分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: This paper is the second in a series aimed at examining the gaseous environments of z$\le$0.3 quasars and ultraluminous infrared galaxies (ULIRGs) as a function of AGN/host galaxy properties across the merger sequence. This second paper focuses on the Ly$\alpha$ emission and O VI and N V absorption features, tracers of highly ionized gas outflows, in ULIRGs observed with HST/COS. Ly$\alpha$ emission is detected in 15 out of 19 ULIRGs, and 12 of the 14 clear Ly$\alpha$ detections show emission with blueshifted velocity centroids and/or wings. The equivalent widths of the Ly$\alpha$ emission increase with increasing AGN luminosities and AGN bolometric fractions. The blueshifts of the Ly$\alpha$ emission correlate positively with those of the [O III] emission, where the latter traces the ionized gas outflows. The Ly$\alpha$ escape fractions tend to be slightly larger in objects with stronger AGN and larger outflow velocities, but they do not correlate with nebular line reddening. Among the 12 ULIRGs with good continuum signal-to-noise ratios, O VI and/or N V absorption features are robustly detected in 6 of them, all of which are blueshifted, indicative of outflows. In the combined ULIRG $+$ quasar sample, the outflows are more frequently detected in the X-ray weak or absorbed sources. The absorption equivalent widths, velocities and velocity dispersions of the outflows are also higher in the X-ray weak sources. No other strong correlations are visible between the properties of the outflows and those of the AGN or host galaxies.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Extremely red quasars, with bolometric luminosities exceeding $10^{47}$ erg s$^{-1}$, are a fascinating high-redshift population that is absent in the local universe. They are the best candidates for supermassive black holes accreting at rates at or above the Eddington limit, and they are associated with the most rapid and powerful outflows of ionized gas known to date. They are also hosted by massive galaxies. Here we present the first integral field unit (IFU) observations of a high-redshift quasar obtained by the Near Infrared Spectrograph (NIRSpec) on board the James Webb Space Telescope (JWST), which targeted SDSSJ165202.64+172852.3, an extremely red quasar at $z=2.94$. JWST observations reveal extended ionized gas - as traced by [OIII]$\lambda$5007\AA - in the host galaxy of the quasar, its outflow, and the circumgalactic medium. The complex morphology and kinematics imply that the quasar resides in a very dense environment with several interacting companion galaxies within projected distances of 10-15 kpc. The high density of the environment and the large velocities of the companion galaxies suggest that this system may represent the core of a forming cluster of galaxies. The system is a good candidate for a merger of two or more dark matter halos, each with a mass of a few $10^{13}$ M$_\odot$ and traces potentially one of the densest knots at $z\sim3$.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The Line Emission Mapper (LEM) is an X-ray Probe for the 2030s that will answer the outstanding questions of the Universe's structure formation. It will also provide transformative new observing capabilities for every area of astrophysics, and to heliophysics and planetary physics as well. LEM's main goal is a comprehensive look at the physics of galaxy formation, including stellar and black-hole feedback and flows of baryonic matter into and out of galaxies. These processes are best studied in X-rays, and emission-line mapping is the pressing need in this area. LEM will use a large microcalorimeter array/IFU, covering a 30x30' field with 10" angular resolution, to map the soft X-ray line emission from objects that constitute galactic ecosystems. These include supernova remnants, star-forming regions, superbubbles, galactic outflows (such as the Fermi/eROSITA bubbles in the Milky Way and their analogs in other galaxies), the Circumgalactic Medium in the Milky Way and other galaxies, and the Intergalactic Medium at the outskirts and beyond the confines of galaxies and clusters. LEM's 1-2 eV spectral resolution in the 0.2-2 keV band will make it possible to disentangle the faintest emission lines in those objects from the bright Milky Way foreground, providing groundbreaking measurements of the physics of these plasmas, from temperatures, densities, chemical composition to gas dynamics. While LEM's main focus is on galaxy formation, it will provide transformative capability for all classes of astrophysical objects, from the Earth's magnetosphere, planets and comets to the interstellar medium and X-ray binaries in nearby galaxies, AGN, and cooling gas in galaxy clusters. In addition to pointed observations, LEM will perform a shallow all-sky survey that will dramatically expand the discovery space.