Spotting the birth of compact objects using X-ray timing of fast-rising transients
Abstract
Fast-rising, blue optical transients (FBOTs) are a new class of optical transients identified by optical sky surveys with high observing cadence. These are extra-galactic, off-nuclear flares that rise on less than a week timescale and fade within a month or two. Their optical spectra are blue and featureless with occasional presence of broad Hydrogen and Helium lines. Their fast evolution and featureless optical spectra suggest that they are unlike normal supernovae which evolve much slower and have characteristic optical spectra. Current theories for FBOTs include merging compact objects, newly formed compact objects in supernovae or failed supernovae, or intermediate-mass black holes disrupting low-mass stars. AT2018cow is the first FBOT discovered in real time and this facilitated unprecedented coverage across the entire electromagnetic spectrum. In spite of multi-wavelength coverage, the nature of the flare has remained a mystery. I will discuss the X-ray properties of the source and the possible detection of a highly-stable, quasi-periodic oscillation (QPO) using NICER monitoring data and its implications for a newly formed compact object in this event. I will also discuss prospects of detecting newly born compact objects using NICER in the coming years and the need for a large area timing instrument, viz., STROBE-X/ATHENA in the next decade.
- Publication:
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AAS/High Energy Astrophysics Division
- Pub Date:
- March 2019
- Bibcode:
- 2019HEAD...1711116R