1,963 research outputs found
The Keck/OSIRIS Nearby AGN Survey (KONA) I. The Nuclear K-band Properties of Nearby AGN
We introduce the Keck Osiris Nearby AGN survey (KONA), a new adaptive
optics-assisted integral-field spectroscopic survey of Seyfert galaxies. KONA
permits at ~0.1" resolution a detailed study of the nuclear kinematic structure
of gas and stars in a representative sample of 40 local bona fide active
galactic nucleus (AGN). KONA seeks to characterize the physical processes
responsible for the coevolution of supermassive black holes and galaxies,
principally inflows and outflows. With these IFU data of the nuclear regions of
40 Seyfert galaxies, the KONA survey will be able to study, for the first time,
a number of key topics with meaningful statistics. In this paper we study the
nuclear K-band properties of nearby AGN. We find that the luminosities of the
unresolved Seyfert 1 sources at 2.1 microns are correlated with the hard X-ray
luminosities, implying that the majority of the emission is non-stellar. The
best-fit correlation is logLK = 0.9logL2-10 keV + 4 over 3 orders of magnitude
in both K-band and X-ray luminosities. We find no strong correlation between
2.1 microns luminosity and hard X-ray luminosity for the Seyfert 2 galaxies.
The spatial extent and spectral slope of the Seyfert 2 galaxies indicate the
presence of nuclear star formation and attenuating material (gas and dust),
which in some cases is compact and in some galaxies extended. We detect
coronal-line emission in 36 galaxies and for the first time in five galaxies.
Finally, we find 4/20 galaxies that are optically classified as Seyfert 2 show
broad emission lines in the near-IR, and one galaxy (NGC 7465) shows evidence
of a double nucleus.Comment: Accepted for publication in ApJ, 19 pages with 18 figure
Excursions in Indiana Geology
Our purpose on these excursions arranged for the 58th meeting of the Association of American State Ge ologists is to bring about an awareness of Indiana geology and its attraction. Although our State lacks a Grand Canyon and production of glamour metals, features which in themselves would assure success of a field trip, it nevertheless offers many geologic challenges--challenges that we shall in part take up during these two days
Excursions in Indiana Geology
Indiana Geological Survey Guidebook 12Indiana lies wholly within the Central Lowland Province and thus calls to mind widespread, thin, nearly flat-lying Paleozoic rocks, major unconformities, and extensive plains. These features express epeirogenic submergences of the central part of the continent, long periods of general stability, and, nevertheless, repeatedly interrupted episodes of sedimentation and landform sculpture. Outstanding among these episodes was continental glaciation that carried to the Ohio River. Receiving ice from two principal directions the State's surface nearly everywhere attests to its latest experience, most obviously in the form of a great till plain that is interrupted in its gross appearance by end moraines, valley trains, and ice-contact deposits.
Structurally, the State lies athwart a broad crestal area, the Cincinnati Arch, which separates the Michigan Basin on the north from the Illinois Basin on the southwest. Some structural instability, manifest as long ago as Precambrian time, is evident in such sedimentational or second-rank structural features as lithofacies, Silurian-Devonian and Mississippian-Pennsylvanian unconformities that change both locally and regionally in magnitude, and faulting.
The more recent erosional record reflects structural history as well, and Paleozoic rocks from middle Ordovician to middle Pennsylvanian in age crop out at the bedrock surface according to their order of superposition. The Paleozoic units west and south of the Cincinnati Arch have special interest on these excursions. Their truncated edges, having differing resistances, are expressed alternately by open vales of gentle relief and uplands consisting of partly dissected westward-facing dip slopes and rugged forested scarps.
Within easy range of Bloomington we can demonstrate much of the variety of geologic form characteristic of the State. Crossing the regional strike and the boundary between driftless and glaciated areas, the first day's excursion (inside front cover) is generally eastward to traverse bedrock of Mississippian to Silurian age and drifts assigned to the Kansan, Illinoian, and Wisconsin Stages. It emphasizes the State's most widely known natural product, the Indiana Limestone, and relationships of physiography to bedrock and drift. The second day's excursion (inside back cover) is northwestward from Bloomington and crosses younger bedrock (to middle Pennsylvanian in age). It emphasizes the Mississippian-Pennsylvanian unconformity, stratigraphic relationships of drifts, and some of the newest methods of coal mining and land reclamation.Indiana Geological Survey
Indiana Department of Natural Resources
American Association of State Geologist
The Eye of the Tornado - an isolated, high mass young stellar object near the Galactic centre
We present infrared (AAT, UKIRT) and radio (VLA, SEST) observations of the
Eye of the Tornado, a compact source apparently near the head of the Tornado
Nebula. The near-infrared Br-gamma and He I lines are broad (FWHM 40 and 30
km/s, respectively) and have a line centre at Vlsr = -205 km/s. This
corresponds to a feature at the same velocity in the 12CO J=1-0 line profile.
The kinematic velocity derived from Galactic rotation places the Eye at the
distance of the Galactic Centre (i.e. 8.5 kpc) and separated (probably
foreground) from the Tornado Nebula. Four knots of emission are seen in the
Br-gamma line and at 6 and 20 cm. Together with the flat radio spectral index,
we confirm that the Eye contains ionized gas, but that this is embedded within
a dense molecular core. The spectral energy distribution can be modelled as a
two-component blackbody + greybody, peaking at far-IR wavelengths. The knots
are UC HII regions, and the core contains a luminous (2 x 10^4 Lsun), embedded,
massive young stellar source. We also propose a geometrical model for the Eye
to account for both its spectral energy distribution and its morphology.Comment: 25 pages, including 5 figures. Accepted by Monthly Notices of the
Royal Astronomical Society on 27/10/0
A New Approach toward Transition State Spectroscopy
Chirped-Pulse millimetre-Wave (CPmmW) rotational spectroscopy provides a new
class of information about photolysis transition state(s). Measured intensities
in rotational spectra determine species-isomer-vibrational populations,
provided that rotational populations can be thermalized. The formation and
detection of S0 vinylidene is discussed in the limits of low and high initial
rotational excitation. CPmmW spectra of 193 nm photolysis of Vinyl Cyanide
(Acrylonitrile) contain J=0-1 transitions in more than 20 vibrational levels of
HCN, HNC, but no transitions in vinylidene or highly excited local-bender
vibrational levels of acetylene. Reasons for the non-observation of the
vinylidene co-product of HCN are discussed.Comment: Accepted by Faraday Discussion
Shocked molecular hydrogen towards the Tornado nebula
We present near-infrared and millimetre-line observations of the Tornado
nebula (G357.7-0.1). We detected 2.12 micron_m H2 1-0 S(1) line emission
towards the suspected site of interaction with a molecular cloud revealed by
the presence of an OH(1720 MHz) maser. The distribution of the H2 emission is
well correlated with the nonthermal radio continuum emission from the Tornado,
and the velocity of the H2 emission spans over 100 km/s, which both imply that
the H2 emission is shock excited. We also detected millimetre-lines from 12CO
and 13CO transitions at the velocity of the maser, and mapped the distribution
of the molecular cloud in a 2 x 2 arcmin^2 region around the maser. The peak of
the molecular cloud aligns well with an indentation in the nebula's radio
continuum distribution, suggesting that the nebula's shock is being decelerated
at this location, which is consistent with the presence of the OH(1720 MHz)
maser and shocked H2 emission at that location.Comment: 10 pages, 8 figures, minor changes, accepted to MNRA
The Merging System Am 2049-691
Spectroscopic and photometric observations of the peculiar object AM 2049-691
are presented here. Its systemic velocity is V(GSR) = (10956 +-30) km/s, and
the derived distance (H(0) = 75 km/s/Mpc) results 146 Mpc. A bridge is observed
between two very distinct nuclei whose separation is about 10 kpc, as well as
two tails that emerge from the extremes SW and NE of the main body and extend
up to 41 and 58 kpc respectively. The spectral characteristics of the all
observed zones are typical of H II regions of low excitation. The internal
reddening is quit high, particularly in the NE nucleus. All the derived
equivalent widths of the H(alpha)+[N II] lines indicate enhanced star formation
compared with isolated galaxies, specially in the NE nucleus; the equivalent
width corresponding to the integrated spectrum reflects starburst activity in
the whole object, and is compatible with a merger of two disk galaxies. All the
observed characteristics of AM 2049-691 indicate it is a merger, where a
overabundance of nitrogen is detected in one of the nuclei, which has the most
evolved population and would be the most massive one. The detected total IR
emission is not very high. The integrated total color B - V corresponds to a
Sc-Scd galaxy and its average integrated population is about F7 type.
Indicative B - V colors of the nuclei, corrected for internal absorption, are
in agreement with the spectroscopic results. The central radial velocity
dispersions at the nuclei suggest that the most massive galaxy would be the
progenitor of the SW component. The observed radial velocity curve shows the
presence of two subsystems, each one associated with a different nucleus.Comment: 5 pages, 4 figure
The Molecule-Rich Tail of the Peculiar Galaxy NGC 2782 (Arp 215)
We present the first detection of a large quantity of molecular gas in the
extended tail of an interacting galaxy. Using the NRAO 12m telescope, we have
detected CO (1 - 0) at five locations in the eastern tail of the peculiar
starburst galaxy NGC 2782. The CO velocities and narrow (FWHM = 50 km/s) line
widths in these positions agree with those seen in HI, confirming that the
molecular gas is indeed associated with the tail rather than the main disk. As
noted previously, the gas in this tail has an apparent `counter-rotation'
compared to gas in the core of the galaxy, probably because the tails do not
lie in the same plane as the disk. Assuming the standard Galactic conversion
N(H2)/I(CO) factor, these observations indicate a total molecular gas mass of 6
X 10**8 M(sun) in this tail. This may be an underestimate of the total H2 mass
if the gas is metal-poor. This molecular gas mass, and the implied H2/HI mass
ratio of 0.6, are higher than that found in many dwarf irregular galaxies.
Comparison with an available H-alpha map of this galaxy, however, shows that
the rate of star formation in this feature is extremely low relative to the
available molecular gas, compared to L(H-alpha)/M(H2) values for both spiral
and irregular galaxies. Thus the timescale for depletion of the gas in this
feature is very long.Comment: 19 pages, 6 figures, Latex. To appear in the Astronomical Journa
The Early Bird Catches The Term: Combining Twitter and News Data For Event Detection and Situational Awareness
Twitter updates now represent an enormous stream of information originating
from a wide variety of formal and informal sources, much of which is relevant
to real-world events. In this paper we adapt existing bio-surveillance
algorithms to detect localised spikes in Twitter activity corresponding to real
events with a high level of confidence. We then develop a methodology to
automatically summarise these events, both by providing the tweets which fully
describe the event and by linking to highly relevant news articles. We apply
our methods to outbreaks of illness and events strongly affecting sentiment. In
both case studies we are able to detect events verifiable by third party
sources and produce high quality summaries
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