Black Holes and Neutron Stars in Nearby Galaxies: Insights from NuSTAR.

摘要: Nearby galaxy surveys have long classified X-ray binaries (XRBs) by the mass category of their donor stars (high-mass and low-mass). The NuSTAR observatory, which provides imaging data at E $>10$ keV, has enabled classification extragalactic XRBs compact object type: neutron star (NS) or black hole (BH). We analyzed NuSTAR/Chandra/XMM-Newton observations from a NuSTAR-selected sample 12 galaxies within 5 Mpc having stellar masses ($M_{\star}$) $10^{7-11}$ $M_{\odot}$ formation rates (SFR) $\approx0.01-15$ yr$^{-1}$. detect 128 sources to sensitivity $\approx10^{38}$ erg s$^{-1}$. Using color-intensity color-color diagrams we classify 43 these as candidate NS 47 BH. further subdivide BH accretion states (soft, intermediate, hard) weak (Z/Atoll) strong (accreting pulsar) magnetic field. 8 normal (Milky Way-type) in sample, confirm relation between SFR point source luminosity 4-25 12-25 keV energy bands. also constrain using $L_{\rm{X}}=\alpha M_{\star}+\beta\text{SFR}$, finding agreement with previous work. XLF all bands matches $\alpha=1.6$ slope for high-mass XRBs. find that XLFs suggest decline beginning Eddington limit 1.4 NS, whereas fraction shows an approximate monotonic increase 12-25keV calculate overall ratio be $\approx1$ $\approx2$ keV.