AGN feedback and gas mixing in the core of NGC 4636

Chandra observations of NGC 4636 show disturbances in the galaxy X-ray halo, including arm-like high surface brightness features (tentatively identified as AGN driven shocks) and a possible cavity on the west side of the galaxy core. We present Chandra and XMM spectral maps of NGC 4636 which confirm the presence of the cavity and show it to be bounded by the arm features. The maps also reveal a ~15 kpc wide plume of low temperature, high abundance gas extending 25-30 kpc to the southwest of the galaxy. The cavity appears to be embedded in this plume, and we interpret the structure as being entrained gas drawn out of the galaxy core during previous episodes of AGN activity. The end of the plume is marked by a well defined edge, with significant falls in surface brightness, temperature and abundance, indicating a boundary between galaxy and group/cluster gas. This may be evidence that as well as preventing gas cooling through direct heating, AGN outbursts can produce significant gas mixing, disturbing the temperature structure of the halo and transporting metals out from the galaxy into the surrounding intra-group medium.Comment: 4 Pages, 2 colour figures, accepted for publication in ApJ Letters. Version with high quality images at http://hea-www.harvard.edu/~ejos/files/N4636_hires.pd

Captures of Red Giant Stars by Black Holes in Elliptical Galaxies: Feedback to the Hot Gas

The highly disturbed hot gas in elliptical galaxies, as revealed in many {\em Chandra} X-ray images, implies a source of energy in the galactic nucleus. In some elliptical galaxies faint X-ray ``ghost'' cavities appear without corresponding radio lobes. It has been suggested that ghost cavities are caused by short-lived activity with a timescale of $\sim 10^3-10^4$ years, but this is difficult to understand within the popular paradigm of active galactic nuclei. We suggest an episode model for ghost cavities, invoking captures of red giant stars by the black hole located at the center of the elliptical galaxies at a typical rate of $10^{-5}$yr$^{-1}$ per galaxy. The accretion of tidally disrupted red giant stars onto the black hole powers activity in a timescale of a few years. The total energy channeled into the jet/outflow during the cooling time of the hot gas is $\sim 10^{56}$ erg, which is the typical work required to form the observed cavities. In this scenario, the faint cavities are produced by the feedback following accretion of the debris of the captured red giant stars onto the black holes. We apply the present model to several elliptical galaxies and find that it can explain the formation of the ghost cavities. This model can be tested in the future by comparisons between radio and X-ray observations.Comment: 4 pages in emulateapj5.sty. to Appear in ApJ Letter

Scaling Mass Profiles around Elliptical Galaxies Observed with Chandra and XMM-Newton

We investigated the dynamical structure of 53 elliptical galaxies, based on the {\it Chandra} archival X-ray data. In X-ray luminous galaxies, a temperature increases with radius and a gas density is systematically higher at the optical outskirts, indicating a presence of a significant amount of the group-scale hot gas. In contrast, X-ray dim galaxies show a flat or declining temperature profile against radius and the gas density is relatively lower at the optical outskirts. Thus it is found that X-ray bright and faint elliptical galaxies are clearly distinguished by the temperature and gas density profile. The mass profile is well scaled by a virial radius $r_{200}$ rather than an optical-half radius $r_e$, and is quite similar at $(0.001-0.03)r_{200}$ between X-ray luminous and dim galaxies, and smoothly connects to those of clusters of galaxies. At the inner region of $(0.001-0.01)r_{200}$ or $(0.1-1)r_e$, the mass profile well traces a stellar mass with a constant mass-to-light ratio of $M/L_{\rm B}=3-10(M_{\odot}/L_{\odot})$. $M/L_{\rm B}$ ratio of X-ray bright galaxies rises up steeply beyond $0.01r_{200}$, and thus requires a presence of massive dark matter halo. From the deprojection analysis combined with the {\it XMM-Newton} data, we found that X-ray dim galaxies, NGC 3923, NGC 720, and IC 1459, also have a high $M/L_{\rm B}$ ratio of 20--30 at 20 kpc, comparable to that of X-ray luminous galaxies. Therefore, dark matter is indicated to be common in elliptical galaxies, and their distribution almost follows the NFW profile, as well as galaxy clusters.Comment: 33 pages, 11 figures, to appear in ApJ 636 No.2, ApJ 10 January 200

Vibrational couplings and energy transfer pathways of water's bending mode

Yu, CC., Chiang, KY., Okuno, M. et al. Vibrational couplings and energy transfer pathways of water’s bending mode. Nat Commun 11, 5977 (2020). https://doi.org/10.1038/s41467-020-19759-

Morphine activates neuroinflammation in a manner parallel to endotoxin

Opioids create a neuroinflammatory response within the CNS, compromising opioid-induced analgesia and contributing to various unwanted actions. How this occurs is unknown but has been assumed to be via classic opioid receptors. Herein, we provide direct evidence that morphine creates neuroinflammation via the activation of an innate immune receptor and not via classic opioid receptors. We demonstrate that morphine binds to an accessory protein of Toll-like receptor 4 (TLR4), myeloid differentiation protein 2 (MD-2), thereby inducing TLR4 oligomerization and triggering proinflammation. Small-molecule inhibitors, RNA interference, and genetic knockout validate the TLR4/MD-2 complex as a feasible target for beneficially modifying morphine actions. Disrupting TLR4/MD-2 protein–protein association potentiated morphine analgesia in vivo and abolished morphine-induced proinflammation in vitro, the latter demonstrating that morphine-induced proinflammation only depends on TLR4, despite the presence of opioid receptors. These results provide an exciting, nonconventional avenue to improving the clinical efficacy of opioids.Xiaohui Wang, Lisa C. Loram, Khara Ramos, Armando J. de Jesus, Jacob Thomas, Kui Cheng, Anireddy Reddy, Andrew A. Somogyi, Mark R. Hutchinson, Linda R. Watkins and Hang Yi

Radio Bubbles in Clusters

We extend our earlier work on cluster cores with distinct radio bubbles, adding more active bubbles, i.e. those with Ghz radio emission, to our sample, and also investigating ``ghost bubbles,'' i.e. those without GHz radio emission. We have determined k, which is the ratio of the total particle energy to that of the electrons radiating between 10 MHz and 10 GHz. Constraints on the ages of the active bubbles confirm that the ratio of the energy factor, k, to the volume filling factor, f lies within the range 1 < k/f < 1000. In the assumption that there is pressure equilibrium between the radio-emitting plasma and the surrounding thermal X-ray gas, none of the radio lobes has equipartition between the relativistic particles and the magnetic field. A Monte-Carlo simulation of the data led to the conclusion that there are not enough bubbles present in the current sample to be able to determine the shape of the population. An analysis of the ghost bubbles in our sample showed that on the whole they have higher upper limits on k/f than the active bubbles, especially when compared to those in the same cluster. A study of the Brightest 55 cluster sample shows that 17, possibly 20, clusters required some form of heating as they have a short central cooling time, t_cool < 3 Gyr, and a large central temperature drop, T_centre/T_outer< 1/2. Of these between 12 (70 per cent) and 15 (75 per cent), contain bubbles. This indicates that the duty cycle of bubbles is large in such clusters and that they can play a major role in the heating process.Comment: 12 pages, Accepted for publication in MNRA

HST/ACS observations of shell galaxies: inner shells, shell colours and dust

AIM:Learn more about the origin of shells and dust in early type galaxies. METHOD: V-I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. RESULT: The ACS images reveal shells well within the effective radius in some galaxies (at 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some inner shells are redder than the galaxy. All six shell galaxies show out of dynamical equilibrium dust features, like lanes or patches, in their central regions. Our detection rate for dust in the shell ellipticals is greater than that found from HST archive data for a sample of normal early-type galaxies, at the 95% confidence level. CONCLUSIONS: The merger model describes better the shell distributions and morphologies than the interaction model. Red shell colours are most likely due to the presence of dust and/or older stellar populations. The high prevalence and out of dynamical equilibrium morphologies of the central dust features point towards external influences being responsible for visible dust features in early type shell galaxies. Inner shells are able to manifest themselves in relatively old shell systems.Comment: accepted by A&A; 36 Figures, 25 pages. A version with full resolution Figures can be found here: http://www.astro.rug.nl/~sikkema/shells.p

Effects of APETALA2 on embryo, endosperm, and seed coat development determine seed size in Arabidopsis

Arabidopsis APETALA2 (AP2) controls seed mass maternally, with ap2 mutants producing larger seeds than wild type. Here, we show that AP2 influences development of the three major seed compartments: embryo, endosperm, and seed coat. AP2 appears to have a significant effect on endosperm development. ap2 mutant seeds undergo an extended period of rapid endosperm growth early in development relative to wild type. This early expanded growth period in ap2 seeds is associated with delayed endosperm cellularization and overgrowth of the endosperm central vacuole. The subsequent period of moderate endosperm growth is also extended in ap2 seeds largely due to persistent cell divisions at the endosperm periphery. The effect of AP2 on endosperm development is mediated by different mechanisms than parent-of-origin effects on seed size observed in interploidy crosses. Seed coat development is affected; integument cells of ap2 mutants are more elongated than wild type. We conclude that endosperm overgrowth and/or integument cell elongation create a larger postfertilization embryo sac into which the ap2 embryo can grow. Morphological development of the embryo is initially delayed in ap2 compared with wild-type seeds, but ap2 embryos become larger than wild type after the bent-cotyledon stage of development. ap2 embryos are able to fill the enlarged postfertilization embryo sac, because they undergo extended periods of cell proliferation and seed filling. We discuss potential mechanisms by which maternally acting AP2 influences development of the zygotic embryo and endosperm to repress seed size