Chandra Fails to Detect X-ray Emission from Type Ia SN 2018fhw/ASASSN-18tb
Vikram V. Dwarkadas (University of Chicago)

TL;DR
This study reports non-detection of X-ray emission from the low luminosity Type Ia supernova 2018fhw, setting upper limits and comparing with other Type Ia-CSM supernovae to understand their circumstellar environments.
Contribution
It provides the first X-ray upper limits for SN 2018fhw and compares these with other Type Ia-CSM supernovae to explore their circumstellar medium properties.
Findings
No X-ray emission detected from SN 2018fhw.
Upper limits are below the luminosity of X-ray detected Type Ia-CSM SNe.
Circumstellar medium density likely decreased from 10^8 to below 5×10^6 cm^-3.
Abstract
We report on Chandra X-ray observations of ASASSN-18tb/SN 2018fhw, a low luminosity Type Ia supernova that showed a H line in its optical spectrum. No X-ray emission was detected at the location of the SN. Upper limits to the luminosity of up to 3 erg s are calculated, depending on the assumed spectral model, temperature and column density. These are compared to two Type Ia-CSM SNe, SN 2005gj and SN 2002ic, that have been observed with Chandra in the past. The upper limits are lower than the X-ray luminosity found for the Type Ia-CSM SN 2012ca, the only Type Ia SN to have been detected in X-rays. Consideration of various scenarios for the H line suggests that the density of the surrounding medium at the time of H line detection could have been as high as 10 cm, but must have decreased below 5 cm at the time of…
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Taxonomy
TopicsGamma-ray bursts and supernovae · Astronomy and Astrophysical Research · Astrophysical Phenomena and Observations
