23 research outputs found

    The near-infrared spectrum of Mrk 1239: direct evidence of the dusty torus?

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    We report 0.8-4.5 micron SpeX spectroscopy of the narrow-line Seyfert 1 galaxy Mrk1239. The spectrum is outstanding because the nuclear continuum emission in the near-infrared is dominated by a strong bump of emission peaking at 2.2 micron, with a strength not reported before in an AGN. A comparison of the Mrk1239 spectrum to that of Ark564 allowed us to conclude that the continuum is strongly reddened by E(B-V)=0.54. The excess of emission, confirmed by aperture photometry and additional NIR spectroscopy, follows a simple blackbody curve at T=1200 K. This suggest that we may be observing direct evidence of dust heated near to the sublimation temperature, likely produced by the putative torus of the unification model. Although other alternatives are also plausible, the lack of star formation, the strong polarization and low extinction derived for the emission lines support the scenario where the hot dust is located between the narrow line region and the broad line region.Comment: 5 pages, 3 figures. Accepted to MNRAS letter

    The supermassive black hole and double nucleus of the core elliptical NGC5419

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    We obtained adaptive-optics assisted SINFONI observations of the central regions of the giant elliptical galaxy NGC5419 with a spatial resolution of 0.2 arcsec (55\approx 55 pc). NGC5419 has a large depleted stellar core with a radius of 1.58 arcsec (430 pc). HST and SINFONI images show a point source located at the galaxy's photocentre, which is likely associated with the low-luminosity AGN previously detected in NGC5419. Both the HST and SINFONI images also show a second nucleus, off-centred by 0.25 arcsec (70\approx 70 pc). Outside of the central double nucleus, we measure an almost constant velocity dispersion of σ350\sigma \sim 350 km/s. In the region where the double nucleus is located, the dispersion rises steeply to a peak value of 420\sim 420 km/s. In addition to the SINFONI data, we also obtained stellar kinematics at larger radii from the South African Large Telescope. While NGC5419 shows low rotation (v<50v < 50 km/s), the central regions (inside 4rb\sim 4 \, r_b) clearly rotate in the opposite direction to the galaxy's outer parts. We use orbit-based dynamical models to measure the black hole mass of NGC5419 from the kinematical data outside of the double nuclear structure. The models imply MBH=7.21.9+2.7×109_{\rm BH}=7.2^{+2.7}_{-1.9} \times 10^9 M_{\odot}. The enhanced velocity dispersion in the region of the double nucleus suggests that NGC5419 possibly hosts two supermassive black holes at its centre, separated by only 70\approx 70 pc. Yet our measured MBH_{\rm BH} is consistent with the black hole mass expected from the size of the galaxy's depleted stellar core. This suggests, that systematic uncertainties in MBH_{\rm BH} related to the secondary nucleus are small.Comment: Accepted for publication in MNRA

    The SINFONI Black Hole Survey: The Black Hole Fundamental Plane revisited and the paths of (co-) evolution of supermassive black holes and bulges

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    We investigate the correlations between the black hole mass MBHM_{BH}, the velocity dispersion σ\sigma, the bulge mass MBuM_{Bu}, the bulge average spherical density ρh\rho_h and its spherical half mass radius rhr_h, constructing a database of 97 galaxies (31 core ellipticals, 17 power-law ellipticals, 30 classical bulges, 19 pseudo bulges) by joining 72 galaxies from the literature to 25 galaxies observed during our recent SINFONI black hole survey. For the first time we discuss the full error covariance matrix. We analyse the well known MBHσM_{BH}-\sigma and MBHMBuM_{BH}-M_{Bu} relations and establish the existence of statistically significant correlations between MBuM_{Bu} and rhr_h and anti-correlations between MBuM_{Bu} and ρh\rho_h. We establish five significant bivariate correlations (MBHσρhM_{BH}-\sigma-\rho_h, MBHσrhM_{BH}-\sigma-r_h, MBHMBuσM_{BH}-M_{Bu}-\sigma, MBHMBuρhM_{BH}-M_{Bu}-\rho_h, MBHMBurhM_{BH}-M_{Bu}-r_h) that predict MBHM_{BH} of 77 core and power-law ellipticals and classical bulges with measured and intrinsic scatter as small as 0.36\approx 0.36 dex and 0.33\approx 0.33 dex respectively, or 0.26 dex when the subsample of 45 galaxies defined by Kormendy and Ho (2013) is considered. In contrast, pseudo bulges have systematically lower MBHM_{BH}, but approach the predictions of all the above relations at spherical densities ρh1010M/kpc3\rho_h\ge 10^{10} M_\odot/kpc^3 or scale lengths rh1r_h\le 1 kpc. These findings fit in a scenario of co-evolution of BH and classical-bulge masses, where core ellipticals are the product of dry mergers of power-law bulges and power-law Es 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 pseudo bulge hosts, except when (gas) densities are high enough to trigger the feedback mechanism responsible for the existence of the correlations between MBHM_{BH} and galaxy structural parameters.Comment: Accepted for publication in ApJ, proofs correcte

    Molecular gas in the centre of nearby galaxies from VLT/SINFONI integral field spectroscopy - II. Kinematics(star)

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    We present an analysis of the H2 emission-line gas kinematics in the inner ≲4 arcsec radius of six nearby spiral galaxies, based on adaptive optics-assisted integral-field observations obtained in the K band with SINFONI/VLT. Four of the six galaxies in our sample display ordered H2 velocity fields, consistent with gas moving in the plane of the galaxy and rotating in the same direction as the stars. However, the gas kinematics is typically far from simple circular motion. We can classify the observed velocity fields into four different types of flows, ordered by increasing complexity: (1) circular motion in a disc (NGC 3351); (2) oval motion in the galaxy plane (NGC 3627 and NGC 4536); (3) streaming motion superimposed on circular rotation (NGC 4501); and (4) disordered streaming motions (NGC 4569 and NGC 4579). The H2 velocity dispersion in the galaxies is usually higher than 50 km s−1 in the inner 1–2 arcsec radii. The four galaxies with ordered kinematics have v/σ < 1 at radii less than 40–80 pc. The radius at which v/σ = 1 is independent of the type of nuclear activity. While the low values of v/σ could be taken as an indication of a thick disc in the innermost regions of the galaxies, other lines of evidence (e.g. H2 morphologies and velocity fields) argue for a thin disc interpretation in the case of NGC 3351 and NGC 4536. We discuss the implications of the high values of velocity dispersion for the dynamics of the gaseous disc and suggest caution when interpreting the velocity dispersion of ionized and warm tracers as being entirely dynamical. Understanding the nature and role of the velocity dispersion in the gas dynamics, together with the full 2D information of the gas, is essential for obtaining accurate black hole masses from gas kinematics

    Optical and NIR spectroscopy of Mrk 1210: constraints and physical conditions of the active nucleus

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    Aims.Mrk 1210 is an outstanding Seyfert 2 galaxy because it displays signatures of recent circumnuclear star formation and a high level of X-ray activity, in addition to the classical spectral characteristics typical of an AGN. Here we investigate the extinction affecting the nuclear and extended emitting gas, the kinematics of the narrow-line region, and the physical properties and conditions of that gas. Methods.Near-infrared and optical spectra of the nuclear and extended emission region of Mrk 1210 are presented, covering the interval 0.4-2.4 μm. Emission and absorption lines were used to infer, respectively, the geometrical extension of the ionized gas and the contribution of the underlying stellar population to the observed integrated continuum. The emission line profiles were employed to study the kinematics in the NLR. The reddening and physical condition of the gas were investigated by means of flux ratios among permitted and forbidden lines. Results.The NIR nuclear spectrum is dominated by \ion{H}{i} and \ion{He}{i} recombination lines, as well as [\ion{S}{ii}], [\ion{S}{iii}], and [\ion{Fe}{ii}] forbidden lines. Coronal lines of [\ion{S}{viii}], [\ion{S}{ix}], [\ion{Si}{vi}], [\ion{Si}{x}], and [\ion{Ca}{viii}], in addition to molecular H2 lines, were also detected. The 12CO(63)^{12}{\rm CO(6{-}3)} 1.618 μm overtone bandhead helped to estimate the contribution of the stellar population to the continuum. It was found that 83±8%83\pm8\% of the H-band continuum has a stellar origin. It improves previous estimates, which claimed that at least 50% of the observed continuum was attributed to the AGN. Analysis of the emission line profiles, both allowed and forbidden, shows a narrower (FWHM500{\it FWHM} \sim 500 km s-1) line on top of a broad (FWHM>1000{\it FWHM} > 1000 km s-1) blue-shifted component. This seems to be associated to a nuclear outflow. This hypothesis is supported by 6 cm VLBI observations, which show a radio ejecta extending up to ~30 pc from the nucleus. This result does not require the presence of the hidden BLR claimed to be present in previous NIR observations of this object. Internal extinction, calculated by means of several indicators including [\ion{Fe}{ii}] flux ratios not previously used before in AGNs, reveals a dusty AGN, while the extended regions are barely affected by dust, if at all. The density and temperature are calculated for the NLR using optical and NIR lines as diagnostic ratios. The results show electronic temperatures from 10 000 K up to 40 000 K and densities between 10310510^3{-}10^5 cm-3. The higher temperatures show that shocks, most probably related to the radio outflow, must contribute to the line emission

    The coronal emission-line region in AGNs: a Hubble Space Telescope view

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    Resolving the coronal line region of NGC 1068 with near-infrared integral field spectroscopy

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    We present adaptive optics-assisted J- and K-band integral field spectroscopy of the inner 300 × 300 pc of the Seyfert 2 galaxy NGC 1068. The data were obtained with the Gemini Near-infrared Integral-Field Spectrograph integral field unit spectrometer,
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