chemical composition in a merging galaxy ngc3256...
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Chemical Composition in a Merging Galaxy NGC3256 ~ALMA cycle3 observation (Band3 line survey)~
Tomonari Michiyama (SOKENDAI,NAOJ), D.Iono, K.Nakanishi , T.Kodama J.Ueda , T.Satio,
M.Ando, T.Yamashita, and M.Yun
Me
ALMA
AstrochemistryThe science of the abundance and reaction
of chemical elements and molecules in the universe
→ very ambiguous term
1. science of the structure and synthesis model → strict sense 2. underlying physical processes leading to molecular
formation and destruction (dust chemistry, shock chemistry) 3. abundance of molecules in a certain region
4. (nucleo-)synthesis 5. abundance of chemical elements and their isotopes
→ In addition, astronomers use the term “ chemistry ” in
Mauersberger&Henkel+93
Galaxy and galaxy merger
early stage mid stage late stage
Most of galaxies have experienced galaxy and galaxy merger. (or in the future)
Not only change morphology, but affect activity of galaxies. (e.g., AGN, starburst activity)
Important event for the galaxy evolution.
Our science goal
early stage mid stage late stage
To establish the chemical evolution scenario during galaxy merger. Where (When, How) molecules are enhanced ? → AGN or SB might affect chemistry.
We can investigate time evolution by observing merging galaxy (separation of two galaxies roughly mean the time from interaction )
How chemical (or physical) properties evolve ?
Our science goal
early stage mid stage late stage
NGC 3256
To establish the chemical evolution scenario during galaxy merger. Where (When, How) molecules are enhanced ? → AGN or SB might affect chemistry.
We can investigate time evolution by observing merging galaxy (separation of two galaxies roughly mean the time from interaction )
NGC 3256
NGC 3256
LMT (Large Millimeter Telescope @ Mexico) have detected many molecules.
What molecules are seen when merger proceeded ?
NGC 3256
NGC 3256
LMT (Large Millimeter Telescope @ Mexico) have detected many molecules.
What molecules are seen when merger proceeded ?
ALMA CO image → two nuclei(Sakamoto+14)
NGC 3256
We check those suggestions with a new eye of astrochemistry.
South Nucleus AGN galaxy
Both has molecular gas outflow
North Nucleus SB galaxy
(Emonts+14, Lehmer+15, Ohyama+15)
ALMA Observation
Observation was conducted at 3/4,7,8,9,11 → 6 hours Data was fully delivered at 4/27 Resolution~2”(~300pc), r.m.s 0.3 mJy
LMT spectrum and ALMA frequency coverage
ALMA results (preliminary)
85 90 95 100 105 110
85 90 95 100 105 110
5
10
15
20
25
30
0
5
10
15
20
25
30
0
c-C3H2
C2H
HCN
HCO+
HNC
CS
CH3CCHC18 O
13 CO
c-C3H2 C2H
HCN
HCO+
HNC
CSCH3CCH
C18 O
13 CO
North
South
mJy/beam
ALMA results (preliminary)
85 90 95
85 90 95
5
10
15
20
25
30
0
5
10
15
20
25
30
0
c-C3H2
C2H HCN
HCO+
HNC
CS
c-C3H2 C2H
HCN
HCO+
HNC
CS
North
South
mJy/beam
ALMA results (preliminary)
c-C3H2
CH3CCH
c-C3H2
CH3CCH
C4H
C4H
H13 CN H13 CO+
SiO
C2H
C2H
HCN
HCN
North
South
mJy/beam
HCO+
HCN
13CO
HNC
CCH F=2-1
CCH F=1-0
CS
C18O
c-C3H2
CH3OH(2k-1k)
CH3CCH
ALMA results (preliminary)
* dirty image
(Quick) Discussion - shockSiO(2-1)
(Quick) Discussion - shockHNCO(40,4-30,3)
(Quick) Discussion - shockCH3OH(2k-1k)
(Quick) Discussion - shockCH3OH(00-1-1)
(Quick) Discussion - shockSiO(2-1) HNCO(40,4-30,3)
CH3OH(2k-1k) CH3OH(00-1-1)
(Quick) Discussion - shockSiO(2-1) HNCO(40,4-30,3)
CH3OH(2k-1k) CH3OH(00-1-1)
Only the SiO is enhanced in Northern
(Quick) Discussion - shockSiO(2-1) HNCO(40,4-30,3)
CH3OH(2k-1k) CH3OH(00-1-1)
Collision front ?
Collision front ?
Collision front ?
(Quick) Discussion - shockSiO(2-1) HNCO(40,4-30,3)
CH3OH(2k-1k) CH3OH(00-1-1)
Offset from nuclei
Offset from nuclei
Offset from nuclei
Offset from nuclei
(Quick) Discussion - shockSiO(2-1) HNCO(40,4-30,3)
CH3OH(2k-1k) CH3OH(00-1-1)
Only shock tracers are enhanced
Only shock tracers are enhanced
Only shock tracers are enhanced
Only shock tracers are enhanced
(Quick) Discussion - shock
physical shock due to collision
What phenomena enhance the shock tracers ?
offset from nuclei
90 95 100
90 95 100
C2H HCN
HCO+
HNC
CS
CH3CCH
C2H
HCN
HCO+
HNC
CS
CH3CCH
HCN/HCO+ ~ 1.0
HCN/HCO+ < 1.0
inconsistent with the previous studies
SB
AGN
(Quick) Discussion - HCN/HCO+
90 95 100
90 95 100
C2H HCN
HCO+
HNC
CS
CH3CCH
C2H
HCN
HCO+
HNC
CS
CH3CCH
HCN/HCO+ ~ 1.0
HCN/HCO+ < 1.0
inconsistent with the previous studies
SB
AGN
(Quick) Discussion - HCN/HCO+
H13CN and H13CO+
H13CO+
Future Works
Chemistry → Where (When, How) PDR, XDR, shock, and etc… is enhanced
Physical properties → derive the temperature, density, and etc … e.g., using RADEX code for 12CO(3-2),12CO(1-0), and 13CO(1-0)
Kinematics → Which lines are seen in outflowing gas ? The physical properties of outflowing gas. inflowing gas ?
What occur in NGC 3256 ?
early stage mid stage late stage
Line survey for many merging galaxies with ALMA (following cycle) ↓
achieve the science goal To establish the chemical evolution scenario
during galaxy merger.
Future Works
1. What is astrochemistry ?; The science of the abundance and reaction of chemical elements and molecules in the universe
2. NGC 3256 case study; LMT (single dish)→ ALMA (Interferomter)
3. ALMA new results;many lines, spatially resolved image shock and CH3OH, HCN/HCO+ … etc
4. Future Works;Chemical, Physical, and Kinematical explanation We are planning ALMA observation for other interacting galaxies.
Summary