Miracle-dz/UniFAR-FTUs huggingface dataset:
The Megaparsec Environments of Radio Galaxies

This paper presents an analysis of the Mpc environments of powerful radio galaxies (with z < 0.5 and radio powers P408 MHz > 1026 W Hz-1, using H0 = 50 km s-1 Mpc-1 and q0 = 0.0). We find that most radio galaxies reside in rather poor clusters (or loosely “groups”) that have three to 10 members (whose magnitudes are brighter than -19 and that lie within 0.5 Mpc of the radio galaxy). Although there is a possibility that up to 5% of all radio galaxies are field galaxies (and up to 13% are pairs), our result is consistent with all radio galaxies being in groups. The distributions in group richness and Bautz-Morgan (BM) class of radio-selected groups are different from those of optically selected groups. Radio-selected groups are preferentially of BM type I, while optically selected groups are preferentially of BM type III. The richness distributions are comparable for rich groups (with N0.5−19>12); however, poor radio-selected groups are ~1.5 times less abundant. A second result is that the environments of FR I and FR II radio galaxies are different. FR I galaxies are found on average in richer groups than FR II galaxies. At low redshifts, FR II galaxies avoid rich groups; however, they do exist in rich groups at high redshifts. Most groups surrounding FR I galaxies (FR I groups) are of Bautz-Morgan class I, while most groups surrounding FR II galaxies (FR II groups) are of Bautz-Morgan class III. FR I groups have relatively fewer blue members than FR II groups. FR I galaxies are relatively closer to the nominal group centers than FR II galaxies. About twice as many FR II galaxies as FR I galaxies show either signatures of galaxy interactions and/or have a neighbor within 50 kpc. Together with the results presented in the first paper in this series, we argue that FR I sources are associated with centrally dominant cD-like galaxies that have been exposed to galactic cannibalism while FR II sources are more often associated with galaxies that are involved with galaxy interactions. Finally, we show that the high- and low-redshift FR I and FR II groups belong to separate subsets of groups and that each subset is different from optically selected groups. We propose that FR I groups are dynamically more evolved and FR II groups less evolved than normal groups. Since no correlations exist between the properties of group members and the radio activity of the FR I and FR II sources, radio-selected groups can still be used to study the general evolution of galaxies in groups. Since radio-selected groups are richer at high redshifts, they provide a good method of finding distant groups.
Quantitative estimates of magnetic field reconnection properties from electric and magnetic field measurements

Reconnection occurs in a reconnection magnetic field geometry when there are positive electric field components tangential to the magnetopause and a magnetic field component normal to it. Because these three components are the smallest of the six electric and magnetic fields, their magnitudes are difficult to determine because of errors in, or oscillations of, the assumed constant direction normal to the current sheet. A method is described for minimizing these errors by appropriate selection of the normal direction and by analyzing the correlations between the large normal electric field and the large tangential magnetic field. The correlation coefficients are equal to ratios of the small fields, which are combined with the less accurate measurements of the averages of the small fields to produce best estimates of the small fields. For more than 120 magnetopause crossings, about 40% had such correlations that signify static conditions during those crossings. This method is applied to 22 polar subsolar magnetopause crossings to show that most were located in the ion diffusion region, as defined by the change of the total magnetic field, and that 14 had a large and steady reconnection rate with a zero parallel electric field. In these events the reconnection rate decreased with increasing guide magnetic field.
Neutral Atom Diffusion in a Partially Ionized Prominence Plasma

The support of solar prominences is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force. Because the prominence plasma is only partially ionized, this support needs to be understood in terms of the frictional coupling between the neutral and ionized components of the prominence plasma, the efficacy of which depends directly on the ion density. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a plasma with a sufficiently small vertical ion column density, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma and consider the variation of the draining with a variety of prominence parameters. Our calculations show that the loss timescale for hydrogen is much longer than that for helium, which for typical prominence parameters is about one day.
NGC 2180 : a disrupting open cluster?

The spatial dependence of luminosity and mass functions of evolved open clusters is discussed in this work using J and H 2MASS photometry, which allows a wide spatial coverage and proper background determination. The target objects are the intermediate-age open cluster NGC 3680 (� = 286.76 ◦ and b = 16.92 ◦ ), which has been reported as being in an advanced state of dissolution, and NGC 2180 (� = 203.85 ◦ , b = −7.01 ◦ ), a possible dynamically evolved open cluster. At the 1 − σ level, NGC 2180 presents a radial distribution of stars that can be represented by a King law. We conclude that, although in an advanced dynamical state (mass segregated), NGC 3680 does not present strong signs of dissolution, having luminosity and mass functions very similar to those of the τage ≈ 3.2 Gyr open cluster M 67. On the other hand, NGC 2180 appears to have flat, eroded luminosity functions throughout its structure, suggesting that in addition to mass segregation, Galactic tidal stripping has been effective in depleting this object. Accordingly, NGC 2180 may be the missing link between evolved open clusters and remnants. For NGC 2180 we infer a distance to the Sun d� = 0.91 ± 0.15 kpc, an age τage ≈ 710 Myr and an observed stellar mass of mobs ∼ 47 M� . For NGC 3680 we derive an age τage ≈ 1. 6G yr,E(B − V) = 0. 0a ndd� = 1.00 ± 0.09 kpc, confirming previous estimates. The observed stellar mass mobs ≈ 130 Magrees with previous values. We study both clusters in the context of dynamical states estimated from diagnostic diagrams involving photometric and structural parameters. Both objects appear to be dynamically evolved systems. In particular, NGC 2180 is closer to open cluster remnants than NGC 3680.
Scalar perturbations in an $\alpha'$-regularised cosmological bounce

We consider the evolution of scalar perturbations in a class of non-singular bouncing universes obtained with higher-order corrections to the low-energy bosonic string action. We show that previous studies have relied on a singular evolution equation for the perturbations. From a simple criterium we show that scalar perturbations cannot be described at all times by an homogeneous second-order perturbation equation in pre-big bang type universes if we are to regularise the background evolution with higher-order curvature and string coupling corrections, and we propose a new system of first-order coupled differential equations. Given a bouncing cosmological background with inflation driven by the kinetic energy of the dilaton field, we obtain numerically the final power spectra generated from the vacuum quantum fluctuations of the metric and the dilaton field during inflation. Our result shows that both Bardeen's potential, $\Phi(\eta,k)$, and the curvature perturbation in the uniform curvature gauge, ${\mathcal R}(\eta,k)$, lead to a blue spectral distribution long after the transition.
Velocity Trends in the Debris of Sagittarius and the Shape of the Dark Matter Halo of Our Galaxy

Recently, radial velocities have been measured for a large sample of M giants from the Two Micron All Sky Survey catalog, selected to be part of the Sgr dwarf leading and trailing streams. Here we present a comparison of their kinematics to models of the Sgr dwarf debris orbiting Galactic potentials, with halo components of varying degrees of flattening and elongation. This comparison shows that the portion of the trailing stream mapped so far is dynamically young and hence does not provide very stringent constraints on the shape of the Galactic dark matter halo. The leading stream, however, contains slightly older debris, and its kinematics provide for the first time direct evidence that the dark matter halo of our Galaxy has a prolate shape with an average density axis ratio within the orbit of Sgr close to 5/3.
A number?phase Wigner function

One of the most prominent quasiprobability functions in quantum mechanics is the Wigner function, which gives the correct marginal probability functions if integrated over position or momentum. Here we depart from the definition of the position–momentum Wigner function to, by analogy, construct a number–phase Wigner function that, if summed over photon numbers, gives the correct phase distribution and, if integrated over phase, gives the correct photon distribution.
Deep and narrow CO absorption revealing molecular clouds in the Hydra-A brightest cluster galaxy

Active galactic nuclei play a crucial role in the accretion and ejection of gas in galaxies. Although their outflows are well studied, finding direct evidence of accretion has proved very difficult and has so far been done for very few sources. A promising way to study the significance of cold accretion is by observing the absorption of an active galactic nucleus’s extremely bright radio emission by the cold gas lying along the line-of-sight. As such, we present ALMA CO(1-0) and CO(2-1) observations of the Hydra-A brightest cluster galaxy (z=0.054) which reveal the existence of cold, molecular gas clouds along the line-of-sight to the galaxy’s extremely bright and compact mm-continuum source. They have apparent motions relative to the central supermassive black hole of between -43 and -4 km s−1 and are most likely moving along stable, low ellipticity orbits. The identified clouds form part of a ∼109 M⊙, approximately edge-on disc of cold molecular gas. With peak CO(2-1) optical depths of τ=0.88 +0.06−0.06⁠, they include the narrowest and by far the deepest absorption of this type which has been observed to date in a brightest cluster galaxy. By comparing the relative strengths of the lines for the most strongly absorbing region, we are able to estimate a gas temperature of 42+25−11 K and line-of-sight column densities of NCO=2+3−1×1017cm−2 and NH2=7+10−4×1020cm−2⁠.
The EDGE-CALIFA Survey: Interferometric Observations of 126 Galaxies with CARMA

We present interferometric CO observations, made with the Combined Array for Millimeter-wave Astronomy (CARMA) interferometer, of galaxies from the Extragalactic Database for Galaxy Evolution survey (EDGE). These galaxies are selected from the Calar Alto Legacy Integral Field Area (CALIFA) sample, mapped with optical integral field spectroscopy. EDGE provides good-quality CO data (3σ sensitivity before inclination correction, resolution ∼1.4 kpc) for 126 galaxies, constituting the largest interferometric CO survey of galaxies in the nearby universe. We describe the survey and data characteristics and products, then present initial science results. We find that the exponential scale lengths of the molecular, stellar, and star-forming disks are approximately equal, and galaxies that are more compact in molecular gas than in stars tend to show signs of interaction. We characterize the molecular-to-stellar ratio as a function of Hubble type and stellar mass and present preliminary results on the resolved relations between the molecular gas, stars, and star-formation rate. We then discuss the dependence of the resolved molecular depletion time on stellar surface density, nebular extinction, and gas metallicity. EDGE provides a key data set to address outstanding topics regarding gas and its role in star formation and galaxy evolution, which will be publicly available on completion of the quality assessment.
Optical Spectroscopy of GRO J1655–40

We have obtained optical spectra of the soft X-ray transient GRO J1655-40 during different X-ray spectral states (quiescence, high-soft, and hard outburst) between 1994 August and 1997 June. Characteristic features observed during the 1996-1997 high-soft state were: (1) broad absorption lines at Hα and Hβ, probably formed in the inner disk; (2) double-peaked He II λ4686 emission lines, formed in a temperature-inversion layer on the disk surface, created by the soft X-ray irradiation; and (3) double-peaked Hα emission, with a strength associated with the hard X-ray flux, suggesting that it was probably emitted from deeper layers than He II λ4686. The He II λ4686 line profile appeared approximately symmetric, as we would expect from a disk surface with an axisymmetric emissivity function. The Balmer emission, on the other hand, appeared to come only from a double-armed region on the disk, possibly the locations of tidal density waves or spiral shocks. The observed rotational velocities of all the double-peaked lines suggest that the disk was extended slightly beyond its tidal radius. Three classes of lines were identified in the spectra taken in 1994 August-September, during a period of low X-ray activity between two strong X-ray flares: broad absorption, broad (flat-topped) emission, and narrow emission. We have found that the narrow (single-peaked or double-peaked) emission lines cannot be explained by a conventional thin accretion disk model. We propose that the system was in a transient state, in which the accretion disk might have had an extended optically thin cocoon and significant matter outflow, which would also explain the systematic blueshift of the narrow emission lines and the flat-topped profiles of the broad emission lines. After the onset of a hard X-ray flare the disk signatures disappeared, and strong single-peaked Hα and Paschen emission was detected, suggesting that the cocoon became opaque to optical radiation. High-ionization lines disappeared or weakened. Two weeks after the end of the flare, the cocoon appeared to be once again optically thin.
On the weakly nonlinear development of the elliptic instability

Results are presented for the outcome of the elliptic instability, investigated by methods of dynamical-systems theory. Finite-dimensional nonlinear systems are obtained through Galerkin truncation using a systematic truncation criterion that exactly captures any fluid behavior that can also be captured via amplitude expansions. Six different regions of parameter space are explored, corresponding to linear instabilities of different symmetries and temporal types (“steady” or “oscillatory”). Four different kinds of bifurcation behavior are found among the six cases considered. One of these equilibrates at small amplitude, and the others do not, but depart significantly from the unstable equilibrium solution.
Crater 2: An Extremely Cold Dark Matter Halo

We present results from MMT/Hectochelle spectroscopy of 390 red giant candidate stars along the line of sight to the recently discovered Galactic satellite Crater 2. Modeling the joint distribution of stellar positions, velocities, and metallicities as a mixture of Crater 2 and Galactic foreground populations, we identify ∼62 members of Crater 2, for which we resolve a line-of-sight velocity dispersion of = km s−1 and a mean velocity of = km s−1 (solar rest frame). We also resolve a metallicity dispersion of = dex and a mean of = dex that is 0.28 ± 0.14 dex poorer than estimated from photometry. Despite Crater 2's relatively large size (projected halflight radius Rh ∼ 1 kpc) and intermediate luminosity (MV ∼ −8), its velocity dispersion is the coldest that has been resolved for any dwarf galaxy. These properties make Crater 2 the most extreme low-density outlier in dynamical as well as structural scaling relations among the Milky Way’s dwarf spheroidals. Even so, under assumptions of dynamical equilibrium and negligible contamination by unresolved binary stars, the observed velocity distribution implies a gravitationally dominant dark matter halo, with a dynamical mass of M⊙ and a mass-to-light ratio of enclosed within a radius of ∼1 kpc, where the equivalent circular velocity is km s−1.
A stochastically sampled IMF alters the stellar content of simulated dwarf galaxies

Cosmological simulations are reaching the resolution necessary to study ultra-faint dwarf galaxies. Observations indicate that in small populations, the stellar initial mass function (IMF) is not fully populated; rather, stars are sampled in a way that can be approximated as coming from an underlying probability density function. To ensure the accuracy of cosmological simulations in the ultra-faint regime, we present an improved treatment of the IMF. We implement a self-consistent, stochastically populated IMF in cosmological hydrodynamic simulations. We test our method using high-resolution simulations of a Milky Way halo, run to z = 6, yielding a sample of nearly 100 galaxies. We also use an isolated dwarf galaxy to investigate the resulting systematic differences in galaxy properties. We find that a stochastic IMF in simulations makes feedback burstier, strengthening feedback, and quenching star formation earlier in small dwarf galaxies. For galaxies in haloes with mass ≲ 108.5 M⊙, a stochastic IMF typically leads to lower stellar mass compared to a continuous IMF, sometimes by more than an order of magnitude. We show that existing methods of ensuring discrete supernovae incorrectly determine the mass of the star particle and its associated feedback. This leads to overcooling of surrounding gas, with at least ∼10 per cent higher star formation and ∼30 per cent higher cold gas content. Going forwards, to accurately model dwarf galaxies and compare to observations, it will be necessary to incorporate a stochastically populated IMF that samples the full spectrum of stellar masses.
Time Dilation from Spectral Feature Age Measurements of Type Ia Supernovae

We have developed a quantitative, empirical method for estimating the age of Type Ia supernovae (SNe Ia) from a single spectral epoch. The technique examines the goodness of fit of spectral features as a function of the temporal evolution of a large database of SNe Ia spectral features. When a SN Ia spectrum with good signal-to-noise ratio over the rest frame range 3800 to 6800 A is available, the precision of a spectral feature age (SFA) is (1-sigma) ~ 1.4 days. SFA estimates are made for two spectral epochs of SN 1996bj (z=0.574) to measure the rate of aging at high redshift. In the 10.05 days which elapsed between spectral observations, SN 1996bj aged 3.35 $\pm$ 3.2 days, consistent with the 6.38 days of aging expected in an expanding Universe and inconsistent with no time dilation at the 96.4 % confidence level. The precision to which individual features constrain the supernova age has implications for the source of inhomogeneities among SNe Ia.
An Enormous Molecular Gas Flow in the RX J0821+0752 Galaxy Cluster

We present recent Chandra X-ray observations of the RX J0821.0+0752 galaxy cluster, in addition to ALMA observations of the CO(1–0) and CO(3–2) line emission tracing the molecular gas in its central galaxy. All of the CO line emission, originating from a molecular gas reservoir, is located several kiloparsecs away from the nucleus of the central galaxy. The cold gas is concentrated into two main clumps surrounded by a diffuse envelope. They form a wide filament coincident with a plume of bright X-ray emission emanating from the cluster core. This plume encompasses a putative X-ray cavity that is only large enough to have uplifted a small percent of the molecular gas. Unlike other brightest cluster galaxies, stimulated cooling, where X-ray cavities lift low-entropy cluster gas until it becomes thermally unstable, cannot have produced the observed gas reservoir. Instead, the molecular gas has likely formed as a result of sloshing motions in the intracluster medium induced by a nearby galaxy. Sloshing can emulate uplift by dislodging gas from the galactic center. This gas has the shortest cooling time, so it will condense if disrupted for long enough.
Quantum oscillations in insulators with neutral Fermi surfaces

We develop a theory of quantum oscillations in insulators with an emergent fermi sea of neutral fermions minimally coupled to an emergent $U(1)$ gauge field. As pointed out by Motrunich (Phys. Rev. B 73, 155115 (2006)), in the presence of a physical magnetic field the emergent magnetic field develops a non-zero value leading to Landau quantization for the neutral fermions. We focus on the magnetic field and temperature dependence of the analogue of the de Haas-van Alphen effect in two- and three-dimensions. At temperatures above the effective cyclotron energy, the magnetization oscillations behave similarly to those of an ordinary metal, albeit in a field of a strength that differs from the physical magnetic field. At low temperatures the oscillations evolve into a series of phase transitions. We provide analytical expressions for the amplitude and period of the oscillations in both of these regimes and simple extrapolations that capture well their crossover. We also describe oscillations in the electrical resistivity of these systems that are expected to be superimposed with the activated temperature behavior characteristic of their insulating nature and discuss suitable experimental conditions for the observation of these effects in mixed-valence insulators and triangular lattice organic materials.
Pentacene ultrathin film formation on reduced and oxidized Si surfaces

We have compared the nucleation of pentacene on reduced and oxidized Si surfaces by a combination of x-ray reflectivity measurements and atomic force microscopy. For the reduced surface, the nucleation density is 0.007 μm - 2 . Second monolayer (ML) formation starts at a coverage of Θ=0.6 ML, and the first layer is completely closed at a total coverage of 2 ML. For the oxidized surface, the nucleation density is larger by a factor of 100 (0.7 μm - 2 ). Second ML formation also starts at Θ=0.6 ML, but the first layer closes already at 1.1 ML coverage, indicating nearly ideal layer-by-layer growth. For both terminations, the electron density obtained for the closed first monolayer is only 75% of the bulk value, indicating a reduced mass packing efficiency of the layer. Second ML islands are aligned relative to each other on an area limited by the lateral size of first ML islands, which act as templates for epitaxial growth.
GWs from S-stars Revolving Around SMBH at Sgr A*

A preliminary estimation of gravitational waves (GWs) from the extreme-mass-ratio-inspirals (EMRIs) system in the Galactic Centre (GC) is given for the 37 observed S-stars revolving around the supermassive black hole (SMBH) at Sagittarius (Sgr) A*. Within this century, the total strain of the gravitational waveform calculated from the post-Newtonian (PN) method with eccentricity is well below the current planned sensitivity of pulsar-timing-array (PTA). New technology might be required in order to extract GW signal from this EMRIs system for future PTA detections.