32 research outputs found
ALMA Observations of Circumnuclear Disks in Early Type Galaxies: 12CO(2-1) and Continuum Properties
We present results from an Atacama Large Millimeter/submillimeter Array
(ALMA) Cycle 2 program to map CO(2-1) emission in nearby early-type galaxies
(ETGs) that host circumnuclear gas disks. We obtained resolution
Band 6 observations of seven ETGs selected on the basis of dust disks in Hubble
Space Telescope images. We detect CO emission in five at high signal-to-noise
ratio with the remaining two only faintly detected. All CO emission is
coincident with the dust and is in dynamically cold rotation. Four ETGs show
evidence of rapid central rotation; these are prime candidates for
higher-resolution ALMA observations to measure the black hole masses. In this
paper we focus on the molecular gas and continuum properties. Total gas masses
and H column densities for our five CO-bright galaxies are on average
and cm over the kpc-scale
disks, and analysis suggests that these disks are stabilized against
gravitational fragmentation. The continuum emission of all seven galaxies is
dominated by a central, unresolved source, and in five we also detect a
spatially extended component. The 230 GHz nuclear continua are modeled as
power laws ranging from to within the
observed frequency band. The extended continuum profiles of the two
radio-bright (and CO-faint) galaxies are roughly aligned with their radio jet
and suggests resolved synchrotron jets. The extended continua of the CO-bright
disks are coincident with optically thick dust absorption and have spectral
slopes that are consistent with thermal dust emission.Comment: 20 pages, 10 figures; accepted for publication in Ap
A Precision Measurement of the Mass of the Black Hole in NGC 3258 from High-Resolution ALMA Observations of its Circumnuclear Disk
We present resolution Atacama Large
Millimeter/submillimeter Array (ALMA) CO(21) imaging of the arcsecond-scale
( pc) dusty molecular disk in the giant elliptical galaxy NGC
3258. The data provide unprecedented resolution of cold gas disk kinematics
within the dynamical sphere of influence of a supermassive black hole,
revealing a quasi-Keplerian central increase in projected rotation speed rising
from 280 km s at the disk's outer edge to km s near the
disk center. We construct dynamical models for the rotating disk and fit
beam-smeared model CO line profiles directly to the ALMA data cube. Our models
incorporate both flat disks and tilted-ring disks that provide a better fit of
the mildly warped structure in NGC 3258. We show that the exceptional angular
resolution of the ALMA data makes it possible to infer the host galaxy's mass
profile within pc solely from the ALMA CO kinematics, without relying
on optical or near-infrared imaging data to determine the stellar mass profile.
Our model therefore circumvents any uncertainty in the black hole mass that
would result from the substantial dust extinction in the galaxy's central
region. The best model fit yields
with a statistical model-fitting uncertainty of just 0.18\%, and systematic
uncertainties of 0.62\% from various aspects of the model construction and 12\%
from uncertainty in the distance to NGC 3258. This observation demonstrates the
full potential of ALMA for carrying out highly precise measurements of
in early-type galaxies containing circumnuclear gas disksComment: Accepted for publication in ApJ. 32 pages, 22 figure
MEASUREMENT OF THE BLACK HOLE MASS IN NGC 1332 FROM ALMA OBSERVATIONS AT 0.044 ARCSECOND RESOLUTION
We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 3 observations of CO(2-1) emission from the circumnuclear disk in the E/S0 galaxy NGC 1332 at 0.″044 resolution. The disk exhibits regular rotational kinematics and central high-velocity emission (±500 km s ) consistent with the presence of a compact central mass. We construct models for a thin, dynamically cold disk in the gravitational potential of the host galaxy and black hole and fit the beam-smeared model line profiles directly to the ALMA data cube. Model fits successfully reproduce the disk kinematics out to r = 200 pc. Fitting models just to spatial pixels within projected r = 50 pc of the nucleus (two times larger than the black hole's gravitational radius of influence), we find M =(6.64 ) × 10 M . This observation demonstrates ALMA's powerful capability to determine the masses of supermassive black holes by resolving gas kinematics on small angular scales in galaxy nuclei. -1 +0.65 8 BH -0.63
Gas inflows in the polar ring of NGC 4111 : the birth of an AGN
We have used Hubble Space Telescope (HST) images, SAURON Integral Field Spectroscopy (IFS), and adaptative optics assisted Gemini NIFS near-infrared K-band IFS to map the stellar and gas distribution, excitation and kinematics of the inner few kpc of the nearby edge-on S0 galaxy NGC 4111. The HST images map its ≈450 pc diameter dusty polar ring, with an estimated gas mass ≥107 M . The NIFS data cube maps the inner 110 pc radius at ≈7 pc spatial resolution, revealing a ≈220 pc diameter polar ring in hot (2267 ± 166 K) molecular H2 1–0 S(1) gas embedded in the polar ring. The stellar velocity field shows disc-dominated kinematics along the galaxy plane both in the SAURON large scale and in the NIFS nuclear-scale data. The large-scale [O III] λ5007 Å velocity field shows a superposition of two disc kinematics: one similar to that of the stars and another along the polar ring, showing non-circular motions that seem to connect with the velocity field of the nuclear H2 ring, whose kinematics indicate accelerated inflow to the nucleus. The estimated mass inflow rate is enough not only to feed an active galactic nucleus (AGN) but also to trigger circumnuclear star formation in the near future. We propose a scenario in which gas from the polar ring, which probably originated from the capture of a dwarf galaxy, is moving inwards and triggering an AGN, as supported by the local X-ray emission, which seems to be the source of the H2 1–0 S(1) excitation. The fact that we see neither near-UV nor Br γ emission suggests that the nascent AGN is still deeply buried under the optically thick dust of the polar ring
Gas inflows in the polar ring of NGC 4111: the birth of an AGN
We have used Hubble Space Telescope (HST) images, SAURON Integral Field
Spectroscopy (IFS) and adaptative optics assisted Gemini NIFS near-infrared
K-band IFS to map the stellar and gas distribution, excitation and kinematics
of the inner few kpc of the nearby edge-on S0 galaxy NGC 4111. The HST images
map its 450 pc diameter dusty polar ring, with an estimated gas mass
M. The NIFS datacube maps the inner 110 pc radius at
7 pc spatial resolution revealing a 220 pc diameter polar
ring in hot ( K) molecular H 1-0 S(1) gas embedded in the polar
ring. The stellar velocity field shows disk-dominated kinematics along the
galaxy plane both in the SAURON large-scale and in the NIFS nuclear-scale data.
The large-scale [O III] \AA velocity field shows a superposition
of two disk kinematics: one similar to that of the stars and another along the
polar ring, showing non-circular motions that seem to connect with the velocity
field of the nuclear H ring, whose kinematics indicate accelerated inflow
to the nucleus. The estimated mass inflow rate is enough not only to feed an
Active Galactic Nucleus (AGN) but also to trigger circumnuclear star formation
in the near future. We propose a scenario in which gas from the polar ring,
which probably originated from the capture of a dwarf galaxy, is moving inwards
and triggering an AGN, as supported by the local X-ray emission, which seems to
be the source of the H 1-0 S(1) excitation. The fact that we see neither
near-UV nor Br emission suggests that the nascent AGN is still deeply
buried under the optically thick dust of the polar ring.Comment: 18 pages, 21 figure
AGN life cycles, SMBH Masses, and Galactic Winds: Advancing our Understanding of SMBH-Galaxy Co-evolution with the ngVLA
A key missing element in our understanding of cosmic assembly is the nature of energetic feedback from supermassive black holes (SMHBs) and the impact of active galactic nuclei (AGN) on galaxy evolution. The next-generation Very Large Array (ngVLA), which will provide a ten-fold improvement in sensitivity and angular resolution compared to the current VLA, will serve as a transformational new tool in our understanding of AGN feedback as a function of redshift and environment. By combining broadband continuum data with spectral line measurements of the cold gas contents and kinematics of galaxies, the ngVLA will probe the evolution and life cycles of the radio-quiet and radio-loud AGN populations in unprecedented detail, quantify the energetic impact of AGN feedback on the star-forming reservoirs of gas-rich galaxies, and place constraints on SMBH formation and growth. Here, we present an overview of how the current reference design of the ngVLA will facilitate these advancements in our understanding of SMBH-galaxy co-evolution, with an emphasis on prospects for continuum surveys, the detection of molecular outflows out to high redshifts, and precision CO-dynamics-based SMBH mass measurements. We also discuss the importance of the next-generation Low-band Observatory (ngLOBO), a commensal low-frequency enhancement to the main ngVLA design, to maximize the utility of the ngVLA for AGN science
The Lick AGN Monitoring Project 2016: Dynamical Modeling of Velocity-Resolved H\b{eta} Lags in Luminous Seyfert Galaxies
We have modeled the velocity-resolved reverberation response of the H\b{eta}
broad emission line in nine Seyfert 1 galaxies from the Lick Active Galactic
Nucleus (AGN) Monitioring Project 2016 sample, drawing inferences on the
geometry and structure of the low-ionization broad-line region (BLR) and the
mass of the central supermassive black hole. Overall, we find that the H\b{eta}
BLR is generally a thick disk viewed at low to moderate inclination angles. We
combine our sample with prior studies and investigate line-profile shape
dependence, such as log10(FWHM/{\sigma}), on BLR structure and kinematics and
search for any BLR luminosity-dependent trends. We find marginal evidence for
an anticorrelation between the profile shape of the broad H\b{eta} emission
line and the Eddington ratio, when using the root-mean-square spectrum.
However, we do not find any luminosity-dependent trends, and conclude that AGNs
have diverse BLR structure and kinematics, consistent with the hypothesis of
transient AGN/BLR conditions rather than systematic trends
The Lick AGN Monitoring Project 2016 : velocity-resolved Hβ lags in luminous Seyfert galaxies
Funding: K.H. acknowledges support from STFC grant ST/R000824/1.We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on the 3 m Shane telescope at Lick Observatory from April 2016 to May 2017. Targetingactive galactic nuclei (AGN) with luminosities of λLλ(5100 Å) ≈ 1044 erg s−1 and predicted Hβ lags of∼ 20–30 days or black hole masses of 107–108.5 M⊙, our campaign probes luminosity-dependent trends in broad-line region (BLR) structure and dynamics as well as to improve calibrations for single-epoch estimates of quasar black hole masses. Here we present the first results from the campaign, including Hβ emission-line light curves, integrated Hβ lag times (8–30 days) measured against V -band continuum light curves, velocity-resolved reverberation lags, line widths of the broad Hβ components, and virial black hole mass estimates (107.1–108.1 M⊙). Our results add significantly to the number of existing velocity-resolved lag measurements and reveal a diversity of BLR gas kinematics at moderately high AGN luminosities. AGN continuum luminosity appears not to be correlated with the type of kinematics that its BLR gas may exhibit. Follow-up direct modeling of this dataset will elucidate the detailed kinematics and provide robust dynamical black hole masses for several objects in this sample.Publisher PDFPeer reviewe