Related papers: The connection between merging double compact obje…
Accumulating evidence indicates that some of ultra-luminous X-ray sources (ULXs) are intermediate mass black holes (IMBHs), but the formation process of IMBHs is unknown. One possibility is that they were formed as remnants of population…
The formation of compact stellar-mass binaries is a difficult, but interesting problem in astrophysics. There are two main formation channels: In the field via binary star evolution, or in dense stellar systems via dynamical interactions.…
Ultra-/hyper-luminous X-ray sources (ULX/HLX) could be interesting laboratories to improve our understanding of the supermassive black hole growth through super-Eddington accretion episodes and successive mergers of lighter holes. ULXs are…
The population of binary black hole (BBH) mergers observed by the LIGO-Virgo-KAGRA (LVK) collaboration offers a window into the cosmic evolution of compact binaries and their formation. We employ the semi-analytic population-synthesis code…
Prior to the detection of black holes (BHs) via the gravitational waves (GWs) they generate at merger, the presence of BHs was inferred in X-ray binaries, mostly via dynamical measurements, with masses in the range between $\sim…
After the nearly hundred gravitational-wave detections reported by the LIGO-Virgo-KAGRA Collaboration, the question of the cosmological origin of merging binary black holes (BBHs) remains open. The two main formation channels generally…
Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are among the densest systems in the Universe, harbouring millions of stars and compact objects (COs). Within a few parsecs from the SMBH, stars can…
From a Chandra survey of nine interacting galaxy systems the evolution of X-ray emission during the merger process has been investigated. From comparing Lx/Lk and Lfir/Lb it is found that the X-ray luminosity peaks around 300 Myr before…
Ultraluminous infrared galaxies (ULIRGs) with multiple ($\ge 3$) nuclei are frequently observed. It has been suggested that these nuclei are produced by multiple major mergers of galaxies. The expected rate of such mergers is, however, too…
The point-like X-ray source HLX-1, close to the S0 galaxy ESO 243-49, is the brightest known ultraluminous X-ray source and one the strongest intermediate-mass black hole candidates. We argue that the counterpart of HLX-1 may be the nucleus…
Star clusters appear to be the ideal environment for the assembly of neutron star-neutron star (NS-NS) and black hole-neutron star (BH-NS) binaries. These binaries are among the most interesting astrophysical objects, being potential…
Ultra-compact X-ray binaries (UCXBs) are a subclass of low-mass X-ray binaries (LMXBs) characterized by ultra-short orbital periods, typically less than $60-80\,$min. They consist of a compact mass-accretor and a hydrogen-poor mass-donor,…
We explore a newly proposed channel to create binary black holes of stellar origin. This scenario applies to massive, tight binaries where mixing induced by rotation and tides transports the products of hydrogen burning throughout the…
We have studied the candidate optical counterparts and the stellar population in the star-forming complex around a bright ULX in NGC4559, using HST/WFPC2, XMM-Newton/OM, and ground-based data. We find that the ULX is located near a small…
The advanced capabilities of the Chandra and XMM-Newton observatories mean that, for the first time, the detailed study of the brightest point-like X-ray sources in nearby galaxies outside of the local group is a realistic aim. Here, we…
The recent observations of gravitational waves (GWs) by the LIGO-Virgo-KAGRA collaboration (LVK) have provided a new opportunity for studying our Universe. By detecting several merging events of black holes (BHs), LVK has spurred the…
The LIGO/Virgo detections of gravitational waves from merging black holes of $\simeq$ 30 solar mass suggest progenitor stars of low metallicity (Z/Z$_{\odot} \lesssim 0.3$). In this talk I will provide constrains on where the progenitors of…
Ultra-compact X-ray binaries (UCXBs) are low-mass X-ray binaries with ultra-short orbital periods (usually less than 1 hour) and hydrogen-poor donor stars, which are proposed to be the potential LISA sources. In this work, we firstly employ…
A binary star orbited by an outer companion constitutes a hierarchical triple system. The outer body may excite the eccentricity of the inner binary through the von~Zeipel-Lidov-Kozai (ZLK) mechanism, triggering the gravitational wave (GW)…
Line-of-sight acceleration of a compact binary coalescence (CBC) event would modulate the shape of the gravitational waves (GWs) it produces with respect to the corresponding non-accelerated CBC. Such modulations could be indicative of its…