| 1341. |
- Saglia, R. P., et al.
(författare)
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THE SINFONI BLACK HOLE SURVEY : THE BLACK HOLE FUNDAMENTAL PLANE REVISITED AND THE PATHS OF (CO)EVOLUTION OF SUPERMASSIVE BLACK HOLES AND BULGES
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 818:1
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the correlations between the black hole (BH) mass M-BH, the velocity dispersion sigma, the bulge mass M-Bu, the bulge average spherical density rho(h), and its spherical half-mass radius r(h), constructing a database of 97 galaxies (31 core ellipticals, 17 power-law ellipticals, 30 classical bulges, and 19 pseudobulges) by joining 72 galaxies from the literature to 25 galaxies observed during our recent SINFONI BH survey. For the first time we discuss the full error covariance matrix. We analyze the well-known M-BH-sigma and M-BH-M-Bu relations and establish the existence of statistically significant correlations between M-Bu and r(h) and anticorrelations between M-Bu and rho(h). We establish five significant bivariate correlations (M-BH-sigma-rho(h), M-BH-sigma-r(h), M-BH-M-Bu-sigma, M-BH-M-Bu-rho(h), M-BH-M-Bu-r(h)) that predict MBH of 77 core and power-law ellipticals and classical bulges with measured and intrinsic scatter as small as approximate to 0.36 dex and approximate to 0.33 dex, respectively, or 0.26 dex when the subsample of 45 galaxies defined by Kormendy & Ho is considered. In contrast, pseudobulges have systematically lower MBH but approach the predictions of all of the above relations at spherical densities rho(h) >= 10(10) M-circle dot kpc(-3). or scale lengths r(h) <= 1 kpc. These findings fit in a scenario of coevolution of BH and classical-bulge masses, where core ellipticals are the product of dry mergers of power-law bulges and power-law ellipticals and bulges the result of (early) gas-rich mergers and of disk galaxies. In contrast, the (secular) growth of BHs is decoupled from the growth of their pseudobulge hosts, except when (gas) densities are high enough to trigger the feedback mechanism responsible for the existence of the correlations between MBH and galaxy structural parameters.
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| 1342. |
- Sahai, R., et al.
(författare)
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ALMA OBSERVATIONS OF THE COLDEST PLACE IN THE UNIVERSE: THE BOOMERANG NEBULA
- 2013
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 777:2, s. 11-
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Tidskriftsartikel (refereegranskat)abstract
- The Boomerang Nebula is the coldest known object in the universe, and an extreme member of the class of pre-planetary nebulae, objects which represent a short-lived transitional phase between the asymptotic giant branch and planetary nebula evolutionary stages. Previous single-dish CO (J = 1-0) observations (with a 45 '' beam) showed that the high-speed outflow in this object has cooled to a temperature significantly below the temperature of the cosmic background radiation. Here we report the first observations of the Boomerang Nebula with ALMA in the CO J = 2-1 and J = 1-0 lines to resolve the structure of this ultra-cold nebula. We find a central hourglass-shaped nebula surrounded by a patchy, but roughly round, cold high-velocity outflow. We compare the ALMA data with visible-light images obtained with the Hubble Space Telescope and confirm that the limb-brightened bipolar lobes seen in these data represent hollow cavities with dense walls of molecular gas and dust producing both the molecular-emission-line and scattered-light structures seen at millimeter and visible wavelengths. The large diffuse biconical shape of the nebula seen in the visible wavelength range is likely due to preferential illumination of the cold, high-velocity outflow. We find a compact source of millimeter-wave continuum in the nebular waist-these data, together with sensitive upper limits on the radio continuum using observations with ATCA, indicate the presence of a substantial mass of very large (millimeter-sized) grains in the waist of the nebula. Another unanticipated result is the detection of CO emission regions beyond the ultra-cold region which indicate the re-warming of the cold gas, most likely due to photoelectric grain heating.
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| 1343. |
- Saito, Toshiki, et al.
(författare)
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Spatially Resolved CO SLED of the Luminous Merger Remnant NGC 1614 with ALMA
- 2017
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 835:2
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Tidskriftsartikel (refereegranskat)abstract
- We present high-resolution (1.?0) Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO (1-0) and CO (2-1) rotational transitions toward the nearby IR-luminous merger NGC 1614 supplemented with ALMA archival data of CO (3-2) and CO (6-5) transitions. The CO (6-5) emission arises from the starburst ring (central 590 pc in radius), while the lower-J CO lines are distributed over the outer disk (?3.3 kpc in radius). Radiative transfer and photon-dominated region (PDR) modeling reveals that the starburst ring has a single warmer gas component with more a intense far-ultraviolet radiation field (nh2 ? 104.6 cm-3, Tkin ?42 K, and G0 ?102.7) relative to the outer disk (nh2 ? 105.1 cm-3, Tkin ? 22 K, and G0 ?100.9 cm-3, K, and ). A two-phase molecular interstellar medium with a warm and cold (>70 and ?19 K) component is also an applicable model for the starburst ring. A possible source for heating the warm gas component is mechanical heating due to stellar feedback rather than PDR. Furthermore, we find evidence for non-circular motions along the north-south optical bar in the lower-J CO images, suggesting a cold gas inflow. We suggest that star formation in the starburst ring is sustained by the bar-driven cold gas inflow and that starburst activities radiatively and mechanically power the CO excitation. The absence of a bright active galactic nucleus can be explained by a scenario where cold gas accumulating on the starburst ring is exhausted as the fuel for star formation or is launched as an outflow before being able to feed to the nucleus.
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| 1344. |
- Sakamoto, K., et al.
(författare)
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An infrared-luminous merger with two bipolar molecular outflows: ALMA and SMA observations of NGC3256
- 2014
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 797:2
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Tidskriftsartikel (refereegranskat)abstract
- We report Atacama Large Millimeter/sub-millimeter Array and Submillimeter Array observations of the infrared-luminous merger NGC3256, the most luminous galaxy within z = 0.01. Both of the two merger nuclei separated by 5 '' (0.8 kpc) have a molecular gas concentration, a nuclear disk, with Sigma(mol) > 10(3) M-circle dot pc(-2). The northern nucleus is more massive and is surrounded by molecular spiral arms. Its nuclear disk is face-on, while the southern nuclear disk is almost edge-on. The high-velocity molecular gas in the system can be resolved into two molecular outflows from the two nuclei. The one from the northern nucleus is part of a starburst-driven superwind seen nearly pole-on. Its maximum velocity is > 750 km s(-1) and its mass outflow rate is > 60M(circle dot) yr(-1) for a conversion factor X-CO = N-H2 / ICO(1-0) of 1 x 10(20) cm(-2) (K km s(-1))(-1). The molecular outflow from the southern nucleus is a highly collimated bipolar jet seen nearly edge-on. Its line-of-sight velocity increases with distance, out to 300 pc from the nucleus, to the maximum de-projected velocity of similar to 2000 km s(-1) for the estimated inclination and greater than or similar to 1000 km s(-1) taking into account the uncertainty. Its mass outflow rate is estimated to be > 50M(circle dot) yr(-1) for the same XCO. This southern outflow has indications of being driven by a bipolar radio jet from an active galactic nucleus that recently weakened. The sum of these outflow rates, although subject to the uncertainty in the molecular mass estimate, either exceeds or compares to the total star formation rate. The feedback from nuclear activity through molecular outflows is therefore significant in the gas consumption, and hence evolution, of this system.
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| 1345. |
- Sakamoto, K., et al.
(författare)
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Submillimeter Interferometry of the Luminous Infrared Galaxy NGC 4418: A Hidden Hot Nucleus with an Inflow and an Outflow
- 2013
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 764:1, s. 42-66
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Tidskriftsartikel (refereegranskat)abstract
- We have observed the nucleus of the nearby luminous infrared galaxy NGC 4418 with subarcsec resolution at 860and 450 μmfor the first time to characterize its hidden power source. A∼20 pc (0″.1) hot dusty core was found inside a 100 pc scale concentration of molecular gas at the galactic center. The 860 μm continuum core has a deconvolved (peak) brightness temperature of 120–210 K. The CO(3–2) peak brightness temperature there is as high as 90 K at 50 pc resolution. The core has a bolometric luminosity of about 1011 L☉ which accounts for most of the galaxy luminosity. It is Compton thick (NH≳1025 cm−2) and has a high luminosity-to-mass ratio (L/M) ∼ 500 L☉ M☉−1 as well as a high luminosity surface density 108.5±0.5L☉ pc−2. These parameters are consistent with an activegalactic nucleus to be the main luminosity source (with an Eddington ratio about 0.3), while they can be also due to a young starburst near its maximum L/M. We also found an optical color (reddening) feature that we attribute to an outflow cone emanating from the nucleus. The hidden hot nucleus thus shows evidence of both an inflow, previously seen with absorption lines, and the new outflow reported here in a different direction. The nucleus must be rapidly evolving with these gas flows.
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| 1346. |
- Sakamoto, T., et al.
(författare)
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IDENTIFYING THE LOCATION IN THE HOST GALAXY OF THE SHORT GRB 111117A WITH THE CHANDRA SUBARCSECOND POSITION
- 2013
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 766:1, s. 41-
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Tidskriftsartikel (refereegranskat)abstract
- We present our successful Chandra program designed to identify, with subarcsecond accuracy, the X-ray afterglow of the short GRB 111117A, which was discovered by Swift and Fermi. Thanks to our rapid target of opportunity request, Chandra clearly detected the X-ray afterglow, though no optical afterglow was found in deep optical observations. The host galaxy was clearly detected in the optical and near-infrared band, with the best photometric redshift of z = 1.31(-0.23)(+0.46) (90% confidence), making it one of the highest known short gamma-ray burst ( GRB) redshifts. Furthermore, we see an offset of 1.0 +/- 0.2 arcsec, which corresponds to 8.4 +/- 1.7 kpc, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining subarcsecond X-ray localizations of short GRB afterglows to study GRB environments.
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| 1347. |
- Sako, Masao, et al.
(författare)
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Photometric Type Ia Supernova Candidates from the Three-year SDSS-II SN Survey Data
- 2011
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 738, s. 162-
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the three-year Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey data and identify a sample of 1070 photometric Type Ia supernova (SN Ia) candidates based on their multiband light curve data. This sample consists of SN candidates with no spectroscopic confirmation, with a subset of 210 candidates having spectroscopic redshifts of their host galaxies measured while the remaining 860 candidates are purely photometric in their identification. We describe a method for estimating the efficiency and purity of photometric SN Ia classification when spectroscopic confirmation of only a limited sample is available, and demonstrate that SN Ia candidates from SDSS-II can be identified photometrically with ~91% efficiency and with a contamination of ~6%. Although this is the largest uniform sample of SN candidates to date for studying photometric identification, we find that a larger spectroscopic sample of contaminating sources is required to obtain a better characterization of the background events. A Hubble diagram using SN candidates with no spectroscopic confirmation, but with host galaxy spectroscopic redshifts, yields a distance modulus dispersion that is only ~20%-40% larger than that of the spectroscopically confirmed SN Ia sample alone with no significant bias. A Hubble diagram with purely photometric classification and redshift-distance measurements, however, exhibits biases that require further investigation for precision cosmology.
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| 1348. |
- Saur, Joachim, et al.
(författare)
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HUBBLE SPACE TELESCOPE/ADVANCED CAMERA FOR SURVEYS OBSERVATIONS OF EUROPA’S ATMOSPHERIC ULTRAVIOLET EMISSION AT EASTERN ELONGATION
- 2011
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 738:2
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Tidskriftsartikel (refereegranskat)abstract
- We report results of a Hubble Space Telescope (HST) campaign with the Advanced Camera for Surveys to observe Europa at eastern elongation, i.e., Europa's leading side, on 2008 June 29. With five consecutive HST orbits, we constrain Europa's atmospheric OI 1304 angstrom and OI 1356 angstrom emissions using the prism PR130L. The total emissions of both oxygen multiplets range between 132 +/- 14 and 226 +/- 14 Rayleigh. An additional systematic error with values on the same order as the statistical errors may be due to uncertainties in modeling the reflected light from Europa's surface. The total emission also shows a clear dependence of Europa's position with respect to Jupiter's magnetospheric plasma sheet. We derive a lower limit for the O-2 column density of 6 x 10(18) m(-2). Previous observations of Europa's atmosphere with the Space Telescope Imaging Spectrograph in 1999 of Europa's trailing side show an enigmatic surplus of radiation on the anti-Jovian side within the disk of Europa. With emission from a radially symmetric atmosphere as a reference, we searched for an anti-Jovian versus sub-Jovian asymmetry with respect to the central meridian on the leading side and found none. Likewise, we searched for departures from a radially symmetric atmospheric emission and found an emission surplus centered around 90 degrees west longitude, for which plausible mechanisms exist. Previous work about the possibility of plumes on Europa due to tidally driven shear heating found longitudes with strongest local strain rates which might be consistent with the longitudes of maximum UV emissions. Alternatively, asymmetries in Europa's UV emission can also be caused by inhomogeneous surface properties, an optically thick atmospheric contribution of atomic oxygen, and/or by Europa's complex plasma interaction with Jupiter's magnetosphere.
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| 1349. |
- Savcheva, A., et al.
(författare)
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THE RELATION BETWEEN SOLAR ERUPTION TOPOLOGIES AND OBSERVED FLARE FEATURES. I. FLARE RIBBONS
- 2015
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 810:2
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a topological magnetic field investigation of seven two-ribbon flares in sigmoidal active regions observed with Hinode, STEREO, and Solar Dynamics Observatory. We first derive the 3D coronal magnetic field structure of all regions using marginally unstable 3D coronal magnetic field models created with the flux rope insertion method. The unstable models have been shown to be a good model of the flaring magnetic field configurations. Regions are selected based on their pre-flare configurations along with the appearance and observational coverage of flare ribbons, and the model is constrained using pre-flare features observed in extreme ultraviolet and X-ray passbands. We perform a topology analysis of the models by computing the squashing factor, Q, in order to determine the locations of prominent quasi-separatrix layers (QSLs). QSLs from these maps are compared to flare ribbons at their full extents. We show that in all cases the straight segments of the two J-shaped ribbons are matched very well by the flux-rope-related QSLs, and the matches to the hooked segments are less consistent but still good for most cases. In addition, we show that these QSLs overlay ridges in the electric current density maps. This study is the largest sample of regions with QSLs derived from 3D coronal magnetic field models, and it shows that the magnetofrictional modeling technique that we employ gives a very good representation of flaring regions, with the power to predict flare ribbon locations in the event of a flare following the time of the model.
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| 1350. |
- Schad, A., et al.
(författare)
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A UNIFIED APPROACH TO THE HELIOSEISMIC INVERSION PROBLEM OF THE SOLAR MERIDIONAL FLOW FROM GLOBAL OSCILLATIONS
- 2011
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Ingår i: Astrophysical Journal. - : University of Chicago Press. - 0004-637X .- 1538-4357. ; 734:2, s. 97-
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Tidskriftsartikel (refereegranskat)abstract
- Measurements from tracers and local helioseismology indicate the existence of a meridional flow in the Sun with strength in the order of 15 m s(-1) near the solar surface. Different attempts were made to obtain information on the flow profile at depths up to 20 Mm below the solar surface. We propose a method using global helioseismic Doppler measurements with the prospect of inferring the meridional flow profile at greater depths. Our approach is based on the perturbation of the p-mode eigenfunctions of a solar model due to the presence of a flow. The distortion of the oscillation eigenfunctions is manifested in the mixing of p-modes, which may be measured from global solar oscillation time series. As a new helioseismic measurement quantity, we propose amplitude ratios between oscillations in the Fourier domain. We relate this quantity to the meridional flow and unify the concepts presented here for an inversion procedure to infer the meridional flow from global solar oscillations.
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