Constraining the Final Decline of the Kilonova AT 2017gfo
Abstract
Spitzer observations of the neutron star merger GW170817 provide the only infrared constraints on its electromagnetic counterpart (a kilonova called AT 2017gfo) between 25 and 110 days after merger. Indeed, the decline rate of this emission in two epochs of IRAC Channel 2 observations 43 and 74 days after merger is consistent with the decay of some long-lived radioisotopes in the ejecta, perhaps providing the first smoking gun evidence for third peak r-process material synthesized in the merger. However, analysis of these data is severely limited by 1) the current depth of template observations obtained 264 days after merger, which is comparable to the original observations, 2) the possibility that the kilonova emission is blended with non-thermal synchrotron emission from a jet launched by the merger, and 3) the non-detection of any emission in contemporaneous Channel 1 data. We can address all of these issues by obtaining a fourth epoch of observations, providing an independent template, which will enable cleaner subtractions and detection of fainter sources in the early time imaging.
- Publication:
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Spitzer Proposal
- Pub Date:
- May 2019
- Bibcode:
- 2019sptz.prop14288K