Related papers: Wolf-Rayet -- compact object binaries as progenito…
White dwarfs (WDs) are the stellar core remnants of low mass stars. They are typically divided into three main composition groups: Oxygen Neon (ONe), Carbon Oxygen (CO) and Helium (He) WDs. The evolution of binary systems can significantly…
High-frequency gravitational-wave (GW) radiation has been detected by LIGO-Virgo-KAGRA in the merger of compact stars. However, two GW events, GW190814 and GW200210, the mass of one companion object falls into the mass region of…
One of the largest surprises from the LIGO results regarding the first gravitational wave detection (GW 150914) was the fact the black holes (BHs) were "heavy", of order 30 - 40 solar masses. The most promising explanation for this obesity…
Many compact objects (black holes and neutron stars) exist in binaries. These binaries are normally discovered through their interactions, either from accretion as an X-ray binary or collisions as a gravitational wave source. However, the…
Wolf-Rayet (WR) stars are the evolved descendants of massive O-type stars and are considered to be progenitor candidates for Type Ib/c core-collapse supernovae (SNe). Recent results of our HST/WFC3 survey of Wolf-Rayet stars in M101 are…
In their third observing run, the LIGO-Virgo-KAGRA gravitational-wave (GW) observatory was sensitive to binary black hole (BBH) mergers out to redshifts $z_\mathrm{merge}\approx1$. Because GWs are inefficient at shrinking the binary orbit,…
Close binary systems are the progenitors to both Type Ia supernovae and the compact object mergers that can be detected via gravitational waves. To achieve a binary with a small radial separation, it is believed that the system likely…
Recent evolutionary computations predict that a few percent of massive OB stars in binary systems should have a dormant BH companion. Despite several reported X-ray quiet OB+BH systems over the last couple of years, finding them with…
Observations of gravitational waves (GWs) from merging compact binaries have become a regular occurrence. The continued advancement of the LIGO-Virgo-KAGRA (LVK) Collaboration detectors have now produced a catalog of over 90 such mergers,…
Context. Common envelope evolution of a massive star and a neutron star companion has two possible outcomes: formation of a short-period binary (a potential gravitational wave source progenitor) or a merger of the massive star with the…
Context. Massive-binary evolution models predict that some systems will go through an evolutionary phase where the original primary has become a supernova and left a compact object behind that then orbits a Wolf-Rayet (hereafter, WR) star.…
Gravitational Wave (GW) sources offer a valuable window to the physical processes that govern the formation of binary compact objects (BCOs). However, deciphering such information from GW data is substantially challenging due to the…
Cyg X-3 is a highly interesting accreting X-ray binary, emitting from the radio to high-energy gamma-rays. It consists of a compact object wind-fed by a Wolf-Rayet (WR) star, but the masses of the components and the mass-loss rate have been…
We explore the different formation channels of merging double compact objects (DCOs: BH-BH/BH-NS/NS-NS) that went through a ultraluminous X-ray phase (ULX: X-ray sources with apparent luminosity exceeding $10^{39}$ erg s$^{-1}$). There are…
Merging compact binaries are the most viable and best studied candidates for gravitational wave (GW) detection by the fully operational network of ground-based observatories. In anticipation of the first detections, the expected…
We investigate Wolf-Rayet (WR) stars as a source of feedback contributing to the removal of natal material in the early evolution of massive star clusters. Despite previous work suggesting that massive star clusters clear out their natal…
Classical Wolf-Rayet (WR) stars are massive, hydrogen depleted, post main-sequence stars that exhibit emission-line dominated spectra. For a given metallicity Z, stars exceeding a certain initial mass M_single(Z) can reach the WR phase…
We investigate a possible method for determining the progenitors of black hole (BH) mergers observed via their gravitational wave (GW) signal. We argue that measurements of the cross-correlation of the GW events with overlapping galaxy…
We report the results of a high-spatial-resoltion search for the progenitor of type Ic supernova SN 2004gt, using the newly commissioned Keck laser-guide star adaptive optics system (LGSAO) along with archival Hubble Space Telescope data.…
The origin of the observed population of Wolf-Rayet (WR) stars in low-metallicity (low-Z) galaxies, such as the Small Magellanic Cloud (SMC), is not yet understood. Standard, single-star evolutionary models predict that WR stars should stem…