• Xinwu Cao

      Articles written in Journal of Astrophysics and Astronomy

    • Unification of Radio Galaxies and their Accretion Jet Properties

      Qingwen Wu Ya-Di Xu Xinwu Cao

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      We investigate the relation between black hole mass, 𝑀bh, and jet power, 𝑄jet, for a sample of BL Lacs and radio quasars. We find that BL Lacs are separated from radio quasars by the FR I/II dividing line in 𝑀bh-𝑄jet plane, which strongly supports the unification scheme of FR I/BL Lac and FR II/radio quasar. The Eddington ratio distribution of BL Lacs and radio quasars exhibits a bimodal nature with a rough division at 𝐿bol/𝐿Edd ∼ 0.01, which imply that they may have different accretion modes. We calculate the jet power extracted from advection-dominated accretion flow (ADAF), and find that it requires dimensionless angular momentum of black hole 𝑗 ≃ 0.9 - 0.99 to reproduce the dividing line between FR I/II or BL Lac/radio quasar if dimensionless accretion rate $\dot{m} = 0.01$ is adopted, which is required by the above bimodal distribution of Eddington ratios. Our results suggest that black holes in radio galaxies are rapidly spinning.

    • What Governs Lorentz Factors of Jet Components in Blazars?

      Xinwu Cao Bo Chai Ming Zhou Minfeng Gu

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      We use a sample of radio-loud Active Galactic Nuclei (AGNs) with measured black hole masses to explore the jet formation mechanisms in these sources. We find a significant correlation between black hole mass and the bulk Lorentz factor of the jet components for this sample, while no significant correlation is present between the bulk Lorentz factor and the Eddington ratio. Recent investigations suggested that the most super-massive black holes in elliptical galaxies have on average higher spins than the black holes in spiral galaxies. The correlation between black hole mass and bulk Lorentz factor of the jet components found in this work implies that the motion velocity of the jet components is probably governed by the black hole spin. The faster moving jets are magnetically accelerated by the magnetic fields threading the horizon of more rapidly rotating black holes.

    • Estimating Black Hole Spin of PG 1322+659 with Observed Optical and X-ray Continuum Spectrum

      Bei You Xinwu Cao

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      We fit the observed Spectral Energy Distribution (SED) of a bright radio quite quasar PG 1322+659 in optical and hard X-ray bands with an accretion disk–corona model to estimate BH spin a.

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

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