589 research outputs found
Determination of masses of the central black holes in NGC524 and NGC2549 using Laser Guide Star Adaptive Optics
[abridged] We present observations of NGC524 and NGC2549 with LGS AO obtained
at GEMINI North telescope using the NIFS IFU in the K band. The purpose of
these observations, together with previously obtained observations with the
SAURON IFU, is to determine the masses (Mbh) of the supermassive black holes
(SMBH). The targeted galaxies were chosen to have central light profiles
showing a core (NGC524) and a cusp (NGC2549), to probe the feasibility of using
the galaxy centre as the NGS required for LGS AO. We employ an innovative `open
loop' technique. The data have spatial resolution of 0.23" and 0.17" FWHM,
showing that high quality LGS AO observations of these objects are possible. We
construct axisymmetric three-integral dynamical models which are constrained
with both the NIFS and SAURON data. The best fitting models yield Mbh=(8.3 +2.7
-1.3) x 10^8 Msun for NGC524 and Mbh=(1.4 +0.2 -1.3) x 10^7 Msun for NGC2549
(all errors are at the 3 sigma CL). We demonstrate that the wide-field SAURON
data play a crucial role in the M/L determination increasing the accuracy of
M/L by a factor of at least 5, and constraining the upper limits on Mbh. The
NIFS data are crucial in constraining the lower limits of Mbh and in
combination with the large scale data reducing the uncertainty by a factor of 2
or more. We find that the orbital structure of NGC524 shows significant
tangential anisotropy, while at larger radii both galaxies are consistent with
having almost perfectly oblate velocity ellipsoids. Tangential anisotropy in
NGC524 coincides with the size of SMBH sphere of influence and the core region
in the light profile. We test the accuracy to which Mbh can be measured using
seeings obtained from typical LGS AO observations, and conclude that for a
typical conditions and Mbh the expected uncertainty is of the order of 50%.Comment: 19 pages, 14 figure
Functional rescue of dystrophin deficiency in mice caused by frameshift mutations using Campylobacter jejuni Cas9
Duchenne muscular dystrophy (DMD) is a fatal, X-linked muscle wasting disease caused by mutations in the DMD gene. In 51% of DMD cases, a reading frame is disrupted because of deletion of several exons. Here, we show that CjCas9 derived from Campylobacter jejuni can be
used as a gene editing tool to correct an out-of-frame Dmd exon in Dmd knockout mice. Herein, we used Cas9 derived from S. pyogenes to generate Dmd knockout (KO) mice with a frameshift mutation in Dmd gene. Then, we expressed CjCas9, its single-guide RNA, and the eGFP gene
in the tibialis anterior muscle of the Dmd KO mice using an all-in-one adeno-associated virus (AAV) vector. CjCas9 cleaved the target site in the Dmd gene efficiently in vivo and induced small insertions or deletions at the target site. This treatment resulted in conversion of the
disrupted Dmd reading frame from out-of-frame to in-frame, leading to the expression of dystrophin in the sarcolemma. Importantly, muscle strength was enhanced in the CjCas9-treated muscles, without off-target mutations, indicating high efficiency and specificity of CjCas9. This work suggests that in vivo DMD frame correction, mediated by CjCas9 has great potential for the treatment of DMD and other neuromuscular diseases
Galaxy Masses
Galaxy masses play a fundamental role in our understanding of structure
formation models. This review addresses the variety and reliability of mass
estimators that pertain to stars, gas, and dark matter. The different sections
on masses from stellar populations, dynamical masses of gas-rich and gas-poor
galaxies, with some attention paid to our Milky Way, and masses from weak and
strong lensing methods, all provide review material on galaxy masses in a
self-consistent manner.Comment: 145 pages, 28 figures, to appear in Reviews of Modern Physics. Figure
22 is missing here, and Figs. 15, 26-28 are at low resolution. This version
has a slightly different title and some typos fixed in Chapter 5. For the
full review with figures, please consult:
http://www.astro.queensu.ca/~courteau/GalaxyMasses_28apr2014.pd
A SAURON look at galaxy bulges
Kinematic and population studies show that bulges are generally rotationally
flattened systems similar to low-luminosity ellipticals. However, observations
with state-of-the-art integral field spectrographs, such as SAURON, indicate
that the situation is much more complex, and allow us to investigate phenomena
such as triaxiality, kinematic decoupling and population substructure, and to
study their connection to current formation and evolution scenarios for bulges
of early-type galaxies. We present the examples of two S0 bulges from galaxies
in our sample of nearby galaxies: one that shows all the properties expected
from classical bulges (NGC5866), and another case that presents kinematic
features appropriate for barred disk galaxies (NGC7332).Comment: 4 pages, 3 figures, accepted for publishing in AN (refereed conf.
proc. of the Euro3D Science workshop, IoA Cambridge, May 2003
Correlations Between Central Massive Objects And Their Host Galaxies: From Bulgeless Spirals to Ellipticals
Recent observations by Ferrarese et al. (2006) and Wehner et al. (2006)
reveal that a majority of galaxies contain a central massive object (CMO),
either a supermassive black hole (SMBH) or a compact stellar nucleus,
regardless of the galaxy mass or morphological type, and that there is a tight
relation between the masses of CMOs and those of the host galaxies. Several
recent studies show that feedback from black holes can successfully explain the
\msigma correlation in massive elliptical galaxies that contain SMBHs.
However, puzzles remain in spirals or dwarf spheroids that do not appear to
have black holes but instead harbor a compact central stellar cluster. Here we
use three-dimensional, smoothed particle hydrodynamics simulations of isolated
galaxies to study the formation and evolution of CMOs in bulgeless disk
galaxies, and simulations of merging galaxies to study the transition of the
CMO--host mass relation from late-type bulgeless spirals to early-type
ellipticals. Our results suggest that the observed correlations may be
established primarily by the depletion of gas in the central region by
accretion and star-formation, and may hold for all galaxy types. A systematic
search for CMOs in the nuclei of bulgeless disk galaxies would offer a test of
this conclusion. (Abridged)Comment: 11 pages, 8 figures, accepted to Ap
SAURON Observations of Disks in Spheroids
The panoramic integral-field spectrograph SAURON is currently being used to
map the stellar kinematics, gaseous kinematics, and stellar populations of a
large number of early-type galaxies and bulges. Here, we describe SAURON
observations of cold stellar disks embedded in spheroids (NGC3384, NGC4459,
NGC4526), we illustrate the kinematics and ionization state of large-scale
gaseous disks (NGC4278, NGC7742), and we show preliminary comparisons of SAURON
data with barred galaxy N-body simulations (NGC3623).Comment: 8 pages including 5 figures. To appear in Galaxies: The Third
Dimension, eds. M. Rosado, L. Binnette, & L. Arias (ASP: San Francisco
SAURON: An Innovative Look at Early-Type Galaxies
A summary of the SAURON project and its current status is presented. SAURON
is a panoramic integral-field spectrograph designed to study the stellar
kinematics, gaseous kinematics, and stellar populations of spheroids. Here, the
sample of galaxies and its properties are described. The instrument is detailed
and its capabilities illustrated through observational examples. These includes
results on the structure of central stellar disks, the kinematics and
ionization state of gaseous disks, and the stellar populations of galaxies with
decoupled cores.Comment: 10 pages, 6 figures. To appear in "The Dynamics, Structure & History
of Galaxies", eds. G. S. Da Costa & E. M. Sadler (San Francisco: ASP).
Version with full resolution images available at
http://www.strw.leidenuniv.nl/~dynamics/Instruments/Sauron/pub_list.htm
Towards a new classification of early-type galaxies: an integral-field view
In this proceeding we make use of the two-dimensional stellar kinematics of a
representative sample of E and S0 galaxies obtained with the SAURON
integral-field spectrograph to reveal that early-type galaxies appear in two
broad flavours, depending on whether they exhibit clear large-scale rotation or
not. We measure the level of rotation via a new parameter LambdaR and use it as
a basis for a new kinematic classification that separates early-type galaxies
into slow and fast rotators. With the aid of broad-band imaging we will
reinforce this finding by comparing our kinematic results to the photometric
properties of these two classes.Comment: 4 pages, 2 figures, to appear in "Pathways Through an Eclectic
Universe", J. H. Knappen, T. J. Mahoney, and A. Vazedekis (Eds.), ASP Conf.
Ser., 200
A SAURON view of galaxies
We have measured the two-dimensional kinematics and line-strength
distributions of 72 representative nearby early-type galaxies, out to
approximately one effective radius, with our panoramic integral-field
spectrograph SAURON. The resulting maps reveal a rich variety in kinematical
structures and linestrength distributions, indicating that early-type galaxies
are more complex systems than often assumed. We are building detailed dynamical
models for these galaxies, to derive their intrinsic shape and dynamical
structure, and to determine the mass of the supermassive central black hole.
Here we focus on two examples, the compact elliptical M32 and the E3 galaxy
NGC4365. These objects represent two extreme cases: M32 has very regular
kinematics which can be represented accurately by an axisymmetric model in
which all stars rotate around the short axis, while NGC4365 is a triaxial
galaxy with a prominent kinematically decoupled core, with an inner core that
rotates about an axis that is nearly perpendicular to the rotation axis of the
main body of the galaxy. Our dynamical models for these objects demonstrate
that two-dimensional observations are essential for deriving the intrinsic
orbital structure and dark matter content of galaxies.Comment: 7 pages (3 figures, full resolution Fig. 1 available at
http://www.strw.leidenuniv.nl/~verolme/M32.ps). Contributed talk to the
Athens Workshop on Galaxies and Chaos, Theory and Observations; Proceedings
to appear in "Galaxies and Chaos", eds. G. Contopoulos and N. Vogli
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