987 research outputs found
Gas rotation, shocks and outflow within the inner 3 kpc of the radio galaxy 3C 33
We present optical integral field spectroscopy obtained with the Gemini
Multi-Object Spectrograph of the inner kpc of the
narrow line radio galaxy 3C 33 at a spatial resolution of 0.58 kpc. The gas
emission shows three brightest structures: a strong knot of nuclear emission
and two other knots at kpc south-west and north-east of the
nucleus along the ionization axis. We detect two kinematic components in the
emission lines profiles, with a "broader component" (with velocity dispersion
km s) being dominant within a 1 kpc wide strip
("the nuclear strip") running from the south-east to the north-west,
perpendicular to the radio jet, and a narrower component ( km
s) dominating elsewhere. Centroid velocity maps reveal a rotation
pattern with velocity amplitudes reaching km s in the
region dominated by the narrow component, while residual blueshifts and
redshifts relative to rotation are observed in the nuclear strip, where we also
observe the highest values of the [N II]/H{\alpha}, [S II]/H{\alpha} and [O
I]/H{\alpha} line ratios, and an increase of the gas temperature (
K), velocity dispersion and electron density ( cm). We
interpret these residuals and increased line ratios as due to a lateral
expansion of the ambient gas in the nuclear strip due to shocks produced by the
passage of the radio jet. The effect of this expansion in the surrounding
medium is very small, as its estimated kinetic power represents only of the AGN bolometric luminosity. A possible signature of
inflow is revealed by an increase in the [O I]/H{\alpha} ratio values and
velocity dispersions in the shape of two spiral arms extending to 2.3 kpc
north-east and south-west from the nucleus.Comment: 16 pages, 14 figures, accepted by MNRA
Feeding and Feedback in the Inner Kiloparsec of the Active Galaxy NGC2110
We present two-dimensional gaseous kinematics of the inner 1.1 x 1.6kpc^2 of
the Seyfert 2 galaxy NGC2110, from optical spectra obtained with the GMOS
integral field spectrograph on the Gemini South telescope at a spatial
resolution of 100pc. Gas emission is observed over the whole field-of-view,
with complex - and frequently double - emission-line profiles. We have
identified four components in the emitting gas, according to their velocity
dispersion (sigma), which we refer to as: (1) warm gas disk (sigma =
100-220km/s); (2) cold gas disk (sigma = 60-90km/s); (3) nuclear component
(sigma = 220-600km/s); and (4) northern cloud (sigma = 60-80km/s). Both the
cold and warm disk components are dominated by rotation and have similar gas
densities, but the cold gas disk has lower velocity dispersions and reaches
higher rotation velocities. We attribute the warm gas disk to a thick gas layer
which encompasses the cold disk as observed in some edge-on spiral galaxies.
After subtraction of a rotation model from the cold disk velocity field, we
observe excess blueshifts of 50km/s in the far side of the galaxy as well as
similar excess redshifts in the near side. These residuals can be interpreted
as due to nuclear inflow in the cold gas, with an estimated ionized gas mass
inflow rate of 2.2 x 10^(-2)Msun/yr. We have also subtracted a rotating model
from the warm disk velocity field and found excess blueshifts of 100km/s to the
SW of the nucleus and excess redshifts of 40km/s to the NE, which we attribute
to gas disturbed by an interaction with a nuclear spherical outflow. This
nuclear outflow is the origin of the nuclear component observed within the
inner 300pc and it has a mass outflow rate of 0.9Msun/yr. In a region between
1" and 4" north of the nucleus we find a new low sigma component of ionized gas
which we attribute to a high latitude cloud photoionized by the nuclear source.Comment: 17 pages, 13 figures, 1 table; accepted for publication in MNRA
The complex gas kinematics in the nucleus of the Seyfert 2 galaxy NGC 1386: rotation, outflows and inflows
We present optical integral field spectroscopy of the circum-nuclear gas of
the Seyfert 2 galaxy NGC 1386. The data cover the central 7 (530 680 pc) at a spatial resolution of 0.9"
(68 pc), and the spectral range 5700-7000 \AA\ at a resolution of 66 km
s. The line emission is dominated by a bright central component, with
two lobes extending 3 north and south of the
nucleus. We identify three main kinematic components. The first has low
velocity dispersion ( 90 km s), extends over the
whole field-of-view, and has a velocity field consistent with gas rotating in
the galaxy disk. We interpret the lobes as resulting from photoionization of
disk gas in regions where the AGN radiation cones intercept the disk. The
second has higher velocity dispersion ( 200 km s)
and is observed in the inner 150 pc around the continuum peak. This component
is double peaked, with redshifted and blueshifted components separated by
500 km s. Together with previous HST imaging, these features
suggest the presence of a bipolar outflow for which we estimate a mass outflow
rate of 0.1 M yr. The third
component is revealed by velocity residuals associated with enhanced velocity
dispersion and suggests that outflow and/or rotation is occurring approximately
in the equatorial plane of the torus. A second system of velocity residuals may
indicate the presence of streaming motions along dusty spirals in the disk.Comment: 24 pages, 16 figures, 3 tables, interesting results, accepted for
publication in Ap
Solving the Shortest Vector Problem in Lattices Faster Using Quantum Search
By applying Grover's quantum search algorithm to the lattice algorithms of
Micciancio and Voulgaris, Nguyen and Vidick, Wang et al., and Pujol and
Stehl\'{e}, we obtain improved asymptotic quantum results for solving the
shortest vector problem. With quantum computers we can provably find a shortest
vector in time , improving upon the classical time
complexity of of Pujol and Stehl\'{e} and the of Micciancio and Voulgaris, while heuristically we expect to find a
shortest vector in time , improving upon the classical time
complexity of of Wang et al. These quantum complexities
will be an important guide for the selection of parameters for post-quantum
cryptosystems based on the hardness of the shortest vector problem.Comment: 19 page
Sustainable Energy Storage
This Final Design Review document covers the work we, students at California Polytechnic State University – San Luis Obispo, have performed in collaboration with Mr. Harish Bhutani and Dr. Mohammad Noori. The project’s intent is to create an energy storage system for off-grid and developing region applications using alternative technologies to lithium-ion battery storage. We plan to manufacture and assemble a scale model of the energy storage system to prove effectiveness and practicality. This system will store enough energy to power basic appliances and essential devices for a house or community. The chosen design direction will be a flywheel, as it is very energy dense and is less complex than other options. The following will outline the entire design process, including the ideas we created, the design challenges, and the testing of our physical build. To meet climate change goals set around the globe, our world needs to head towards a more sustainable future, and the energy sector is no exception. This project aims to help with the research and design of this new field and present a final product that will have a meaningful impact on our world
The Origin of Massive Compact Galaxies: Lessons from IllustrisTNG
We investigate the formation and evolution of z=0 massive compact galaxies
(MCGs) in the IllustrisTNG cosmological simulation. We found that, as in
observations, MCGs are mainly old (median age Gyr), have
super-solar metallicities (median ) and are
-enhanced (median ). The age distribution extends
to younger ages, however, and a few MCGs are as young as Gyr. In
general, MCGs assemble their mass early and accrete low angular momentum gas,
significantly increasing their mass while growing their size much slower. A
small fraction of MCGs follow another evolutionary path, going through a
compaction event, with their sizes shrinking by 40% or more. The accretion of
low angular momentum gas leads to enhanced SMBH growth, and MCGs reach the
threshold SMBH mass of - when kinetic
AGN feedback kicks in and quenches the galaxy - earlier than non-compact
galaxies. Comparing MCGs to a sample of median-sized quiescent galaxies matched
in effective velocity dispersion, we find that their accretion histories are
very different. 71% of MCGs do not merge after quenching compared to 37% of
median-sized quiescent galaxies. Moreover, tracing these populations back in
time, we find that at least a third of median-sized quiescent galaxies do not
have a compact progenitor, underscoring that both dry mergers and progenitor
bias effects are responsible for the differences in the kinematics and stellar
population properties of MCGs and median-sized quiescent galaxies.Comment: 15 pages, 15 figures (not including appendices). Accepted for
publication in the Monthly Notices of the Royal Astronomical Societ
Election Verifiability for Helios under Weaker Trust Assumptions
Most electronic voting schemes aim at providing verifiability: voters should trust the result without having to rely on some authorities. Actually, even a prominent voting system like Helios cannot fully achieve verifiability since a dishonest bulletin board may add ballots. This problem is called ballot stuffing. In this paper we give a definition of verifiability in the computational model to account for a malicious bulletin board that may add ballots. Next, we provide a generic construction that transforms a voting scheme that is verifiable against an honest bulletin board and an honest registration authority (weak verifiability) into a verifiable voting scheme under the weaker trust assumption that the registration authority and the bulletin board are not simultaneously dishonest (strong verifiability). This construction simply adds a registration authority that sends private credentials to the voters, and publishes the corresponding public credentials. We further provide simple and natural criteria that imply weak verifiability. As an application of these criteria, we formally prove the latest variant of Helios by Bernhard, Pereira and Warinschi weakly verifiable. By applying our generic construction we obtain a Helios-like scheme that has ballot privacy and strong verifiability (and thus prevents ballot stuffing). The resulting voting scheme, Helios-C, retains the simplicity of Helios and has been implemented and tested
ROYALE: A Framework for Universally Composable Card Games with Financial Rewards and Penalties Enforcement
While many tailor made card game protocols are known, the vast majority of those suffer from three main issues: lack of mechanisms for distributing financial rewards and punishing cheaters, lack of composability guarantees and little flexibility, focusing on the specific game of poker. Even though folklore holds that poker protocols can be used to play any card game, this conjecture remains unproven and, in fact, does not hold for a number of protocols (including recent results). We both tackle the problem of constructing protocols for general card games and initiate a treatment of such protocols in the Universal Composability (UC) framework, introducing an ideal functionality that captures general card games constructed from a set of core card operations. Based on this formalism, we introduce Royale, the first UC-secure general card games which supports financial rewards/penalties enforcement. We remark that Royale also yields the first UC-secure poker protocol. Interestingly, Royale performs better than most previous works (that do not have composability guarantees), which we highlight through a detailed concrete complexity analysis and benchmarks from a prototype implementation
An outflow in the Seyfert ESO 362-G18 revealed by Gemini-GMOS/IFU Observations
We present two-dimensional stellar and gaseous kinematics of the inner 0.7
1.2 kpc of the Seyfert galaxy ESO 362-G18, derived from optical
spectra obtained with the GMOS/IFU on the Gemini South telescope at a spatial
resolution of 170 pc and spectral resolution of 36 km s. ESO
362-G18 is a strongly perturbed galaxy of morphological type Sa or S0/a, with a
minor merger approaching along the NE direction. Previous studies have shown
that the [OIII] emission shows a fan-shaped extension of 10\arcsec\
to the SE. We detect the [OIII] doublet, [NII] and H emission lines
throughout our field of view. The stellar kinematics is dominated by circular
motions in the galaxy plane, with a kinematic position angle of
137. The gas kinematics is also dominated by rotation, with
kinematic position angles ranging from 122 to 139. A
double-Gaussian fit to the [OIII]5007 and H lines, which
have the highest signal to noise ratios of the emission lines, reveal two
kinematic components: (1) a component at lower radial velocities which we
interpret as gas rotating in the galactic disk; and (2) a component with line
of sight velocities 100-250 km s higher than the systemic velocity,
interpreted as originating in the outflowing gas within the AGN ionization
cone. We estimate a mass outflow rate of 7.4 10 M
yr in the SE ionization cone (this rate doubles if we assume a biconical
configuration), and a mass accretion rate on the supermassive black hole (SMBH)
of 2.2 10 M yr. The total ionized gas mass
within 84 pc of the nucleus is 3.3 10 M; infall
velocities of 34 km s in this gas would be required to feed both
the outflow and SMBH accretion.Comment: 18 pages, 14 figure
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