Chandra Fails to Detect X-ray Emission from Type Ia SN 2018fhw/ASASSN-18tb

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 $\times 10^{39}$ erg s${}^{-1}$ 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$\alpha$ line suggests that the density of the surrounding medium at the time of H$\alpha$ line detection could have been as high as 10${}^8$ cm${}^{-3}$, but must have decreased below 5 $\times 10^6$ cm${}^{-3}$ at the time of X-ray observation. Continual X-ray observations of SNe which show a H line in their spectrum are necessary in order to establish Type Ia SNe as an X-ray emitting class.

9 pages, 1 figure, 3 tables. Accepted to MNRAS

References in corpus (11)

• Improved Distances to Type Ia Supernovae with Two Spectroscopic Subclasses
• No X-rays from the very nearby Type Ia SN2014J: constraints on its environment
• Double-Detonation Models for Type Ia Supernovae: Trigger of Detonation in Companion White Dwarfs and Signatures of Companions' Stripped-off Materials
• On the Nature of Type Ia-CSM Supernovae: Optical and Near-Infrared Spectra of SN 2012ca and SN 2013dn
• H-$\alpha$ emission in the nebular spectrum of the Type Ia supernova ASASSN-18tb
• X-ray Emission from SN 2012ca: A Type Ia-CSM Supernova Explosion in a Dense Surrounding Medium
• Chandra Observations of Type Ia Supernovae: Upper Limits to the X-ray Flux of SN 2002bo, SN 2002ic, SN 2005gj, and SN 2005ke
• Swift X-Ray Upper Limits on Type Ia Supernova Environments
• X-Ray and Radio Emission from the Luminous Supernova 2005kd
• Nebular H$\alpha$ Limits for Fast Declining Type Ia Supernovae
• Nebular Halpha emission in SN Ia 2016jae

Cited by in corpus (3)

• Early excess emission in Type Ia supernovae from the interaction between supernova ejecta and their circumstellar wind
• A diverse, overlooked population of Type Ia supernovae exhibiting mid-infrared signatures of delayed circumstellar interaction
• X-Ray Observations of Type Ia Supernova 2018cqj