Physical Conditions in the Low-Ionization Component of Starburst Outflows: The Shape of Near-Ultraviolet and Optical Absorption-Line Troughs in Keck Spectra of ULIRGs

We analyze the physical conditions in the low-ionization component of starburst outflows (in contrast to the high-ionization wind fluid observed in X-rays), based on new Keck/LRIS spectroscopy of partially resolved absorption troughs in near-ultraviolet and optical spectra of Ultraluminous Infrared Galaxies. The large velocity width and blueshift present in seven, atomic transitions indicate a macroscopic velocity gradient within the outflowing gas. The \mgII 2796, 2803 (and \feII 2587, 2600) doublet lines in these data constrains the gas kinematics better than the heavily blended \nad 5892, 98 doublet. The identical shape of the \mgII 2796 absorption troughs to that of the normally weaker transition at 2803\AA requires both transitions be optically thick at all outflow velocities. The fraction of the galactic continuum covered by the outflow at each velocity therefore dictates the shape of these absorption troughs. We suggest that the velocity offset of the deepest part of the troughs, where the covering factor of low-ionization gas is near unity, reflects the speed of a shell of swept-up, interstellar gas at the time of blowout. In a spherical outflow, we show that the fragments of this shell expand slowly relative to the geometrical dilution; and the covering fraction of low-ionization gas decreases with increasing radius. Our measurement of a covering factor that decreases with increasing velocity can therefore be interpreted as evidence that the low-ionization outflow is accelerating. We also present measurements of C_f(v) in 4 species, place an upper limit of 3000 cm3 on the density of the outflowing gas, and discuss lower limits on the mass outflow rate.Comment: 28 pages, 10 figures, to appear in Ap

A Comparison of Circumgalactic Mg ii Absorption between the TNG50 Simulation and the MEGAFLOW Survey

The circumgalactic medium (CGM) contains information on gas flows around galaxies, such as accretion and supernova-driven winds, which are difficult to constrain from observations alone. Here, we use the high-resolution TNG50 cosmological magnetohydrodynamical simulation to study the properties and kinematics of the CGM around star-forming galaxies in 1011.5-1012 M o˙ halos at z ≃ 1 using mock Mg ii absorption lines, which we generate by postprocessing halos to account for photoionization in the presence of a UV background. We find that the Mg ii gas is a very good tracer of the cold CGM, which is accreting inward at inflow velocities of up to 50 km s-1. For sight lines aligned with the galaxy's major axis, we find that Mg ii absorption lines are kinematically shifted due to the cold CGM's significant corotation at speeds up to 50% of the virial velocity for impact parameters up to 60 kpc. We compare mock Mg ii spectra to observations from the MusE GAs FLow and Wind (MEGAFLOW) survey of strong Mg ii absorbers (EW2796 Å0 > 0.5 Å). After matching the equivalent-width (EW) selection, we find that the mock Mg ii spectra reflect the diversity of observed kinematics and EWs from MEGAFLOW, even though the sight lines probe a very small fraction of the CGM. Mg ii absorption in higher-mass halos is stronger and broader than in lower-mass halos but has qualitatively similar kinematics. The median-specific angular momentum of the Mg ii CGM gas in TNG50 is very similar to that of the entire CGM and only differs from non-CGM components of the halo by normalization factors of ≲1 dex

Optical properties and spatial distribution of MgII absorbers from SDSS image stacking

We present a statistical analysis of the photometric properties and spatial distribution of more than 2,800 MgII absorbers with 0.37<z<1 and rest equivalent width W_0(\lambda2796)>0.8\AA detected in SDSS quasar spectra. Using an improved image stacking technique, we measure the cross-correlation between MgII gas and light (in the g, r, i and z-bands) from 10 to 200 kpc and infer the light-weighted impact parameter distribution of MgII absorbers. Such a quantity is well described by a power-law with an index that strongly depends on W_0, ranging from ~-1 for W_0~ 1.5\AA. At redshift 0.37<z<0.55, we find the average luminosity enclosed within 100 kpc around MgII absorbers to be M_g=-20.65+-0.11 mag, which is ~0.5 L_g*. The global luminosity-weighted colors are typical of present-day intermediate type galaxies. However, while the light of weaker absorbers originates mostly from red passive galaxies, stronger systems display the colors of blue star-forming galaxies. Based on these observations, we argue that the origin of strong MgII absorber systems might be better explained by models of metal-enriched gas outflows from star-forming/bursting galaxies. Our analysis does not show any redshift dependence for both impact parameter and rest-frame colors up to z=1. However, we do observe a brightening of the absorbers related light at high redshift (~50% from z~0.4 to 1). We argue that MgII absorbers are a phenomenon typical of a given evolutionary phase that more massive galaxies experience earlier than less massive ones, in a downsizing fashion. (abridged)Comment: ApJ in press, 28 pages, 16 figures, using emulateapj. Only typo corrections wrt the original submission (v1

Injury-experienced satellite cells retain long-term enhanced regenerative capacity

Background: Inflammatory memory or trained immunity is a recently described process in immune and non-immune tissue resident cells, whereby previous exposure to inflammation mediators leads to a faster and stronger responses upon secondary challenge. Whether previous muscle injury is associated with altered responses to subsequent injury by satellite cells (SCs), the muscle stem cells, is not known. Methods: We used a mouse model of repeated muscle injury, in which intramuscular cardiotoxin (CTX) injections were administered 50&nbsp;days apart in order to allow for full recovery of the injured muscle before the second injury. The effect of prior injury on the phenotype, proliferation and regenerative potential of satellite cells following a second injury was examined in vitro and in vivo by immunohistochemistry, RT-qPCR and histological analysis. Results: We show that SCs isolated from muscle at 50&nbsp;days post-injury (injury-experienced SCs (ieSCs)) enter the cell cycle faster and form bigger myotubes when cultured in vitro, compared to control SCs isolated from uninjured contralateral muscle. Injury-experienced SCs were characterized by the activation of the mTORC 1 signaling pathway, suggesting they are poised to activate sooner following a second injury. Consequently, upon second injury, SCs accumulate in greater numbers in muscle at 3 and 10&nbsp;days after injury. These changes in SC phenotype and behavior were associated with accelerated muscle regeneration, as evidenced by an earlier appearance of bigger fibers and increased number of myonuclei per fiber at day 10 after the second injury. Conclusions: Overall, we show that skeletal muscle injury has a lasting effect on SC function priming them to respond faster to a subsequent injury. The ieSCs have long-term enhanced regenerative properties that contribute to accelerated regeneration following a secondary challenge

SINFONI Integral Field Spectroscopy of z~2 UV-selected Galaxies: Rotation Curves and Dynamical Evolution

We present 0.5" resolution near-IR integral field spectroscopy of the Ha line emission of 14 z~2 UV-selected BM/BX galaxies obtained with SINFONI at ESO/VLT. The mean Ha half-light radius r_1/2 is about 4kpc and line emission is detected over > ~20kpc in several sources. In 9 sources, we detect spatially-resolved velocity gradients, from 40 to 410 km/s over ~10kpc. The observed kinematics of the larger systems are consistent with orbital motions. Four galaxies are well described by rotating disks with clumpy morphologies and we extract rotation curves out to radii > ~10kpc. One or two galaxies exhibit signatures more consistent with mergers. Analyzing all 14 galaxies in the framework of rotating disks, we infer mean inclination- and beam-corrected maximum circular velocities v_c of 180+-90 km/s and dynamical masses of (0.5-25)x10^10 Msun within r_1/2. On average, the dynamical masses are consistent with photometric stellar masses assuming a Chabrier/Kroupa IMF but too small for a 0.1-100 Msun Salpeter IMF. The specific angular momenta of our BM/BX galaxies are similar to those of local late-type galaxies. The specific angular momenta of their baryons are comparable to those of their dark matter halos. Extrapolating from the average v_c at 10kpc, the virial mass of the typical halo of a galaxy in our sample is 10^(11.7+-0.5) Msun. Kinematic modeling of the 3 best cases implies a ratio of v_c to local velocity dispersion of order 2-4 and accordingly a large geometric thickness. We argue that this suggests a mass accretion (alternatively, gas exhaustion) timescale of ~500Myr. We also argue that if our BM/BX galaxies were initially gas rich, their clumpy disks will subsequently lose their angular momentum and form compact bulges on a timescale of ~1 Gyr. [ABRIDGED]Comment: Accepted for publication in the Astrophysical Journal. 17 pages, 5 color figure

Dynamical Properties of z~2 Star Forming Galaxies and a Universal Star Formation Relation

We present the first comparison of the dynamical properties of different samples of z~1.4-3.4 star forming galaxies from spatially resolved imaging spectroscopy from SINFONI/VLT integral field spectroscopy and IRAM CO millimeter interferometry. Our samples include 16 rest-frame UV-selected, 16 rest-frame optically-selected and 13 submillimeter galaxies (SMGs). We find that restframe UV- and optically bright (K<20) z~2 star forming galaxies are dynamically similar, and follow the same velocity-size relation as disk galaxies at z~0. In the theoretical framework of rotating disks forming from dissipative collapse in dark matter halos, the two samples require a spin parameter ranging from 0.06 to 0.2. In contrast bright SMGs have larger velocity widths and are much more compact. Hence, SMGs have lower angular momenta and higher matter densities than either of the UV- or optically selected populations. This indicates that dissipative major mergers may dominate the SMGs population, resulting in early spheroids, and that the majority of UV/optically bright galaxies have evolved less violently [...]. These early disks may later evolve into spheroids via disk instabilities or mergers. Because of their small sizes and large densities, SMGs lie at the high surface density end of a universal (out to z=2.5) "Schmidt-Kennicutt" relation between gas surface density and star formation rate surface density with a slope of ~1.7.Comment: 14 pages, 3 figures, accepted for publication in ApJ, minor typos correcte

The Blue Straggler population in the globular cluster M53 (NGC5024): a combined HST, LBT, CFHT study

We used a proper combination of multiband high-resolution and wide field multi-wavelength observations collected at three different telescopes (HST, LBT and CFHT) to probe Blue Straggler Star (BSS) populations in the globular cluster M53. Almost 200 BSS have been identified over the entire cluster extension. The radial distribution of these stars has been found to be bimodal (similarly to that of several other clusters) with a prominent dip at ~60'' (~2 r_c) from the cluster center. This value turns out to be a factor of two smaller than the radius of avoidance (r_avoid, the radius within which all the stars of ~1.2 M_sun have sunk to the core because of dynamical friction effects in an Hubble time). While in most of the clusters with a bimodal BSS radial distribution, r_avoid has been found to be located in the region of the observed minimum, this is the second case (after NGC6388) where this discrepancy is noted. This evidence suggests that in a few clusters the dynamical friction seems to be somehow less efficient than expected. We have also used this data base to construct the radial star density profile of the cluster: this is the most extended and accurate radial profile ever published for this cluster, including detailed star counts in the very inner region. The star density profile is reproduced by a standard King Model with an extended core (~25'') and a modest value of the concentration parameter (c=1.58). A deviation from the model is noted in the most external region of the cluster (at r>6.5' from the center). This feature needs to be further investigated in order to address the possible presence of a tidal tail in this cluster.Comment: 25 pages, 9 figures, accepted for publication on Ap

Non variability of intervening absorbers observed in the UVES spectra of the "naked-eye" GRB080319

The aim of this paper is to investigate the properties of the intervening absorbers lying along the line of sight of Gamma-Ray Burst (GRB) 080319B through the analysis of its optical absorption features. To this purpose, we analyze a multi-epoch, high resolution spectroscopic observations (R=40000, corresponding to 7.5 km/s) of the optical afterglow of GRB080319B (z=0.937), taken with UVES at the VLT. Thanks to the rapid response mode (RRM), we observed the afterglow just 8m:30s after the GRB onset when the magnitude was R ~ 12. This allowed us to obtain the best signal-to-noise, high resolution spectrum of a GRB afterglow ever (S/N per resolution element ~ 50). Two further RRM and target of opportunity observations were obtained starting 1.0 and 2.4 hours after the event, respectively. Four MgII absorption systems lying along the line of sight to the afterglow have been detected in the redshift range 0.5 < z < 0.8, most of them showing a complex structure featuring several components. Absorptions due to FeII, MgI and MnII are also present; they appear in four, two and one intervening absorbers, respectively. One out of four systems show a MgII2796 rest frame equivalent width larger than 1A. This confirms the excess of strong MgII absorbers compared to quasars, with dn/dz = 0.9, ~ 4 times larger than the one observed along quasar lines of sight. In addition, the analysis of multi-epoch, high-resolution spectra allowed us to exclude a significant variability in the column density of the single components of each absorber. Combining this result with estimates of the size of the emitting region, we can reject the hypothesis that the difference between GRB and QSO MgII absorbers is due to a different size of the emitting regions.Comment: 10 pages, 15 ps figures, submitted to MNRA

o.OM: Structured-Functional Communication between Computer Music Systems using OSC and Odot

International audienceO.—odot—is a portable media programming framework based on the OSC data encoding. It embeds a small expression language which allows writing and executing programs in OSC structures. The integration of programming and declarative functional descriptions within data transfer protocols enables structured and expressive communication in media systems: program snippets can be distributed in OSC messages, which evaluate to further OSC messages in the different communicating software. We present experiments using this framework in the OpenMusic computer-aided composition environment , and illustrate via case studies some advantages of such integrated system

Galaxy Clusters in the Line of Sight to Background Quasars: II. Environmental effects on the sizes of baryonic halo sizes

Based on recent results on the frequency of MgII absorption line systems in the "QSO behind RCS clusters" survey (QbC), we analyse the effects of the cluster environment on the sizes of baryonic haloes around galaxies. We use two independent models, i) an empirical halo occupation model which fits current measurements of the clustering and luminosity function of galaxies at low and high redshifts, and ii) the GALFORM semi-analytic model of galaxy formation, which follows the evolution of the galaxy population from first principles, adjusted to match the statistics of low and high redshift galaxies. In both models we constrain the MgII halo sizes of field and cluster galaxies using observational results on the observed MgII statistics. Our results for the field are in good agreement with previous works, indicating a typical \mgii\ halo size of $r_MgII ~ 50h_71^-1kpc in the semi-analytic model, and slightly lower in the halo occupation number approach. For the cluster environment, we find that both models require a median MgII halo size of r_MgII< 10h_71^-1kpc in order to reproduce the observed statistics on absorption line systems in clusters of galaxies. Based on the Chen & Tinker (2008) result that stronger systems occur closer to the MgII halo centre, we find that strong absorption systems in clusters of galaxies occur at roughly a fixed fraction of the cold-warm halo size out to 1h_71^-1Mpc from the cluster centres. In contrast, weaker absorption systems appear to occur at progressively shorter relative fractions of this halo as the distance to the cluster centre decreases.Comment: 12 pages, 8 figures, accepted for publication in MNRA