Chen, Yi-Ping Supervisor: Hirano, Naomi 12 CO J=2-1 Observation Of M51 With SMA Physical Department of Tamkang University August,27, 2002 Summer Student Program,Institute of Astronomy and Astrophysics, Academia Sinica

Introduction Galaxy M51 SMA C 12 O Emission J=2-1 Data Reduction Analysis Data

Galaxy M51 Position (J2000): R.A. 13h 29m 52.37s Dec. +47°11' 40.8" Constellation: Canes Venatici Distance:About 9.6 Mpc Visual Magnitude: arcmin 9.3 kpc 1acrmin 50 arcsec (Field of view)

Sub-Millimeter Array Antenna: 5 Diameter:6-meter Covering bands : GHz Position: Summit of Mauna Kea, Hawaii

OC Because of CO molecule has a permanent dipole moment,the binary molecule with a simples ladder of rotational level spaced such that the lowest transition are in the millimeter wavelength. 12 CO Emission J=2-1

J is the quantum number of total angular momentum correspond to the rotational level. Frequency : GHz Energy : 16.6 Κ (upper level above ground) J=0 J=1 J=2 h ν= E 2 -E 1 h ν =E 1 -E 0

Observation Observation date : 2002 Feb 17,18 Telescope : SMA 6m(diameter)×5(antenna) 10 baseline Field of view : GH Z Bandwidth : 320 MH Z ~ km/s((82 MH Z ~106.7 km/s)× 4) Spectral resolution : KH Z ~1.06 km/s Gain calibrator : Band pass calibrator : Jupiter

Data Reduction Why using the Gain Calibration? Phase Amplitude t t Due to the instrument instability and atmosphere variation, it is necessary to do the gain calibration, and the better calibrator is quasar because it’s has a simple visibility function. V(u,v)=∫ ∞ - ∞ ∫ ∞ - ∞ A(x,y) I(x,y)e i2(ux+vy) dxdy 0 0 constant

I. Gain Calibraiton Before Gain Calibration Blue *-- ( ) Red *-- NGC5194 Row data

Blue--NGC5194 Red-- Cailbrator ( ) Set amplitude—1Jy

After Gain Calibration After calibration the phase is becoming zero(blue)&M51 drift like function.

II.Band Pass Calibration In the SMA Aarry each channel have four chunks Before band Pass Calibration

1chunk=82MHZ ≒ km/s 1channel =4×chunk ≒ 320MHZ ≒ Calibrator : Jupiter This calibrator must be strong enough that can clear display each of the chuck’s pattern. After Calibration Jupiter’s Spectra Spectra

After band Pass Calibration

Analysis Data -- Make Maps UV Coverage Beam Map Dirty Map(obtained from the inversion visibility function) Obtained by convolving the δ-function Clean Map UV plane FFT XY plane (Visibility function)

UV Coverage Beam map UV coverage

Dirty Map(Feb 18,chunk 2) Clean Map(Feb 18,chunk 2) Major axis = / asec Minor axis = / asec Position angle = / degrees Synthesize beam Beam map

Combine Map Total integration intensity V LSR =374.57~ km/s V LSR = 479.2~574.3 km/s V LSR =374~480.7 km/s

Contour Map Due to the sigh of phase is flipped the map must rotate 180°

12 CO J=1-0 HCN J=1-0 ©The Astrophysical Journal,461:L29-L32,1996 April 10

Compare 12 CO J=2-1 & 12 CO J=1-0

Compare HCN J=1-0 &C 12 O J=2-1