Witnessing the circumgalactic medium in formation: Imaging OVI in the warm-hot CGM of a record-breaking galactic wind
Abstract
The massive, compact galaxy Makani hosts one of the largest [OII] nebulae, and perhaps the largest starburst-driven galactic wind, yet detected. This wind extends well into the CGM of its host (r_wind > 20r_stars) and is a snapshot of the CGM-in-formation. The cool, dense medium of the wind-CGM interface in Makani (traced in emission by [OII], MgII, and CO emission) on scales of 100 kpc show an outflow forming the cool CGM in real time. Much of our knowledge of the CGM in other galaxies is derived from statistical studies of the warm-hot (10^5-10^6 K) phase. The enormous and lumionus oxygen nebula in Makani is the ideal target to *image* the warm-hot CGM, which is difficult in most other sources. We propose to make the first "rebirth picture'' of the warm-hot CGM as it is being formed anew by the giant wind in Makani. We will image Makani in OVI 1032, 1038 A with ACS/SBC, a technique that recently yielded the first OVI image of the halo of a starburst galaxy (Hayes et al. 2016). We will apply the same synthetic narrowband technique which is perfectly suited for Makani, whose observed-frame OVI line (at z=0.459) lies at the peak of the F150LP filter. These observations are optimally-timed to meet simulated images of OVI that are emerging from the latest simulations. The morphology of the OVI image and line flux ratios with [OII] will constrain the physical state of the gas in the nebula through comparison with models and simulations of the wind-CGM interaction and shock+photoionization models.
- Publication:
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HST Proposal
- Pub Date:
- May 2020
- Bibcode:
- 2020hst..prop16231R