Meir Schochet

Meir Schochet

I am a first year PhD student, studying baby stars and their activity

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portfolio

publications

A Lack of Mass-gap Compact Object Binaries in APOGEE

Published in Research Notes of the American Astronomical Society Meir Schochet et al 2024 Res. Notes AAS 8 166 3., 2024

Depending principally on mass, the compact object remnant left behind after a star’s life may be a white dwarf (WD), neutron star (NS), or black hole (BH). While we have large samples of each of these remnants, we lack knowledge of the exact conditions separating these outcomes. The boundary between low-mass BHs and massive NSs is particularly poorly understood, as few objects between 2-5 M⊙ are known. To probe this regime, we search the APOGEE DR17 dataset of 657,000 unique stars for binary systems with one stellar component that exhibit large radial velocity shifts over multiple observations. We identify 4751 likely binary systems, and estimate a minimum mass for each system’s “invisible companion” under the assumption of tidal synchronization. Two systems have companion masses ≳ 2 M⊙, although we conclude that neither are good candidates for possessing a mass-gap NS or BH companions. Read more

Recommended citation: Meir Schochet et al 2024 Res. Notes AAS 8 166
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talks

‘Where Are the Smallest Black Holes?’: Probing the mass gap with APOGEE

Published:

The existence of the least massive black holes and most massive neutron stars are still debated, and with few objects identified between two to five solar masses, many believe in a “compact object mass gap”. Compact objects are dim and small, a consequence of being end of life stellar remnants. Therefore, our best chance to observe them is through influences on a close companion star in a binary system, where the objects orbit around a shared center of mass and can be detected by a radial velocity (RV) Doppler shift of the system’s spectral lines between observations. Using the Apache Point Observatory Galactic Evolution Experiment (APOGEE) we search for candidate host systems that have considerable evidence of binary interactions including RV variations, rapid rotation indicative of tidal interaction, and a single set of stellar spectral lines suggesting the secondary is compact. We find that only 0.7% of the APOGEE catalog possesses all these signatures, and we explore the 120 systems whose companion mass estimates are in the mass-gap regime. While previous efforts have identified individual systems, our work provides a more comprehensive search of a large sample that will help constrain the history and evolution of stellar-mass compact objects. Read more

Using Rotation to Explore Stellar Binarity and Period Prediction Techniques

Published:

Stars rotate, and measuring that rotation is critical to understanding the star’s history and future evolution. First, I will discuss the utility of rapid rotation for finding close companions to binary systems using APOGEE DR17. We identify 4,751 binary systems with rapid rotation, radial velocity scatter, and evidence of only one set of spectral lines. By assuming tidal synchronization, we estimate minimum masses for companions to 4,288 of these systems. Second, I will present a method for stellar rotation period prediction using a convolutional neural network on ASAS-SN light curves. We feed the network a transformed 2D frequency-time representation of the light curve and train the network using quiescent light curves injected with simulated rotation models. Finally, we present the efficacy of the network at period prediction and discuss ASAS-SN systematics that make period prediction difficult. Read more

teaching