Testing the Origin and Consequences of Vast Extended Molecular Gas Outside High-Redshift Post-Starburst Galaxies

0 Assigned ID: 196 ----- Attempting Submission 1 (Thu Mar 05 00:05:12 GMT 2020) ----- HST Phase I Proposal 196 successfully submitted. Receipt: # 196-1 ----- Attempting Submission 2 (Thu Mar 05 22:22:34 GMT 2020) ----- HST Phase I Proposal 196 successfully submitted. Receipt: # 196-2 ----- Attempting Submission 3 (Thu Mar 05 22:58:45 GMT 2020) ----- swapped direct imaging filter to F098M per CS recommendation 171162610 ----- Attempting Submission 1 (Fri Jun 26 18:04:20 GMT 2020) ----- ----- Attempting Submission 2 (Wed Sep 30 18:52:20 GMT 2020) ----- Testing the Origin and Consequences of Vast Extended Molecular Gas Outside High-Redshift Post-Starburst Galaxies We have discovered spectacular vast molecular gas reservoirs reaching tens of kpc outside of two high-redshift post-starburst galaxies as part of an ongoing ALMA survey of such objects. While the host galaxies are only 3-5kpc in size, nearly half the total molecular gas in each system extends 25-45kpc from the hosts. This discovery was unexpected and both the scale and magnitude of the extended gas features are unprecedented at any redshift. The origin of the highly extended molecular gas we have discovered is unclear, but may be related to AGN outflows, stripped tidal tails, and/or material cooled from hotter circumgalactic gas - the spatial resolution and sensitivity of HST are needed to distinguish which. We propose an efficient, high-impact program using WFC3 G102 slitless spectroscopy and F105W direct imaging to determine the origins of the remarkable gas features and their broader implications for galaxy evolution, including galactic feedback, the formation of extended stellar halos, and circumgalactic metal enrichment. These observations are designed to detect and resolve in-situ star formation within the extended gas features, identify stellar tidal debris and close-in merging companions, and spectroscopically map out the local environment on 1Mpc scales. Together, the combination of direct imaging and slitless spectroscopy can uniquely determine the origin of the incredible molecular gas structures we have found and place this unexpected discovery in broader context. This program will acquire 2 orbits of WFC3/G102 imaging data for each of 2 target z~0.6 post-starburst galaxies. The primay goal is to search for extended H-alpha emission arising from large features seen in CO molecular gas maps of the galaxies that extend out to a few arcsec from the galaxy centers. Observations of each target are split into two visits of a single orbit each. In order to disentangle the possibly-complex Halpha distribution, one visit for each target is requested to have ORIENT FROM 30 to 150degrees compared to the other visit (with unconstrained roll angle). This should enforce a minimum roll angle difference between the two visits of at least 30degrees. We follow the 3D-HST dithering strategy, and take grism data in 4 dither positions per orbit. We use POS-TARG offsets to set the dither positions, using a slightly wider pattern than the default WFC3-IR-DITHER-BOX-MIN since some bad pixels come in clumps. As in 3D-HST, the pattern is: POS-TARG: (0,0) (1.355,0.424) (0.881,1.212) (-0.474,0.788) pixels: (0,0) (10.0,3.5) (6.5,10.0) (-3.5,6.5) Each grism position integrates for ~550s using SAMP-SEQ = SPARS50 and NSAMP=12, for a total of ~2200s integration in the grism in each orbit. We use the F098M filter for direct imaging wavelength calibration, taking an image in the first and last dither positions at the beginning and end of the orbit, respectively. The direct imaging exposures are ~130s each using NSAMP=14 and SAMP-SEQ = SPARS10. Our team includes a wide array of expertise, including observers and theorists with a range of specialties. Bezanson, Greene, Kriek and Suess have extensive experience with optical and NIR imaging. We have used and developed working reduction pipelines for a range of long-slit, multi-object, and IFU spectrographs and imagers. Bezanson, Greene, Kriek, and Suess have extensive experience with HST data specifically and Bezanson and Kriek were members of the 3D-HST HST 248-orbit Treasury Program Team using the WFC3-G141 grism. Setton is a graduate student at the University of Pittsburgh whose current project involves the reduction and analysis of Gemini/GMOS (optical) spectroscopic IFU datacubes. Spilker is an expert in radio and sub-mm interferometric data. Feldmann and Narayanan are experts in the construction and analysis of simulations of galaxy formation and evolution, both at small-scales and in cosmological volumes. The scientific interests and expertise of our team spans all facets (theoretical and observational) of the related scientific themes including - but not limited to - star formation and the ISM (Feldmann, Narayanan, Spilker), galaxy structures and kinematics (Bezanson, Feldmann, Greene, Kriek, Suess, Setton), active galactic nuclei and outflows (Greene, Spilker), and stellar population modeling (Kriek, Greene). We all have strong records of the prompt and high-impact publication of our results. Galaxies 6 false false false false false false false SUPPORTED GALAXY HIGH REDSHIFT GALAXY INTERACTING GALAXY TIDAL TAIL J2000 J2000 GALAXY HIGH REDSHIFT GALAXY INTERACTING GALAXY TIDAL TAIL J2000 J2000 WFC3/IR Spectroscopic No No G102 WFC3/IR Imaging No No F105W WFC3/IR Spectroscopic No No G102 WFC3/IR Imaging No No F105W 1601393689262 /Users/jspilker/Desktop/OP-cache/tmp-v01.xml The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. 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