23 research outputs found
The near-infrared spectrum of Mrk 1239: direct evidence of the dusty torus?
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
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 ( 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 (
pc). Outside of the central double nucleus, we measure an almost constant
velocity dispersion of km/s. In the region where the double
nucleus is located, the dispersion rises steeply to a peak value of
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 ( km/s), the central regions (inside ) 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
M M. 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 pc. Yet our measured M is consistent with the black hole mass
expected from the size of the galaxy's depleted stellar core. This suggests,
that systematic uncertainties in M 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
We investigate the correlations between the black hole mass , the
velocity dispersion , the bulge mass , the bulge average
spherical density and its spherical half mass radius ,
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 and relations and
establish the existence of statistically significant correlations between
and and anti-correlations between and . We
establish five significant bivariate correlations (,
, , ,
) that predict of 77 core and power-law ellipticals
and classical bulges with measured and intrinsic scatter as small as dex and 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 , but approach the predictions
of all the above relations at spherical densities or scale lengths 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
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)
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
Recommended from our members
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the large-scale two-point correlation function
We obtain constraints on cosmological parameters from the spherically
averaged redshift-space correlation function of the CMASS Data Release 9 (DR9)
sample of the Baryonic Oscillation Spectroscopic Survey (BOSS). We combine this
information with additional data from recent CMB, SN and BAO measurements. Our
results show no significant evidence of deviations from the standard
flat-Lambda CDM model, whose basic parameters can be specified by Omega_m =
0.285 +- 0.009, 100 Omega_b = 4.59 +- 0.09, n_s = 0.96 +- 0.009, H_0 = 69.4 +-
0.8 km/s/Mpc and sigma_8 = 0.80 +- 0.02. The CMB+CMASS combination sets tight
constraints on the curvature of the Universe, with Omega_k = -0.0043 +- 0.0049,
and the tensor-to-scalar amplitude ratio, for which we find r < 0.16 at the 95
per cent confidence level (CL). These data show a clear signature of a
deviation from scale-invariance also in the presence of tensor modes, with n_s
<1 at the 99.7 per cent CL. We derive constraints on the fraction of massive
neutrinos of f_nu < 0.049 (95 per cent CL), implying a limit of sum m_nu < 0.51
eV. We find no signature of a deviation from a cosmological constant from the
combination of all datasets, with a constraint of w_DE = -1.033 +- 0.073 when
this parameter is assumed time-independent, and no evidence of a departure from
this value when it is allowed to evolve as w_DE(a) = w_0 + w_a (1 - a). The
achieved accuracy on our cosmological constraints is a clear demonstration of
the constraining power of current cosmological observations.Comment: 26 pages, 15 figures. Minor changes to match version accepted by
MNRA
Optical and NIR spectroscopy of Mrk 1210: constraints and physical conditions of the active nucleus
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 1.618 μm
overtone bandhead helped to estimate the contribution of the stellar population to the continuum.
It was found that 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
( km s-1) line on top of a broad ( 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 cm-3.
The higher temperatures show that shocks, most probably
related to the radio outflow, must contribute
to the line emission
Resolving the coronal line region of NGC 1068 with near-infrared integral field spectroscopy
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,