IRMS Spectroscopically resolved Hα Sensitivity
1/5/2010 updated.

To investigage what star formation rates will be observable with IRMS,
we simulate Hα emission from z=1.5 galaxies with various integrated star formation rates.
A Kennicutt law is used to estimate the total luminosity of each source.

SFR [M_solar/yr] = 7.9 × 10-42 L(Hα) [erg/s]

We then derive the observed flux using cosmology parameters as below.

F(Hα) [erg/s/m2/μm] = L(Hα) / dλ 4 π dL2  (&lambda=[μm], dL=[m])
                               = SFR / dλ 4 π dL2 × 7.9 × 10-42

Instrument parameters are the same as S/N Sensitivity

Other Parameters




H&alpha Redshift
H&alpha@z=1.5 (H-band)
H&alpha@z=2.4 (K-band)



H&alpha Wavelength
1.65 um (&lambda0 of H-band)
2.20 um (&lambda0 of K-band)



Cosmology Parameter
H0=71,  &OmegaM=0.27,  &OmegaV=0.73
Calculator


Lookback Time
9.5 Gyr
10.9 Gyr
Calculator


Light Distance (dL)
35.906 Gly
64.218 Gly
Calculator


Scale 
8540 pc/arcsec
8257 pc/arcsec
Calculator


Sampling Scale
0.06 arcsec (60 mas)
0.06 arcsec (60 mas)



Slit width
0.16 arcsec (160 mas) ~2.7pix
0.16 arcsec (160 mas) ~2.7pix
MOSFIRE minimum slit width


Angular Diameter at each redshift
0.16 mas = 1366 pc
0.16 mas = 1321 pc



Assumed Encircled Energy inside Slit
NFIRAOS wide-field mode for &Phi 120 arcmin
On-axis: 0.65@J, 0.75@H, 0.8@K
Average: 0.4@J, 0.5@H, 0.6@K
TMT Instrument Handbook(2010)


Exposure Time
18000 s (900s x 20)
18000 s (900s x 20)



[OII]3727 Wavelength
9317 A @z-band
1.27 um @J-band



Hβ4860 Wavelength
1.22 um @J-band
1.65 um @H-band


[OIII]5007 Wavelength
1.25 um @J-band
1.70 um @H-band






Estimated S/N vs Star Formation Rate for Hα emission line of z=1.5 and z=2.4 galaxy.
Flux distribution size (angular diameter) is assumed 0.16 mas (the same with MOSFIRE minimum slit width).
Compared to IRIS 50 mas sensitivity (below), NFIRAOS effect is poor, but coarse spatial scale is suit 
for observations of high-z galaxies.

  


IRIS IFS(Integral Field Spectroscopy) sensitivity in case of 50 mas sampling. (from IRIS Homepage)