Miracle-dz/UniFAR-FTUs huggingface dataset:
Cosmological fast radio bursts as a cosmic ruler

We discuss the possibility of using fast radio bursts (FRBs)-if cosmological-as a viable cosmic probe. We find that the contribution of the host galaxies to the detected dispersion measures can be inapparent for the FRBs that are not from galaxy centers or star-forming regions. The inhomogeneity of the intergalactic medium (IGM), however, causes significant deviation of the dispersion measure from that predicted in the simplified homogeneous IGM model for an individual event. Fortunately, with sufficient FRBs along different sightlines but within a very narrow redshift interval (e. g., Delta z similar to 0.05), the mean obtained from averaging observed dispersion measures does not suffer such a problem and hence may be used as a cosmic probe. We show that in the optimistic case (e. g., about 20 FRBs in each Delta z have been measured; the most distant FRBs were at redshift >= 3; the host galaxies and the FRB sources contribute little to the detected dispersion measures) and with all the uncertainties (i.e., the inhomogeneity of the IGM, the contribution and uncertainty of host galaxies, and the evolution and error of f(IGM)) considered, FRBs could help constrain the equation of state of dark energy.
Exploring the nature of the broadband variability in the flat spectrum radio quasar 3C 273

The detailed investigation of the broadband flux variability in the blazar 3C 273 allowed us to probe the location and size of emission regions and their physical conditions. We conducted correlation studies of the flaring activity in 3C 273, which was observed for the period between 2008 and 2012. The observed broadband variations were investigated using the structure function and the discrete correlation function methods. Starting from the commonly used power spectral density (PSD) analysis at X-ray frequencies, we extended our investigation to characterise the nature of variability at radio, optical, and γ -ray frequencies. The PSD analysis showed that the optical and infrared light-curve slopes are consistent with the slope of white-noise processes, while the PSD slopes at radio, X-ray, and γ -ray energies are consistent with red-noise processes. We found that the estimated fractional variability amplitudes strongly depend on the observed frequency. The flux variations at γ -ray and mm-radio bands are found to be significantly correlated. Using the estimated time lag of (110 ± 27) days between γ -ray and radio light-curves, where γ -ray variations lead the radio bands, we constrained the location of the γ -ray emission region at a de-projected distance of 1.2 ± 0.9 pc from the jet apex. Flux variations at X-ray bands were found to have a significant correlation with variations at both radio and γ -ray energies. The correlation between X-ray and γ -ray light curves indicates two possible time lags, which suggests that two components are responsible for the X-ray emission. A negative time lag of −(50 ± 20) days, where the X-rays are leading the emission, suggests that X-rays are emitted closer to the jet apex from a compact region (0.02–0.05 pc in size), most likely from the corona at a distance of (0.5 ± 0.4) pc from the jet apex. A positive time lag of (110 ± 20) days ( γ -rays are leading the emission) suggests a jet-base origin of the other X-ray component at ~4 to 5 pc from the jet apex. The flux variations at radio frequencies were found to be well correlated with each other such that the variations at higher frequencies are leading the lower frequencies, which is expected from the standard shock-in-jet model.
An evaluation of Lean deployment in Irish micro-enterprises

This study investigates the reasons for Lean deployment in Micro Enterprises, the types of tools used, the challenges involved and the results obtained in Micro Enterprises in Ireland. Qualitative interviews were conducted with 22 Micro Enterprises in Ireland that have started Lean implementation over the last three years. Lean offers many benefits to Micro Enterprises similar to those observed in larger-sized enterprises, including improved productivity, quality and reduced costs. In addition, leadership support for Lean in Micro Enterprises is not a challenge for Lean deployment as many Micro Enterprises are owner-managers and thus embrace and facilitate the deployment of Lean in organisations. Furthermore, a Critical success factor for Lean in Micro Enterprises is government support and availability of Lean mentorship. Further longitudinal studies on Micro Enterprises would help study how Lean evolves in these organisations over time especially in enterprises who have employed Lean for several Leans. This is one of the first studies specific to the practical application of Lean in ME’s in Ireland and globally. For academics and practitioners and informing government funding policy, this study demonstrates that Lean can successfully be deployed in Micro Enterprises. This study demonstrates that government supports can aid Lean and enhance economic competitiveness.
Quantum Gravity: Has Spacetime Quantum Properties?

The incompatibility between GR and QM is generally seen as a sufficient motivation for the development of a theory of Quantum Gravity. If - so a typical argumentation - QM gives a universally valid basis for the description of all natural systems, then the gravitational field should have quantum properties. Together with the arguments against semi-classical theories of gravity, this leads to a strategy which takes a quantization of GR as the natural avenue to Quantum Gravity. And a quantization of the gravitational field would in some sense correspond to a quantization of geometry. Spacetime would have quantum properties. But, this strategy will only be successful, if gravity is a fundamental interaction. - What, if gravity is instead an intrinsically classical phenomenon? Then, if QM is nevertheless fundamentally valid, gravity can not be a fundamental interaction. An intrinsically classical gravity in a quantum world would have to be an emergent, induced or residual, macroscopic effect, caused by other interactions. The gravitational field (as well as spacetime) would not have any quantum properties. A quantization of GR would lead to artifacts without any relation to nature. The serious problems of all approaches to Quantum Gravity that start from a direct quantization of GR or try to capture the quantum properties of gravity in form of a 'graviton' dynamics - together with the, meanwhile, rich spectrum of approaches to an emergent gravity and/or spacetime - make this latter option more and more interesting for the development of a theory of Quantum Gravity. The most advanced emergent gravity (and spacetime) scenarios are of an information-theoretical, quantum-computational type.
ELECTRONIC SPECTROSCOPY OF MEDIUM-SIZED POLYCYCLIC AROMATIC HYDROCARBONS: IMPLICATIONS FOR THE CARRIERS OF THE 2175 Å UV BUMP

Mixtures of polycyclic aromatic hydrocarbons (PAHs) have been produced by means of laser pyrolysis. The main fraction of the extracted PAHs was primarily medium-sized, up to a maximum size of 38 carbon atoms per molecule. The use of different extraction solvents and subsequent chromatographic fractionation provided mixtures of different size distributions. UV–VIS absorption spectra have been measured at low temperature by matrix isolation spectroscopy and at room temperature with PAHs as film-like deposits on transparent substrates. In accordance with semi-empirical calculations, our findings suggest that large PAHs with sizes around 50–60 carbon atoms per molecule could be responsible for the interstellar UV bump at 217.5 nm.
CMB LENSING POWER SPECTRUM BIASES FROM GALAXIES AND CLUSTERS USING HIGH-ANGULAR RESOLUTION TEMPERATURE MAPS

The lensing power spectrum from cosmic microwave background (CMB) temperature maps will be measured with unprecedented precision with upcoming experiments, including upgrades to the Atacama Cosmology Telescope and the South Pole Telescope. Achieving significant improvements in cosmological parameter constraints, such as percent level errors on σ8 and an uncertainty on the total neutrino mass of ∼50 meV, requires percent level measurements of the CMB lensing power. This necessitates tight control of systematic biases. We study several types of biases to the temperature-based lensing reconstruction signal from foreground sources such as radio and infrared galaxies and the thermal Sunyaev–Zel'dovich effect from galaxy clusters. These foregrounds bias the CMB lensing signal due to their non-Gaussian nature. Using simulations as well as some analytical models we find that these sources can substantially impact the measured signal if left untreated. However, these biases can be brought to the percent level if one masks galaxies with fluxes at 150 GHz above 1 mJy and galaxy clusters with masses above Mvir = 1014 M☉. To achieve such percent level bias, we find that only modes up to a maximum multipole of lmax ∼ 2500 should be included in the lensing reconstruction. We also discuss ways to minimize additional bias induced by such aggressive foreground masking by, for example, exploring a two-step masking and in-painting algorithm.
Mapping the prestellar core Ophiuchus D (L1696A) in ammonia

Context. The gas kinetic temperature in the centres of starless, high -density cores is predicted to fall as low as 5-6 K. The temperature gradient, which affects the dynamics and chemistry of these objects, should be discernible with radio interferometers reaching a spatial resolution of 1000 AU or better. Aims. The aim of this study was to determine the kinetic temperature distribution in the low-mass prestellar core Oph D where previous observations suggest a very low central temperature. Methods. The densest part of the Oph D core was mapped in the NH3(1,1) and (2,2) inversion lines using the Very Large Array (VLA). The physical quantities were derived from the observed spectra by fitting the hyperfine structure of the lines, and subseq uently the temperature distribution of Oph D was calculated using the standard rotational temperature techniques. A physical model of the cores was constructed, and the simulated spectra after radiative transfer calculations with a 3D Monte Carlo code were compared with the observed spectra. Temperature, density, and ammonia abundance of the core model were tuned until a satisfactory match with the observation was obtained. Results. The high resolution of the interferometric data reveals tha t the southern part of Oph D comprises of two small cores in consistence with the 1.3mm dust continuum map of Motte et al. (1998, A&A, 336, 150). The gas kinetic temperatures, as derived from ammonia towards the centres of the southern and northern core are 7.4 and 8.9 K, respectively. These values represent line-ofsight averages using the LTE assumption. A model using modifi ed Bonnor-Ebert spheres, in which the temperature decreases to 6.1 K and 8.9 K in the centres of southern and northern core, matched the observed values satisfactorily. The southern core, which has more steep temperature gradient, has central density of nc = 4× 10 6 cm −3 , and the data suggests depletion of ammonia within 700 AU from the centre. The northern core, which is almost isothermal, seems to be less dense. The radial velocity gradients in t hese cores are almost opposite in direction, which may be an indication that turbulent fragmentation has a role in the formation of thes e cores. The observed masses of the cores are only∼ 0.2 M⊙. Their potential collapse could lead to formation of brown dwarfs or low-mass stars.
Recurrence to Shrinking Targets on Typical Self-Affine Fractals

Abstract We explore the problem of finding the Hausdorff dimension of the set of points that recur to shrinking targets on a self-affine fractal. To be exact, we study the dimension of a certain related symbolic recurrence set. In many cases, this set is equivalent to the recurring set on the fractal.
Trade liberalisation, imperfect pass-through and cost of living: evidence from Chinese cities

This article investigates the consumption effect of trade liberalisation through changes in the cost of living in Chinese cities. We use fixed effects model and dynamic panel model based on household survey data from 2002 to 2009. We identify the imperfect pass-through mechanism of tariffs and non-tariff measures at city level. The main findings show that the aggregate cost of living in Chinese cities is an inverted-V trend. Tariffs reduction and the high incidence of non-tariff measures can decrease cost of living in Chinese cities, which improves the overall consumption welfare and narrows down the regional disparities. The consumption effects are heterogenous due to the diverse spatial effects, demand effects and competition effects across Chinese cities. Cities with a high expenditure share of manufactured goods have a larger effect on the reduction of cost of living. Tariffs have a larger marginal effect in small cities and cities with high level of privatisation. While the incidence of non-tariff measures has a larger marginal effect in small cities and cities with low level of privatisation.
Timing of pulsars found in a deep Parkes multibeam survey

We have carried out a sensitive radio pulsar survey along the northern Galactic plane ($50^{\circ} < l < 60^{\circ}$ and $|b| \lapp 2^{\circ}$) using the Parkes 20-cm multibeam system. We observed each position for 70-min on two separate epochs. Our analyses to date have so far resulted in the detection of 32 pulsars, of which 17 were previously unknown. Here we summarize the observations and analysis and present the timing observations of 11 pulsars and discovery parameters for a further 6 pulsars. We also present a timing solution for the 166-ms bursting pulsar, PSR~J1938+2213, previously discovered during an Arecibo drift-scan survey. Our survey data for this pulsar show that the emission can be described by a steady pulse component with bursting emission, which lasts for typically 20--25 pulse periods, superposed. Other new discoveries are the young 80.1-ms pulsar PSR~J1935+2025 which exhibits a significant amount of unmodeled low-frequency noise in its timing residuals, and the 4.2-ms pulsar PSR~J1935+1726 which is in a low-mass binary system with a 90.7-day circular orbit.
Area law violations and quantum phase transitions in modified Motzkin walk spin chains

Area law violations for entanglement entropy in the form of a square root have recently been studied for one-dimensional frustration-free quantum systems based on the Motzkin walks and their variations. Here we consider a Motzkin walk with a different Hilbert space on each step of the walk spanned by the elements of a symmetric inverse semigroup with the direction of each step governed by its algebraic structure. This change alters the number of paths allowed in the Motzkin walk and introduces a ground state degeneracy that is sensitive to boundary perturbations. We study the frustration-free spin chains based on three symmetric inverse semigroups, S13, S23 and S12. The system based on S13 and S23 provides examples of quantum phase transitions in one dimension, with the former exhibiting a transition between the area law and a logarithmic violation of the area law and the latter providing an example of transition from logarithmic scaling to a square root scaling in the system size, mimicking a colored S13 system. The system with S12 is much simpler and produces states that continue to obey the area law.
Investigating the origin and spectroscopic variability of the near-infrared H I lines in the Herbig star VV Ser

The origin of the near-infrared (NIR) HI emission lines in young stellar objects are not yet understood. To probe it, we present multi-epoch LBT-LUCIFER spectroscopic observations of the Pa{\delta}, Pa{\beta}, and Br{\gamma} lines observed in the Herbig star VVSer, along with VLTI-AMBER Br{\gamma} spectro-interferometric observations at medium resolution. Our spectroscopic observations show line profile variability in all the HI lines. The strongest variability is observed in the redshifted part of the line profiles. The Br{\gamma} spectro-interferometric observations indicate that the Br{\gamma} line emitting region is smaller than the continuum emitting region. To interpret our results, we employed radiative transfer models with three different flow configurations: magnetospheric accretion, a magneto-centrifugally driven disc wind, and a schematic bipolar outflow. Our models suggest that the HI line emission in VVSer is dominated by the contribution of an extended wind, perhaps a bipolar outflow. Although the exact physical process for producing such outflow is not known, this model is capable of reproducing the averaged single-peaked line profiles of the HI lines. Additionally, the observed visibilities, differential and closure phases are best reproduced when a wind is considered. Nevertheless, the complex line profiles and variability could be explained by changes in the relative contribution of the magnetosphere and/or winds to the line emission. This might indicate that the NIR HI lines are formed in a complex inner disc region where inflow and outflow components might coexist. Furthermore, the contribution of each of these mechanisms to the line appears time variable, suggesting a non-steady accretion/ejection flow.
Quantum criticality at the Anderson transition: A typical medium theory perspective

We present a complete analytical and numerical solution of the Typical Medium Theory (TMT) of the Anderson metal-insulator transition. This theory, which self-consistently calculates the typical amplitude of the electronic wave-functions, represents the conceptually simplest order-parameter formulation for the Anderson transition. Here we classify all possible forms of the critical behavior that can be found within such a mean-field approach, providing insight on how possible interaction-induced renormalizations of the disorder potential may produce qualitative modifications. Using the new perspective obtained from our full analytic solution, we also formulate a simplified description of the leading critical behavior, and thus obtain an effective Landau theory for Anderson localization.
Agegraphic dark energy: growth index and cosmological implications

We study the main cosmological properties of the agegraphic dark energy model at the expansion and perturbation levels. Initially, using the latest cosmological data we implement a joint likelihood analysis in order to constrain the cosmological parameters. Then we test the performance of the agegraphic dark energy model at the perturbation level and we define its difference from the usual $\Lambda$CDM model. Within this context, we verify that the growth index of matter fluctuations depends on the choice of the considered agegraphic dark energy (homogeneous or clustered). In particular, assuming a homogeneous agegraphic dark energy we find, for the first time, that the asymptotic value of the growth index is $\gamma \approx 5/9$, which is close to that of the usual $\Lambda$ cosmology, $\gamma^{(\Lambda)} \approx 6/11$. Finally, if the distribution of dark energy is clustered then we obtain $\gamma \approx 1/2$ which is $\sim 8\%$ smaller than that of the $\Lambda$CDM model.
LYMAN-ALPHA SPECTRA FROM MULTIPHASE OUTFLOWS, AND THEIR CONNECTION TO SHELL MODELS

We perform Lyman-α (Lyα) Monte-Carlo radiative transfer calculations on a suite of 2500 models of multiphase, outflowing media, which are characterized by 14 parameters. We focus on the Lyα spectra emerging from these media and investigate which properties are dominant in shaping the emerging Lyα profile. Multiphase models give rise to a wide variety of emerging spectra, including single-, double-, and triple-peaked spectra. We find that the dominant parameters in shaping the spectra include (i) the cloud covering factor, fc, which is in agreement with earlier studies, and (ii) the temperature and number density of residual H i in the hot ionized medium. We attempt to reproduce spectra emerging from multiphase models with “shell models” which are commonly used to fit observed Lyα spectra, and investigate the connection between shell-model parameters and the physical parameters of the clumpy media. In shell models, the neutral hydrogen content of the shell is one of the key parameters controlling Lyα radiative transfer. Because Lyα spectra emerging from multiphase media depend much less on the neutral hydrogen content of the clumps, the shell-model parameters such as H i column density (but also shell velocity and dust content) are generally not well matched to the associated physical parameters of the clumpy media.
A DARK ENERGY CAMERA SEARCH FOR MISSING SUPERGIANTS IN THE LMC AFTER THE ADVANCED LIGO GRAVITATIONAL-WAVE EVENT GW150914

The collapse of a stellar core is expected to produce gravitational waves (GWs), neutrinos, and in most cases a luminous supernova. Sometimes, however, the optical event could be significantly less luminous than a supernova and a direct collapse to a black hole, where the star just disappears, is possible. The GW event GW150914 was detected by the LIGO Virgo Collaboration via a burst analysis that gave localization contours enclosing the Large Magellanic Cloud (LMC). Shortly thereafter, we used DECam to observe 102 deg2 of the localization area, including 38 deg2 on the LMC for a missing supergiant search. We construct a complete catalog of LMC luminous red supergiants, the best candidates to undergo invisible core collapse, and collected catalogs of other candidates: less luminous red supergiants, yellow supergiants, blue supergiants, luminous blue variable stars, and Wolf–Rayet stars. Of the objects in the imaging region, all are recovered in the images. The timescale for stellar disappearance is set by the free-fall time, which is a function of the stellar radius. Our observations at 4 and 13 days after the event result in a search sensitive to objects of up to about 200 solar radii. We conclude that it is unlikely that GW150914 was caused by the core collapse of a relatively compact supergiant in the LMC, consistent with the LIGO Collaboration analyses of the gravitational waveform as best interpreted as a high mass binary black hole merger. We discuss how to generalize this search for future very nearby core-collapse candidates.