ALBERT

Description: In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 x 10(45) erg s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McDonald, M -- Bayliss, M -- Benson, B A -- Foley, R J -- Ruel, J -- Sullivan, P -- Veilleux, S -- Aird, K A -- Ashby, M L N -- Bautz, M -- Bazin, G -- Bleem, L E -- Brodwin, M -- Carlstrom, J E -- Chang, C L -- Cho, H M -- Clocchiatti, A -- Crawford, T M -- Crites, A T -- de Haan, T -- Desai, S -- Dobbs, M A -- Dudley, J P -- Egami, E -- Forman, W R -- Garmire, G P -- George, E M -- Gladders, M D -- Gonzalez, A H -- Halverson, N W -- Harrington, N L -- High, F W -- Holder, G P -- Holzapfel, W L -- Hoover, S -- Hrubes, J D -- Jones, C -- Joy, M -- Keisler, R -- Knox, L -- Lee, A T -- Leitch, E M -- Liu, J -- Lueker, M -- Luong-Van, D -- Mantz, A -- Marrone, D P -- McMahon, J J -- Mehl, J -- Meyer, S S -- Miller, E D -- Mocanu, L -- Mohr, J J -- Montroy, T E -- Murray, S S -- Natoli, T -- Padin, S -- Plagge, T -- Pryke, C -- Rawle, T D -- Reichardt, C L -- Rest, A -- Rex, M -- Ruhl, J E -- Saliwanchik, B R -- Saro, A -- Sayre, J T -- Schaffer, K K -- Shaw, L -- Shirokoff, E -- Simcoe, R -- Song, J -- Spieler, H G -- Stalder, B -- Staniszewski, Z -- Stark, A A -- Story, K -- Stubbs, C W -- Suhada, R -- van Engelen, A -- Vanderlinde, K -- Vieira, J D -- Vikhlinin, A -- Williamson, R -- Zahn, O -- Zenteno, A -- England -- Nature. 2012 Aug 16;488(7411):349-52. doi: 10.1038/nature11379.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. mcdonald@space.mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22895340" target="_blank"〉PubMed〈/a〉

Description: The under-abundance of very massive galaxies in the Universe is frequently attributed to the effect of galactic winds. Although ionized galactic winds are readily observable, most of the expelled mass (that is, the total mass flowing out from the nuclear region) is likely to be in atomic and molecular phases that are cooler than the ionized phases. Expanding molecular shells observed in starburst systems such as NGC 253 (ref. 12) and M 82 (refs 13, 14) may facilitate the entrainment of molecular gas in the wind. Although shell properties are well constrained, determining the amount of outflowing gas emerging from such shells and the connection between this gas and the ionized wind requires spatial resolution better than 100 parsecs coupled with sensitivity to a wide range of spatial scales, a combination hitherto not available. Here we report observations of NGC 253, a nearby starburst galaxy (distance approximately 3.4 megaparsecs) known to possess a wind, that trace the cool molecular wind at 50-parsec resolution. At this resolution, the extraplanar molecular gas closely tracks the Halpha filaments, and it appears to be connected to expanding molecular shells located in the starburst region. These observations allow us to determine that the molecular outflow rate is greater than 3 solar masses per year and probably about 9 solar masses per year. This implies a ratio of mass-outflow rate to star-formation rate of at least 1, and probably approximately 3, indicating that the starburst-driven wind limits the star-formation activity and the final stellar content.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bolatto, Alberto D -- Warren, Steven R -- Leroy, Adam K -- Walter, Fabian -- Veilleux, Sylvain -- Ostriker, Eve C -- Ott, Jurgen -- Zwaan, Martin -- Fisher, David B -- Weiss, Axel -- Rosolowsky, Erik -- Hodge, Jacqueline -- England -- Nature. 2013 Jul 25;499(7459):450-3. doi: 10.1038/nature12351.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, Laboratory for Millimeter-wave Astronomy, and Joint Space Institute, University of Maryland, College Park, Maryland 20742, USA. bolatto@astro.umd.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23887428" target="_blank"〉PubMed〈/a〉

Description: Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies. Recent observations of large-scale molecular outflows in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies and a few higher-redshift quasars. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity of 1.5 x 10(46) ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism that is the basis of the quasar feedback in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tombesi, F -- Melendez, M -- Veilleux, S -- Reeves, J N -- Gonzalez-Alfonso, E -- Reynolds, C S -- England -- Nature. 2015 Mar 26;519(7544):436-8. doi: 10.1038/nature14261.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA [2] Department of Astronomy and CRESST, University of Maryland, College Park, Maryland 20742, USA. ; Department of Astronomy and CRESST, University of Maryland, College Park, Maryland 20742, USA. ; 1] Department of Astronomy and CRESST, University of Maryland, College Park, Maryland 20742, USA [2] Joint Space Science Institute, University of Maryland, College Park, Maryland 20742, USA. ; 1] Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK [2] Center for Space Science and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA. ; Universidad de Alcala, Departamento de Fisica y Matematicas, Campus Universitario, E-28871 Alcala de Henares, Madrid, Spain.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25810204" target="_blank"〉PubMed〈/a〉

Description: We investigate the relationship between X-ray and optical line emission in 340 nearby ( z ~= 0.04) AGN selected above 10 keV using Swift BAT. We find a weak correlation between the extinction corrected [O iii ] and hard X-ray luminosity ( $L_{\left[{\rm O}\,\small {III}\right] }^{\text{int}} \propto L_{14\text{--}195}$ ) with a large scatter ( R Pear = 0.64, = 0.62 dex) and a similarly large scatter with the intrinsic 2–10 keV to [O iii ] luminosities ( R Pear = 0.63, = 0.63 dex). Correlations of the hard X-ray fluxes with the fluxes of high-ionization narrow lines ([O iii ], He ii , [Ne iii ] and [Ne v ]) are not significantly better than with the low-ionization lines (H α, [S ii ]). Factors like obscuration or physical slit size are not found to be a significant part of the large scatter. In contrast, the optical emission lines show much better correlations with each other ( = 0.3 dex) than with the X-ray flux. The inherent large scatter questions the common usage of narrow emission lines as AGN bolometric luminosity indicators and suggests that other issues such as geometrical differences in the scattering of the ionized gas or long-term AGN variability are important.

Description: We present constraints on the molecular outflows in a sample of five hyperluminous infrared galaxies using Herschel observations of the OH doublet at 119 μm. We have detected the OH doublet in three cases: one purely in emission and two purely in absorption. The observed emission profile has a significant blueshifted wing suggesting the possibility of tracing an outflow. Out of the two absorption profiles, one seems to be consistent with the systemic velocity while the other clearly indicates the presence of a molecular outflow whose maximum velocity is about ~1500 km s –1 . Our analysis shows that this system is in general agreement with previous results on ultraluminous infrared galaxies and QSOs, whose outflow velocities do not seem to correlate with stellar masses or starburst luminosities (star formation rates). Instead, the galaxy outflow likely arises from an embedded active galactic nuclei.

Description: While performing a survey to detect recoiling supermassive black holes, we have identified an unusual source having a projected offset of 800 pc from a nearby dwarf galaxy. The object, SDSS J113323.97+550415.8, exhibits broad emission lines and strong variability. While originally classified as a supernova (SN) because of its non-detection in 2005, we detect it in recent and past observations over 63 yr and find over a magnitude of rebrightening in the last 2 yr. Using high-resolution adaptive optics observations, we constrain the source emission region to be 12 pc and find a disturbed host-galaxy morphology indicative of recent merger activity. Observations taken over more than a decade show narrow [O iii ] lines, constant ultraviolet emission, broad Balmer lines, a constant putative black hole mass over a decade of observations despite changes in the continuum, and optical emission-line diagnostics consistent with an active galactic nucleus (AGN). However, the optical spectra exhibit blueshifted absorption, and eventually narrow Fe ii and [Ca ii ] emission, each of which is rarely found in AGN spectra. While this peculiar source displays many of the observational properties expected of a potential black hole recoil candidate, some of the properties could also be explained by a luminous blue variable star (LBV) erupting for decades since 1950, followed by a Type IIn SN in 2001. Interpreted as an LBV followed by an SN analogous to SN 2009ip, the multidecade LBV eruptions would be the longest ever observed, and the broad Hα emission would be the most luminous ever observed at late times (〉10 yr), larger than that of unusually luminous SNe such as SN 1988Z, suggesting one of the most extreme episodes of pre-SN mass-loss ever discovered.

Description: We report the discovery of a grand-design spiral galaxy associated with a double-lobed radio source. J1649+2635 ( z  = 0.0545) is a red spiral galaxy with a prominent bulge that it is associated with a L 1.4 GHz  ~ 10 24  W Hz –1 double-lobed radio source that spans almost 100 kpc. J1649+2635 has a black hole mass of M BH  ~ 3–7 10 8  M and SFR ~ 0.26–2.6 M  yr –1 . The galaxy hosts an ~96 kpc diffuse optical halo, which is unprecedented for spiral galaxies. We find that J1649+2635 resides in an overdense environment with a mass of $M_{\rm dyn} = 7.7^{+7.9}_{-4.3} \times 10^{13}$  M , likely a galaxy group below the detection threshold of the ROSAT All-Sky Survey. We suggest one possible scenario for the association of double-lobed radio emission from J1649+2635 is that the source may be similar to a Seyfert galaxy, located in a denser-than-normal environment. The study of spiral galaxies that host large-scale radio emission is important because although rare in the local Universe, these sources may be more common at high redshifts.

Description: We use high-spectral resolution ( R  〉 8000) data covering 3800–13 000 Å to study the physical conditions of the broad-line region (BLR) of nine nearby Seyfert 1 galaxies. Up to six broad H i lines are present in each spectrum. A comparison – for the first time using simultaneous optical to near-infrared observations – to photoionization calculations with our devised simple scheme yields the extinction to the BLR at the same time as determining the density and photon flux, and hence distance from the nucleus, of the emitting gas. This points to a typical density for the H i emitting gas of 10 11  cm –3 and shows that a significant amount of this gas lies at regions near the dust sublimation radius, consistent with theoretical predictions. We also confirm that in many objects, the line ratios are far from case B, the best-fitting intrinsic broad-line Hα/H β ratios being in the range 2.5–6.6 as derived with our photoionization modelling scheme. The extinction to the BLR, based on independent estimates from H i and He ii lines, is A V  ≤ 3 for Seyfert 1–1.5s, while Seyfert 1.8–1.9s have A V in the range 4–8. A comparison of the extinction towards the BLR and narrow-line region (NLR) indicates that the structure obscuring the BLR exists on scales smaller than the NLR. This could be the dusty torus, but dusty nuclear spirals or filaments could also be responsible. The ratios between the X-ray absorbing column N H and the extinction to the BLR are consistent with the Galactic gas-to-dust ratio if N H variations are considered.

Description: We investigate the observed relationship between black hole mass ( M BH ), bolometric luminosity ( L bol ) and Eddington ratio ( Edd ) with optical emission-line ratios ([N  ii ] 6583/Hα, [S  ii ] 6716, 6731/Hα, [O  i ] 6300/Hα, [O  iii ] 5007/Hβ, [Ne  iii ] 3869/Hβ and He  ii 4686/Hβ) of hard X-ray-selected active galactic nuclei (AGN) from the BAT AGN Spectroscopic Survey. We show that the [N  ii ] 6583/Hα ratio exhibits a significant correlation with Edd ( R Pear = –0.44, p -value = 3 x 10 –13 , = 0.28 dex), and the correlation is not solely driven by M BH or L bol . The observed correlation between [N  ii ] 6583/Hα ratio and M BH is stronger than the correlation with L bol , but both are weaker than the Edd correlation. This implies that the large-scale narrow lines of AGN host galaxies carry information about the accretion state of the AGN central engine. We propose that [N  ii ] 6583/Hα is a useful indicator of Eddington ratio with 0.6 dex of rms scatter, and that it can be used to measure Edd and thus M BH from the measured L bol , even for high-redshift obscured AGN. We briefly discuss possible physical mechanisms behind this correlation, such as the mass–metallicity relation, X-ray heating, and radiatively driven outflows.