41,197 research outputs found
Made-to-Measure models of the Galactic Box/Peanut bulge: stellar and total mass in the bulge region
We construct dynamical models of the Milky Way's Box/Peanut (B/P) bulge,
using the recently measured 3D density of Red Clump Giants (RCGs) as well as
kinematic data from the BRAVA survey. We match these data using the NMAGIC
Made-to-Measure method, starting with N-body models for barred discs in
different dark matter haloes. We determine the total mass in the bulge volume
of the RCGs measurement (+-2.2 x +- 1.4 x +- 1.2 kpc) with unprecedented
accuracy and robustness to be 1.84 +- 0.07 x10^10 Msun. The stellar mass in
this volume varies between 1.25-1.6 x10^10 Msun, depending on the amount of
dark matter in the bulge. We evaluate the mass-to-light and mass-to-clump
ratios in the bulge and compare them to theoretical predictions from population
synthesis models. We find a mass-to-light ratio in the K-band in the range
0.8-1.1. The models are consistent with a Kroupa or Chabrier IMF, but a
Salpeter IMF is ruled out for stellar ages of 10 Gyr. To match predictions from
the Zoccali IMF derived from the bulge stellar luminosity function requires
about 40% or 0.7 x10^10 Msun dark matter in the bulge region. The BRAVA data
together with the RCGs 3D density imply a low pattern speed for the Galactic
B/P bulge of 25-30 km.s-1.kpc-1. This would place the Galaxy among the slow
rotators (R >= 1.5). Finally, we show that the Milky Way's B/P bulge has an
off-centred X structure, and that the stellar mass involved in the peanut shape
accounts for at least 20% of the stellar mass of the bulge, significantly
larger than previously thought.Comment: Accepted for publication in MNRA
Experimental study of optimal measurements for quantum state tomography
Quantum tomography is a critically important tool to evaluate quantum
hardware, making it essential to develop optimized measurement strategies that
are both accurate and efficient. We compare a variety of strategies using
nearly pure test states. Those that are informationally complete for all states
are found to be accurate and reliable even in the presence of errors in the
measurements themselves, while those designed to be complete only for pure
states are far more efficient but highly sensitive to such errors. Our results
highlight the unavoidable tradeoffs inherent to quantum tomography.Comment: 5 pages, 3 figure
The 2D analogue of the Reissner-Nordstrom solution
A two-dimensional (2D) dilaton gravity model, whose static solutions have the
same features of the Reissner-Nordstrom solutions, is obtained from the
dimensional reduction of a four-dimensional (4D) string effective action
invariant under S-duality transformations. The black hole solutions of the 2D
model and their relationship with those of the 4D theory are discussed.Comment: 5 pages, Plain-Tex, no figure
Herschel GASPS spectral observations of T Tauri stars in Taurus: unraveling far-infrared line emission from jets and discs
At early stages of stellar evolution young stars show powerful jets and/or
outflows that interact with protoplanetary discs and their surroundings.
Despite the scarce knowledge about the interaction of jets and/or outflows with
discs, spectroscopic studies based on Herschel and ISO data suggests that gas
shocked by jets and/or outflows can be traced by far-IR (FIR) emission in
certain sources. We want to provide a consistent catalogue of selected atomic
([OI] and [CII]) and molecular (CO, OH, and HO) line fluxes observed in
the FIR, separate and characterize the contribution from the jet and the disc
to the observed line emission, and place the observations in an evolutionary
picture. The atomic and molecular FIR (60-190 ) line emission of
protoplanetary discs around 76 T Tauri stars located in Taurus are analysed.
The observations were carried out within the Herschel key programme Gas in
Protoplanetary Systems (GASPS). The spectra were obtained with the
Photodetector Array Camera and Spectrometer (PACS). The sample is first divided
in outflow and non-outflow sources according to literature tabulations. With
the aid of archival stellar/disc and jet/outflow tracers and model predictions
(PDRs and shocks), correlations are explored to constrain the physical
mechanisms behind the observed line emission. The much higher detection rate of
emission lines in outflow sources and the compatibility of line ratios with
shock model predictions supports the idea of a dominant contribution from the
jet/outflow to the line emission, in particular at earlier stages of the
stellar evolution as the brightness of FIR lines depends in large part on the
specific evolutionary stage. [Abridged Abstract]Comment: 37 pages, 27 figures, accepted for publication in A&
The impact of human resources practices on consumers’ investment intentions
Purpose: Research has shown that corporate policies affect customers’ decisions. The purpose of this paper is to focus on the influence of human resources (HR) practices on investment intentions in the financial sector. Design/methodology/approach: Data were obtained from 548 managers and management students. Participants were presented real news regarding two banks with contrasting HR practices. Subsequently, they had to choose – from a given virtual amount – their investment allocations. Findings: Results primarily showed that participants decided to invest more money in the bank which was more profitable to them, regardless of that bank’s HR practice. But, most importantly, when the news was specifically addressed to the in-group (managers), participants decided to invest more money in the bank with the HR practice by which they identified more, although being less profitable to them. Originality/value: The findings demonstrate the urgency for organizations to manage effectively their HR practices, as they serve as a vehicle to corporate reputation, thus affecting the relationship with the stakeholders and investors’ decisions.info:eu-repo/semantics/acceptedVersio
High sensitivity phonon-mediated kinetic inductance detector with combined amplitude and phase read-out
The development of wide-area cryogenic light detectors with good energy
resolution is one of the priorities of next generation bolometric experiments
searching for rare interactions, as the simultaneous read-out of the light and
heat signals enables background suppression through particle identification.
Among the proposed technological approaches for the phonon sensor, the
naturally-multiplexed Kinetic Inductance Detectors (KIDs) stand out for their
excellent intrinsic energy resolution and reproducibility. To satisfy the large
surface requirement (several cm) KIDs are deposited on an insulating
substrate that converts the impinging photons into phonons. A fraction of
phonons is absorbed by the KID, producing a signal proportional to the energy
of the original photons. The potential of this technique was proved by the
CALDER project, that reached a baseline resolution of 1547 eV RMS by
sampling a 22 cm Silicon substrate with 4 Aluminum KIDs. In this
paper we present a prototype of Aluminum KID with improved geometry and quality
factor. The design improvement, as well as the combined analysis of amplitude
and phase signals, allowed to reach a baseline resolution of 824 eV by
sampling the same substrate with a single Aluminum KID
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