (0.5 – 8) keV Muno et al. ApJ 589, 225 (2003)
Warwick, Sakano Decourchelle (2006) Revnivtsev et al. (2006)
X-ray: Chandra comes to rescue?
X-ray sources diffuse gas or point source?Mostly diffuse Mostly discrete
Koyama, Maeda, Sonobe, Takeshima, et al. 1996
Muno, Baganoff, Bautz, Brandt, et al. 2003
Wang, Gotthelf, Lang, 2002
Koyama, Makishima, Tanaka, Tsunemi, 1986
Revnivtsev, Sazonov, Gilfanov, et al. 2006
Warwick, Sakano, Decourchelle, 2006
Muno, Baganoff, Bautz, Brandt, et al. 2004
Koyama, Awaki, Kunieda, Takano, et al., 1989
Tanaka, 2002
Ebisawa, et al., 2005
Koyama et al. 2007Suzaku Dec. 6, 2006
Lazio & Cordes, ApJ 505, 715 (1998)
0.8 107 K
0.1 106 K 10 cm-3
0.1 102 K 104 cm-3
Enter a new category of gas in the CMZ
Warm and diffuse gas250 K 102 cm-3
0.01
?
Summary
Spectroscopy of H3+ has revealed a new category of gas in the
Central Molecular Zone with high temperature (~ 250 K) and low density ( ≤ 100 cm-3) with a large volume filling factor (f ~ 1).CO Oka, Hasegawa, Hayashi, Handa, Sakamoto, ApJ 493, 730 (1998)
Dahmen, Hüttemeister, Wilson, Mauersberger, A&A 331, 959 (1998) H2 Rodriguez-Fernandez, Martin-Pintad, Fuente, et al. A&A 365, 174 (2001)
CH Magnani, Zelenik, Dame, Engebreth, ApJ 636, 267 (2006)
The finding drastically change the previous picture of the gas in the Central Molecular Zone.
We are in the process of observing a wider region of the Central Molecular Zone. We need bright YSO’s!
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