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Register a new userSynthetic catalog of black holes in the Milky Way
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We present an open-access database which includes a synthetic catalog of black holes in the Milky Way. To calculate evolution of single and binary stars we used updated population synthesis code StarTrack. We applied a new model of star formation history and chemical evolution of Galactic disk, bulge and halo synthesized from observational and theoretical data. We find that at the current moment Milky Way (disk+bulge+halo) contains about 1.2 x 10^8 single black holes with average mass of about 14 Msun and 9.3 x 10^6 BHs in binary systems with average mass of 19 Msun. We present basic statistical properties of BH populations such as distributions of single and binary BH masses, velocities, orbital parameters or numbers of BH binary systems in different evolutionary configurations. We find that the most massive BHs are formed in mergers of binary systems, such as BH-MS, BH+He, BH-BH. The metallicity of stellar population has a significant impact on the final BH mass due to the stellar winds. Therefore the most massive single BH in our simulation, 113 Msun, originates from a merger of a helium star and a black hole in a low metallicity stellar environment in Galactic halo. The most massive BH in binary system is 60 Msun and was also formed in Galactic halo. We constrain that only 0.006% of total Galactic halo mass (including dark matter) could be hidden in the form of stellar origin BHs which are not detectable by current observational surveys. Galactic binary BHs are minority (10% of all Galactic BHs) and most of them are in BH-BH systems. The current Galactic merger rates for two considered common envelope models which are: 3-81 Myr^-1 for BH-BH, 1-9 Myr^-1, for BH-NS and 14-59 Myr^-1 for NS-NS systems. Data files are available at https://bhc.syntheticuniverse.org/.
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The Milky Way hosts on average a few supernova explosions per century, yet in the past millennium only five supernovae have been identified confidently in the historical record. This deficit of naked-eye supernovae is at least partly due to dust extinction in the Galactic plane. We explore this effect quantitatively, developing a formalism for the supernova probability distribution, accounting for dust and for the observers flux limit. We then construct a fiducial axisymmetric model for the supernova and dust densities, featuring an exponential dependence on galactocentric radius and height, with core-collapse events in a thin disk and Type Ia events including a thick disk component. When no flux limit is applied, our model predicts supernovae are intrinsically concentrated in the Galactic plane, with Type Ia events extending to higher latitudes reflecting their thick disk component. We then apply a flux limit and include dust effects, to predict the sky distribution of historical supernovae. We use well-observed supernovae as light-curve templates, and introduce naked-eye discovery criteria. The resulting sky distributions are strikingly inconsistent with the locations of confident historical supernovae, none of which lie near our models central peaks. Indeed, SN 1054 lies off the plane almost exactly in the anticenter, and SN 1181 is in the 2nd Galactic quadrant. We discuss possible explanations for these discrepancies. We calculate the percentage of all supernovae bright enough for historical discovery: $simeq 13%$ of core-collapse and $simeq 33%$ of Type Ia events. Using these and the confident historical supernovae, we estimate the intrinsic Galactic supernova rates, finding general agreement with other methods. Finally, we urge searches for supernovae in historical records from civilizations in the southern hemisphere.
As massive black holes (MBHs) grow from lower-mass seeds, it is natural to expect that a leftover population of progenitor MBHs should also exist in the present universe. Dwarf galaxies undergo a quiet merger history, and as a result, we expect that dwarfs observed in the local Universe retain some `memory of the original seed mass distribution. Consequently, the properties of MBHs in nearby dwarf galaxies may provide clean indicators of the efficiency of MBH formation. In order to examine the properties of MBHs in dwarf galaxies, we evolve different MBH populations within a Milky Way halo from high-redshift to today. We consider two plausible MBH formation mechanisms: `massive seeds formed via gas-dynamical instabilities and a Population III remnant seed model. `Massive seeds have larger masses than PopIII remnants, but form in rarer hosts. We dynamically evolve all halos merging with the central system, taking into consideration how the interaction modifies the satellites, stripping their outer mass layers. We compute different properties of the MBH population hosted in these satellites. We find that for the most part MBHs retain the original mass, thus providing a clear indication of what the properties of the seeds were. We derive the black hole occupation fraction (BHOF) of the satellite population at z=0. MBHs generated as `massive seeds have large masses that would favour their identification, but their typical BHOF is always below 40 per cent and decreases to less than per cent for observed dwarf galaxy sizes. In contrast, Population III remnants have a higher BHOF, but their masses have not grown much since formation, inhibiting their detection.
We determine the main properties of the Galactic binary black hole (BBH) population detectable by LISA and strategies to distinguish them from the much more numerous white dwarf binaries. We simulate BBH populations based on cosmological simulations of Milky Way-like galaxies and binary evolution models. We then determine their gravitational wave emission as observed by LISA and build mock catalogs. According to our model LISA will detect $approx4(6)$ binary black holes assuming 4(10) years of operations. Those figures grow to $approx6(9)$ when models are re-normalized to the inferred LIGO/Virgo merger rates. About 40%(70%) of the sources will have a good enough chirp mass measurement to separate them from the much lighter white dwarf and neutron star binaries. Most of the remaining sources should be identifiable by their lack of electromagnetic counterpart within $approx100$ pc. These results are robust with respect to the current uncertainties of the BBH merger rate as measured by LIGO/Virgo as well as the global mass spectrum of the binaries. We determine there is a 94 per cent chance that LISA finds at least one of these systems, which will allow us to pinpoint the conditions where they were formed and possibly find unique electromagnetic signatures.
We estimate the rate of inspiral for a population of stellar mass BHs in the star cluster around the super massive black hole at the center of Milky Way mass galaxies. Our approach is based on an orbit averaged Fokker Planck approach. This is then followed by a post-processing approach, which incorporates the impact of the angular momentum diffusion and the GW dissipation in the evolution of system. We make a sample of 10000 BHs with different initial semi-major and eccentricities with the distribution of $f_c(a)/a$ and $e$, respectively. Where $f_c(a)$ refers to the phase-space distribution function for cth species. Angular momentum diffusion leads to an enhancement in the eccentricity of every system in the above sample and so increases the rate of inspiral. We compute the fraction of time that every system spends in the LISA band with the signal to noise ratio $rm{SNR} geq 8$. Every system eventually approaches the loss-cone with a replenishment rate given by the diffusion rate of the cluster, $mu/ rm{Gyr}^{-1} lesssim 1 $. This small rate reduces the total rate of the inspiral for individual MW mass galaxies with an estimate $R_{obs} lesssim 10^{-5} yr^{-1}$. It is expected though that a collection of $N_{gal} simeq 10^4$ MW mass galaxies lead to an observable GW signal in the LISA band.
We identify 709 arc-shaped mid-infrared nebula in 24 micron Spitzer Space Telescope or 22 micron Wide Field Infrared Explorer surveys of the Galactic Plane as probable dusty interstellar bowshocks powered by early-type stars. About 20% are visible at 8 microns or shorter mid-infrared wavelengths as well. The vast majority (660) have no previous identification in the literature. These extended infrared sources are strongly concentrated near Galactic mid-Plane with an angular scale height of ~0.6 degrees. All host a symmetrically placed star implicated as the source of a stellar wind sweeping up interstellar material. These are candidate runaway stars potentially having high velocities in the reference frame of the local medium. Among the 286 objects with measured proper motions, we find an unambiguous excess having velocity vectors aligned with the infrared morphology --- kinematic evidence that many of these are runaway stars with large peculiar motions responsible for the bowshock signature. We discuss a population of in-situ bowshocks (103 objects) that face giant HII regions where the relative motions between the star and ISM may be caused by bulk outflows from an overpressured bubble. We also identify 58 objects that face 8 micron bright-rimmed clouds and apparently constitute a sub-class of in-situ bowshocks where the stellar wind interacts with a photo-evaporative flow from an eroding molecular cloud interface (i.e., PEF bowshocks). Orientations of the arcuate nebulae exhibit a correlation over small angular scales, indicating that external influences such as HII regions are responsible for producing some bowshock nebulae. However, the vast majority of this sample appear to be isolated (499 objects) from obvious external influences.
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