Steep Relation Research Articles

Kinematics of Galactic Centre clouds shaped by shear-seeded solenoidal turbulence

ABSTRACT The Central Molecular Zone (CMZ; the central ∼500 pc of the Galaxy) is a kinematically unusual environment relative to the Galactic disc, with high-velocity dispersions and a steep size–linewidth relation of the molecular clouds. In addition, the CMZ region has a significantly lower star formation rate (SFR) than expected by its large amount of dense gas. An important factor in explaining the low SFR is the turbulent state of the star-forming gas, which seems to be dominated by rotational modes. However, the turbulence driving mechanism remains unclear. In this work, we investigate how the Galactic gravitational potential affects the turbulence in CMZ clouds. We focus on the CMZ cloud G0.253+0.016 (‘the Brick’), which is very quiescent and unlikely to be kinematically dominated by stellar feedback. We demonstrate that several kinematic properties of the Brick arise naturally in a cloud-scale hydrodynamics simulation, that takes into account the Galactic gravitational potential. These properties include the line-of-sight velocity distribution, the steepened size–linewidth relation, and the predominantly solenoidal nature of the turbulence. Within the simulation, these properties result from the Galactic shear in combination with the cloud’s gravitational collapse. This is a strong indication that the Galactic gravitational potential plays a crucial role in shaping the CMZ gas kinematics, and is a major contributor to suppressing the SFR, by inducing predominantly solenoidal turbulent modes.

Sub-Nanosecond Switching of Si:HfO2 Ferroelectric Field-Effect Transistor.

The discovery of ferroelectric doped HfO2 enabled the emergence of scalable and CMOS-compatible ferroelectric field-effect transistor (FeFET) technology which has the potential to meet the growing need for fast, low-power, low-cost, and high-density nonvolatile memory, and neuromorphic devices. Although HfO2 FeFETs have been widely studied in the past few years, their fundamental switching speed is yet to be explored. Importantly, the shortest polarization time demonstrated to date in HfO2-based FeFET was ∼10 ns. Here, we report that a single subnanosecond pulse can fully switch HfO2-based FeFET. We also study the polarization switching kinetics across 11 orders of magnitude in time (300 ps to 8 s) and find a remarkably steep time-voltage relation, which is captured by the classical nucleation theory across this wide range of pulse widths. These results demonstrate the high-speed capabilities of FeFETs and help better understand their fundamental polarization switching speed limits and switching kinetics.

Widespread subsonic turbulence in Ophiuchus North 1

Context. Supersonic motions are common in molecular clouds. (Sub)sonic turbulence is usually detected toward dense cores and filaments. However, it remains unknown whether (sub)sonic motions at larger scales (≳1 pc) may be present in various environments. Aims. Located at a distance of about 110 pc, Ophiuchus North 1 (Oph N1) is one of the nearest molecular clouds that would allow for an in-depth investigation of its turbulence properties via large-scale mapping observations of single-dish telescopes. Methods. We carried out the 12CO (J = 1−0) and C18O (J = 1−0) imaging observations toward Oph N1 with the Purple Mountain Observatory 13.7 m telescope. The observations have an angular resolution of ~55″ (i.e., 0.03 pc). Results. Most of the whole C18O emitting regions have Mach numbers of ≲1, demonstrating the large-scale (sub)sonic turbulence across Oph N1. Based on the polarization measurements, we estimate the magnetic field strength of the plane-of-sky component to be ≳9 µG. We infer that Oph N1 is globally sub-Alfvénic, and is supported against gravity mainly by the magnetic field. The steep velocity structure function can be caused by the expansion of the Sh 2–27 HII region or the dissipative range of incompressible turbulence. Conclusions. Our observations reveal a surprising case of clouds that are characterized by widespread subsonic turbulence and a steep relation between the size and the linewidth. This cloud is magnetized where ion-neutral friction is assumed to play an important role.

Black Hole Mass Scaling Relations for Early-type Galaxies. I. MBH–M*, sph and MBH–M*,gal

Abstract Analyzing a sample of 84 early-type galaxies (ETGs) with directly measured supermassive black hole masses—nearly doubling the sample size of such galaxies with multicomponent decompositions—a symmetric linear regression on the reduced (merger-free) sample of 76 galaxies reveals with a total scatter of Δrms = 0.52 dex in the direction. Importantly, however, we discover that the ES/S0-type galaxies with disks are offset from the E-type galaxies by more than a factor of ten in their ratio, with ramifications for formation theories, simulations, and some virial factor measurements used to convert AGN virial masses into M BH. Separately, each population follows a steeper relation with slopes of 1.86 ± 0.20 and 1.90 ± 0.20, respectively. The offset mass ratio is mainly due to the exclusion of the disk mass, with the two populations offset by only a factor of two in their ratio in the M BH– diagram where and dex depending on the sample. For , we detect no significant bend nor offset in either the M BH– or M BH– relations due to barred versus non-barred, or core-Sérsic versus Sérsic, ETGs. For reference, the ensemble of late-type galaxies (which invariably are Sérsic galaxies) follow M BH– and M BH– relations with slopes equal to 2.16 ± 0.32 and 3.05 ± 0.70, respectively. Finally, we provide some useful conversion coefficients, υ, accounting for the different stellar mass-to-light ratios used in the literature, and we report the discovery of a local, compact massive spheroid in NGC 5252.

The Superoutburst Duration versus Orbital Period Relation for AM CVn Stars

Abstract We examine the relationship between superoutburst duration t dur and orbital period P orb in AM CVn ultra-compact binary systems. We show that the previously determined steep relation derived by Levitan et al. was strongly influenced by the inclusion of upper limits for systems with a relatively long orbital period in their fit. Excluding the upper limit values and including t dur values for three systems at long P orb that were not considered previously, then is flat as predicted by Cannizzo & Nelemans.

Hyper Suprime-Cam view of the CMASS galaxy sample

Aims. We wish to determine the distribution of dark matter halo masses as a function of the stellar mass and the stellar mass profile for massive galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) constant-mass (CMASS) sample. Methods. We used grizy photometry from the Hyper Suprime-Cam (HSC) to obtain Sérsic fits and stellar masses of CMASS galaxies for which HSC weak-lensing data are available. This sample was visually selected to have spheroidal morphology. We applied a cut in stellar mass, log M*/M⊙ > 11.0, and selected ∼10 000 objects thus. Using a Bayesian hierarchical inference method, we first investigated the distribution of Sérsic index and size as a function of stellar mass. Then, making use of shear measurements from HSC, we measured the distribution of halo mass as a function of stellar mass, size, and Sérsic index. Results. Our data reveal a steep stellar mass-size relation Re ∝ M*βR, with βR larger than unity, and a positive correlation between Sérsic index and stellar mass: n ∝ M*0.46. The halo mass scales approximately with the 1.7 power of the stellar mass. We do not find evidence for an additional dependence of halo mass on size or Sérsic index at fixed stellar mass. Conclusions. Our results disfavour galaxy evolution models that predict significant differences in the size growth efficiency of galaxies living in low- and high-mass halos.

Black Hole Mass Scaling Relations for Spiral Galaxies. II. MBH–M*,tot and MBH–M*,disk

Abstract Black hole mass (M BH) scaling relations are typically derived using the properties of a galaxy’s bulge and samples dominated by (high-mass) early-type galaxies. Studying late-type galaxies should provide greater insight into the mutual growth of black holes and galaxies in more gas-rich environments. We have used 40 spiral galaxies to establish how M BH scales with both the total stellar mass ( M * , tot ) and the disk’s stellar mass, having measured the spheroid (bulge) stellar mass ( M * , sph ) and presented the M BH– M * , sph relation in Paper I. The relation involving M * , tot may be beneficial for estimating M BH either from pipeline data or at higher redshift, conditions that are not ideal for the accurate isolation of the bulge. A symmetric Bayesian analysis finds log ( M BH / M ⊙ ) = ( 3.05 − 0.49 + 0.57 ) log { M * , tot / [ υ ( 6.37 × 10 10 M ⊙ ) ] } + ( 7.25 − 0.14 + 0.13 ) . The scatter from the regression of M BH on M * , tot is 0.66 dex; compare 0.56 dex for M BH on M * , sph and 0.57 dex for M BH on σ *. The slope is >2 times that obtained using core-Sérsic early-type galaxies, echoing a similar result involving M * , sph , and supporting a varied growth mechanism among different morphological types. This steeper relation has consequences for galaxy/black hole formation theories, simulations, and predicting black hole masses. We caution that (i) an M BH– M * , tot relation built from a mixture of early- and late-type galaxies will find an arbitrary slope of approximately 1–3, with no physical meaning beyond one’s sample selection, and (ii) evolutionary studies of the M BH– M * , tot relation need to be mindful of the galaxy types included at each epoch. We additionally update the M * , tot –(face-on spiral arm pitch angle) relation.

Dynamical cluster disruption and its implications for multiple population models in the E-MOSAICS simulations

ABSTRACT Several models have been advanced to explain the multiple stellar populations observed in globular clusters (GCs). Most models necessitate a large initial population of unenriched stars that provide the pollution for an enriched population, and which are subsequently lost from the cluster. This scenario generally requires clusters to lose >90 per cent of their birth mass. We use a suite of 25 cosmological zoom-in simulations of present-day Milky Way mass galaxies from the e-mosaics project to study whether dynamical disruption by evaporation and tidal shocking provides the necessary mass-loss. We find that GCs with present-day masses $M\gt 10^5 $ M⊙ were only 2–4 times more massive at birth, in conflict with the requirements of the proposed models. This factor correlates weakly with metallicity, gas pressure at birth, or galactocentric radius, but increases towards lower GC masses. To reconcile our results with observational data, either an unphysically steep cluster mass-size relation must be assumed, or the initial enriched fractions must be similar to their present values. We provide the required relation between the initial enriched fraction and cluster mass. Dynamical cluster mass-loss cannot reproduce the high observed enriched fractions nor their trend with cluster mass.

Hydrogen embrittlement II. Analysis of hydrogen-enhanced decohesion across (111) planes in α -Fe

This is the second of two papers that present a theoretical analysis of the phenomenon of hydrogen embrittlement of $\ensuremath{\alpha}$-Fe. We make contact between the thermodynamic-kinetic continuum and cohesive zone models and the quantum-mechanical magnetic tight-binding approximation to interatomic forces. We are able to solve a coupled set of equations using quantum mechanically obtained atomistic data to follow the decohesion process in time as traction is applied to a hydrogen charged crystal and decohesion occurs between two (111) crystal planes. This scheme will be readily extended from transgranular to intergranular failure, although the complexities of the trapping sites in the cohesive zone associated with a grain boundary will greatly complicate the calculation of the configurational energy. Hydrogen-enhanced decohesion postulated widely in the field has not yet been demonstrated experimentally, although our calculations find a reduction in the ideal cohesive strength as a result of dissolved hydrogen in $\ensuremath{\alpha}$-Fe from 30 to 22 GPa. Because of the well-known steep and nonlinear relation between plastic and ideal elastic work of fracture, this represents a very significant reduction in toughness as a result of a hydrogen concentration of less than ten atomic parts per million.

Mufasa: the assembly of the red sequence

We examine the growth and evolution of quenched galaxies in the Mufasa cosmological hydrodynamic simulations that include an evolving halo mass-based quenching prescription, with galaxy colours computed accounting for line-of-sight extinction to individual star particles. Mufasa reproduces the observed present-day red sequence reasonably well, including its slope, amplitude, and scatter. In Mufasa, the red sequence slope is driven entirely by the steep stellar mass-stellar metallicity relation, which independently agrees with observations. High-mass star-forming galaxies blend smoothly onto the red sequence, indicating the lack of a well-defined green valley at M*>10^10.5 Mo. The most massive galaxies quench the earliest and then grow very little in mass via dry merging; they attain their high masses at earlier epochs when cold inflows more effectively penetrate hot halos. To higher redshifts, the red sequence becomes increasingly contaminated with massive dusty star-forming galaxies; UVJ selection subtly but effectively separates these populations. We then examine the evolution of the mass functions of central and satellite galaxies split into passive and star-forming via UVJ. Massive quenched systems show good agreement with observations out to z~2, despite not including a rapid early quenching mode associated with mergers. However, low-mass quenched galaxies are far too numerous at z<1 in Mufasa, indicating that Mufasa strongly over-quenches satellites. A challenge for hydrodynamic simulations is to devise a quenching model that produces enough early massive quenched galaxies and keeps them quenched to z=0, while not being so strong as to over-quench satellites; Mufasa's current scheme fails at the latter.

Effect of Inorganic Phosphate and Low pH on the Force-Velocity Relation of Single Skinned Skeletal Muscle Fibers Studied by Applying Parabolic Fiber Length Changes

Although force-velocity (P-V) relation is important to obtain insights into kinetics of actin-myosin interaction in muscle, determination of P-V relation in skinned muscle fibers are difficult mainly due to gradual deterioration at the two cut fiber ends, which makes it impossible to obtain enough data points to construct P-V curve over the whole range of forces. In addition, determination of the maximum shortening velocity Vmax by back extrapolation of limited data points to velocity axis is ambiguous because of the steep force versus velocity relation. To overcome these difficulties, we developed a novel method to obtain continuous P-V curves over the whole range of forces from 0 to the maximum isometric force Po, by applying length changes, with time course L=-kt2, to Ca2+-activated skinned fibers, so that time derivative of length change, i.e. shortening velocity V=-dL/dt=-2kt; namely, V increased linearly with time t. By recording the resulting chane in force P, we could obtain continuous P-V curve in one shot. Using the above method, we examined effect of high inorganic phosphate (Pi) concentration and low pH (6.5) on P-V relation of skinned rabbit psoas muscle fibers at 20°C and at 5°C with the following results: (1) The P-V curves obtained exhibited a distinct hump at high force region >0.5-0.6Po. The P-V curves, deviated from rectangular hyperbola with forces > ~0.2Po, did not change their shape appreciably by Pi and low pH.; (2) Pi (30 mM) reduced Po by ~30% at 20°C and ~45% at 5°C; (3) Low pH (6.5) showed no significant effect on Vmax at both 20 and 5°C; and (4) Pi (30 mM) at low pH (6.5) reduced Po by ~43% at 20°C and ~45% at 5°C. These results are discussed in relation of other published results.

A STEEPER THAN LINEAR DISK MASS–STELLAR MASS SCALING RELATION

ABSTRACT The disk mass is among the most important input parameter for every planet formation model to determine the number and masses of the planets that can form. We present an ALMA 887 μm survey of the disk population around objects from ∼2 to 0.03 M ⊙ in the nearby ∼2 Myr old Chamaeleon I star-forming region. We detect thermal dust emission from 66 out of 93 disks, spatially resolve 34 of them, and identify two disks with large dust cavities of about 45 au in radius. Assuming isothermal and optically thin emission, we convert the 887 μm flux densities into dust disk masses, hereafter M dust. We find that the relation is steeper than linear and of the form M dust ∝ (M *)1.3–1.9, where the range in the power-law index reflects two extremes of the possible relation between the average dust temperature and stellar luminosity. By reanalyzing all millimeter data available for nearby regions in a self-consistent way, we show that the 1–3 Myr old regions of Taurus, Lupus, and Chamaeleon I share the same relation, while the 10 Myr old Upper Sco association has a steeper relation. Theoretical models of grain growth, drift, and fragmentation reproduce this trend and suggest that disks are in the fragmentation-limited regime. In this regime millimeter grains will be located closer in around lower-mass stars, a prediction that can be tested with deeper and higher spatial resolution ALMA observations.

DOES THE INTERMEDIATE-MASS BLACK HOLE IN LEDA 87300 (RGG 118) FOLLOW THE NEAR-QUADRATIC Mbh–Mspheroid RELATION?

ABSTRACT The mass scaling relation between supermassive black holes and their host spheroids has previously been described by a quadratic or steeper relation at low masses (105 &lt; M bh/M ⊙ ≲ 107). How this extends into the realm of intermediate-mass black holes (102 &lt; M bh/M ⊙ &lt; 105) is not yet clear, although for the barred Sm galaxy LEDA 87300, Baldassare et al. recently reported a nominal virial mass of M bh = 5 × 104 M ⊙ residing in a “spheroid” of stellar mass equal to 6.3 × 108 M ⊙. We point out, for the first time, that LEDA 87300 therefore appears to reside on the near-quadratic M bh–M sph,* relation. However, Baldassare et al. modeled the bulge and bar as the single spheroidal component of this galaxy. Here we perform a 3-component bulge+bar+disk decomposition and find a bulge luminosity which is 7.7 times fainter than the published “bulge” luminosity. After correcting for dust, we find that M bulge = 0.9 × 108 M ⊙ and M bulge/M disk = 0.04—which is now in accord with ratios typically found in Scd–Sm galaxies. We go on to discuss slight revisions to the stellar velocity dispersion (40 ± 11 km s−1) and black hole mass ( M bh = 2.9 &minus; 2.3 &plus; 6.7 &times; 10 4 f 2.3 M &CircleDot; ?> ) and show that LEDA 87300 remains consistent with the M bh–σ relation, and also the near-quadratic M bh–M sph,* relation when using the reduced bulge mass. LEDA 87300 therefore offers the first support for the rapid but regulated (near-quadratic) growth of black holes, relative to their host bulge/spheroid, extending into the domain of intermediate-mass black holes.

Assessing the Performance of In-Stream Restoration Projects Using Radio Frequency Identification (RFID) Transponders

Instream channel restoration is a common practice in river engineering that presents a challenge for research. One research gap is the development of monitoring techniques that allow for testable predictions of sediment transport and supply. Here we use Radio Frequency Identification (RFID) transponders to compare the short-term (1-year) sediment transport response to flood events in a restored and a control reach. The field site is Wilket Creek, an enlarged creek in a fully urbanized catchment without stormwater management control in Toronto, Ontario. The responses to three flooding periods, each of which are at or above the design bankfull discharge, are described. Key results are that (i) particle mobility is lower in the restored reach for all three periods; (ii) full mobility occurs in the control reach during the first two floods while partial mobility occurs in the restored reach; and (iii) the constructed morphology exerted a controlling influence on particle entrainment, with higher mobility in the pools. Log-transformed travel distances exhibit normal distributions when grouped by particle size class, which allows a statistical comparison with power law and other predictive travel-distance relations. Results show that three bedload transport conditions can occur, with partial mobility associated with a mild relation between particle size and travel distance and full mobility associated with either a flat or steep relation depending on the degree of integration of particles in the bed. Recommendations on seeding strategy and sample sizes are made to improve the precision of the results by minimizing confidence intervals for mobility and travel distances. Even in a short term study, the RFID sediment tracking technique allows a process-based assessment of stream restoration outcomes that can be used to justify the instream intervention and plan future attempts to stabilize and enhance the system.

Scaling of the 1-halo terms with bias

In the Halo Model, galaxies are hosted by dark matter halos, while the halos themselves are biased tracers of the underlying matter distribution. Measurements of galaxy correlation functions include contributions both from galaxies in different halos, and from galaxies in the same halo (the so-called 1-halo terms). We show that, for highly biased tracers, the 1-halo term of the power spectrum obeys a steep scaling relation in terms of bias. We also show that the 1-halo term of the trispectrum has a steep scaling with bias. The steepness of these scaling relations is such that the 1-halo terms can become key contributions to the $n$-point correlation functions, even at large scales. We interpret these results through analytical arguments and semi-analytical calculations in terms of the statistical properties of halos.

Massive main-sequence stars evolving at the Eddington limit

The evolution of massive stars even on the main sequence is not yet well understood. Due to the steep mass-luminosity relation, massive main sequence stars become very luminous. This brings their envelopes very close to the Eddington limit. We are analysing stellar evolutionary models in which the Eddington limit is reached and exceeded, and explore the rich diversity of physical phenomena which take place in their envelopes, and investigate their observational consequences. We use the grids of detailed stellar models by Brott et al. (2011) and Koehler et al. (2015), to investigate the envelope properties of core hydrogen burning massive stars. We find that at the stellar surface, the Eddington limit is almost never reached, even for stars up to 500 Msun. When an appropriate Eddington limit is defined locally in the stellar envelope, most stars more massive than 40 Msun actually exceed this limit, in particular in the partial ionization zones of iron, helium or hydrogen. While most models adjust their structure such that the local Eddington limit is exceeded at most by a few per cent, our most extreme models do so by a factor of more than seven. We find that the local violation of the Eddington limit has severe consequences for the envelope structure, as it leads to envelope inflation, convection, density inversions and possibly to pulsations. We find that all models with luminosities higher than 4*10^5 Lsun i.e. stars above 40 Msun show inflation, with a radius increase of up to a factor of about 40. We find that the hot edge of the S Dor variability region coincides with a line beyond which our models are inflated by more than a factor of two, indicating a possible connection between S Dor variability and inflation. Furthermore, our coolest models show highly inflated envelopes with masses of up to several solar masses, and appear to be candidates to produce major LBV eruptions.

OBSERVATIONAL EVIDENCE FOR A DARK SIDE TO NGC 5128’S GLOBULAR CLUSTER SYSTEM

We present a study of the dynamical properties of 125 compact stellar systems (CSSs) in the nearby giant elliptical galaxy NGC5128, using high-resolution spectra (R 26,000) obtained with VLT/FLAMES. Our results provide evidence for a new type of star cluster, based on the CSS dynamical mass scaling relations. All radial velocity (v_r) and line-of-sight velocity dispersion (sigma_los) measurements are performed with the penalized pixel fitting (ppxf) technique, which provided sigma_ppxf estimates for 115 targets. The sigma_ppxf estimates are corrected to the 2D projected half-light radii, sigma_{1/2}, as well as the cluster cores, sigma_0, accounting for observational/aperture effects and are combined with structural parameters, from high spatial resolution imaging, in order to derive total dynamical masses (M_dyn) for 112 members of NGC5128's star cluster system. In total, 89 CSSs have dynamical masses measured for the first time along with the corresponding dynamical mass-to-light ratios (Upsilon_V^dyn). We find two distinct sequences in the Upsilon_V^dyn - M_dyn plane, which are well approximated by power laws of the forms Upsilon_V^dyn M_dyn^0.33+\-0.04 and Upsilon_V^dyn - M_dyn^0.79+\-0.04. The shallower sequence corresponds to the very bright tail of the globular cluster luminosity function (GCLF), while the steeper relation appears to be populated by a distinct group of objects which require significant dark gravitating components such as central massive black holes and/or exotically concentrated dark matter distributions. This result would suggest that the formation and evolution of these CSSs are markedly different from the "classical" globular clusters in NGC5128 and the Local Group, despite the fact that these clusters have luminosities similar to the GCLF turn-over magnitude. We include a thorough discussion of myriad factors potentially influencing our measurements.

Star formation rates from young-star counts and the structure of the ISM across the NGC 346/N66 complex in the SMC★

The rate at which interstellar gas is converted into stars, and its dependence on environment, is one of the pillars on which our understanding of the visible Universe is build. We present a comparison of the surface density of young stars (Sigma_*) and dust surface density (Sigma_d) across NGC346 (N66) in 115 independent pixels of 6x6 pc^2. We find a correlation between Sigma_* and Sigma_d with a considerable scatter. A power law fit to the data yields a steep relation with an exponent of 2.6+-0.2. We convert Sigma_d to gas surface density (Sigma_g) and Sigma_* to star formation rate (SFR) surface densities (Sigma_SFR), using simple assumptions for the gas-to-dust mass ratio and the duration of star formation. The derived total SFR (4+-1 10^-3 M_sun/yr) is consistent with SFR estimated from the Ha emission integrated over the Ha nebula. On small scales the Sigma_SFR derived using Ha systematically underestimates the count-based Sigma_SFR, by up to a factor of 10. This is due to ionizing photons escaping the area, where the stars are counted. We find that individual 36 pc^2 pixels fall systematically above integrated disc-galaxies in the Schmidt-Kennicutt diagram by on average a factor of ~7. The NGC346 average SFR over a larger area (90 pc radius) lies closer to the relation but remains high by a factor of ~3. The fraction of the total mass (gas plus young stars) locked in young stars is systematically high (~10 per cent) within the central 15 pc and systematically lower outside (2 per cent), which we interpret as variations in star formation efficiency. The inner 15 pc is dominated by young stars belonging to a centrally condensed cluster, while the outer parts are dominated by a dispersed population. Therefore, the observed trend could reflect a change of star formation efficiency between clustered and non-clustered star-formation.

THE (BLACK HOLE)-BULGE MASS SCALING RELATION AT LOW MASSES

Several recent papers have reported on the occurrence of active galactic nuclei (AGN) containing under-massive black holes relative to a linear scaling relation between black hole mass (M_bh) and host spheroid stellar mass (M_sph,*). Dramatic revisions to the M_bh-M_sph,* and M_bh-L_sph relations, based on samples containing predominantly inactive galaxies, have however recently identified a new steeper relation at M_bh < (2-10)x10^8 M_Sun, roughly corresponding to M_sph,* < (0.3-1)x10^{11} M_Sun. We show that this steeper, quadratic-like M_bh-M_sph,* relation defined by the Sersic galaxies, i.e. galaxies without partially depleted cores, roughly tracks the apparent offset of the AGN having 10^5 < M_bh/M_Sun < 0.5x10^8. That is, these AGN are not randomly offset with low black hole masses, but also follow a steeper (non-linear) relation. As noted by Busch et al., confirmation or rejection of a possible AGN offset from the steeper M_bh-M_sph,* relation defined by the Sersic galaxies will benefit from improved stellar mass-to-light ratios for the spheroids hosting these AGN. Several implications for formation theories are noted. Furthermore, reasons for possible under- and over-massive black holes, the potential existence of intermediate mass black holes (<10^5 M_Sun), and the new steep (black hole)--(nuclear star cluster) relation, M_bh ~ (M_nc)^{2.7+/-0.7}, are also discussed.

Impaired exercise capacity following atrial septal defect closure: an invasive study of the right heart and pulmonary circulation.

Patients with early repair of an isolated atrial septal defect (ASD) are expected to have unremarkable right ventricular (RV) and pulmonary circulation physiology. Some studies, however, suggest persistent functional impairment. We aimed to examine the role of abnormal RV and pulmonary vascular response to exercise in patients who had undergone ASD closure. Using a previously published data set, we reviewed invasive exercise cardiopulmonary testing with right-sided hemodynamic data for 12 asymptomatic patients who had undergone ASD closure. The 5 (42%) patients with impaired maximal oxygen uptake ([Formula: see text]) were older and exhibited a lower peak cardiac index (5.6 ± 0.8 vs. 9.0 ± 1.2 L/min/m(2); P = .005) because of abnormal stroke volume augmentation (+3.2 ± 3.9 vs. +17.4 ± 10.2 mL/m(2); P = .02). While all resting hemodynamic variables were similar, patients with low [Formula: see text] tended to have abnormal total pulmonary vascular resistance change during exercise (+11% ± 41% vs. -28% ± 26%; P = .06) and had a steeper relation between mean pulmonary arterial pressure and cardiac index (5.8 ± 0.6 vs. 2.2 ± 0.1 L/min/m(2); P = .02). The increase in peak mean RV power during exercise was also significantly lower in the impaired-[Formula: see text] patients (4.7 ± 1.6 vs. 7.6 ± 2.1 J/s; P = .04). As described in the original study, despite normal resting hemodynamics, a subset of asymptomatic patients with repaired ASD had diminished exercise capacity. Our analysis allows us to conclude that this is due to a combination of abnormal pulmonary vascular response to exercise and impaired RV function.