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Abstract
摘要 |
Understanding the host galaxy properties of stellar binary black hole (SBBH) mergers is important for revealing the origin of the SBBH gravitational-wave sources detected by advanced LIGO/VIRGO and helpful for identifying their electromagnetic counterparts. In this talk, I will report our recent investigations on the host galaxy properties of SBBHs by implementing semi-analytical recipes for SBBH formation and merger into cosmological galaxy formation model. If the time delay between SBBH formation and merger ranges from Gyr to the Hubble time, SBBH mergers at redshift z<~0.3 occur preferentially in big galaxies with stellar mass >~2x10^{10}M_sun and metallicities Z peaking at ∼0.6Z_sun. However, the host galaxy stellar mass distribution of heavy SBBH mergers (with mass >~50M_sun) is bimodal with one peak at ~10^9M_sun and the other peak at ~2x10^{10}M_sun. The contribution fraction from host galaxies with Z<~0.2Z_sun to heavy mergers is much larger than that to less heavy mergers. If SBBHs were formed in the early universe (e.g., z>6), their mergers detected at z<~0.3 occur preferentially in even more massive galaxies with stellar mass >3x10^{10}M_sun and in galaxies with metallicities mostly >~0.2Z_nun and peaking at ∼0.6Z_sun, due to later cosmic assembly and enrichment of their host galaxies. SBBH mergers at z<~0.3 mainly occur in spiral galaxies, but the fraction of SBBH mergers occur in elliptical galaxies can be significant if those SBBHs were formed in the early universe; and about two thirds of those mergers occur in the central galaxies of dark matter halos. I will also talk about the clustering and other statistical properties of those GW sources. |
