Exponentially growing bubbles around early super massive black holes

We addressed the so far unexplored issue of outflows induced by exponentially growing power sources, focusing on early supermassive black holes (BHs). We assumed that these objects grow to $10^9\;M_{\odot}$ by z=6 by Eddington-limited accretion and convert 5% of their bolometric output into a wind. We first considered the case of energy-driven and momentum-driven outflows expanding in a region where the gas and total mass densities are uniform and equal to the average values in the Universe at $z>6$. We derived analytic solutions for the evolution of the outflow, finding that, for an exponentially growing power with e-folding time $t_{Sal}$, the late time expansion of the outflow radius is also exponential, with e-folding time of $5t_{Sal}$ and $4t_{Sal}$ in the energy-driven and momentum-driven limit, respectively. We then considered energy-driven outflows produced by QSOs at the center of early dark matter halos of different masses and powered by BHs growing from different seeds. We followed the evolution of the source power and of the gas and dark matter density profiles in the halos from the beginning of the accretion until $z=6$. The final bubble radius and velocity do not depend on the seed BH mass but are instead smaller for larger halo masses. At z=6, bubble radii in the range 50-180 kpc and velocities in the range 400-1000 km s$^{-1}$ are expected for QSOs hosted by halos in the mass range $3\times10^{11}-10^{13}\;M_{\odot}$. By the time the QSO is observed, we found that the total thermal energy injected within the bubble in the case of an energy-driven outflow is $E_{th}\sim5 \times 10^{60}$ erg. This is in excellent agreement with the value of $E_{th}=(6.2\pm 1.7)\times 10^{60}$ erg measured through the detection of the thermal Sunyaev-Zeldovich effect around a large population of luminous QSOs at lower redshift. [abridged]Comment: 17 pages and 14 figures. Typos corrected. It matches the version published in A&

Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy

Powerful winds driven by active galactic nuclei (AGN) are often invoked to play a fundamental role in the evolution of both supermassive black holes (SMBHs) and their host galaxies, quenching star formation and explaining the tight SMBH-galaxy relations. Recent observations of large-scale molecular outflows in ultra-luminous infrared galaxies (ULIRGs) have provided the evidence to support these studies, as they directly trace the gas out of which stars form. Theoretical models suggest an origin of these outflows as energy-conserving flows driven by fast AGN accretion disk winds. Previous claims of a connection between large-scale molecular outflows and AGN activity in ULIRGs were incomplete because they were lacking the detection of the putative inner wind. Conversely, studies of powerful AGN accretion disk winds to date have focused only on X-ray observations of local Seyferts and a few higher redshift quasars. Here we show the clear detection of a powerful AGN accretion disk wind with a mildly relativistic velocity of 0.25c in the X-ray spectrum of IRAS F11119+3257, a nearby (z = 0.189) optically classified type 1 ULIRG hosting a powerful molecular outflow. The AGN is responsible for ~80% of the emission, with a quasar-like luminosity of L_AGN = 1.5x10^46 erg/s. The energetics of these winds are consistent with the energy-conserving mechanism, which is the basis of the quasar mode feedback in AGN lacking powerful radio jets.Comment: Revised file including the letter, methods and supplementary information. Published in the March 26th 2015 issue of Natur

Participatory-deliberative processes and public policy agendas:Lessons for policy and practice

open access journalParticipatory and deliberative processes have proliferated over recent decades in public administration. These seek to increase the effectiveness and democratic quality of policy making by involving citizens in policy. However, these have mainly operated at local levels of governance, and democratic theorists and practitioners have developed an ambition to scale these up in order to democratize higher tiers of government. This paper draws policy lessons from research on a “multi-level” process that held a similar ambition. The Sustainable Communities Act sought to integrate the results of various locally organized citizen deliberations within the policy development processes of central UK government. In doing so, it aimed to democratize central government problem definition and agenda-setting processes. The paper distinguishes between achievements and failures explained by process design, and more fundamental obstacles to do with broader contextual factors. As such, it identifies lessons for the amelioration of design features, while recognizing constraints that are often beyond the agency of local practitioners. The findings offer practical insights for policy workers and democratic reformers seeking to institutionalize participatory and deliberative innovations

Gas reservoir of a hyper-luminous quasar at z= 2.6

Understanding the relationship between the formation and evolution of galaxies and their central super massive black holes (SMBH) is one of the main topics in extragalactic astrophysics. Links and feedback may reciprocally affect both black hole and galaxy growth. Observations of the CO line at redshifts of 2-4 are crucial to investigate the gas mass, star formation activity and accretion onto SMBHs, as well as the effect of AGN feedback. Potential correlations between AGN and host galaxy properties can be highlighted by observing extreme objects. Despite their luminosity, hyper-luminous QSOs at z=2-4 are still little studied at mm wavelengths. We targeted CO(3-2) in ULAS J1539+0557, an hyper-luminos QSO (Lbol> 10^48 erg/s) at z=2.658, selected through its unusual red colors in the UKIDSS Large Area Survey (ULAS). We find a molecular gas mass of 4.1+-0.8 10^10 Msun, and a gas fraction of 0.4-0.1, depending mostly on the assumed source inclination. We also find a robust lower limit to the star-formation rate (SFR=250-1600 Msun/yr) and star-formation efficiency (SFE=25-350 Lsun/(K km s-1 pc2) by comparing the observed optical-near-infrared spectral energy distribution with AGN and galaxy templates. The black hole gas consumption timescale, M(H_2)/dM(accretion)/dt, is ~160 Myr, similar or higher than the gas consumption timescale. The gas content and the star formation efficiency are similar to those of other high-luminosity, highly obscured QSOs, and at the lower end of the star-formation efficiency of unobscured QSOs, in line with predictions from AGN-galaxy co-evolutionary scenarios. Further measurements of the (sub)-mm continuum in this and similar sources are mandatory to obtain a robust observational picture of the AGN evolutionary sequence.32912

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

Protein disulphide isomerase-mediated grafting of cysteine-containing peptides onto over-bleached hair

The ability of Protein disulphide isomerase (PDI) to promote the grafting of two cysteine-containing peptides onto hair was investigated in order to develop an alternative treatment for over-bleached hair. The studied peptides were designed based on human keratin and human lung surfactant proteins and were linked to a fluorescent dye to facilitate visualisation of the grafting process and to assess hair penetration. The ability of the peptides to restore mechanical and thermal properties lost by repeated bleaching treatments was also studied. After eight bleaching treatments, hair samples displayed 42% less mechanical resistance, coupled with a decrease in α-helix denaturation enthalpies and temperatures. Hair surface damage following bleaching was visualized by scanning electron microscopy. Addition of PDI to the treatment formulations promoted peptide attachment to the hair via disulphide bonds, facilitating their penetration into the hair cortex, as observed by fluorescence microscopy. The proposed peptide treatment resulted in an increase in α-helix denaturation enthalpy in over-bleached hair, as well as an increase in both Young's modulus and tensile strength. Thus, mechanical and thermal properties were improved after the peptide treatment in the presence of PDI; suggesting that the formulations presented in this work are promising candidates for hair-care applications

Altered T Cell Memory and Effector Cell Development in Chronic Lymphatic Filarial Infection That Is Independent of Persistent Parasite Antigen

Chronic lymphatic filarial (LF) infection is associated with suppression of parasite-specific T cell responses that persist even following elimination of infection. While several mechanisms have been implicated in mediating this T cell specific downregulation, a role for alterations in the homeostasis of T effector and memory cell populations has not been explored. Using multiparameter flow cytometry, we investigated the role of persistent filarial infection on the maintenance of T cell memory in patients from the filarial-endemic Cook Islands. Compared to filarial-uninfected endemic normals (EN), microfilaria (mf) positive infected patients (Inf) had a reduced CD4 central memory (TCM) compartment. In addition, Inf patients tended to have more effector memory cells (TEM) and fewer effector cells (TEFF) than did ENs giving significantly smaller TEFF ∶ TEM ratios. These contracted TCM and TEFF populations were still evident in patients previously mf+ who had cleared their infection (CLInf). Moreover, the density of IL-7Rα, necessary for T memory cell maintenance (but decreased in T effector cells), was significantly higher on memory cells of Inf and CLInf patients, although there was no evidence for decreased IL-7 or increased soluble IL7-Rα, both possible mechanisms for signaling defects in memory cells. However, effector cells that were present in Inf and CLInf patients had lower percentages of HLA-DR suggesting impaired function. These changes in T cell populations appear to reflect chronicity of infection, as filarial-infected children, despite the presence of active infection, did not show alterations in the frequencies of these T cell phenotypes. These data indicate that filarial-infected patients have contracted TCM compartments and a defect in effector cell development, defects that persist even following clearance of infection. The fact that these global changes in memory and effector cell compartments do not yet occur in infected children makes early treatment of LF even more crucial