early results from the irs jim houck and the irs team - aas denver 6/1/04
Post on 20-Dec-2015
214 views
TRANSCRIPT
Early results from the IRS
Jim Houck and the IRS team - AAS Denver 6/1/04
IRS Status
• The hardware is working well:– The responsively is better than expected– The noise is the same as in the lab– Suffered a major solar proton event; 2.5 year dose in 2.5 days!
• The data in the archive have one known and one suspected problem. The first is being fixed, and the second should be fixed in a few weeks.
• The sensitivity is ~2x worse due to lingering, few percent, issues with the darks, flats, etc.
• The first 18 ULIRGs from Spitzer.
• Very complex spectra with intertwined variations.
• Featuring:• PAHs• Ices• HACs• Silicates• H2
• NeII et al.• •
H.Spoon, V. Charmandaris, L. Armus et al.
[NeV]
[OIV]
J. Bernard-Salas
IRS Goes Faint: CFRS 14.1157
1σ ~ 0.35 mJy in 2880 sec.
Blue Peak-up
S.Higdon et al. ApJS 2004
• L(IR)=8E13 L(sun)• z=1.1• Automated fitting with NGC1068 template
Mid-IR spectrum is clearly AGN-like
Blue Compact Dwarf SBS 0335-052:
a nearby laboratory for the early Universe
with V. Charmandaris, B. Brandl, B. Bernard-Salas, et al.
SBS = Second Byurakan Survey Markarian et al. 1983
SBS0335-052: Selected Properties (pre Spitzer)
• z = 0.0136; D = 57 Mpc*; 280 pc / arcsec• L ~ 1.2x109 Lo
• LOptical ~ 3x108 Lo & LMIR ~ 9x108 Lo
• Z = Zo/41 from optical HII regions#
• Age ~ 5x106 yr • Md/Mo ~ 1X105
• M*/Mo ~ 1X107 • Radio: (Hunt et al. 2004)
– Diameter 17 pc (optical dia. ~ 1kpc)– Fluxes from 1.4 to 22 GHz – Separates the thermal and nonthermal components
* WMAP Cosmology # I Zw18 holds the record at Zo/50 Searle & Sargent 1972
SBS0335-052• Red peak-up image.F = 71 +/- 11 mJy18.5 to 26.0 microns48 sec. exposure.
• Image is identical tothat of a point source.
30”
IRS Spectra of SBS0335-052 & NGC7714
Red Peak-up
GeminiPAH
[NeII]
A(9.7μm) ~ 0.5
Implications for the Dust Mass
• ISO & IRS fit by two component model, 150 & 64K in both cases
• The cool dust component:– Contributes ~4 time less flux in the Spitzer case
– Therefore ~4 times less mass is needed, 2.5x104 Mo
– (The luminosity is dominated by the warm dust component and only changes at the 20% level.)
• However, the cool mass may also be inferred from the FIR flux, Hildebrand 1983:– Md ~ 1.5x103 Mo an even smaller dust mass.
Mid-infrared Line Radiation
• An infrared fine structure line flux & Hβ (derived from f-f radio flux) leads to an abundance:– The infrared flux is a weak function of electron
temperature and extinction– We detect only a single ionic line for S3+ and Ne2+
• Z(S3+) ~ 0.02 Zo(S) & Z(Ne2+) ~ 0.09 Zo(Ne)
– The SIV line is consistent with the expected emission from the optical regions.
– The NeIII is twice the flux predicted using the [NeIII] 3869A optical line.
HST: Thuan et al. 1997
Dist. ~ 57Mpc
SBS 0335-052
Cool Dust &HIVisible HII
regionsZ~Zo/41
SNe shell
Buried HII & SSC 17 pc dia.Age ~ 5x106 yr
~ 1 kpc ~ 4 arcsec
N
SBS0335-052 Properties (with Spitzer)
• z = 0.0136; D = 57 Mpc; 278 pc / arcsec
• L ~ 1.2x109 Lo 1.0x109 Lo
• LOptical ~ 3x108 Lo
• Z = Zo/41 from optical HII regions
• Hidden infrared HII regions may have higher metallicity.
• Age ~ 5x106 yr for SSC
• Md/Mo ~ 1X105 ~ 2.5x104
• High Resolution observations are planned for SBS 0335-052: SIII(2), SIV, NeII, NeIII(2), & NeV.
• ~20 well studied BCDs will be observed in Low res. and Hi res. if appropriate.
Conclusions & Future Plans • The peak in the luminosity, vFv,is at 20 microns while
the peak in the flux, Fv, is at 28 microns.
• The dust mass is smaller than previously thought• There is more [NeIII]15.55 micron flux than predicted
by the optical 3869 A line.