FirstLight.doc

The data points indicate measurements from the

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The data points indicate measurements from the literature at other redshifts.
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The early, distant epochs of the universe are extremely elusive with present-day facilities because of a lack of sensitivity. Current telescopes will likely discover larger populations of Lyman a sources. However, with discovery limits in the vicinity of a few x 10 -18 erg/s/cm 2 , 8-10-meter class telescopes will likely not reveal Lyman a emission from dwarf galaxies at z ~ 7, unless they are gravitationally lensed (see Figure 1). 1 Thus, this project is essentially impossible in the era before 20-to-30-meter telescopes. Technical Details: This multi-step project includes 3 tiers of observations: 1. By 2016, the James Webb Space Telescope will regularly deliver deep infrared images that reveal the most massive star-forming galaxies and proto-clusters of galaxies at z > 7. We will identify the most luminous at z ~ 7.7, where Lyman a falls in an atmospheric window between night sky lines, and conduct a narrow- band imaging search with IRMS. Using current state-of-the-art models, we will search for Lyman a from tiny dwarf galaxies in the locally ionized region around the star-forming galaxy. Because the size scales of ionized “bubbles” at that epoch are of order of Mpc (~3.3´) the 2´ field of view of the IRMS imager will allow a deep image of a substantial fraction of the edge of the bubble. The actual length scale over which these sources are discovered will reveal or set a lower limit on the size of the local bubble. The exposure time of 4 hours will allow detections in the range of ~6 x 10 -19 erg/s/cm 2 . 2. If we discover multiple strong Lyman a sources in the first phase of the project, we will follow the strongest up with longslit observations using the IRMS instrument. We will focus on both the profile of the 1.07 m Lyman a feature and on the region in which HeII is expected, at 1.44 m (H-band). Most likely, two separate observations of 4 hours each, in J and H, at R ~ 4000 will be required. The likely sensitivity to unresolved emission is ~1.5 x 10 -19 erg/s/cm 2 . If a very strong HeII feature is discovered (relative to the UV continuum limits from JWST and the Lyman a feature), the observations will provide compelling evidence for a very hard radiation field from pristine star formation and/or an AGN. If no strong
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  • Fall '19
  • Interstellar medium, James Webb Space Telescope, Lyman, Quasar

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