Common Envelope Transients - Progenitors, Precursors, and Properties of their Outbursts

Introduction

Common envelope evolution (CEE) is a crucial phase in binary evolution, as it is responsible for the formation of many of the most exciting systems in astrophysics, including sources of gravitational waves. Despite its importance, there are several unanswered questions that hamper the urgently needed progress in this field:

• What systems enter CEE?
• What happens during CEE?
• How do the CEE remnants evolve?

Luminous Red Novae

Recently, a new type of astrophysical transients called luminous red novae (LRNe) has emerged as direct observational evidence of the dynamical ejection of the CE in binaries. My work on their progenitor systems and their late-time evolution has shown their potential to study the initial and final state of binary systems entering CEE.

Unique Opportunities

The imminent start of operations of the large transient surveys BlackGEM and LSST provides a unique opportunity to bring CEE observational studies to the next level with LRNe population studies. The aim of this project is to study the different stages of CEE in massive binaries using observations of extragalactic LRNe.

Project Details

The sample will contain approximately 30 transients within 15 Mpc from massive binary progenitors with HST archival data. My team will use a novel transient selection strategy to identify a fraction of these LRNe years before their main outburst and study the extensive mass loss leading to coalescence.

Methodology

Novel observational and modeling techniques in optical and infrared wavelengths will allow me to derive the energetics, chemistry, dust content, and the geometry of the outbursts.

Expected Outcomes

My study will provide the much-needed evidence of the physical processes that occur before, during, and after the ejection of the CE in massive binary systems, the characteristics of their progenitors, and their rate in our Local Universe. This will, in turn, have a fundamental impact on several fields of astrophysics such as:

1. Binary population synthesis
2. Simulations of CEE
3. Understanding of mass transfer in the progenitor systems