Simulating Self-lensing and Eclipsing Signals due to Detached Compact Objects in the TESS Light Curves

Abstract A fraction of Galactic stars have compact companions that could be white dwarfs (WDs), neutron stars (NSs), or stellar-mass black holes (SBHs). In a detached and edge-on binary system including a main-sequence star and a compact object (denoted by WD main-sequence (WDMS), NS main-sequence (NSMS), and SBH main-sequence (BHMS) systems), the stellar brightness can change periodically due to self-lensing or eclipsing features. The shape of a self-lensing signal is a degenerate function of stellar radius and the compact object’s mass because the self-lensing peak strongly depends on the projected source radius normalized to the Einstein radius. Increasing the inclination angle i changes the self-lensing shape from a strict top-hat model to one with slowly increasing edges. We simulate stellar light curves due to these binary systems that are observed by NASA’s Transiting Exoplanet Survey Satellite (TESS) telescope and evaluate the efficiencies to detect their periodic signatures using two sets of criteria: (i) signal-to-noise ratio (SNR) &gt;3 and N tran &gt; 1 (low confidence, LC), and (ii) SNR &gt;5 and N tran &gt; 2 (high confidence, HC). The HC efficiencies for detecting WDMS, NSMS, and BHMS systems with the inclination angle i &lt; 20° during different time spans are 5%–7%, 4.5%–6%, and 4%–5%, respectively. Detecting lensing-induced features is possible in only ≲3% and ≲33% of detectable WDMS and NSMS events. The detection efficiencies for closer source stars with higher priorities are higher and drop to zero for b ≳ R ⋆ , where <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>b</mml:mi> <mml:mo>≃</mml:mo> <mml:mi>tan</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>i</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mi>a</mml:mi> </mml:math> is the impact parameter ( a is the semimajor axis). We predict the numbers of WDs, NSs, and SBHs that are discovered from the TESS Candidate Target List stars are 15–18, 6–7, and &lt;1.