The origin of superluminous supernovae and their role in galaxy evolution from the first progenitor iron abundance measurements

0 Assigned ID: 7449 ----- Attempting Submission 1 (Thu Apr 16 16:21:52 GMT 2026) ----- Could not connect to APT Status Server COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. Please check that I have set up the offset acquisition correctly for visit 3. Thanks! -1212182904 ----- Attempting Submission 1 (Tue Aug 11 08:29:58 GMT 2026) ----- ----- Attempting Submission 2 (Fri Aug 14 16:06:57 GMT 2026) ----- The warnings are all about COS spectra of extended sources. I have read the relevant part of the handbook, but I don't see any way to resolve the warnings. The origin of superluminous supernovae and their role in galaxy evolution from the first progenitor iron abundance measurements It is a remarkable fact of our Universe that "superluminous" supernovae (SLSNe) occur preferentially in low-luminosity galaxies, but the reason for this is not well understood. Metallicity is likely to play a role, as it effects stellar evolution directly through the wind-driving efficiency. However, all metallicity constraints to date in SLSN host galaxies have been oxygen abundances measured via gas-phase emission lines, rather than the stellar iron abundances needed for detailed progenitor modelling. This program will provide the first direct iron abundances in a pilot sample of carefully selected SLSN hosts using far-UV spectroscopy with the Cosmic Origins Spectrograph. Established methods allow us to extract the iron abundance directly from the FUV continuum between 1200-2000 Angstroms. We will combine the HST FUV spectra with ground-based oxygen abundances to measure the alpha/Fe ratio in these galaxies. We can then test a clear prediction: since it is the iron, rather than oxygen, that primarily affects stellar evolution, if metallicity is the key ingredient in forming SLSNe these galaxies should show a strong preference for low iron abundance and would appear alpha-enhanced relative to other galaxies of a similar mass. With a modest time request, this proposal provides an entirely new approach to resolve the question of why SLSNe favour dwarf galaxies, and will provide a crucial input to stellar evolution models of SLSN progenitors. COS UV spectroscopy of four low-redshift SLSN host galaxies with GALEX detections. Three orbits per galaxy using G140L. Expected SNR~5-10 per pixel. Acquisition requirements for extended sources: For PTF12dam, SN2020tcw and SN2018bsz, we target the UV-brightest part of the galaxy, centering on the GALEX coordinates. For this ACQ/IMAGE should be the most effective method For SN2017egm, the explosion did not occur in the brightest part of the galaxy. In this case we do not want to recentre to point at the brightest UV pixels. However, the light profile is relatively smooth around the SN location, and obtaining a spectrum centred with ~1 arcsecond of the quoted coordinates is sufficient. Nicholl and Angus are experts in superluminous supernovae and experienced HST users. Chen has worked extensively on the host galaxies of SLSNe. Cullen, Begley and McGee are experts in galaxy evolution. Cullen devised the method to extract metallicities from these data. Magill and Smith are students working with Nicholl on energetic transients. Moore is an expert in supernova observations and space-based observations. 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