81 research outputs found
EIGER III. JWST/NIRCam observations of the ultra-luminous high-redshift quasar J0100+2802
We present the first rest-frame optical spectrum of a high-redshift quasar
observed with JWST/NIRCam in Wide Field Slitless (WFSS) mode. The observed
quasar, J0100+2802, is the most luminous quasar known at . We measure the
mass of the central supermassive black hole (SMBH) by means of the rest-frame
optical H emission line, and find consistent mass measurements of the
quasar's SMBH of when compared to the
estimates based on the properties of rest-frame UV emission lines CIV and MgII,
which are accessible from ground-based observatories. To this end, we also
present a newly reduced rest-frame UV spectrum of the quasar observed with
X-Shooter/VLT and FIRE/Magellan for a total of 16.8 hours. We readdress the
question whether this ultra-luminous quasar could be effected by strong
gravitational lensing making use of the diffraction limited NIRCam images in
three different wide band filters (F115W, F200W, F356W), which improves the
achieved spatial resolution compared to previous images taken with the Hubble
Space Telescope by a factor of two. We do not find any evidence for a
foreground deflecting galaxy, nor for multiple images of the quasar, and
determine the probability for magnification due to strong gravitational lensing
with image separations below the diffraction limit of to be . Our observations therefore confirm
that this quasar hosts a ten billion solar mass black hole less than Gyr
after the Big Bang, which is challenging to explain with current black hole
formation models.Comment: Accepted for publication in Ap
EIGER V. Characterizing the Host Galaxies of Luminous Quasars at
We report {\em JWST}/NIRCam measurements of quasar host galaxy emissions and
supermassive black hole (SMBH) masses for six quasars at in the
\textit{Emission-line galaxies and Intergalactic Gas in the Epoch of
Reionization} (EIGER) project. We obtain deep NIRCam imaging in the F115W,
F200W, and F356W bands, as well as F356W grism spectroscopy of the quasars. We
use bright unsaturated stars to construct models of the point spread function
(PSF) and estimate the errors of these PSFs. We then measure or constrain the
fluxes and morphology of the quasar host galaxies by fitting the quasar images
as a point source plus an exponential disk. We successfully detect the host
galaxy of three quasars, which have host-to-quasar flux ratios of
. Spectral Energy Distribution (SED) fitting suggests that these
quasar host galaxies have stellar masses of . For
quasars with host galaxy non-detections, we estimate the upper limits of their
stellar masses. We use the grism spectra to measure the {\hb} line profile and
the continuum luminosity, then estimate the SMBH masses for the quasars. Our
results indicate that the positive relation between SMBH masses and host galaxy
stellar masses already exists at redshift . The quasars in our
sample show a high black hole to stellar mass ratio of
, which is about dex higher than the local
relations. This result suggests that luminous quasars at form a
biased sample with overmassive black holes, which might have experienced early
SMBH growth compared to their host galaxies' star formation.Comment: 21 pages, 12 figures, submitted to AAS journals. Comments welcome
Experimental Evidence for a Spin-Polarized Ground State in the \nu=5/2 Fractional Quantum Hall Effect
We study the \nu=5/2 even-denominator fractional quantum Hall effect (FQHE)
over a wide range of magnetic (B) field in a heterojunction insulated gate
field-effect transistor (HIGFET). The electron density can be tuned from n=0 to
7.6 \times 10^{11} cm^{-2} with a peak mobility \mu = 5.5 \times 10^6 cm^2/Vs.
The \nu=5/2 state shows a strong minimum in diagonal resistance and a
developing Hall plateau at magnetic fields as high as 12.6T. The strength of
the energy gap varies smoothly with B-field. We interpret these observations as
strong evidence for a spin-polarized ground state at \nu=5/2.Comment: new references adde
Possible composite-fermion liquid as a crossover from Wigner crystal to bubble phase in higher Landau level
The ground state cohesive energies per electron of the composite fermion (CF)
Fermi sea, the Laughlin state and the charge density wave (CDW) at higher
Landau levels (LLs) are computed. It is shown that whereas for LL,
the CDW state is generally more energetically preferable than those of the CF
liquid and the Laughlin liquid, the CF liquid state unexpectedly
has lower ground state energy than that of the CDW state. We suggest this CF
liquid between the Wigner crystal and the bubble phase may lead to the
crossover from the normal integer quantum Hall liquid to the novel re-entrant
integer quantum Hall state observed in the recent magneto-transport
experiments
Coulomb drag of Luttinger liquids and quantum-Hall edges
We study the transconductance for two coupled one-dimensional wires or edge
states described by Luttinger liquid models. The wires are assumed to interact
over a finite segment. We find for the interaction parameter that the
drag rate is finite at zero temperature, which cannot occur in a Fermi-liquid
system. The zero temperature drag is, however, cut off at low temperature due
to the finite length of the wires. We also consider edge states in the
fractional quantum Hall regime, and we suggest that the low temperature
enhancement of the drag effect might be seen in the fractional quantum Hall
regime.Comment: 5 pages, 2 figures; to appear in Phys. Rev. Let
Active Galactic Nucleus Pairs from the Sloan Digital Sky Survey. II. Evidence for Tidally Enhanced Star Formation and Black Hole Accretion
Active galactic nuclei (AGNs) are occasionally seen in pairs, suggesting that
tidal encounters are responsible for the accretion of material by both central
supermassive black holes (BHs). In Paper I of this series, we selected a sample
of AGN pairs with projected separations r_p < 100 kpc and velocity offsets <
600 km/s from the SDSS DR7 and quantified their frequency. In this paper, we
address the BH accretion and recent star formation properties in their host
galaxies. AGN pairs experience stronger BH accretion, as measured by their [O
III]5007 luminosities (corrected for contribution from star formation) and
Eddington ratios, than do control samples of single AGNs matched in redshift
and host stellar mass. Their host galaxies have stronger post-starburst
activity and younger mean stellar ages, as indicated by stronger H-delta
absorption and smaller 4000 A break in their spectra. The BH accretion and
recent star formation in the host galaxies both increase with decreasing
projected separation in AGN pairs, for r_p ~< 10-30 kpc. The intensity of BH
accretion, the post-starburst strength, and the mean stellar ages are
correlated between the two AGNs in a pair. The luminosities and Eddington
ratios of AGN pairs are correlated with recent star formation in their host
galaxies, with a scaling relation consistent with that observed in single AGNs.
Our results suggest that galaxy tidal interactions enhance both BH accretion
and star formation in AGN pairs, even though the majority of low redshift AGNs
is not coincident with on-going interactions.Comment: 16 pages, 12 figures; to appear in Ap
The Demographics of Broad Line Quasars in the Mass-Luminosity Plane II. Black Hole Mass and Eddington Ratio Functions
We employ a flexible Bayesian technique to estimate the black hole mass and
Eddington ratio functions for Type 1 (i.e., broad line) quasars from a
uniformly-selected data set of ~58,000 quasars from the SDSS DR7. We find that
the SDSS becomes significantly incomplete at M_{BH} < 3 x 10^8 M_{Sun} or L /
L_{Edd} < 0.07, and that the number densities of Type 1 quasars continue to
increase down to these limits. Both the mass and Eddington ratio functions show
evidence of downsizing, with the most massive and highest Eddington ratio black
holes experiencing Type 1 quasar phases first, although the Eddington ratio
number densities are flat at z < 2. We estimate the maximum Eddington ratio of
Type 1 quasars in the observable Universe to be L / L_{Edd} ~ 3. Consistent
with our results in Paper I, we do not find statistical evidence for a
so-called "sub-Eddington boundary" in the mass-luminosity plane of broad line
quasars, and demonstrate that such an apparent boundary in the observed
distribution can be caused by selection effect and errors in virial BH mass
estimates. Based on the typical Eddington ratio in a given mass bin, we
estimate typical growth times for the black holes in Type 1 quasars and find
that they are typically comparable to or longer than the age of the universe,
implying an earlier phase of accelerated (i.e., with higher Eddington ratios)
and possibly obscured growth. The large masses probed by our sample imply that
most of our black holes reside in what are locally early type galaxies, and we
interpret our results within the context of models of self-regulated black hole
growth.Comment: Submitted to ApJ, 25 pages (emulateapj), 15 figures; revised to match
accepted version with primary changes to the introduction and discussion,
replaced Fig 1
Little Red Dots: an abundant population of faint AGN at revealed by the EIGER and FRESCO JWST surveys
Characterising the prevalence and properties of faint active galactic nuclei
(AGN) in the early Universe is key for understanding the formation of
supermassive black holes (SMBHs) and determining their role in cosmic
reionization. We perform a spectroscopic search for broad H emitters at
using deep JWST/NIRCam imaging and wide field slitless
spectroscopy from the EIGER and FRESCO surveys. We identify 20 H lines
at that have broad components with line widths from km s, contributing % of the total line flux. We
interpret these broad components as being powered by accretion onto SMBHs with
implied masses M. In the UV luminosity range M = -21 to -18, we measure number densities of cMpc.
This is an order of magnitude higher than expected from extrapolating quasar UV
luminosity functions. Yet, such AGN are found in only % of star-forming
galaxies at . The SMBH mass function agrees with large cosmological
simulations. In two objects we detect narrow red- and blue-shifted H
absorption indicative, respectively, of dense gas fueling SMBH growth and
outflows. We may be witnessing early AGN feedback that will clear dust-free
pathways through which more massive blue quasars are seen. We uncover a strong
correlation between reddening and the fraction of total galaxy luminosity
arising from faint AGN. This implies that early SMBH growth is highly obscured
and that faint AGN are only minor contributors to cosmic reionization.Comment: 23 pages, 17 figures. Submitted to ApJ. Main Figs 4, 10, 15 (faint
AGN UV luminosity function) and 16 (SMBH mass function). Fig. 17 summarises
the results. Comments welcom
Cell Type–dependent Requirement for PIP Box–regulated Cdt1 Destruction During S Phase
Previous studies have shown that Cdt1 overexpression in cultured cells can trigger re-replication, but not whether CRL4Cdt2-triggered destruction of Cdt1 is required for normal mitotic cell cycle progression in vivo. We demonstrate that PIP box–mediated destruction of Cdt1Dup during S phase is necessary for the cell division cycle in Drosophila
Turbulent kinetic energy budgets in a model canopy: comparisons between LES and wind-tunnel experiments
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