839 research outputs found
Size and properties of the narrow-line region in Seyfert-2 galaxies from spatially-resolved optical spectroscopy
While [OIII] narrow-band imaging is commonly used to measure the size of the
narrow-line regions (NLRs) in active galactic nuclei (AGNs), it can be
contaminated by emission from surrounding starbursts. Recently, we have shown
that long-slit spectroscopy provides a valuable alternative approach to probe
the size in terms of AGN photoionisation. Moreover, several parameters of the
NLR can be directly accessed. We here apply the same methods developed and
described for the Seyfert-2 galaxy NGC1386 to study the NLR of five other
Seyfert-2 galaxies by using high-sensitivity spatially-resolved optical
spectroscopy obtained at the VLT and the NTT. We probe the AGN-photoionisation
of the NLR and thus, its ``real'' size using diagnostic line-ratio diagrams.We
derive physical properties of the NLR such as reddening, ionisation parameter,
electron density, and velocity as a function of distance from the nucleus. For
NGC5643, the diagnostic diagrams unveil a similar transition between line
ratios falling in the AGN regime and those typical for HII regions as found for
NGC1386, thus determining the size of the NLR. For the other four objects, all
measured line ratios fall in the AGN regime. In almost all cases, both electron
density and ionisation parameter decrease with radius. Deviations from this
general behaviour (such as a secondary peak) seen in both the ionisation
parameter and electron density can be interpreted as signs of shocks from the
interaction of a radio jet and the NLR gas. In several objects, the gaseous
velocity distribution is characteristic for rotational motion in an (inclined)
emission-line disk in the centre. We compare our results to those of NGC1386
and show that the latter can be considered as prototypical also for this larger
sample. We discuss our findings in detail for each object.Comment: 23 pages, 41 figures, accepted for publication in A&
Andragogy In Continuing Medical Education Development: A Case Study On The Perception Of Its Worth
Continuing medical education (CME) curriculum development is often staffed and developed with little exposure to teaching skill expertise and andragogy. This qualitative case study examined the perceptions of the skills needed for successful development of CME, learning from the experience of an international nongovernmental organization (NGO)’s first time developing an online CME course. The questions that guided this study were “What were the team’s perceptions of the skills and roles needed when first designing and developing a CME curriculum? and “How did the experiences of the team, when developing, delivering, and evaluating the program, determine their perceptions of the skills and roles needed for curriculum development for CME?” The population for this study was the primary staff and subject-matter experts, directly involved with the design, development, implementation, and evaluation of the NGO’s first course that it had developed. The data collected was from a preinterview survey, individual interviews, and course artifacts. Four specific circumstances shaped the participants final perceptions of the skills needed. They were (a) a lack of institutional experience, (b) educational partner constraints, (c) donor constraints, and (d) misalignment of staff expertise and “bandwidth.” Final determination was that an andragogical expert, as well as a dedicated project management, vision holder, and a marketing expert were essential in this process. Without these experts in place, a course development project risks misalignment to the goals of the course and audience needs, leading to staff burnout and attrition, with lasting damage to those staff
Relationship between the physical examination and the PFI test
Thesis (Ed.M.)--Boston University, 1939. This item was digitized by the Internet Archive
The Relation between Black Hole Mass and Host Spheroid Stellar Mass out to z~2
We combine Hubble Space Telescope images from the Great Observatories Origins
Deep Survey with archival Very Large Telescope and Keck spectra of a sample of
11 X-ray selected broad-line active galactic nuclei in the redshift range 1<z<2
to study the black hole mass - stellar mass relation out to a lookback time of
10 Gyrs. Stellar masses of the spheroidal component are derived from
multi-filter surface photometry. Black hole masses are estimated from the width
of the broad MgII emission line and the 3000A nuclear luminosity. Comparing
with a uniformly measured local sample and taking into account selection
effects, we find evolution in the form M_BH/M_spheroid ~ (1+z)^(1.96+/-0.55),
in agreement with our earlier studies based on spheroid luminosity. However,
this result is more accurate because it does not require a correction for
luminosity evolution and therefore avoids the related and dominant systematic
uncertainty. We also measure total stellar masses. Combining our sample with
data from the literature, we find M_BH/M_host ~ (1+z)^(1.15+/-0.15), consistent
with the hypothesis that black holes (in the range M_BH ~ 10^8-9 M_sun) predate
the formation of their host galaxies. Roughly one third of our objects reside
in spiral galaxies; none of the host galaxies reveal signs of interaction or
major merger activity. Combined with the slower evolution in host stellar
masses compared to spheroid stellar masses, our results indicate that secular
evolution or minor mergers play a non-negligible role in growing both BHs and
spheroids.Comment: 7 pages, 3 figures. Final version, accepted for publication in The
Astrophysical Journa
A sub-kpc-scale binary AGN with double narrow-line regions
We present the kinematic properties of a type-2 QSO, SDSS J132323.33-015941.9
at z~0.35, based on the analysis of Very Large Telescope integral field
spectroscopy and Hubble Space Telescope (HST) imaging, which suggest that the
target is a binary active galactic nucleus (AGN) with double narrow-line
regions. The QSO features double-peaked emission lines ([OIII] and Hb) which
can be decomposed into two kinematic components. The flux-weighted centroids of
the blue and red components are separated by ~0.2" (0.8 kpc in projection) and
coincide with the location of the two stellar cores detected in the HST
broad-band images, implying that both stellar cores host an active black hole.
The line-of-sight velocity of the blue component is comparable to the
luminosity-weighted velocity of stars in the host galaxy while the red
component is redshifted by ~240 km/s, consistent with typical velocity offsets
of two cores in a late stage of a galaxy merger. If confirmed, the target is
one of the rare cases of sub-kpc scale binary AGNs, providing a test-bed for
understanding the binary AGN population.Comment: 5 pages, 3 figure
A Local Baseline of the Black Hole Mass Scaling Relations for Active Galaxies. I. Methodology and Results of Pilot Study
We present high-quality Keck/LRIS longslit spectroscopy of a pilot sample of
25 local active galaxies selected from the SDSS (0.0210^7 M_sun) to
study the relations between black hole mass (MBH) and host-galaxy properties.
We determine stellar kinematics of the host galaxy, deriving stellar-velocity
dispersion profiles and rotation curves from three spectral regions (including
CaH&K, MgIb triplet, and CaII triplet). In addition, we perform surface
photometry on SDSS images, using a newly developed code for joint multi-band
analysis. BH masses are estimated from the width of the Hbeta emission line and
the host-galaxy free 5100A AGN luminosity. Combining results from spectroscopy
and imaging allows us to study four MBH scaling relations: MBH-sigma,
MBH-L(sph), MBH-M(sph,*), MBH-M(sph,dyn). We find the following results. First,
stellar-velocity dispersions determined from aperture spectra (e.g. SDSS fiber
spectra or unresolved data from distant galaxies) can be biased, depending on
aperture size, AGN contamination, and host-galaxy morphology. However, such a
bias cannot explain the offset seen in the MBH-sigma relation at higher
redshifts. Second, while the CaT region is the cleanest to determine
stellar-velocity dispersions, both the MgIb region, corrected for FeII
emission, and the CaHK region, although often swamped by the AGN powerlaw
continuum and emission lines, can give results accurate to within a few
percent. Third, the MBH scaling relations of our pilot sample agree in slope
and scatter with those of other local active and inactive galaxies. In the next
papers of the series we will quantify the scaling relations, exploiting the
full sample of ~100 objects.Comment: 28 pages, 19 figures. Final version, accepted for publication in The
Astrophysical Journal (ApJ, 726, 59
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