The first population of X-ray binaries (XRBs) is expected to affect the thermal and ionization states of the gas in the early Universe. Although these X-ray sources are predicted to have important implications for high-redshift observable signals, such as the hydrogen 21-cm signal from cosmic dawn and the cosmic X-ray background, their properties are poorly explored, leaving theoretical models largely uninformed. In this paper we model a population of X-ray binaries arising from zero metallicity stars. We explore how their properties depend on the adopted initial mass function (IMF) of primordial stars, finding a strong effect on their number and X-ray production efficiency. We also present scaling relations between XRBs and their X-ray emission with the local star formation rate, which can be used in sub-grid models in numerical simulations to improve the X-ray feedback prescriptions. Specifically, we find that the uniformity and strength of the X-ray feedback in the intergalactic medium is strongly dependant on the IMF. Bottom-heavy IMFs result in a smoother distribution of XRBs, but have a luminosity orders of magnitude lower than more top-heavy IMFs. Top-heavy IMFs lead to more spatially uneven, albeit strong, X-ray emission. An intermediate IMF has a strong X-ray feedback while sustaining an even emission across the intergalactic medium. These differences in X-ray feedback could be probed in the future with measurements of the cosmic dawn 21-cm line of neutral hydrogen, which offers us a new way of constraining population III IMF.
Using a reliably measured intrinsic (i.e. corrected for absorption effects) present-day luminosity function of high-mass X-ray binaries (HMXBs) in the 0.25-2 keV energy band per unit star-formation rate, we estimate the preheating of the early Universe by soft X-rays from such systems. We find that X-ray irradiation, mainly executed by ultraluminous and supersoft ultraluminous X-ray sources with luminosity L> 10^39 erg/s, could significantly heat (T>T_cmb, where T_cmb is the temperature of the cosmic microwave background) the intergalactic medium by z~10 if the specific X-ray emissivity of the…
We assess the feasibility of detecting the compact object remnants from Population III (Pop III) stars in nearby dense star clusters, where they become luminous again as X-ray binaries (XRBs) and tidal disruption events (TDEs) via strong tidal encounters. Analytically modelling the formation of Pop III stars, coupled with a top-heavy initial mass function predicted by numerical simulations, we derive the number of (active) Pop III XRBs and TDEs in the present-day Milky Way (MW) nuclear star cluster as $\sim 0.06-0.3$ and $\lesssim 4\times 10^{-6}$, rendering any detection unlikely. The detecti…
The abundance of primordial black holes (PBHs) in the mass range $0.1 - 10^3 M_\odot$ can potentially be tested by gravitational wave observations due to the large merger rate of PBH binaries formed in the early universe. To put the estimates of the latter on a firmer footing, we first derive analytical PBH merger rate for general PBH mass functions while imposing a minimal initial comoving distance between the binary and the PBH nearest to it, in order to pick only initial configurations where the binary would not get disrupted. We then study the formation and evolution of PBH binaries before…
Surface abundance observations of halo stars hint at the occurrence of $r$-process nucleosynthesis at low metallicity ($\rm{[Fe/H]< -3}$), possibly within the first $10^8$ yr after the formation of the first stars. Possible loci of early-Universe $r$-process nucleosynthesis are the ejecta of either black hole--neutron star or neutron star--neutron star binary mergers. Here we study the effect of the inclination--eccentricity oscillations raised by a tertiary (e.g. a star) on the coalescence time scale of the inner compact object binaries. Our results are highly sensitive to the assumed initial…
In the population synthesis simulations of Pop III stars, many BH (Black Hole)-BH binaries with merger time less than the age of the Universe $(τ_{\rm H})$ are formed, while NS (Neutron Star)-BH binaries are not. The reason is that Pop III stars have no metal so that no mass loss is expected. Then, in the final supernova explosion to NS, much mass is lost so that the semi major axis becomes too large for Pop III NS-BH binaries to merge within $τ_{\rm H}$. However it is almost established that the kick velocity of the order of $200-500{\rm~ km~s^{-1}}$ exists for NS from the observation of the …
We study formation of stellar mass binary black holes (BBHs) originating from Population III (PopIII) stars, performing stellar evolution simulations for PopIII binaries with MESA. We find that a significant fraction of PopIII binaries form massive BBHs through stable mass transfer between two stars in a binary, without experiencing common envelope phases. We investigate necessary conditions required for PopIII binaries to form BBHs coalescing within the Hubble time with a semi-analytical model calibrated by the stellar evolution simulations. The formation efficiency of coalescing PopIII BBHs …
We present the results of the stellar feedback from Pop III binaries by employing improved, more realistic Pop III evolutionary stellar models. To facilitate a meaningful comparison, we consider a fixed mass of 60 solar masses (Msun) incorporated in Pop III stars, either contained in a single star, or split up in binary stars of 30 Msun each or an asymmetric case of one 45 Msun and one 15 Msun star. Whereas the sizes of the resulting HII regions are comparable across all cases, the HeIII regions around binary stars are significantly smaller than that of the single star. Consequently, the He$^{…
Future GW detector networks and EM observatories will provide a unique opportunity to observe the most luminous events in the Universe involving matter in extreme environs. They will address some of the key questions in physics and astronomy: formation and evolution of compact binaries, sites of formation of heavy elements and the physics of jets.
X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the inter-galactic medium, potentially having a significant contribution to the heating and reionization of the early Universe. The two most important sources of X-ray photons in the Universe are active galactic nuclei (AGN) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z~ 20) until today. We estimate that…
High mass X-ray binaries (HMXBs) may have had a significant impact on the heating of the intergalactic medium in the early universe. Study of HMXBs in nearby, low metallicity galaxies that are local analogues to early galaxies can help us understand early HMXBs. The total luminosity of HMXB populations is dominated by sources at high luminosities. These sources exhibit X-ray spectra that show curvature above 2 keV and the same is likely true of HMXB populations at high redshifts. The spectral curvature changes the K-correction for X-rays from HMXBs in a manner that weakens the constraints on X…
We study the contribution of binary black hole (BH-BH) mergers from the first, metal-free stars in the Universe (Pop III) to gravitational wave detection rates. Our study combines initial conditions for the formation of Pop III stars based on N-body simulations of binary formation (including rates, binary fraction, initial mass function, orbital separation and eccentricity distributions) with an updated model of stellar evolution specific for Pop III stars. We find that the merger rate of these Pop III BH-BH systems is relatively small (< 0.1 Gpc^-3 yr^-1) at low redshifts (z<2), where it can …
Focusing on the remnant black holes after merging binary black holes, we show that ringdown gravitational waves of Population III binary black holes mergers can be detected with the rate of $5.9-500~{\rm events~yr^{-1}}~({\rm SFR_p}/ (10^{-2.5}~M_\odot~{\rm yr^{-1}~Mpc^{-3}})) \cdot ({\rm [f_b/(1+f_b)]/0.33})$ for various parameters and functions. This rate is estimated for the events with SNR$>8$ for the second generation gravitational wave detectors such as KAGRA. Here, ${\rm SFR_p}$ and ${\rm f_b}$ are the peak value of the Population III star formation rate and the fraction of binaries, re…
We produce synthetic spectra and observations for metal-free stellar populations and high mass X-ray binaries in the Renaissance Simulations at a redshift of 15. We extend our methodology from the first paper in the series by modelling the production and extinction of emission lines throughout a dusty and metal-enriched interstellar and circum-galactic media extracted from the simulation, using a Monte Carlo calculation. To capture the impact of high-energy photons, we include all frequencies from hard X-ray to far infrared with enough frequency resolution to discern line emission and absorpti…
The future detection of gravitational wave forces us to consider the many ways in which astrophysics, gravitational wave theory and fundamental theory will interact. In this paper, I summarize some recent work done to develop such an interface. In particular, I concentrate on how non-vacuum astrophysical environments can modify the gravitational wave signal emitted by compact binary inspirals, and whether signatures from the former are detectable by current and future gravitational wave detectors. I also describe the interface between gravitational wave modeling and fundamental theory, focusin…
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 distribution of GW sources in the local universe is of considerable interest. Here we investigate the full phase space distribution of coalescing compact binaries at $z = 0$ using dark matter simulations of structure formation. The fact that these binary systems acquire large barycentric velocities at birth ("kicks") results in merger site distributions that are more d…
We propose a simplified picture of low mass X-ray binaries containing a neutron star (NS-LMXBs) based on data obtained from AqlX-1 and 4U1608-52 which often produce outbursts. In this picture we propose at least three states and three state transitions; i.e., the states: (1) soft state, (2) hard-high state, and (3) hard-low state, and the state transitions: (i) hard-high state to soft state, (ii) soft state to hard-high state, and (iii) hard-high state to hard-low state or vice versa. Gases from the accretion disc of an NS-LMXB penetrate almost the entire magnetic field and accrete onto the ne…
We have compiled the most complete census of High-Mass X-ray Binaries (HMXBs) in the Small Magellanic Cloud with the aim to investigate the formation efficiency of young accreting binaries in its low metallicity environment. In total, we use 127 X-ray sources with detections in our \chandra X-ray Visionary Program (XVP), supplemented by 14 additional (likely and confirmed) HMXBs identified by \cite{2016A&A...586A..81H} that fall within the XVP area, but are not either detected in our survey (9 sources) or matched with any XVP source that has at least one OB counterpart in the OGLE-III catalog …
Due to their small mass, subsolar mass black hole binaries would have to be primordial in origin instead of the result of stellar evolution. Soon after formation in the early universe, primordial black holes can form binaries after decoupling from the cosmic expansion. Alternatively, primordial black holes as dark matter could also form binaries in the late universe due to dynamical encounters and gravitational-wave braking. A significant feature for this channel is the possibility that some sources retain nonzero eccentricity in the LIGO/Virgo band. Assuming all dark matter is primordial blac…
Thanks to long-term X-ray monitoring, a number of interacting binaries are now known to show X-ray periodicities on timescales of tens to hundreds of binary orbits. In some systems, precession of a warped accretion disc is the leading model to explain the superorbital modulation. The High Mass X-ray Binary SMC X-1 showed two excursions in superorbital period (from ~60d to ~45d) during the 1996-2011 interval, suggesting that some characteristic of the accretion disc is varying on a timescale of years. Because its behaviour as an X-ray pulsar has also been intensively monitored, SMC X-1 offers t…
High redshift galaxies permit the study of the formation and evolution of X-ray binary populations on cosmological timescales, probing a wide range of metallicities and star-formation rates. In this paper, we present results from a large scale population synthesis study that models the X-ray binary populations from the first galaxies of the universe until today. We use as input to our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. (2011) to self-consistently account for the star formation history and metallicity evolution of the un…
It has been suggested that the cycles of activity of X-ray Binaries (XrB) are triggered by a switch in the dominant disk torque responsible for accretion (paper I). As the disk accretion rate increases, the disk innermost regions would change from a jet-emitting disk (JED) to a standard accretion disk (SAD). While JEDs have been proven to successfully reproduce hard states (paper II), the existence of an outer cold SAD introduces an extra non local cooling term. We investigate the thermal structure and associated spectra of such a hybrid disk configuration. We use the 2T plasma code elaborated…
Recent ground based and space telescopes that detect high energy photons from a few up to hundreds of gigaelectron volts (GeV) have opened a new window on the universe. However, because of the relatively poor angular resolution of these telescopes, a large fraction of the thousands of sources of gamma-rays observed remains unknown. Compact astrophysical objects are among those high energy sources, and in the Milky Way there is a particular class called "Gamma-Ray Binaries".
Using a sample of two hundred luminous (L_unabs>10^38 erg/s, where L_unabs is the unabsorbed 0.25-8 keV luminosity) high-mass X-ray binary (HMXB) candidates found with Chandra in 27 nearby galaxies, we have constructed the collective X-ray spectrum of HMXBs in the local Universe per unit star formation rate, corrected for observational biases associated with intrinsic diversity of HMXB spectra and X-ray absorption in the interstellar medium. This spectrum is well fit by a power law with a photon index Gamma=2.1+/-0.1 and is dominated by ultraluminous X-ray sources with L_unabs>10^39 erg/s. Har…
The Einstein Telescope (ET), a wide-band, future third generation gravitational wave detector, is expected to have detection rates of $\sim 10^5 - 10^6$ binary black hole (BBH) detections and $\sim 7 \times 10^4$ binary neutron star (BNS) detections in one year. The coalescence of compact binaries with a total mass of 20 - 100 $M_{\odot}$, typical of BH-BH or BH-NS binaries, will be visible up to redshift $z\approx 20$ and even higher, thus facilitating the understanding of the dark era of the Universe preceding the birth of the first stars. The ET will therefore be a crucial instrument for po…
Using state-of-the-art dynamical simulations of globular clusters, including radiation reaction during black hole encounters and a cosmological model of star cluster formation, we create a realistic population of dynamically-formed binary black hole mergers across cosmic space and time. We show that in the local universe, 10% of these binaries form as the result of gravitational-wave emission between unbound black holes during chaotic resonant encounters, with roughly half of those events having eccentricities detectable by current ground-based gravitational-wave detectors. The mergers that oc…
Bridging the micro-Hz gravitational wave gap via Doppler tracking with the Uranus Orbiter and Probe Mission: Massive black hole binaries, early universe signals and ultra-light dark matter
The SecularMultiple code, presented in two previous papers of this series, integrates the long-term dynamical evolution of multiple systems with any number of bodies and hierarchical structure, provided that the system is composed of nested binaries. In the formalism underlying SecularMultiple, we previously averaged over all orbits in the system. This approximation significantly speeds up numerical integration of the equations of motion, making large population synthesis studies possible. However, the orbit averaging approximation can break down when the secular evolution timescale of the sys…
Waveform models for the gravitational-wave memory effect: III. Phenomenological frequency-domain model for nonspinning binaries
Laboratoire d’étude de l’Univers et des phénomènes eXtrêmes (LUX), Observatoire de Paris, Université PSL, Sorbonne Université, CNRS（极端宇宙现象实验室，巴黎天文台，巴黎文理研究大学，索邦大学，法国国家科学研究中心）；Department of Physics, University of Virginia（弗吉尼亚大学物理系）
After the Big Bang nucleosynthesis, the first heavy element enrichment in the Universe was made by a supernova (SN) explosion of a population (Pop) III star (Pop III SN). The abundance ratios of elements produced from Pop III SNe are recorded in abundance patterns of extremely metal-poor (EMP) stars. The observations of the increasing number of EMP stars have made it possible to statistically constrain the explosion properties of Pop III SNe. We present Pop III SN models whose nucleosynthesis yields well-reproduce individually the abundance patterns of 48 such metal-poor stars as [Fe/H] $\math…
Black hole-neutron star binaries with high spins and large mass asymmetries: III. Properties of the ejected material and its electromagnetic signatures
University of Hamburg（汉堡大学）；Goethe Universität（法兰克福歌德大学）；University of Idaho（爱达荷大学）；INAF-Osservatorio di Astrofisica e Scienza dello Spazio（意大利国家天体物理研究所天文与空间科学观测站）；University of Ferrara（费拉拉大学）；INFN, Sezione di Ferrara（意大利国家核物理研究所费拉拉分部）；INAF - Osservatorio Astronomico d’Abruzzo（意大利国家天体物理研究所阿布鲁佐天文台）；New Uzbekistan University（新乌兹别克斯坦大学）；Trinity College（三一学院）
Stellar-remnant black holes (BH) in dense stellar clusters comprise a natural setup to trigger general-relativistic (GR) inspiral and merger of binary black holes (BBH), detectable by the LISA and the LIGO-Virgo, through dynamical encounters inside such environments. In this work, the intricacies of such dynamical interactions are probed utilizing realistic, self-consistent, post-Newtonian, direct N-body evolutionary models of young massive and open stellar clusters. Particularly, the configurations of the compact subsystems, that drive the in-cluster GR BBH coalescences, are tracked on the fl…
We performed Population III (Pop III) binary evolution by using population synthesis simulations for seven different models. We found that Pop III binaries tend to be binary black holes (BBHs) with chirp mass $M_{\rm chirp} \sim 30~M_{\odot}$ and they can merge at present day due to long merger time. The merger rate densities of Pop III BBHs at $z=0$ ranges 3.34--21.2 $\rm /yr/Gpc^3$ which is consistent with the aLIGO/aVIRGO result of 9.7--101 $\rm /yr/Gpc^3$. These Pop III binaries might contribute to some part of the massive BBH gravitational wave (GW) sources detected by aLIGO/aVIRGO. We al…
