# Publications

## Gemini GMOS and WHT SAURON integral-field spectrograph observations of the AGN-driven outflow in NGC1266

Monthly Notices of the Royal Astronomical Society 426 (2012) 1574-1590

TA Davis, D Krajnović, RM McDermid, E Bayet, M Cappellari, RL Davies, M Bureau, M Sarzi, K Nyland, LM Young, K Alatalo, L Blitz, M Bois, F Bournaud, P-A Duc, A Crocker, PT de Zeeuw, E Emsellem, P-Y Lablanche, S Khochfar, H Kuntschner, R Morganti, T Oosterloo, P Serra, T Naab, N Scott, A-M Weijmans

We use the Spectrographic Areal Unit for Research on Optical Nebulae and Gemini Multi-Object Spectrograph integral-field spectrographs to observe the active galactic nucleus (AGN) powered outflow in NGC1266. This unusual galaxy is relatively nearby (D = 30Mpc), allowing us to investigate the process of AGN feedback in action. We present maps of the kinematics and line strengths of the ionized gas emission lines Hα, Hβ, [Oiii], [Oi], [Nii] and [Sii], and report on the detection of sodium D absorption. We use these tracers to explore the structure of the source, derive the ionized and atomic gas kinematics, and investigate the gas excitation and physical conditions. NGC1266 contains two ionized gas components along most lines of sight, tracing the ongoing outflow and a component closer to the galaxy systemic, the origin of which is unclear. This gas appears to be disturbed by a nascent AGN jet. We confirm that the outflow in NGC1266 is truly multiphase, containing radio plasma, atomic, molecular and ionized gas and X-ray emitting plasma. The outflow has velocities of up to ±900 km s away from the systemic velocity and is very likely to remove significant amount of cold gas from the galaxy. The low-ionization nuclear emission region-like line emission in NGC1266 is extended, and it likely arises from fast shocks caused by the interaction of the radio jet with the interstellar medium. These shocks have velocities of up to 800 km s , which match well with the observed velocity of the outflow. Sodium D equivalent width profiles are used to set constraints on the size and orientation of the outflow. The ionized gas morphology correlates with the nascent radio jets observed in 1.4 and 5 GHz continuum emission, supporting the suggestion that an AGN jet is providing the energy required to drive the outflow. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

## Inelastic x-ray scattering from shocked liquid deuterium

Physical Review Letters 109 (2012)

SP Regan, PB Radha, SX Hu, TR Boehly, DD Meyerhofer, TC Sangster, K Falk, G Gregori, BJB Crowley, CD Murphy, SH Glenzer, OL Landen, T Döppner, DO Gericke, J Vorberger

The Fermi-degenerate plasma conditions created in liquid deuterium by a laser-ablation - driven shock wave were probed with noncollective, spectrally resolved, inelastic x-ray Thomson scattering employing Cl Ly line emission at 2.96 keV. These first x-ray Thomson scattering measurements of the microscopic properties of shocked deuterium show an inferred spatially averaged electron temperature of 8±5 eV, an electron density of 2.2(±0.5)×1023 cm3, and an ionization of 0.8 (-0.25, +0.15). Two-dimensional hydrodynamic simulations using equation-of-state models suited for the extreme parameters occurring in inertial confinement fusion research and planetary interiors are consistent with the experimental results. © 2012 American Physical Society.

## Inverse Compton X-ray halos around high-z radio galaxies: A feedback mechanism powered by far-infrared starbursts or the CMB?

ArXiv (2012)

I Smail, KM Blundell, BD Lehmer, DM Alexander

We report the detection of extended X-ray emission around two powerful high-z radio galaxies (HzRGs) at z~3.6 (4C03.24 & 4C19.71) and use these to investigate the origin of extended, Inverse Compton (IC) powered X-ray halos at high z. The halos have X-ray luminosities of Lx~3e44 erg/s and sizes of ~60kpc. Their morphologies are broadly similar to the ~60-kpc long radio lobes around these galaxies suggesting they are formed from IC scattering by relativistic electrons in the radio lobes, of either CMB or FIR photons from the dust-obscured starbursts in these galaxies. These observations double the number of z>3 HzRGs with X-ray detected IC halos. We compare the IC X-ray to radio luminosity ratios for these new detections to the two previously detected z~3.8 HzRGs. Given the similar redshifts, we would expect comparable X-ray IC luminosities if CMB mm photons are the seed field for the IC emission. Instead the two z~3.6 HzRGs, which are ~4x fainter in the FIR, also have ~4x fainter X-ray IC emission. Including a further six z>2 radio sources with IC X-ray halos from the literature, we suggest that in the more compact (lobe sizes <100-200kpc), majority of radio sources, the bulk of the IC emission may be driven by scattering of locally produced FIR photons from luminous, dust-obscured starbursts within these galaxies, rather than CMB photons. The resulting X-ray emission can ionise the gas on ~100-200-kpc scales around these systems and thus form their extended Ly-alpha emission line halos. The starburst and AGN activity in these galaxies are thus combining to produce an effective and wide-spread "feedback" process, acting on the long-term gas reservoir for the galaxy. If episodic radio activity and co-eval starbursts are common in massive, high-z galaxies, then this IC-feedback mechanism may affect the star-formation histories of massive galaxies. [Abridged]

## Measuring electron-positron annihilation radiation from laser plasma interactions

Review of Scientific Instruments 83 (2012)

H Chen, R Tommasini, J Seely, CI Szabo, U Feldman, N Pereira, G Gregori, K Falk, J Mithen, CD Murphy

We investigated various diagnostic techniques to measure the 511 keV annihilation radiations. These include step-wedge filters, transmission crystal spectroscopy, single-hit CCD detectors, and streaked scintillating detection. While none of the diagnostics recorded conclusive results, the step-wedge filter that is sensitive to the energy range between 100 keV and 700 keV shows a signal around 500 keV that is clearly departing from a pure Bremsstrahlung spectrum and that we ascribe to annihilation radiation. © 2012 American Institute of Physics.

## Probing the mass assembly of massive nearby galaxies with deep imaging

Proceedings of the International Astronomical Union 8 (2012) 358-361

P-A Duc, F Bournaud, E Ferriere, J-C Cuillandre, K Alatalo, L Blitz, M Bois, E Emsellem, P-Y Lablanche, L Michel-Dansac, M Bureau, M Cappellari, RL Davies, N Scott, P Côté, L Ferrarese, S Gwyn, TA Davis, PT De Zeeuw, D Krajnovic, H Kuntschner, S Khochfar, RM McDermid, R Morganti, T Oosterloo, P Serra, T Naab, M Sarzi, A Weijmans, LM Young

According to a popular scenario supported by numerical models, the mass assembly and growth of massive galaxies, in particular the Early-Type Galaxies (ETGs), is, below a redshift of 1, mainly due to the accretion of multiple gas-poor satellites. In order to get observational evidence of the role played by minor dry mergers, we are obtaining extremely deep optical images of a complete volume limited sample of nearby ETGs. These observations, done with the CFHT as part of the ATLAS, NGVS and MATLAS projects, reach a stunning 28.5 - 29 mag.arcsec surface brightness limit in the g' band. They allow us to detect the relics of past collisions such as faint stellar tidal tails as well as the very extended stellar halos which keep the memory of the last episodes of galactic accretion. Images and preliminary results from this on-going survey are presented, in particular a possible correlation between the fine structure index (which parametrizes the amount of tidal perturbation) of the ETGs, their stellar mass, effective radius and gas content. © 2013 International Astronomical Union.

## Telescopes of the future

ASTRONOMY & GEOPHYSICS 53 (2012) 15-18

R Davies

## Testing quantum mechanics in non-Minkowski space-time with high power lasers and 4 th generation light sources

Scientific Reports 2 (2012)

BJB Crowley, CD Murphy, JS Wark, G Gregori, R Bingham, PA Norreys, RG Evans, SJ Rose, DO Gericke, OL Landen, T Tschentscher, CH-T Wang

A common misperception of quantum gravity is that it requires accessing energies up to the Planck scale of 10 GeV, which is unattainable from any conceivable particle collider. Thanks to the development of ultra-high intensity optical lasers, very large accelerations can be now the reached at their focal spot, thus mimicking, by virtue of the equivalence principle, a non Minkowski space-time. Here we derive a semiclassical extension of quantum mechanics that applies to different metrics, but under the assumption of weak gravity. We use our results to show that Thomson scattering of photons by uniformly accelerated electrons predicts an observable effect depending upon acceleration and local metric. In the laboratory frame, a broadening of the Thomson scattered x ray light from a fourth generation light source can be used to detect the modification of the metric associated to electrons accelerated in the field of a high power optical laser.

## Self-consistent measurement of the equation of state of liquid deuterium

High Energy Density Physics 8 (2012) 76-80

K Falk, CD Murphy, JS Wark, G Gregori, SP Regan, MA Barrios, TR Boehly, DE Fratanduono, SX Hu, PB Radha, J Vorberger, DO Gericke, SH Glenzer, DG Hicks, S Rothman, AP Jephcoat

We combine experiments and theoretical models to characterize warm dense deuterium. A shockwave was driven in a planar target by the OMEGA laser without a standard pusher making the analysis independent of a quartz or aluminium pressure standard. The conditions of the shocked material were diagnosed with VISAR and optical pyrometry which yields the shock velocity (16.9 ± 0.9 km/s) and the temperature (0.57 ± 0.05 eV). We find a self-consistent description of the data when using ab initio simulations (DFT-MD), but not for other equation of state (EOS) models tested. © 2011 Elsevier B.V.

## Molecular Dynamics Simulations for the Shear Viscosity of the One-Component Plasma

CONTRIBUTIONS TO PLASMA PHYSICS 52 (2012) 58-61

JP Mithen, J Daligault, G Gregori

## Scaling of spontaneous rotation with temperature and plasma current in tokamaks

ArXiv (2011)

FI Parra, MFF Nave, AA Schekochihin, C Giroud, JSD Grassie, JHF Severo, PD Vries, KD Zastrow, JETEFDA Contributors

Using theoretical arguments, a simple scaling law for the size of the intrinsic rotation observed in tokamaks in the absence of momentum injection is found: the velocity generated in the core of a tokamak must be proportional to the ion temperature difference in the core divided by the plasma current, independent of the size of the device. The constant of proportionality is of the order of $10\,\mathrm{km \cdot s^{-1} \cdot MA \cdot keV^{-1}}$. When the intrinsic rotation profile is hollow, i.e. it is counter-current in the core of the tokamak and co-current in the edge, the scaling law presented in this Letter fits the data remarkably well for several tokamaks of vastly different size and heated by different mechanisms.

## 4MOST - 4-metre Multi Object Spectroscopic Telescope

SPIE 8446 (2012) 84460T

R de Jong, O Bellido-Tirado, C Chiappini, E Depagne, R Haynes, D Johl, O Schnurr, A Schwope, J Walcher, F Dionies, D Haynes, A Kelz, F Kituara, G Lamer, I Minchev, V Muller, SE Nuza, J-C Olaya, T Piffl, E Popow, M Steinmetz, U Ural, M Williams, R Winkler, L Wisotski, W Ansorge, M Banerji, E Gonzalez Solares, M Irwin, R Kennicutt, D King, R McMahon, S Koposov, I Parry, D Sun, N Walton, G Finger, O Iwert, M Krumpe, J-L Lizon, M Vincenzo, J-P Amans, P Bonifacio, M Cohen, P Francois, P Jagourel, S Mignot, F Royer, P Sartoretti, R Bender, F Grupp, H-J Hess, F Lang-Bardl, B Muschielok, H Bohringer, T Boller, A Bongiorno, M Brusa, T Dwelly, A Merloni, K Nandra, M Salvato, J Pragt, R Navarro, G Gerlofsma, R Roelfsma, GB Dalton, K Middleton, IAJ Tosh, C Boeche, E Caffau, N Christlieb, E Grebel, C Hansen, A Koch, H-G Ludwig, A Quirrenbach, L Sbordone, W Seifert, G Thimm, T Trifonov, A Helmi, S Trager, S Feltzing, A Korn, W Boland

The 4MOST consortium is currently halfway through a Conceptual Design study for ESO with the aim to develop a wide-field ( &lt; 3 square degree, goal &lt; 5 square degree), high-multiplex ( &lt; 1500 fibres, goal 3000 fibres) spectroscopic survey facility for an ESO 4m-class telescope (VISTA). 4MOST will run permanently on the telescope to perform a 5 year public survey yielding more than 20 million spectra at resolution R∼5000 (&lambda;=390–1000 nm) and more than 2 million spectra at R~20,000 (395–456.5 nm and 587–673 nm). The 4MOST design is especially intended to complement three key all-sky, space-based observatories of prime European interest: Gaia, eROSITA and Euclid. Initial design and performance estimates for the wide-field corrector concepts are presented. Two fibre positioner concepts are being considered for 4MOST. The first one is a Phi-Theta system similar to ones used on existing and planned facilities. The second one is a new R-Theta concept with large patrol area. Both positioner concepts effectively address the issues of fibre focus and pupil pointing. The 4MOST spectrographs are fixed configuration two-arm spectrographs, with dedicated spectrographs for the high- and low-resolution fibres. A full facility simulator is being developed to guide trade-off decisions regarding the optimal field-of-view, number of fibres needed, and the relative fraction of high-to-low resolution fibres. The simulator takes mock catalogues with template spectra from Design Reference Surveys as starting point, calculates the output spectra based on a throughput simulator, assigns targets to fibres based on the capabilities of the fibre positioner designs, and calculates the required survey time by tiling the fields on the sky. The 4MOST consortium aims to deliver the full 4MOST facility by the end of 2018 and start delivering high-level data products for both consortium and ESO community targets a year later with yearly increments.

## A new formula for disc kinematics

Monthly Notices of the Royal Astronomical Society 419 (2012) 1546-1556

R Schönrich, J Binney

In a disc galaxy, the distribution of azimuthal components of velocity is very skew. In the past, this skewness has been modelled by superposed Gaussians. We use dynamical arguments to derive an analytic formula that can be fitted to observed velocity distributions, and validate it by fits to the velocities derived from a dynamically rigorous model, and to a sample of local stars with accurate space velocities. Our formula is much easier to use than a full distribution function. It has fewer parameters than a multi-Gaussian fit, and the best-fitting model parameters give insight into the underlying disc dynamics. In particular, once the azimuthal velocities of a sample have been successfully fitted, the apparatus provides a prediction for the corresponding distribution of radial velocitiesv. An effective formula like ours is invaluable when fitting to data for stars at some distance from the Sun because it enables one to make proper allowance for the errors in distance and proper motion when determining the underlying disc kinematics. The derivation of our formula elucidates the way the horizontal and vertical motions are closely intertwined, and makes it evident that no stellar population can have a scaleheight and vertical velocity dispersions that are simultaneously independent of radius. We show that the oscillation of a star perpendicular to the Galactic plane modifies the effective potential in which the star moves radially in such a way that the more vertical energy a star has, the larger is the mean radius of its orbit. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

## Quantum hydrodynamics of strongly coupled electron fluids

PHYSICAL REVIEW E 85 (2012) ARTN 046408

R Schmidt, BJB Crowley, J Mithen, G Gregori

## Dynamical models of the Galaxy

ASSEMBLING THE PUZZLE OF THE MILKY WAY 19 (2012)

PJ McMillan

## Accretion by the Galaxy

ArXiv (2011)

J Binney, F Fraternali

Cosmology requires at least half of the baryons in the Universe to be in the intergalactic medium, much of which is believed to form hot coronae around galaxies. Star-forming galaxies must be accreting from their coronae. HI observations of external galaxies show that they have HI halos associated with star formation. These halos are naturally modelled as ensembles of clouds driven up by supernova bubbles. These models can fit the data successfully only if clouds exchange mass and momentum with the corona. As a cloud orbits, it is ablated and forms a turbulent wake where cold high-metallicity gas mixes with hot coronal gas causing the prompt cooling of the latter. As a consequence the total mass of HI increases. This model has recently been used to model the Leiden-Argentina-Bonn survey of Galactic HI. The values of the model's parameters that are required to model NGC 891, NGC 2403 and our Galaxy show a remarkable degree of consistency, despite the very different natures of the two external galaxies and the dramatic difference in the nature of the data for our Galaxy and the external galaxies. The parameter values are also consistent with hydrodynamical simulations of the ablation of individual clouds. The model predicts that a galaxy that loses its cool-gas disc for instance through a major merger cannot reform it from its corona; it can return to steady star formation only if it can capture a large body of cool gas, for example by accreting a gas-rich dwarf. Thus the model explains how major mergers can make galaxies "red and dead."

## X-ray surface brightness and gas density fluctuations in the Coma cluster

Monthly Notices of the Royal Astronomical Society 421 (2012) 1123-1135

E Churazov, I Zhuravleva, R Sunyaev, A Vikhlinin, W Forman, S Randall, A Schekochihin, I Parrish, H Böhringer

X-ray surface brightness fluctuations in the core (650 × 650 kpc) region of the Coma cluster observed with XMM-Newton and Chandra are analysed using a 2D power spectrum approach. The resulting 2D spectra are converted to 3D power spectra of gas density fluctuations. Our independent analyses of the XMM-Newton and Chandra observations are in excellent agreement and provide the most sensitive measurements of surface brightness and density fluctuations for a hot cluster. We find that the characteristic amplitude of the volume filling density fluctuations relative to the smooth underlying density distribution varies from 7-10 per cent on scales of ~500kpc down to ~5 per cent on scales of ~30kpc. On smaller spatial scales, projection effects smear the density fluctuations by a large factor, precluding strong limits on the fluctuations in 3D. On the largest scales probed (hundreds of kpc), the dominant contributions to the observed fluctuations most likely arise from perturbations of the gravitational potential by the two most massive galaxies in Coma, NGC4874 and NGC4889, and the low-entropy gas brought to the cluster by an infalling group. Other plausible sources of X-ray surface brightness fluctuations are discussed, including turbulence, metal abundance variations and unresolved sources. Despite a variety of possible origins for density fluctuations, the gas in the Coma cluster core is remarkably homogeneous on scales from ~500 to ~30kpc. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

## Weak Alfvén-wave turbulence revisited.

Phys Rev E Stat Nonlin Soft Matter Phys 85 (2012) 036406-

AA Schekochihin, SV Nazarenko, TA Yousef

Weak Alfvénic turbulence in a periodic domain is considered as a mixed state of Alfvén waves interacting with the two-dimensional (2D) condensate. Unlike in standard treatments, no spectral continuity between the two is assumed, and, indeed, none is found. If the 2D modes are not directly forced, k(-2) and k(-1) spectra are found for the Alfvén waves and the 2D modes, respectively, with the latter less energetic than the former. The wave number at which their energies become comparable marks the transition to strong turbulence. For imbalanced energy injection, the spectra are similar, and the Elsasser ratio scales as the ratio of the energy fluxes in the counterpropagating Alfvén waves. If the 2D modes are forced, a 2D inverse cascade dominates the dynamics at the largest scales, but at small enough scales, the same weak and then strong regimes as described above are achieved.

## Angle-action estimation in a general axisymmetric potential

ArXiv (2012)

J Sanders

The usefulness of angle-action variables in galaxy dynamics is well known, but their use is limited due to the difficulty of their calculation in realistic galaxy potentials. Here we present a method for estimating angle-action variables in a realistic Milky Way axisymmetric potential by locally fitting a St\"ackel potential over the region an orbit probes. The quality of the method is assessed by comparison with other known methods for estimating angle-action variables of a range of disc and halo-type orbits. We conclude by projecting the Geneva-Copenhagen survey into angle-action space.

## Revealing the origin of the cold ISM in massive early-type galaxies

Proceedings of the International Astronomical Union 8 (2012) 324-327

TA Davis, PT De Zeeuw, E Emsellem, D Krajnovic, H Kuntschner, P-Y Lablanche, K Alatalo, L Blitz, M Bureau, E Bayet, M Cappellari, RL Davies, L Young, A Crocker, M Bois, F Bournaud, P-A Duc, J Falcon-Barroso, S Khochfar, RM McDermid, R Morganti, P Serra, T Naab, M Sarzi, N Scott, A Weijmans

Recently, massive early-type galaxies have shed their red-and-dead moniker, thanks to the discovery that many host residual star formation. As part of the ATLAS-3D project, we have conducted a complete, volume-limited survey of the molecular gas in 260 local early-type galaxies with the IRAM-30m telescope and the CARMA interferometer, in an attempt to understand the fuel powering this star formation. We find that around 22% of early-type galaxies in the local volume host molecular gas reservoirs. This detection rate is independent of galaxy luminosity and environment. Here we focus on how kinematic misalignment measurements and gas-to-dust ratios can be used to put constraints on the origin of the cold ISM in these systems. The origin of the cold ISM seems to depend strongly on environment, with misaligned, dust poor gas (indicative of externally acquired material) being common in the field but completely absent in rich groups and in the Virgo cluster. Very massive galaxies also appear to be devoid of accreted gas. This suggests that in the field mergers and/or cold gas accretion dominate the gas supply, while in clusters internal secular processes become more important. This implies that environment has a strong impact on the cold gas properties of ETGs. © 2013 International Astronomical Union.

## XUV spectroscopic characterization of warm dense aluminum plasmas generated by the free-electron-laser FLASH

Laser and Particle Beams 30 (2012) 45-56

U Zastrau, I Uschmann, E Förster, T Burian, J Chalupsky, L Juha, T Döppner, C Fortmann, SH Glenzer, RW Lee, AJ Nelson, TWJ Dzelzainis, CLS Lewis, D Riley, RR Fäustlin, N Medvedev, S Toleikis, E Galtier, HJ Lee, B Nagler, FB Rosmej, G Gregori, SM Vinko, JS Wark, T Whitcher, T Tschentscher

We report on experiments aimed at the generation and characterization of solid density plasmas at the free-electron laser FLASH in Hamburg. Aluminum samples were irradiated with XUV pulses at 13.5 nm wavelength (92 eV photon energy). The pulses with duration of a few tens of femtoseconds and pulse energy up to 100 μJ are focused to intensities ranging between 10 and 10 W/cm . We investigate the absorption and temporal evolution of the sample under irradiation by use of XUV and optical spectroscopy. We discuss the origin of saturable absorption, radiative decay, bremsstrahlung and atomic and ionic line emission. Our experimental results are in good agreement with simulations. © 2012 Cambridge University Press.