115 research outputs found
Galactic Scale Feedback Observed in the 3C 298 Quasar Host Galaxy
We present high angular resolution multi-wavelength data of the 3C 298
radio-loud quasar host galaxy (z=1.439) taken using the W.M. Keck Observatory
OSIRIS integral field spectrograph with adaptive optics, Atacama Large
Millimeter/submillimeter Array (ALMA), Hubble Space Telescope (HST) WFC3, and
the Very Large Array (VLA). Extended emission is detected in the rest-frame
optical nebular emission lines H, [OIII], H, [NII], and [SII],
as well as molecular lines CO (J=3-2) and (J=5-4). Along the path of 3C 298's
relativistic jets we detect conical outflows of ionized gas with velocities up
to 1700 km s and outflow rate of 450-1500 Myr. Near the
spatial center of the conical outflow, CO (J=3-2) emission shows a molecular
gas disc with a total molecular mass () of
6.6M. On the molecular disc's blueshifted side
we observe a molecular outflow with a rate of 2300 Myr and
depletion time scale of 3 Myr. We detect no narrow H emission in the
outflow regions, suggesting a limit on star formation of 0.3
Myrkpc. Quasar driven winds are evacuating the molecular
gas reservoir thereby directly impacting star formation in the host galaxy. The
observed mass of the supermassive black hole is M and
we determine a dynamical bulge mass of 1-1.7
M. The bulge mass of 3C 298 resides 2-2.5 orders of magnitude below
the expected value from the local M relationship. A second
galactic disc observed in nebular emission is offset from the quasar by 9 kpc
suggesting the system is an intermediate stage merger. These results show that
galactic scale negative feedback is occurring early in the merger phase of 3C
298, well before the coalescence of the galactic nuclei and assembly on the
local relationship.Comment: 23 pages, 11 figures, 4 tables, Accepted for publication in the
Astrophysical Journa
Providing stringent star formation rate limits of z2 QSO host galaxies at high angular resolution
We present integral field spectrograph (IFS) with laser guide star adaptive
optics (LGS-AO) observations of z=2 quasi-stellar objects (QSOs) designed to
resolve extended nebular line emission from the host galaxy. Our data was
obtained with W. M. Keck and Gemini-North Observatories using OSIRIS and NIFS
coupled with the LGS-AO systems. We have conducted a pilot survey of five QSOs,
three observed with NIFS+AO and two observed with OSIRIS+AO at an average
redshift of z=2.15. We demonstrate that the combination of AO and IFS provides
the necessary spatial and spectral resolutions required to separate QSO
emission from its host. We present our technique for generating a PSF from the
broad-line region of the QSO and performing PSF subtraction of the QSO emission
to detect the host galaxy. We detect H and [NII] for two sources, SDSS
J1029+6510 and SDSS J0925+06 that have both star formation and extended
narrow-line emission. Assuming that the majority of narrow-line H is
from star formation, we infer a star formation rate for SDSS J1029+6510 of 78.4
Myr originating from a compact region that is kinematically
offset by 290 - 350 km/s. For SDSS J0925+06 we infer a star formation rate of
29 Myr distributed over three clumps that are spatially offset
by 7 kpc. The null detections on three of the QSOs are used to infer
surface brightness limits and we find that at 1.4 kpc distance from the QSO
that the un-reddened star formation limit is 0.3
Myrkpc. If we assume a typical extinction values for z=2
type-1 QSOs, the dereddened star formation rate for our null detections would
be 0.6 Myrkpc. These IFS observations indicate that
if star formation is present in the host it would have to occur diffusely with
significant extinction and not in compact, clumpy regions.Comment: 17 pages, 7 figures, 7 tables, Accepted to Ap
Cold Mode Gas Accretion on Two Galaxy Groups at z2
We present Keck Cosmic Web Imager (KCWI) integral field spectroscopy (IFS)
observations of rest-frame UV emission lines , C IV 1548 \AA, 1550\AA and He II 1640 \AA observed in the circumgalactic
medium (CGM) of two radio-loud quasar host galaxies. We detect extended
emission on 80-90 kpc scale in in both systems with C IV, and He
II emission also detected out to 30-50 kpc. All emission lines show kinematics
with a blue and redshifted gradient pattern consistent with velocities seen in
massive dark matter halos and similar to kinematic patterns of inflowing gas
seen in hydrodynamical simulations. Using the kinematics of both resolved emission and absorption, we can confirm that both kinematic
structures are associated with accretion. Combining the KCWI data with
molecular gas observations with Atacama Large Millimeter/submillimeter Array
(ALMA) and high spatial resolution of ionized gas with Keck OSIRIS, we find
that both quasar host galaxies reside in proto-group environments at . We
estimate M of warm-ionized gas within 30-50 kpc from
the quasar that is likely accreting onto the galaxy group. We estimate inflow
rates of 60-200 Myr, within an order of magnitude of the outflow
rates in these systems. In the 4C 09.17 system, we detect narrow gas streams
associated with satellite galaxies, potentially reminiscent of ram-pressure
stripping seen in local galaxy groups and clusters. We find that the quasar
host galaxies reside in dynamically complex environments, with ongoing mergers,
gas accretion, ISM stripping, and outflows likely playing an important role in
shaping the assembly and evolution of massive galaxies at cosmic noon.Comment: 24 pages, 11 figures, 6 tabes. Accepted for publication in MNRA
A Comprehensive Study of Dielectric-Conductor Junctions in Low Density Plasmas
In this paper, results are presented of an experimental and theoretical study of snapover, glow discharge, and arc phenomena for different materials immersed in argon or xenon plasmas. The effect of snapover is investigated for several metal-dielectric junctions: copper-teflon, copper-Kapton, copper-glass, aluminum-teflon, aluminum-Kapton, steel-teflon, anodized aluminum with pinholes, and copper-ceramics. I-V curves are measured, and snapover inception voltages, essential parameters (increase in current and collection area due to secondary electrons), and glow discharge inception thresholds are determined. Optical spectra are obtained for glow discharges in both argon and xenon plasmas. These spectra provide information regarding atomic species entrapped in the glow region. A video-camera and linear array were used to confirm that snapover inception is accompanied by very low intensity visible light emission. This result seems to be important for the estimate of the light pollution around spacecraft. Optical spectra (wavelengths 380-650 nm) of arcs are also obtained on a negatively biased chromic acid anodized aluminum plate immersed in low density argon and xenon plasmas. Analysis of these spectra confirms our earlier findings that aluminum atoms are ejected from the arc site. Moreover, it is found that chromium atoms are also quite abundant in the arc plasma. It is believed that the latter results contribute considerably to the understanding of processes of plasma contamination caused by arcin
Powerful winds in high-redshift obscured and red quasars
Quasar-driven outflows must have made their most significant impact on galaxy formation during the epoch when massive galaxies were forming most rapidly. To study the impact of quasar feedback, we conducted rest-frame optical integral field spectrograph (IFS) observations of three extremely red quasars (ERQs) and one type-2 quasar at z = 2–3, obtained with the NIFS and OSIRIS instruments at the Gemini North and W. M. Keck Observatory with the assistance of laser-guided adaptive optics. We use the kinematics and morphologies of the [O III] 5007 Å and H α 6563 Å emission lines redshifted into the near-infrared to gauge the extents, kinetic energies and momentum fluxes of the ionized outflows in the quasars host galaxies. For the ERQs, the galactic-scale outflows are likely driven by radiation pressure in a high column density environment or due to an adiabatic shock. The outflows in the ERQs carry a significant amount of energy ranging from 0.05 to 5 per cent of the quasar’s bolometric luminosity, powerful enough to have a significant impact on the quasar host galaxies. The outflows are resolved on kpc scales, the observed outflow sizes are generally smaller than other ionized outflows observed at high redshift. The high ratio between the momentum flux of the ionized outflow and the photon momentum flux from the quasar accretion disc and high nuclear obscuration makes these ERQs great candidates for transitional objects where the outflows are likely responsible for clearing material in the inner regions of each galaxy, unveiling the quasar accretion disc at optical wavelengths
ИНДУЦИРОВАНИЕ СОЛЕУСТОЙЧИВОСТИ 24-ЭПИБРАССИНОЛИДОМ ПРОРОСТКОВ ПРОСА (Panicum miliaceum) С УЧАСТИЕМ АКТИВНЫХ ФОРМ КИСЛОРОДА
The treatment of millet seedlings with 24-epibrassinolide (24-EBL) was shown to cause a transient increase in their hydrogen peroxide content, the subsequent activation of antioxidant enzymes (superoxide dismutase, catalase, guaiacol peroxidase) and the development of their resistance to salt stress. Antioxidant dimethylthiourea and NADPH oxidase inhibitor imidazole leveled these processes. It was concluded that the induction of millet salt tolerance by exogenous 24-EBL was mediated by the enhancement of reactive oxygen species level associated with the increased activity of NADPH oxidase.Показано, что обработка проростков проса 24-эпибрассинолидом (24-ЭБЛ) вызывала транзиторное увеличение в них содержания пероксида водорода, последующую активацию антиоксидантных ферментов (супероксиддисмутазы, каталазы, гваяколпероксидазы) и развитие устойчивости к солевому стрессу. Антиоксидант диметилтиомочевина и ингибитор НАДФН-оксидазы имидазол нивелировали эти процессы. Сделано заключение, что индуцирование солеустойчивости проса экзогенным 24-ЭБЛ опосредовано усилением генерации активных форм кислорода, связанным с повышением активности НАДФН-оксидазы
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