1 / 23

The Infrared Sky: Background Considerations for JWST

The Infrared Sky: Background Considerations for JWST. Dean C. Hines & Christine Chen MIRI Instrument Team. The Visible (Optical) Sky. The Visible vs the Infrared Sky. The Visible vs the Infrared Sky. Infrared Background Sources.

abril
Download Presentation

The Infrared Sky: Background Considerations for JWST

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Infrared Sky: BackgroundConsiderations for JWST Dean C. Hines & Christine ChenMIRI Instrument Team

  2. The Visible (Optical) Sky

  3. The Visible vs the Infrared Sky

  4. The Visible vs the Infrared Sky

  5. Infrared Background Sources • Three primary sources of diffuse light in the astronomical sky • Extragalactic – light from unresolved objects (galaxies and QSOs) • Galactic – mostly star-light reprocessed by material in the Interstellar Medium (ISM) • Solar System – sun light reprocessed by material within the solar system • These astronomical components are highly wavelength dependent • Visible and near-Infrared (NIR) – dominated by scattered/reflected light but with some thermal NIR emission from very hot dust • Longer wavelengths – dominated by thermal emission from warm dust and by broad solid-state and giant molecular emission features • Emission from the telescope and stray light also contribute to the background • Not a large issue for HST (except for NICMOS l > 1.8µm) • For JWST, this is an issue for most wavelengths, and becomes a dominant source for MIRI

  6. HST vsJWST Because JWST operates much colder than HST (~39-46K vs ~290K), diffusegalactic and zodiacal emission dominate the background for l ≤ 16µm JWST HST HST ThermalEmission Diffuse Galactic + Zodi NICMOS Instrument Handbook Glasse et al. (2010)

  7. COBE/DIRBE Blue = 1.25 µm Green = 2.2 µm Red = 3.5 µm Zodi + Galaxy + Exgal All of the images use 4 decade logarithmic color scales. The lowest level is 3.95 kJy/sr at 3.5 microns, 6.67 kJy/sr at 2.2 microns, and 7.08 kJy/sr at 1.25 microns for the upper and middle images, but 0.395 kJy/sr for the lower image. Galaxy + Exgal Exgal

  8. Thermal Emission from Zodi Dust Blue = 12 µm; Green = 60 µm; Red = 100 µm IRAS

  9. Thermal Emission from Zodi Dust Blue = 12 µm; Green = 60 µm; Red = 100 µm IRAS

  10. Thermal Emission from Zodi Dust Blue = 65 µm; Green = 90 µm; Red = 140 µm Akari

  11. Zodi Dust Bands (IRAS)

  12. Zodi Bands & Spectrum Optical

  13. Taurus Spitzer 24µm Residual Zodiacal Dust Band Emission after subtraction of a smooth zodiacal background model based on COBE/DIRBE data. 7.7˚ ZodiacalDust Bands

  14. Galactic ISM (COBE) Blue = 60 µm; Green = 100 µm; Red = 240 µm

  15. Galactic ISM (COBE) Green = 100 µm; Red = 240 µm

  16. PAH Emission from the ISM PAH Emission Features — 3.29, 6.2, 7.7, 8.7, 11.3, and 12.7 µm Wavelength (µm)

  17. Emission from the Galaxy PAH Emission Features — 3.29, 6.2, 7.7, 8.7, 11.3, and 12.7 µm

  18. Zodi + Galactic

  19. Zodi + Galactic

  20. Conclusions • The Infrared Sky is much different in structure and brightness compared the visible sky • At visible wavelengths, the background is dominated by light scattered from dust in the solar system (HST also contends with geocoronal emission and earthshine) • The infrared background is dominated by emission from dust in the solar system and the galaxy, plus broad-band emission features from PAHs associated with diffuse galactic dust • These astronomical background sources will dominate the JWST background for l ≤ 16µm, and will still be important for longer wavelengths • The background will vary in time as our view of the zodiacal emission changes during the year • STScI is working with the Spitzer Science Center (SSC) to develop a background model appropriate for JWST

  21. Fin

  22. WISE

  23. All of the images use 4 decade logarithmic color scales. The lowest level is 3.95 kJy/sr at 3.5 microns, 6.67 kJy/sr at 2.2 microns, and 7.08 kJy/sr at 1.25 microns for the upper and middle images, but 0.395 kJy/sr for the lower image. • The lowest level is 223.2 kJy/sr at 240 microns, 555.3 kJy/sr at 100 microns, and 508.2 kJy/sr at 60 microns for the upper and middle images, but 30.7 kJy/sr for the lower image.

More Related