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Early results from the IRS

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!

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Early results from the IRS

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  1. Early results from the IRS Jim Houck and the IRS team - AAS Denver 6/1/04

  2. 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.

  3. 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.

  4. [NeV] [OIV] J. Bernard-Salas

  5. IRS Goes Faint: CFRS 14.1157 1σ ~ 0.35 mJy in 2880 sec. • L(IR)=8E13 L(sun) • z=1.1 • Automated fitting with NGC1068 template Mid-IR spectrum is clearly AGN-like Blue Peak-up S.Higdon et al. ApJS 2004

  6. Blue Compact Dwarf SBS 0335-052:a nearby laboratory for the early Universewith V. Charmandaris, B. Brandl, B. Bernard-Salas, et al. SBS = Second Byurakan Survey Markarian et al. 1983

  7. 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

  8. 30” • SBS0335-052 • Red peak-up image. • F = 71 +/- 11 mJy • 18.5 to 26.0 microns • 48 sec. exposure. • Image is identical to • that of a point source.

  9. IRS Spectra of SBS0335-052 & NGC7714 Red Peak-up PAH Gemini [NeII] A(9.7μm) ~ 0.5

  10. 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.

  11. 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.

  12. Cool Dust & HI SNeshell Visible HII regions Z~Zo/41 Buried HII & SSC 17 pc dia. Age ~ 5x106 yr ~ 1 kpc ~ 4 arcsec N HST: Thuan et al. 1997 Dist. ~ 57Mpc SBS 0335-052

  13. 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

  14. 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. • 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.

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