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In the hierarchical two-phase formation scenario, the extended halos of early type galaxies (ETGs) are expected to have different physical properties from those of the galaxies' central regions. This work aims at characterizing the kinematic properties of ETG halos using planetary nebulae (PNe) as tracers, which allow us to overcome the limitations of absorption line spectroscopy of continuum at low surface brightness. We present two-dimensional velocity and velocity dispersion fields for 33 ETGs, including both fast (FRs) and slow rotators (SRs), making this the largest kinematic survey to-date of extragalactic PNe. The velocity fields extend out to a median 5.6 effective radii (Re), with a range [3Re-13Re] for the PN.S ETGs. We complemented the PN kinematics with absorption line data from the literature. We find that ETGs typically show a kinematic transition between inner regions and halo. Estimated transition radii in units of Re anticorrelate with stellar mass. SRs have increased but still modest rotational support at large radii, while most of the FRs show a decrease in rotation, due to the fading of the stellar disk in the outer, more slowly rotating spheroid. 30% of the FRs are dominated by rotation also at large radii. Most ETGs have flat or slightly falling halo velocity dispersion profiles, but 15% of the sample have steeply falling profiles. 40% of the FRs show kinematic twists, misalignments, or rotation along two axes, indicating that they turn from oblate at the center to triaxial in the halo, consistently with the distribution of isophote twists from extended photometry. ETGs have more diverse kinematic properties in their halos than in the central regions. The observed kinematic transition to the halo and its dependence on stellar mass is consistent with LambdaCDM simulations and supports a two-phase formation scenario. [abridged], Comment: Accepted for publication in A&A, 52 pages, 30 figures

The $f_0$(1500) meson resonance is one of several contenders to have significant mixing with the lightest glueball. This resonance is well established from several previous experiments. Here we present the first photoproduction data for the $f_0$(1500) via decay into the $K_S^0 K_S^0$ channel using the CLAS detector. The reaction $\gamma p$ -> $f_0 p$ -> $K_S^0 K_S^0 p$, where J = 0, 2, was measured with photon energies from 2.7 to 5.1 GeV. A clear peak is seen at 1500 MeV in the background subtracted invariant mass spectra of the two kaons. This is enhanced if the measured 4-momentum transfer to the proton target is restricted to be less than 1.0 GeV2. By comparing data with simulations, it can be concluded that the peak at 1500 MeV is produced primarily at low t, which is consistent with a t-channel production mechanism., Comment: 12 pages, 12 figures

Selecting disk galaxies from the cosmological, hydrodynamical simulation Magneticum Pathfinder we show that almost half of our poster child disk galaxies at $z=2$ show significantly declining rotation curves and low dark matter fractions, very similar to recently reported observations. These galaxies do not show any anomalous behavior, reside in standard dark matter halos and typically grow significantly in mass until $z = 0$, where they span all morphological classes, including disk galaxies matching present day rotation curves and observed dark matter fractions. Our findings demonstrate that declining rotation curves and low dark matter fractions in rotation dominated galaxies at $z=2$ appear naturally within the $\Lambda$CDM paradigm and reflect the complex baryonic physics, which plays a role at the peak epoch of star-formation. In addition, we find some dispersion dominated galaxies at $z=2$ which host a significant gas disk and exhibit similar shaped rotation curves as the disk galaxy population, rendering it difficult to differentiate between these two populations with currently available observation techniques., Comment: 6 pages, 4 figures, ApJ Letters in press, www.magneticum.org

Accurately predicting the demographics of dark matter (DM) substructure is of paramount importance for many fields of astrophysics, including gravitational lensing, galaxy evolution, halo occupation modeling, and constraining the nature of dark matter. Because of its strongly non-linear nature, DM substructure is typically modeled using N-body simulations, which reveal that large fractions of DM subhaloes undergo complete disruption. In this paper we use both analytical estimates and idealized numerical simulations to investigate whether this disruption is mainly physical, due to tidal heating and stripping, or numerical (i.e., artificial). We show that, contrary to naive expectation, subhaloes that experience a tidal shock $\Delta E$ that exceeds the subhalo's binding energy, $|E_{\rm b}|$, do not undergo disruption, even when $\Delta E/|E_{\rm b}|$ is as large as 100. Along the same line, and contrary to existing claims in the literature, instantaneously stripping matter from the outskirts of a DM subhalo also does not result in its complete disruption, even when the instantaneous remnant has positive binding energy. In addition, we show that tidal heating due to high-speed (impulsive) encounters with other subhaloes (`harassment'), is negligible compared to the tidal effects due to the host halo. Hence, we conclude that, in the absence of baryonic processes, the complete, physical disruption of CDM substructure is extremely rare, and that most disruption in numerical simulations therefore must be artificial. We discuss various processes that have been associated with numerical overmerging, and conclude that inadequate force-softening is the most likely culprit., Comment: 24 pages, 12 figures. Accepted for publication in MNRAS

The photoproduction of $\omega$ mesons off the proton has been studied in the reaction $\gamma p\to p\,\omega$ using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target (FROST) in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry, $T$, has been measured in photoproduction from the decay $\omega\to\pi^+\pi^-\pi^0$, using a transversely-polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant non-zero values are observed for these asymmetries, reaching about 30-40% in the third-resonance region. New measurements for the photon-beam asymmetry, $\Sigma$, are also presented, which agree well with previous CLAS results and extend the world database up to 2.1 GeV. These data and additional $\omega$-photoproduction observables from CLAS were included in a partial-wave analysis within the Bonn-Gatchina framework. Significant contributions from $s$-channel resonance production were found in addition to $t$-channel exchange processes., Comment: 15 pages, 10 figures, author list and references updated

The interplay between gravity, turbulence and the magnetic field determines the evolution of the molecular ISM and the formation of the stars. In spite of growing interests, there remains a lack of understanding of the importance of magnetic field over multiple scales. We derive the magnetic energy spectrum -- a measure that constraints the multi-scale distribution of the magnetic energy, and compare it with the gravitational energy spectrum derived in Li \& Burkert (2016). In our formalism, the gravitational energy spectrum is purely determined by the surface density PDF, and the magnetic energy spectrum is determined by both the surface density PDF and the magnetic-field-density relation. If regions have density PDFs close to $P(\Sigma)\sim \Sigma^{-2}$ and a universal magnetic field-density relation $B\sim \rho^{1/2}$, we expect a multi-scale near equipartition between gravity and the magnetic fields. This equipartition is found to be true in NGC6334 where estimates of magnetic fields over multiple scales (from 0.1 pc to a few parsec) are available. However, the current observations are still limited in sample size. In the future, it is necessary to obtain multi-scale measurements of magnetic fields from different clouds with different surface density PDFs and apply our formalism to further study the gravity-magnetic field interplay., Comment: Accepted by MNRAS

We measured the $g_1$ spin structure function of the deuteron at low $Q^{2}$, where QCD can be approximated with chiral perturbation theory ($\chi$PT). The data cover the resonance region, up to an invariant mass of $W\approx1.9$~GeV. The generalized Gerasimov-Drell-Hearn sum, the moment $\bar{\Gamma}_{1}^{d}$ and the integral $\bar{I}_\gamma^d$ related to the spin polarizability $\gamma_{0}^{d}$ are precisely determined down to a minimum $Q^2$ of 0.02~GeV$^2$ for the first time, about 2.5 times lower than that of previous data. We compare them to several $\chi$PT calculations and models. These results are the first in a program of benchmark measurements of polarization observables in the $\chi$PT domain., Comment: Version 1: version published in Phys. Rev. Lett. 6 pages, 3 figures. Supplementary material: data table for g1d and its moments (10 pages) V2: Figures labels changed and text slightly modified to clarify the exact nature of the measured moments V3: Corrected a typo page 5 for the theoretical value expected for deuteron GDH sum rule (agreement between measurement and expectation is improved)

The star-forming ability of a molecular cloud depends on the fraction of gas it can cycle into the dense-phase. Consequently, one of the crucial questions in reconciling star-formation in clouds is to understand the factors that control this process. While it is widely accepted that the variation in ambient conditions can alter significantly the ability of a cloud to spawn stars, the observed variation in the star-formation rate in nearby clouds that experience similar ambient conditions, presents an interesting question. In this work we attempted to reconcile this variation within the paradigm of colliding flows. To this end we develop self-gravitating, hydrodynamic realisations of identical flows, but allowed to collide off-centre. Typical observational diagnostics such as the gas-velocity dispersion, the fraction of dense-gas, the column density distribution ({\small N-PDF}), the distribution of gas mass as a function of $K$-band extinction and the strength of compressional/solenoidal modes in the post-collision cloud were deduced for different choices of the impact parameter of collision. We find that a strongly sheared cloud is terribly inefficient in cycling gas into the dense phase and that such a cloud can possibly reconcile the sluggish nature of star-formation reported for some clouds. Within the paradigm of cloud-formation via colliding flows this is possible in case of flows colliding with a relatively large impact parameter. We conclude that compressional modes - though probably essential - are insufficient to ensure a relatively higher star-formation efficiency in a cloud., Comment: 12 pages, 8 figures; To appear in MNRAS

[Abridged] The Lupus I cloud is found between the Upper-Scorpius and the Upper-Centaurus-Lupus sub-groups, where the expanding USco HI shell appears to interact with a bubble currently driven by the winds of the remaining B-stars of UCL. We investigate if the Lupus I molecular could have formed in a colliding flow, and how the kinematics of the cloud might have been influenced by the larger scale gas dynamics. We performed APEX 13CO and C18O observations of three parts of Lupus. We compare these results to the atomic hydrogen data from the GASS HI survey and our dust emission results presented in the previous paper. Based on the velocity information, we present a geometric model for the interaction zone between the USco shell and the UCL wind bubble. We present evidence that the molecular gas of Lupus I is tightly linked to the atomic material of the USco shell. The CO emission in Lupus I is found mainly at velocities in the same range as the HI velocities. Thus, the molecular cloud is co-moving with the expanding USco atomic Hi shell. The gas in the cloud shows a complex kinematic structure with several line-of-sight components that overlay each other. The non-thermal velocity dispersion is in the transonic regime in all parts of the cloud and could be injected by external compression. Our observations and the derived geometric model agree with a scenario where Lupus I is located in the interaction zone between the USco shell and the UCL wind bubble. The kinematics observations are consistent with a scenario where the Lupus I cloud formed via shell instabilities. The particular location of Lupus I between USco and UCL suggests that counter-pressure from the UCL wind bubble and pre-existing density enhancements, perhaps left over from the gas stream that formed the stellar subgroups, may have played a role in its formation., Comment: Accepted for publication by A&A

For half a century, the Roper resonance has defied understanding. Discovered in 1963, it appears to be an exact copy of the proton except that its mass is 50% greater. The mass is the first problem: it is difficult to explain with any theoretical tool that can validly be used to study quantum chromodynamics [QCD]. In the last decade, a new challenge has appeared, viz. precise information on the proton-to-Roper electroproduction transition form factors, reaching $Q^2\approx 4.5\,$GeV$^2$. This scale probes the domain within which hard valence-quark degrees-of-freedom could be expected to determine form factor behavior. Hence, with this new data the Roper resonance becomes a problem for strong-QCD [sQCD]. An explanation of how and where the Roper resonance fits into the emerging spectrum of hadrons cannot rest on a description of its mass alone. Instead, it must combine this with a detailed understanding of the Roper's structure and how that is revealed in the transition form factors. Furthermore, it must unify all this with a similarly complete picture of the proton. This is a prodigious task, but a ten-year international effort, drawing together experimentalists and theorists, has presented a solution to the puzzle. Namely, the Roper is at heart the proton's first radial excitation, consisting of a dressed-quark core augmented by a meson cloud that reduces the core mass by approximately 20% and materially alters its electroproduction form factors on $Q^2<2m_N^2$, where $m_N$ is the proton's mass. We describe the experimental motivations and developments which enabled electroproduction data to be procured within a domain that is unambiguously the purview of sQCD, thereby providing a real challenge and opportunity for modern theory; and survey the developments in reaction models and QCD theory that have enabled this conclusion to be drawn about the nature of the Roper resonance., Comment: 23 pages, 19 figures

We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic $^{14}$NH$_3$ target, and extracted double and single target spin asymmetries for $ep\rightarrow e^\prime\pi^0X$ in multidimensional bins in four-momentum transfer ($1.0