418 research outputs found
Shock-Driven Periodic Variability in a Low-Mass-Ratio Supermassive Black Hole Binary
We investigate the time-varying electromagnetic emission of a low-mass-ratio
supermassive black hole binary (SMBHB) embedded in a circumprimary disk, with a
particular interest in variability of shocks driven by the binary. We perform a
2D, locally isothermal hydrodynamics simulation of a SMBHB with mass ratio
and separation , using a physically self-consistent steady
disk model. We estimate the electromagnetic variability from the system by
monitoring accretion onto the secondary and using an artificial viscosity
scheme to capture shocks and monitor the energy dissipated. The SMBHB produces
a wide, eccentric gap in the disk, previously only observed for larger mass
ratios, which we attribute to our disk model being much thinner
( near the secondary) than is typical of previous works. The
eccentric gap drives periodic accretion onto the secondary SMBH on a timescale
matching the orbital period of the binary, ,
implying that the variable accretion regime of the SMBHB parameter space
extends to lower mass ratios than previously established. Shocks driven by the
binary are periodic, with a period matching the orbital period, and the shocks
are correlated with the accretion rate, with peaks in the shock luminosity
lagging peaks in the accretion rate by . We propose that
the correlation of these quantities represents a useful identifier of SMBHB
candidates, via observations of correlated variability in X-ray and UV
monitoring of AGN, rather than single-waveband periodicity alone.Comment: 12 pages, 8 figures, accepted by MNRA
Orbit-Based Dynamical Models of the Sombrero Galaxy (NGC 4594)
We present axisymmetric, orbit-based models to study the central black hole,
stellar mass-to-light ratio, and dark matter halo of NGC 4594 (M104, the
Sombrero Galaxy). For stellar kinematics, we use published high-resolution
kinematics of the central region taken with the Hubble Space Telescope, newly
obtained Gemini long-slit spectra of the major axis, and integral field
kinematics from the SAURON instrument. At large radii, we use globular cluster
kinematics to trace the mass profile and apply extra leverage to recovering the
dark matter halo parameters. We find a black hole of mass M_{\bullet}=(6.6 +/-
0.4) x 10^8 M_{\odot}, and determine the stellar M/L_I=3.4 +/- 0.05
(uncertainties are the 68% confidence band marginalized over the other
parameters). Our best fit dark matter halo is a cored logarithmic model with
asymptotic circular speed V_c=376 +/- 12 km/s and core radius r_c= 4.7 +/- 0.6
kpc. The fraction of dark to total mass contained within the half-light radius
is 0.52. Taking the bulge and disk components into account in our calculation
of \sigma_e puts NGC 4594 squarely on the M-\sigma relation. We also determine
that NGC 4594 lies directly on the M-L relation.Comment: 13 pages, 10 figures, accepted for publication in Ap
A Distinctive Disk-Jet Coupling in the Seyfert-1 AGN NGC 4051
We report on the results of a simultaneous monitoring campaign employing
eight Chandra X-ray (0.5-10 keV) and six VLA/EVLA (8.4 GHz) radio observations
of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4
GHz radio band; This builds on mounting evidence that jet production may be
prevalent even in radio-quiet Seyferts. Assuming comparatively negligible local
diffuse emission in the nucleus, the results also demonstrate an inverse
correlation of L_radio proportional to L_X-ray ^(-0.72+/-0.04) . Current
research linking the mass of supermassive black holes and stellar-mass black
holes in the "low/hard" state to X-ray luminosities and radio luminosities
suggest a "fundamental plane of accretion onto black holes" that has a positive
correlation of L_radio proportional to L_X-ray^(0.67+/-0.12) . Our simultaneous
results differ from this relation by more than 11 sigma, indicating that a
separate mode of accretion and ejection may operate in this system. A review of
the literature shows that the inverse correlation seen in NGC 4051 is seen in
three other black hole systems, all of which accrete at near 10% of their
Eddington luminosity, perhaps suggesting a distinct mode of disk-jet coupling
at high Eddington fractions. We discuss our results in the context of disk and
jets in black holes and accretion across the black hole mass scale.Comment: 12 pages, 9 figure
An Over-Massive Black Hole in the Compact Lenticular Galaxy NGC1277
All massive galaxies likely have supermassive black holes at their centers,
and the masses of the black holes are known to correlate with properties of the
host galaxy bulge component. Several explanations have been proposed for the
existence of these locally-established empirical relationships; they include
the non-causal, statistical process of galaxy-galaxy merging, direct feedback
between the black hole and its host galaxy, or galaxy-galaxy merging and the
subsequent violent relaxation and dissipation. The empirical scaling relations
are thus important for distinguishing between various theoretical models of
galaxy evolution, and they further form the basis for all black hole mass
measurements at large distances. In particular, observations have shown that
the mass of the black hole is typically 0.1% of the stellar bulge mass of the
galaxy. The small galaxy NGC4486B currently has the largest published fraction
of its mass in a black hole at 11%. Here we report observations of the stellar
kinematics of NGC 1277, which is a compact, disky galaxy with a mass of 1.2 x
10^11 Msun. From the data, we determine that the mass of the central black hole
is 1.7 x 10^10 Msun, or 59% its bulge mass. Five other compact galaxies have
properties similar to NGC 1277 and therefore may also contain over-sized black
holes. It is not yet known if these galaxies represent a tail of a
distribution, or if disk-dominated galaxies fail to follow the normal black
hole mass scaling relations.Comment: 7 pages. 6 figures. Nature. Animation at
http://www.mpia.de/~bosch/blackholes.htm
Supermassive black holes do not correlate with dark matter halos of galaxies
Supermassive black holes have been detected in all galaxies that contain
bulge components when the galaxies observed were close enough so that the
searches were feasible. Together with the observation that bigger black holes
live in bigger bulges, this has led to the belief that black hole growth and
bulge formation regulate each other. That is, black holes and bulges
"coevolve". Therefore, reports of a similar correlation between black holes and
the dark matter halos in which visible galaxies are embedded have profound
implications. Dark matter is likely to be nonbaryonic, so these reports suggest
that unknown, exotic physics controls black hole growth. Here we show - based
in part on recent measurements of bulgeless galaxies - that there is almost no
correlation between dark matter and parameters that measure black holes unless
the galaxy also contains a bulge. We conclude that black holes do not correlate
directly with dark matter. They do not correlate with galaxy disks, either.
Therefore black holes coevolve only with bulges. This simplifies the puzzle of
their coevolution by focusing attention on purely baryonic processes in the
galaxy mergers that make bulges.Comment: 12 pages, 9 Postscript figures, 1 table; published in Nature (20
January 2011
Resolving the dynamical mass of a z~1.3 QSO host galaxy using SINFONI and Laser Guide Star assisted Adaptive Optics
Recent studies of the tight scaling relations between the masses of
supermassive black holes and their host galaxies have suggested that in the
past black holes constituted a larger fraction of their host galaxies' mass.
However, these arguments are limited by selection effects and difficulties in
determining robust host galaxy masses at high redshifts. Here we report the
first results of a new, complementary diagnostic route: we directly determine a
dynamical host galaxy mass for the z=1.3 luminous quasar J090543.56+043347.3
through high-spatial-resolution (0.47", 4kpc FWHM) observations of the host
galaxy gas kinematics over 30x40 kpc using ESO/VLT/SINFONI with LGS/AO.
Combining our result of M_dyn = 2.05+1.68_0.74 x 10^11 M_sun (within a radius
5.25 +- 1.05 kpc) with M_BH,MgII = 9.02 \pm 1.43 x 10^8 M_sun, M_BH,Halpha =
2.83 +1.93-1.13 x 10^8 M_sun, we find that the ratio of black hole mass to host
galaxy dynamical mass for J090543.56+043347.3 matches the present-day relation
for M_BH vs. M_Bulge,Dyn, well within the IR scatter, deviating at most a
factor of two from the mean. J090543.56+043347.3 displays clear signs of an
ongoing tidal interaction and of spatially extended star formation at a rate of
50-100 M_sun/yr, above the cosmic average for a galaxy of this mass and
redshift. We argue that its subsequent evolution may move J090543.56+043347.3
even closer to the z=0 relation for M_BH vs. M_Bulge,Dyn. Our results support
the picture where any substantive evolution in these relations must occur prior
to z~1.3. Having demonstrated the power of this modelling approach we are
currently analyzing similar data on seven further objects to better constrain
such evolution.Comment: Accepted for publication in ApJ, 14 pages, 10 Figure
Physics of the Galactic Center Cloud G2, on its Way towards the Super-Massive Black Hole
The origin, structure and evolution of the small gas cloud, G2, is
investigated, that is on an orbit almost straight into the Galactic central
supermassive black hole (SMBH). G2 is a sensitive probe of the hot accretion
zone of Sgr A*, requiring gas temperatures and densities that agree well with
models of captured shock-heated stellar winds. Its mass is equal to the
critical mass below which cold clumps would be destroyed quickly by
evaporation. Its mass is also constrained by the fact that at apocenter its
sound crossing timescale was equal to its orbital timescale. Our numerical
simulations show that the observed structure and evolution of G2 can be well
reproduced if it formed in pressure equilibrium with the surrounding in 1995 at
a distance from the SMBH of 7.6e16 cm. If the cloud would have formed at
apocenter in the 'clockwise' stellar disk as expected from its orbit, it would
be torn into a very elongated spaghetti-like filament by 2011 which is not
observed. This problem can be solved if G2 is the head of a larger, shell-like
structure that formed at apocenter. Our numerical simulations show that this
scenario explains not only G2's observed kinematical and geometrical properties
but also the Br_gamma observations of a low surface brightness gas tail that
trails the cloud. In 2013, while passing the SMBH G2 will break up into a
string of droplets that within the next 30 years mix with the surrounding hot
gas and trigger cycles of AGN activity.Comment: 22 pages, 13 figures, submitted to Ap
The evaluation of morphology of renal pelvicalyceal system’s and infundibulopelvic anatomy of kidney’s lower pole in post-mortem series
Background: Urinary system stones are frequently encountered in the community. Together with technological developments, introduction of new treatment procedures such as extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy and retrograde intrarenal surgery has furtherly reduced morbidity, mortality and hospitalization time of patients. In order to maximize success and to reduce complications of these procedures, it is necessary to evaluate anatomy and morphological differences of kidney collector system before the procedure. This study was conducted for the purpose of determining the morphology of the kidney collector system and the negative anatomic factors of the lower pole in autopsy cases performed in our institution. Materials and methods: 82 kidney units obtained from 41 autopsy cases conducted in Faculty of Medicine Department of Forensic Medicine, Sivas Cumhuriyet University between September 2017 and September 2018 were included in the study. Percentages were found as 78% for intrarenal pelvis, 13.4% for borderline pelvis, %6.1 for extrarenal pelvis and 2.4% for pelvic nonexistence. When pelvicalyceal anatomy was evaluated, percentages were found as 32.9% for bicalyceal, 26.8% for tricalyceal, 20.7% for multicalyceal and 19.5% for unclassified calyceality. When it is evaluated according to opening of calyces into the renal pelvis based on Sampaio classification, percentages were found as 30.5% for AI, 17.1% for Type II, 28% for BI, 18.3% for BII and 6.1% for unevaluated part. Infundibular lengths of kidney’s lower pole were detected as under 3 cm in 39% and over 3 cm in 61% of all cases. Infundibulopelvic angles of kidney’s lower pole were measured as under 700 in 42.7% and over 700 in 57.3% of all cases. Results: In our study, there was no statistically significant difference between the right and left kidneys in terms of collecting system morphology and lower pole’s negative anatomical factors. Only infindibular lengths which is one of the collecting system morphology and lower pole’s negative anatomical factors were statistically shorter in females than males. There was no difference in terms of other parameters. Conclusions: In conclusion, the findings of this study are largely consistent with the results of similar studies. This reveals that renal collecting system morphology and negative anatomic factors in the lower pole collecting system in human are roughly similar. In clinical practice, pre-treatment CT and, if necessary, MR urography evaluation of the lower pole negative anatomic factors may contribute to gain preliminary information about both the clearance of stone fragments especially after SWL and RIRS procedures and perioperative complications proactively
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