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The binding energy liberated by the coalescence of supermassive black hole (SMBH) binaries during galaxy mergers is thought to be responsible for the low density cores often found in bright elliptical galaxies. We use high-resolution $N$-body and Monte Carlo techniques to perform single and multi-stage galaxy merger simulations and systematically study the dependence of the central galaxy properties on the binary mass ratio, the slope of the initial density cusps, and the number of mergers experienced. We study both the amount of depleted stellar mass (or ``mass deficit'), $M_{\rm def}$, and the radial extent of the depleted region, $r_{\rm b}$. We find that $r_{\rm b}\simeq r_{\rm SOI}$ and that $M_{\rm def}$ varies in the range $0.5$ to $4M_{\bullet}$, with $r_{\rm SOI}$ the influence radius of the remnant SMBH and $M_{\bullet}$ its mass. The coefficients in these relations depend weakly on the binary mass ratio and remain remarkably constant through subsequent mergers. We conclude that the core size and mass deficit do not scale linearly with the number of mergers, making it hard to infer merger histories from observations. On the other hand, we show that both $M_{\rm def}$ and $r_{\rm b}$ are sensitive to the morphology of the galaxy merger remnant, and that adopting spherical initial conditions, as done in early work, leads to misleading results. Our models reproduce the range of values for $M_{\rm def}$ found in most observational work, but span nearly an order of magnitude range around the true ejected stellar mass., 19 pages, 9 figures, 4 tables. Accepted for publication to ApJ, comments are welcome

Multiple studies on regional glacier mass balance in the Pamir Mountains have been conducted using the geodetic method, but they were rarely extended to the period before 2000. In this study, we used KH-9 imagery acquired in 1975 to generate the historical DEM for the central Pamir, and then obtained the glacier elevation change by comparing this with the SRTM C-band DEM. The penetration depth of the C-band radar was corrected for different glacier surfaces, i.e. 2.96, 1.68 and 0 m for firn/snow cover, bare ice and debris-covered areas, respectively. The final results suggest that the central Pamir glaciers, overall, experienced a near-zero mass balance of −0.03 ± 0.24 m w.e. a−1 for 1975–99. Due to glacier surge activity, the elevation change patterns of individual glaciers were highly variable, and their mass balances varied from −0.12 ± 0.26 to 0.63 ± 0.20 m w.e. a−1. The mean mass budgets of the surge-type glaciers and non-surge-type glaciers were 0.03 ± 0.14 and −0.05 ± 0.28 m w.e. a−1, respectively. Concurring with previous studies, we conclude that the central Pamir glaciers may have been in a state of approximately balanced mass budget or slight mass deficit from the mid-1970s to the mid-2010s.

In this article, the probability tomography imaging method is applied to airborne vertical gravity gradient data to detect anomalies and estimate their depths and locations. First, the subsurface is divided into a 3D regular grid. Then, the probability tomography function is calculated at each grid node, and the obtained grid values are plotted. The zones of the highest values are the most probable areas for the buried bodies. It is noted that the results fall in the range [-1, +1] that represents the mass excess or mass deficit of density relative to the density of the host volume. The approach is applied to a sphere model and a cube model at certain flight altitudes. The results demonstrate that the approximate mass distribution and depth estimation derived from the approach are reliable up to a certain flight altitude.

Ozone depletion over Polar Regions is monitored each year by satellite and ground-based instruments. The first signs of healing of the ozone layer linked to the decrease of ozone destructive substances (ODSs) were observed in Antarctica using different metrics (ozone mean values, ozone mass deficit, area of the ozone hole) and simple or sophisticated models. Chemistry climate models predict that climate change will not affect expected ozone recovery over Antarctica but will accelerate recovery in the Arctic due to the possible enhancement of the Brewer Dobson circulation. However, ozone loss observations by SAOZ UV-Vis spectrometers do not show a clear sign of recovery in the latter region. In addition, a record of 38% ozone loss in 2010/2011 and 2019/2020 was estimated.In this study, the vortex-averaged ozone loss in the last three decades will be evaluated for both Polar Regions using the passive ozone tracer of two chemical transport models (REPROBUS and SLIMCAT CTMs) and total ozone observations from SAOZ and satellite observations (IASI/METOP and Multi-Sensor Reanalysis (MSR-2)).The tracer method allows us to determine the evolution of the daily rate of ozone destruction, and the amplitude of the cumulative loss at the end of the winter. The cumulative ozone destruction in the Artic varies between 0-10% in relatively warm winters with short vortex duration to up to 25-38% in colder winters with longer vortex persistence, while in Antarctica it is mostly stable, around 50%.Interannual variability of 10-days average rate will be analyzed and compared between both hemispheres as well as the timing to reach different thresholds of absolute ozone loss values. Finally, linear trend of ozone loss and temperature since 2000 will be estimated in both Polar Regions in order to evaluate possible ozone recovery.

Common-envelope evolution is important in the formation of neutron star binaries within the isolated binary formation channel. As a neutron star inspirals within the envelope of a primary massive star, it accretes and spins up. Because neutron stars are in the strong-gravity regime, they have a substantial relativistic mass deficit, i.e., their gravitational mass is less than their baryonic mass. This effect causes some fraction of the accreted baryonic mass to convert into neutron star binding energy. The relativistic mass deficit also depends on the nuclear equation of state, since more compact neutron stars will have larger binding energies. We model the mass growth and spin-up of neutron stars inspiraling within common-envelope environments and quantify how different initial binary conditions and hadronic equations of state affect the post-common-envelope neutron star's mass and spin. From these models, we find that neutron star mass growth is suppressed by $\approx 15-30\%$. We also find that for a given amount of accreted baryonic mass, more compact neutron stars will spin-up faster while gaining less gravitational mass, and vice versa. This work demonstrates that a neutron star's strong gravity and nuclear microphysics plays a role in neutron-star-common-envelope evolution, in addition to the macroscopic astrophysics of the envelope. Strong gravity and the nuclear equation of state may thus affect both the population properties of neutron star binaries and the cosmic double neutron star merger rate., 11 pages, 6 figures, revised version accepted to ApJL

The National Institute of Water and Atmospheric Research/Bodeker Scientific (NIWA–BS) total column ozone (TCO) database and the associated BS-filled TCO database have been updated to cover the period 1979 to 2019, bringing both to version 3.5.1 (V3.5.1). The BS-filled database builds on the NIWA–BS database by using a machine-learning algorithm to fill spatial and temporal data gaps to provide gap-free TCO fields over Antarctica. These filled TCO fields then provide a more complete picture of wintertime changes in the ozone layer over Antarctica. The BS-filled database has been used to calculate continuous, homogeneous time series of indicators of Antarctic ozone depletion from 1979 to 2019, including (i) daily values of the ozone mass deficit based on TCO below a 220 DU threshold; (ii) daily measures of the area over Antarctica where TCO levels are below 150 DU, below 220 DU, more than 30 % below 1979 to 1981 climatological means, and more than 50 % below 1979 to 1981 climatological means; (iii) the date of disappearance of 150 DU TCO values, 220 DU TCO values, values 30 % or more below 1979 to 1981 climatological means, and values 50 % or more below 1979 to 1981 climatological means, for each year; and (iv) daily minimum TCO values over the range 75 to 90∘ S equivalent latitude. Since both the NIWA–BS and BS-filled databases provide uncertainties on every TCO value, the Antarctic ozone depletion metrics are provided, for the first time, with fully traceable uncertainties. To gain insight into how the vertical distribution of ozone over Antarctica has changed over the past 36 years, ozone concentrations, combined and homogenized from several satellite-based ozone monitoring instruments as well as the global ozonesonde network, were also analysed. A robust attribution to changes in the drivers of long-term secular variability in these metrics has not been performed in this analysis. As a result, statements about the recovery of Antarctic TCO from the effects of ozone-depleting substances cannot be made. That said, there are clear indications of a change in trend in many of the metrics reported on here around the turn of the century, close to when Antarctic stratospheric concentrations of chlorine and bromine peaked.

We use satellite ozone records and Global Modeling Initiative chemistry transport model simulations integrated with Modern Era Retrospective for Research and Analysis 2 meteorology to identify a metric that accurately captures the trend in Antarctic ozone attributable to the decline in ozone depleting substances (ODSs). The GMI CTM Baseline simulation with realistically varying ODS levels closely matches observed interannual to decadal scale variations in Antarctic September ozone over the past four decades. The expected increase or recovery trend is obtained from the differences between the Baseline simulation and one with identical meteorology and fixed 1995 ODS levels. The differences show that vortex-averaged column O(3) has the greatest sensitivity to ODS change from 1 to 20 September. The observed vortex-averaged column O(3) during this period produces a trend consistent with the expected recovery attributable to ODS decline. Trends from dates after 20 September have smaller sensitivity to ODS decline and are more uncertain due to transport variability. Simulations show that the greatest decrease in O(3) loss (i.e., recovery) occurs inside the vortex near the edge. The polar cap metrics have vortex size-dependent bias and do not consistently sample this region. Because the 60–90°S 220 Dobson unit O(3) mass deficit metric does not sample the edge region, its trend is lower than the expected trend; this is improved by area weighting. The 250-Dobson unit O(3) mass deficit metric samples more of the edge region, which increases its trend. Approximately 25% of the September Antarctic O(3) increase is due to higher O(3) levels in June prior to winter depletion.

In terrestrial studies, Bouguer gravity data is routinely computed by adopting various numerical schemes, starting from the most basic concept of approximating the actual topography by an infinite Bouguer plate, through adding a planar terrain correction to account for a local/regional terrain geometry, to more advanced schemes that involve the computation of the topographic gravity correction by taking into consideration a gravitational contribution of the whole topography while adopting a spherical (or ellipsoidal) approximation. Moreover, the topographic density information has significantly improved the gravity forward modeling and interpretations, especially in polar regions (by accounting for a density contrast of polar glaciers) and in regions characterized by a complex geological structure. Whereas in geodetic studies (such as a gravimetric geoid modeling) only the gravitational contribution of topographic masses above the geoid is computed and subsequently removed from observed (free-air) gravity data, geophysical studies focusing on interpreting the Earth’s inner structure usually require the application of additional stripping gravity corrections that account for known anomalous density structures in order to reveal an unknown (and sought) density structure or density interface. In planetary studies, numerical schemes applied to compile Bouguer gravity maps might differ from terrestrial studies due to two reasons. While in terrestrial studies the topography is defined by physical heights above the geoid surface (i.e., the geoid-referenced topography), in planetary studies the topography is commonly described by geometric heights above the geometric reference surface (i.e., the geometric-referenced topography). Moreover, large parts of a planetary surface have negative heights. This obviously has implications on the computation of the topographic gravity correction and consequently Bouguer gravity data because in this case the application of this correction not only removes the gravitational contribution of a topographic mass surplus, but also compensates for a topographic mass deficit. In this study, we examine numerically possible options of computing the topographic gravity correction and consequently the Bouguer gravity data in planetary applications. In agreement with a theoretical definition of the Bouguer gravity correction, the Bouguer gravity maps compiled based on adopting the geoid-referenced topography are the most relevant. In this case, the application of the topographic gravity correction removes only the gravitational contribution of the topography. Alternative options based on using geometric heights, on the other hand, subtract an additional gravitational signal, spatially closely correlated with the geoidal undulations, that is often attributed to deep mantle density heterogeneities, mantle plumes or other phenomena that are not directly related to a topographic density distribution.

We compared the structure of two flat and two conical mud volcanoes (MV) in Azerbaijan in order to understand what governs the morphological contrast. We paid particular attention to the structural evolution of the surface, as observed in the field over 5 years and as monitored by satellite images revealing surface activity over that period; in addition, we acquired microgravity measurements to probe deeper structure. The combination of these data reveals in all studied volcanoes significant mass deficit concentric with the surface edifice. Modeling indicates that the mass deficit is consistent with a chamber underlying the summit caldera of conical MVs and the plateau of flat MVs, with a thickness of several hundred meters for a density contrast of 500 kg/m3 between the chamber mud and the surrounding solid mud. Surface structures and their evolution during and in between eruptions provide insight into the depth of the mud chamber, which lies within a few meters of the surface for flat mud volcanoes and one to several hundred meters deep for conical ones. Surface structures and satellite-derived deformation analysis shows that flat mud volcanoes grow by radial expansion and compression of the flanks distributed all around the edifice. In contrast, conical mud volcanoes grow by flow stacking in the summit caldera, deformation being constrained by the caldera rim; excess mud supply is accommodated by occasional rim breaching and mud overflow into flank gullies.

We develop an analytic mass model for lensing galaxies, based on a broken power-law (BPL) density profile, which is a power-law profile with a mass deficit or surplus in the central region. Under the assumption of an elliptically symmetric surface mass distribution, the deflection angle and magnification can be evaluated analytically for this new model. We compute the theoretical prediction for various quantities, including the volume and surface mass density profiles of the galaxies, and the aperture and luminosity-weighted line-of-sight velocity dispersions, and compare them to those measured from the Illustris simulation. We find an excellent agreement between our model prediction and the simulation, which validates our modeling. The high efficiency and accuracy of our model manifests itself as a promising tool for studying properties of galaxies with strong lensing., Comment: 27 pages, 17 figures, 1 table; Accepted for publication in ApJ

We model the ALMA and VLA millimeter radial profiles of the disk around HL Tau to constrain the properties of the dust grains. We adopt the disk evolutionary models of Lynden-Bell \& Pringle and calculate their temperature and density structure and emission. These disks are heated by the internal viscosity and irradiated by the central star and a warm envelope. We consider a dust size distribution $n(a) da \propto a^{-3.5} da $, and vary the maximum grain size in the atmosphere and the midplane, $a_{\rm max}=100\ ��$m, 1 mm, and 1cm. We also include dust settling and vary the dust-to-gas mass ratio from 1 to 9 times the ISM value. We find that the models that can fit the observed level of emission along the profiles at all wavelengths have an atmosphere with a maximum grain size $a_{\rm max} = 100 \ ��$m, and a midplane with $a_{\rm max}=1$ cm. The disk substructure, with a deficit of emission in the gaps, can be due to dust properties in these regions that are different from those in the rings. We test an opacity effect (different $a_{\rm max}$) and a dust mass deficit (smaller dust-to-gas mass ratio) in the gaps. We find that the emission profiles are better reproduced by models with a dust deficit in the gaps, although a combined effect is also possible. These models have a global dust-to-gas mass ratio twice the ISM value, needed to reach the level of emission of the 7.8 mm VLA profile., 17 pages, 11 figures

Nucleon properties and structure should be modified by short-range correlations (SRC) among nucleons. By analyzing SRC ratio data, we extract the mass of a nucleon in an SRC pair and the expected number of pn-SRC pairs in deuterium, under the assumption that the SRC nucleon mass is universal for different nuclei. The nucleon mass of a two-nucleon SRC pair is = 852 ± 18 MeV, and the number of pn-SRC pairs in deuterium is =0.021 ± 0.005. The mass deficit of the strongly overlapping nucleon can be explained by the trace anomaly contribution to the mass in QCD or alternatively by the vacuum energy in the MIT bag model.

We present KETJU, a new regularized tree code based on algorithmic chain regularization and implemented into Gadget-3. This new code is able to follow simultaneously galactic-scale dynamical and astrophysical processes and the small-scale supermassive black hole binary dynamics. We present here the general idea of this new code and show a test simulation of black hole binary dynamics in a galaxy merger of two massive elliptical galaxies. The separation of the black holes at the time of the merger is several orders of magnitude smaller in KETJU than when compared to ordinary Gadget-3 simulations. The merger timescale is also longer by 100 − 200 Myr.

We present 20 years (1996–2015) of austral springtime measurements of chlorine monoxide (ClO) over Antarctica from the Chlorine Oxide Experiment (ChlOE1) ground-based millimeter wave spectrometer at Scott Base, Antarctica, as well 12 years (2004–2015) of ClO measurements from the Aura Microwave Limb Sounder (MLS). From August onwards we observe a strong increase in lower stratospheric ClO, with a peak column amount usually occurring in early September. From mid-September onwards we observe a strong decrease in ClO. In order to study interannual differences, we focus on a 3-week period from 28 August to 17 September for each year and compare the average column ClO anomalies. These column ClO anomalies are shown to be highly correlated with the average ozone mass deficit for September and October of each year. We also show that anomalies in column ClO are strongly anti-correlated with 30 hPa temperature anomalies, both on a daily and an interannual timescale. Making use of this anti-correlation we calculate the linear dependence of the interannual variations in column ClO on interannual variations in temperature. By making use of this relationship, we can better estimate the underlying trend in the total chlorine (Cly = HCl + ClONO2 + HOCl + 2 × Cl2 + 2 × Cl2O2 + ClO + Cl). The resultant trends in Cly, which determine the long-term trend in ClO, are estimated to be −0.5 ± 0.2, −1.4 ± 0.9, and −0.6 ± 0.4 % year−1, for zonal MLS, Scott Base MLS (both 2004–2015), and ChlOE (1996–2015) respectively. These trends are within 1σ of trends in stratospheric Cly previously found at other latitudes. The decrease in ClO is consistent with the trend expected from regulations enacted under the Montreal Protocol.

Galactic bulge microlensing surveys provide a probe of Galactic structure. We present the first field-by-field comparison between microlensing observations and the Besan\c{c}on population synthesis Galactic model. Using an updated version of the model we provide maps of optical depth, average event duration and event rate for resolved source populations and for difference imaging (DIA) events. We also compare the predicted event timescale distribution to that observed. The simulation follows the selection criteria of the MOA-II survey (Sumi et al. 2013). We modify the Besan\c{c}on model to include M dwarfs and brown dwarfs. Our best fit model requires a brown dwarf mass function slope of $-0.4$. The model provides good agreement with the observed average duration, and respectable consistency with the shape of the timescale distribution (reduced $\chi^2 \simeq 2.2$). The DIA and resolved source limiting yields bracket the observed number of events by MOA-II ($2.17\times$ and $0.83\times$ the number observed, respectively). We perform a 2-dimensional fit to the event spatial distribution to predict the optical depth and event rate across the Galactic bulge. The most serious difficulty for the model is that it provides only $\sim 50\%$ of the measured optical depth and event rate per star at low Galactic latitude around the inner bulge ($|b, Comment: 17 pages, 12 figures, 6 tables, Submitted to MNRAS. This work uses the Manchester-Besancon Microlensing Simulator - MaBulS, which is publicly available online at http://www.mabuls.net/

As well as measuring the effects of latitude and height on gravity, an attempt was made during the French expedition to Ecuador to measure the gravity effect of a large mountain. The experiment was repeated on Schiehallion in Scotland by the Astronomer Royal, Neville Maskelyn, and a much better estimate was made of the mass of the Earth. It was later realised, as a result of measurements made during the mapping of India, that the gravitational attraction of the Himalayas was less than would have been expected and that their surface mass must be balanced by a mass deficit at depth. The effects of this ‘isostatic’ balance can be seen in the uplift of Finland in response to the disappearance of the load represented by the extensive ice sheets of the most recent glaciation.

The most likely sources of nanohertz gravitational waves (GWs) are supermassive black holes (SMBHs) at the center of merging galaxies. A stochastic superposition of GWs from these sources is expected to produce a stochastic GW background that will leave a unique signature in the correlations of arrival times of pulses from a collection of radio pulsars. Using the 9-year data release from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration, we perform the first analysis that places constraints on the amplitude and shape of the stochastic GW background. We find that the data favor a turn over in the GW strain spectrum for current models of SMBH merger rates. This result indicates that environmental factors, other than GWs from circular binaries, are influencing the GW spectrum. Furthermore, we map constraints on the spectral shape to constraints on various environmental factors that drive the binary to the GW-driven regime including the stellar mass density for stellar-scattering, mass accretion rate for circumbinary disk interaction, and orbital eccentricity for eccentric binaries.

We explore the effect of varying the mass of a seed black hole on the resulting black hole mass -- bulge mass relation at $z \sim 0$, using a semi-analytic model of galaxy formation combined with large cosmological N-body simulations. When the mass of the seed is set at $10^5 M_\odot$, we find that the model results become inconsistent with recent observational results of the black hole mass -- bulge mass relation for dwarf galaxies. On the other hand, when we employ seed black holes of $10^3 M_\odot$ or select their mass randomly within a $10^{3 -5} M_\odot$ range, the resulting relation is consistent with observational results including the dispersion. We also find that black hole mass -- bulge mass relations for less massive bulges at $z \sim 0$ put stronger constraints on the seed BH mass than the relations at higher redshifts.

We present observations of the double-peaked broad H$\alpha$ profile emitted by the active nucleus of NGC 7213 using the the Gemini South Telescope in 13 epochs between 2011 September 27 and 2013 July 23. This is the first time that the double-peaked line profile of this nucleus -- typical of gas emission from the outer parts of an accretion disk surrounding a supermassive black hole (SMBH) -- is reported to vary. From the analysis of the line profiles we find two variability timescales: (1) the shortest one, between 7 and 28 days, is consistent with the light travel time between the ionizing source and the part of the disk emitting the line; and (2) a longer one of $\gtrsim 3$ months corresponding to variations in the relative intensity of the blue and red sides of the profile, which can be identified with the dynamical timescale of this outer part of the the accretion disk. We modeled the line profiles as due to emission from a region between $\approx$ 300 and 3000 gravitational radii of a relativistic, Keplerian accretion disk surrounding the SMBH. Superposed on the disk emissivity, the model includes an asymmetric feature in the shape of a spiral arm with a rotation period of $\approx$ 21 months, which reproduces the variations in the relative intensity of the blue and red sides of the profile. Besides these variations, the $rms$ variation profile reveals the presence of another variable component in the broad line, with smaller velocity width W$_{68}$ (the width of the profile corresponding to 68$\%$ of the flux) of $\sim 2100$ km s$^{-1}$., Comment: 12 pages, 4 tables, 10 figures

Black hole accretion disks appear to produce invariably plasma outflows that result in blue-shifted absorption features in their spectra. The X-ray absorption-line properties of these outflows are quite diverse, ranging in velocity from non-relativistic ($\sim 300$ km/sec) to sub-relativistic ($\sim 0.1c$ where $c$ is the speed of light) and a similarly broad range in the ionization states of the wind plasma. We report here that semi-analytic, self-similar magnetohydrodynamic (MHD) wind models that have successfully accounted for the X-ray absorber properties of supermassive black holes, also fit well the high-resolution X-ray spectrum of the accreting stellar-mass black hole, GRO J1655-40. This provides an explicit theoretical argument of their MHD origin (aligned with earlier observational claims) and supports the notion of a universal magnetic structure of the observed winds across all known black hole sizes., published in 2017 March 6 Nature Astronomy, 23 pages, 4 figures, 4 supplementary figures

As part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM) project we present an estimate of the mass of the supermassive black hole (SMBH) in the nearby fast-rotating early-type galaxy NGC4429, that is barred and has a boxy/peanut-shaped bulge. This estimate is based on Atacama Large Millimeter/submillimeter Array (ALMA) cycle-2 observations of the 12CO(3-2) emission line with a linear resolution of ~13 pc (0"18x0"14). NGC4429 has a relaxed, flocculent nuclear disc of molecular gas that is truncated at small radii, likely due to the combined effects of gas stability and tidal shear. The warm/dense 12CO(3-2) emitting gas is confined to the inner parts of this disc, likely again because the gas becomes more stable at larger radii, preventing star formation. The gas disc has a low velocity dispersion of 2.2$^{+0.68}_{-0.65}$ km/s. Despite the inner truncation of the gas disc, we are able to model the kinematics of the gas and estimate a mass of (1.5$\pm0.1^{+0.15}_{-0.35}$)$\times$10$^8$ Msun for the SMBH in NGC4429 (where the quoted uncertainties reflect the random and systematic uncertainties, respectively), consistent with a previous upper limit set using ionised gas kinematics. We confirm that the V-band mass-to-light ratio changes by ~30% within the inner 400 pc of NGC4429, as suggested by other authors. This SMBH mass measurement based on molecular gas kinematics, the sixth presented in the literature, once again demonstrates the power of ALMA to constrain SMBH masses., Comment: 18 pages, 16 figures, accepted by MNRAS

We study the spiral arm morphology of a sample of the local spiral galaxies in the Illustris simulation and explore the supermassive black hole - galaxy connection beyond the bulge (e.g., spiral arm pitch angle, total stellar mass, dark matter mass, and total halo mass), finding good agreement with other theoretical studies and observational constraints. It is important to study the properties of supermassive black holes and their host galaxies through both observations and simulations and compare their results in order to understand their physics and formative histories.We find that Illustris prediction for supermassive black hole mass relative to pitch angle is in rather good agreement with observations and that barred and non-barred galaxies follow similar scaling relations. Our work shows that Illustris presents very tight correlations between supermassive black hole mass and large-scale properties of the host galaxy, not only for early-type galaxies but also low-mass, blue and star-forming galaxies. These tight relations beyond the bulge suggest that halo properties determine those of a disc galaxy and its supermassive black hole., Comment: 14 pages, 9 figures, 1 table

Contains fulltext : 180963.pdf (Publisher’s version ) (Open Access)

Isostasy is a key concept in geodesy and geophysics. The classical isostatic models of Airy/Heiskanen and Pratt/Hayford imply that the topographic mass surplus and ocean mass deficit are balanced by mountain roots and anti-roots in the former model and by density variations in the topography and the compensation layer below sea bottom in the latter model. In geophysics gravity inversion is an essential topic where isostasy comes to play. The main objective of this study is to compare the prediction of geoid heights from the above isostatic models based on matched asymptotic expansion with geoid heights observed by the Earth Gravitational Model 2008. Numerical computations were carried out both globally and in several regions, showing poor agreements between the theoretical and observed geoid heights. As an alternative, multiple regression analysis including several non-isostatic terms in addition to the isostatic terms was tested providing only slightly better success rates. Our main conclusion is that the geoid height cannot generally be represented by the simple formulas based on matched asymptotic expansions. This is because (a) both the geoid and isostatic compensation of the topography have regional to global contributions in addition to the pure local signal considered in the classical isostatic models, and (b) geodynamic phenomena are still likely to significantly blur the results despite that all spherical harmonic low-degree (below degree 11) gravity signals were excluded from the study.

We present a set of, large scale direct N-body simulations of the galaxy collision with the central Supermassive Black Hole Binary (SMBHB) system. Based on our simulations which include the accurate Post Newtonian (PN) relativistic dynamical corrections we can estimated the merging time for the real astrophysical object. Each galaxy initially was represented as a set of particles (up to N=500k) with Plummer distribution. The SMBHBs system is described using the two special high mass, i.e. “relativistic”, particles. The interaction between these two particles have an extra PN correction terms (up to 3.5PN). Merging time upper limit was obtained for the closely interacting galaxy system NGC 6240.

In this review, I will briefly discuss the different types of black hole (BH) populations (supermassive, intermediate mass and stellar mass BHs) both in the Galaxy and in the Magellanic Clouds and compare them with each other.

Supermassive black hole binaries (SMBHBs) should be an inevitable consequence of the hierarchical growth of massive galaxies through mergers and the strongest sirens of gravitational waves (GWs) in the cosmos. Yet, their direct detection has remained elusive due to the compact (sub-parsec) orbital separations of gravitationally bound SMBHBs. Here we exploit a theoretically predicted signature of SMBHBs in the time domain. We have begun a systematic search for SMBHB candidates in the Pan-STARRS1 Medium Deep Survey (MDS) and reported our first significant detection of such a candidate from our pilot study of MD09 in Liu et al. (2015). Our candidate PSO J334.2028+01.4075 has a detected period of 542 days, varying persistently over the available baseline. From its archival spectrum, we estimated the black hole mass of the z = 2.06 quasar to be ∼1010 M⊙. The inferred ∼7 Rs binary separation therefore puts this candidate in the regime of GW-dominated orbital decay, opening up the exciting possibility of finding GW sources detectable by pulsar timing arrays (PTAs) in a wide-field optical synoptic survey.

In this letter we carry out the first systematic investigation of the expected gravitational wave (GW) background generated by supermassive black hole (SMBH) binaries in the nHz frequency band accessible to pulsar timing arrays (PTAs). We take from the literature several estimates of the redshift dependent galaxy mass function and of the fraction of close galaxy pairs to derive a wide range of galaxy merger rates. We then exploit empirical black hole-host relations to populate merging galaxies with SMBHs. The result of our procedure is a collection of a large number of phenomenological SMBH binary merger rates consistent with current observational constraints on the galaxy assembly at z, Comment: 6 pages, 3 figures, submitted to MNRAS letter

We study the formation of a supermassive black hole (SMBH) binary and the shrinking of the separation of the two holes to sub-pc scales starting from a realistic major merger between two gas-rich spiral galaxies with mass comparable to our Milky Way. The simulations, carried out with the Adaptive Mesh Refinement (AMR) code RAMSES, are capable of resolving separations as small as 0.1 pc. The collision of the two galaxies produces a gravo-turbulent rotating nuclear disk with mass (10^9 Msun) and size (60 pc) in excellent agreement with previous SPH simulations with particle splitting that used a similar setup (Mayer et al. 2007) but were limited to separations of a few parsecs. The AMR results confirm that the two black holes sink rapidly as a result of dynamical friction onto the gaseous background, reaching a separation of 1 pc in less than 10^7 yr. We show that the dynamical friction wake is well resolved by our model and we find good agreement with analytical predictions of the drag force as a function of the Mach number. Below 1 pc, black hole pairing slows down significantly, as the relative velocity between the sinking SMBH becomes highly subsonic and the mass contained within their orbit falls below the mass of the binary itself, rendering dynamical friction ineffective. In this final stage, the black holes have not opened a gap as the gaseous background is highly pressurized in the center. Non-axisymmetric gas torques do not arise to restart sinking in absence of efficient dynamical friction, at variance with previous calculations using idealized equilibrium nuclear disk models. (abridged), Comment: Accepted for publication in MNRAS. 10 pages, 6 figures

Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of very hot gas. Recent theory and simulations instead predict that accretion can be dominated by a stochastic, clumpy distribution of very cold molecular clouds - a departure from the "hot mode" accretion model - although unambiguous observational support for this prediction remains elusive. Here we report observations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift z=0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma. Under the right conditions, thermal instabilities can precipitate from this hot gas, producing a rain of cold clouds that fall toward the galaxy's centre, sustaining star formation amid a kiloparsec-scale molecular nebula that inhabits its core. The observations show that these cold clouds also fuel black hole accretion, revealing "shadows" cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole in the galaxy centre, which serves as a bright backlight. Corroborating evidence from prior observations of warmer atomic gas at extremely high spatial resolution, along with simple arguments based on geometry and probability, indicate that these clouds are within the innermost hundred parsecs of the black hole, and falling closer towards it., Published in the June 9th, 2016 issue of Nature

We present three-dimensional Smoothed Particle Hydrodynamics (SPH) simulations investigating the dependence of the accretion rate on the disc thickness around an equal-mass, circular black hole binary system. We find that for thick/hot discs, with $H/R\gtrsim 0.1$, the binary torque does not prevent the gas from penetrating the cavity formed in the disc by the binary (in line with previous investigations). The situation drastically changes for thinner discs, in this case the mass accretion rate is suppressed, such that only a fraction (linearly dependent on $H/R$) of the available gas is able to flow within the cavity and accrete on to the binary. Extrapolating this result to the cold and thin accretion discs expected around supermassive black hole binary systems implies that this kind of systems accretes less material than predicted so far, with consequences not only for the electromagnetic and gravitational waves emissions during the late inspiral phase but also for the recoil speed of the black hole formed after binary coalescence, thus influencing also the evolutionary path both of the binary and of the host galaxy. Our results, being scale-free, are also applicable to equal mass, circular binaries of stellar mass black holes, such as the progenitor of the recently discovered gravitational wave source GW150914., 12 pages, 6 figures, 2 tables, accepted for publication in MNRAS

We study accretion rates during the gravitational wave-driven merger of a binary supermassive black hole embedded in an accretion disc, formed by gas driven to the centre of the galaxy. We use 3D simulations performed with PHANTOM, a Smoothed Particle Hydrodynamics code. Contrary to previous investigations, we show that there is evidence of a "squeezing phenomenon", caused by the compression of the inner disc gas when the secondary black hole spirals towards the primary. This causes an increase in the accretion rates that always exceed the Eddington rate. We have studied the main features of the phenomenon for a mass ratio $q = 10^{-3}$ between the black holes, including the effects of numerical resolution, the secondary accretion radius and the disc thickness. With our disc model with a low aspect ratio, we show that the mass expelled from the orbit of the secondary is negligible ($< 5\%$ of the initial disc mass), different to the findings of previous 2D simulations with thicker discs. The increase in the accretion rates in the last stages of the merger leads to an increase in luminosity, making it possible to detect an electromagnetic precursor of the gravitational wave signal emitted by the coalescence., 11 pages, 9 figures, MNRAS accepted

{Abridged} We show that the surface brightness (SB) profiles of elliptical galaxies can be parametrized using a linear superposition of 2-3 components, described by functions developed in Dhar & Williams as the 2D projections of a 3D Einasto profile. For a sample of 23 ellipticals with -24 3{\sigma}. Our models indicate that i) the central component is more concentrated than the outer component; and ii) the central component of 'core' galaxies is much more luminous, extended and concentrated than that of 'cuspy' galaxies, with their near exponential central profiles indicating disk-like systems whose existence must be verified spectroscopically. While such central excess components are not necessarily contrary to the notion of a mass deficit in 'core' galaxies, we show that the existence, amount, radial extent and sign of mass deficits disagree substantially in the literature, both for a given galaxy and on an average over a sample. We discuss possible implications and suggest that SMBH binaries are unlikely to be the sole mechanism for producing the large 'cores'. We also deduce conditions under which the 3D light density can be described with a multi-component Einasto model for both cuspy and core galaxies; indicating an universality in the functional form of the 3D density of light in galaxies and dark matter in LCDM N-body haloes. Finally, we show that our result - the outer component of the SB profiles of massive galaxies has 5 < n < 8 - could imply i) a common feature of collisionless systems; and ii) that galaxies with such n for their outer component are dark matter dominated.

Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon's composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00–15.00°N, 301.85–304.01°E around the MHH, and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille.

We discuss the mechanisms of supermassive primordial black hole formation in the period before the beginning of star formation. We study the dependence of the primordial black hole mass spectrum on the initial conditions at the inflationary stage.

We present a simple estimate of the mass ‘deficits’ in cored spheroids, as a function of galaxy mass and radius within the galaxy. Previous attempts to measure such deficits depended on fitting some functional form to the profile at large radii extrapolating inwards; this is sensitive to the assumed functional form and does not allow for variation in nuclear profile shapes. For example, we show that literally interpreting the residuals from a single/cored Sersic function fit as implied ‘deficit’ can be misleading. Instead, we take advantage of larger data sets to directly construct stellar mass profiles of observed systems and measure the stellar mass enclosed in a series of physical radii (M_*(< R)), for samples of cusp and core spheroids at the same stellar mass. We show that there is a significant (model-independent) bimodality in this distribution of central structure for this sample at small radii. We non-parametrically measure the median offset between core and cusp populations (the ‘deficit’ΔM_*(< R)). We can then construct the scoured mass profile as a function of radius, without reference to any assumed functional form. The mass deficit rises in power-law fashion (ΔM_*(< R) ∝ R^(1.3−1.8)) from a significant but small mass at R ≲ 10 pc, to asymptote to a maximum ∼ 0.5–2 M_(BH) at ∼ 100 pc, where M_(BH) is the mass of the central, supermassive black hole (BH) hosted by the spheroid. At larger radii there is no statistically significant separation between populations; the upper limit to the cumulative scoured mass at ∼kpc is ∼ 2–4 M_(BH). This does not depend strongly on stellar mass. The dispersion in M_*(< R) appears larger in the core population, possibly reflecting the fact that core scouring increases the scatter in central profile shapes. We measure this broadening effect as a function of radius. The relatively low mass deficits inferred, and characteristic radii, are in good agreement with models of ‘scouring’ from BH binary systems.

An analysis of periodic components of flux variability was carried out based on the long-term monitoring of the nuclei of active galaxies 3C454.3, 1633+382, and 3C120, performed in the Crimean Astrophysical Observatory from 1985 to 2008 at 22.2 and 36.8 GHz. Long-period components of the variability (12–14 yrs) were detected and interpreted in terms of the precessional motion of the central body in binary systems. Short-period components (1.5–3 yrs) related to the orbital periods for the motions of the central supermassive black holes were also detected. We concluded that the brightest active galaxies observed as nonstationary sources in a wide range of wavelengths are binary systems of supermassive black holes at the stage of evolution close to coalescence. For the supposed binary black-hole systems, the masses of the central objects and their companions, the orbital radii of the companions, and the coalescence times were determined. The ratios of the masses in the binary systems in all cases proved to be less than ten, pointing to a strong gravitational effect of the companion on the central black hole. The velocities of the central body motion proved to be high, approximately 1000 km/s. This fact should be accounted for in the calculations of the rate of accretion onto the central body. The orbital radii of the companions fall into a narrow range between 4 × 1016 cm and 6 × 1016 cm, demonstrating a strong dependence of the masses of the binary systems on the orbital sizes and the energy loss for the gravitational radiation. Within the orbit of the companion during its motion through the accretion disk, a high temperature of surrounding gas is achieved. The high density of the medium, 109–1010 cm−3, combined with the magnetic field and shock waves propagating in the accretion disk, develop the conditions for powerful energy release in the directed jets.

We study a disordered quantum solid incorporating two-level systems in which a group of atoms (or a single atom) can experience coherent tunnelling between two different positions and demonstrate that an effective mass deficit induced by the presence of such objects can manifest itself only at relatively high frequencies and should vanish in the low-frequency limit. The crossover to the regime which can be associated with the appearance of an effective mass deficit has been observed in recent torsional oscillator experiments., 4 pages, LaTeX

article i nfo Article history: The Norwegian mountains or Scandes represent a long mountain range stretching from southern Norway to the Arctic and is characterised by a rugged topography and peaks up to 2.5 km high. The origin of this mountain chain far away from any plate boundary remains a matter of passionate debates inside the geoscientific community. Hot mantle "fingers" originating from the Iceland Plume, impacting the base of the Scandinavian lithosphere and creating asthenospheric diapirs is one of the most accepted hypotheses for explaining Cenozoic uplift in Norway. In order to test this hypothesis we conducted integrated gravity and thermal modelling. We used the dense NGU gravity grid (i.e. one measurement every ~3 km) and modelled the depth extent and the mass deficit associated to the compensating loads located below the southern Scandes. Assuming that the density deficit below the Scandes is purely thermal in origin, thermal modelling allowed for testing the magnitude of the potentially associated temperature anomaly and its impact on surface heat flow. Recently acquired heat flow data were used in order to constrain the results from the thermal modelling. The results of our integrated geophysical modelling rule out the possibility that the present-day topography of the southern Scandes is compensated by a deep-seated asthenospheric diapir. However, our modelling does not exclude that thermal processes in the deep mantle could have initiated or assisted recent uplift of the southern Scandes.

We study observed correlations between supermassive black hole (BHs) and the properties of their host galaxies, and show that the observations define a BH “fundamental plane” (BHFP), of the form $\mbh\propto\sigma^{3.0\pm0.3}\,\re^{0.43\pm0.19}$ or $\mbh\propto\mstar^{0.54\pm0.17}\,\sigma^{2.2\pm0.5}$, analogous to the FP of elliptical galaxies. The BHFP is preferred over a simple relation between MBH and any of σ, M*, Mdyn, or Re alone at > 3 σ (99.9%) significance. The existence of this BHFP has important implications for the formation of supermassive BHs and the masses of the very largest black holes, and immediately resolves several apparent conflicts between the BH masses expected and measured for outliers in both the MBH − σ and MBH − M* relations.

We have used two astrometric methods developed at the Main Astronomical Observatory of the Russian Academy of Sciences—the method of apparent-motion parameters (AMP) and a direct geometrical method (DGM)—to derive the orbit of the star S2 around the Galactic center, and thereby the mass of the supermassive black hole at the Galactic center. The AMP method, which is based on measurements of the curvature of a fairly short orbital arc, is efficient if observational data on the relative radial velocity are available. The mass of the supermassive black hole was also estimated using astrophysical methods, based on the empirical relation between the masses of the supermassive black holes at the centers of galaxies and quasars and the radio and X-ray luminosities of these regions. We estimate the magnetic-field strength near the event horizon of the supermassive black hole at the Galactic center using a synchrotron self-absorption model.

Pulsar timing arrays (PTAs) are placing increasingly stringent constraints on the strain amplitude of continuous gravitational waves emitted by supermassive black hole binaries on subparsec scales. In this paper, we incorporate independent information about the dynamical masses $M_{bh}$ of supermassive black holes in specific galaxies at known distances and use this additional information to further constrain whether or not those galaxies could host a detectable supermassive black hole binary. We estimate the strain amplitudes from individual binaries as a function of binary mass ratio for two samples of nearby galaxies: (1) those with direct dynamical measurements of $M_{bh}$ in the literature, and (2) the 116 most massive early-type galaxies (and thus likely hosts of the most massive black holes) within 108 Mpc from the MASSIVE Survey. Our exploratory analysis shows that the current PTA upper limits on continuous waves (as a function of angular position in the sky) can already constrain the mass ratios of hypothetical black hole binaries in many galaxies in our samples. The constraints are stronger for galaxies with larger $M_{bh}$ and at smaller distances. For the black holes with $M_{bh} \gtrsim 5\times 10^9 M_\odot$ at the centers of NGC 1600, NGC 4889, NGC 4486 (M87) and NGC 4649 (M60), any binary companion in orbit within the PTA frequency bands would have to have a mass ratio of a few percent or less., 8 pages, 4 figures

We consider the information that can be derived about massive black-hole binary populations and their formation history solely from current and possible future pulsar timing array (PTA) results. We use models of the stochastic gravitational-wave background from circular massive black hole binaries with chirp mass in the range $10^6 - 10^{11} M_\odot$ evolving solely due to radiation reaction. Our parameterised models for the black hole merger history make only weak assumptions about the properties of the black holes merging over cosmic time. We show that current PTA results place an upper limit on the black hole merger density which does not depend on the choice of a particular merger history model, however they provide no information about the redshift or mass distribution. We show that even in the case of a detection resulting from a factor of 10 increase in amplitude sensitivity, PTAs will only put weak constraints on the source merger density as a function of mass, and will not provide any additional information on the redshift distribution. Without additional assumptions or information from other observations, a detection cannot meaningfully bound the massive black hole merger rate above zero or any particular mass., Accepted by MNRAS Letters, 6 pages, 3 figures

We study how the properties of cosmic voids depend on those of the tracer galaxy populations in which they are identified. We use a suite of halo occupation distribution (HOD) mocks in a simulation, identify voids in these populations using the ZOBOV void finder and measure their abundances, sizes, tracer densities, and dark matter content. To separate the effects of bias from those of sampling density, we do the same for voids traced by randomly down-sampled subsets of the simulation dark matter particles. At the same sampling density, galaxy bias reduces the total number of voids by ~50% and can dramatically change their size distribution. The matter content of voids in biased and unbiased tracers also differs. Deducing void properties from simulation therefore requires the use of realistic galaxy mocks. We discuss how the void observables can be related to their matter content. In particular we consider the compensation of the total mass deficit in voids and find that the distinction between over- and under-compensated voids is not a function of void size alone, as has previously been suggested. However, we find a simple linear relationship between the average density of tracers in the void and the total mass compensation on much larger scales. The existence of this linear relationship holds independent of the bias and sampling density of the tracers. This provides a universal tool to classify void environments and will be important for the use of voids in observational cosmology., 13 pages, 10 figures. MNRAS accepted. Main change in this version is addition of new figure (fig. 6), and shorter abstract. Figures 2, 5 and 7 contain the main results

In one of our experiments aimed at studying of the new multi-body decay called collinear cluster tri-partition (CCT) [1–3] additional absorber (Ti foil) was introduced just after the source at the distance of approximately 1 mm. It was motivated by the peculiarity of the CCT manifestation in the experiments namely specific structures in the region of an essential missing mass in the fission fragments (FFs) mass correlation distribution were observed in the spectrometer arm faced to the Cf source backing only. The effect was traced back to some angular divergence between two CCT partners flying in the same direction after passing the scattering medium on the flight pass due to the multiple scattering. As a result one of them can be lost in the PIN diode frame what is observed as” missing mass” or both fragments will be detected independently in the neighboring diodes. We have observed significant mass deficit in the total mass of the fission fragments detected in coincidence with Ti ions knocked out from the foil (fig. 1) [4]. For the sake of convenience, the FFs from such events are labeled as M1, M2 and M3 in an order of decreasing masses in the ternary event. The total mass of the two heavier fragments Ms = M1 + M2 is plotted vs. the mass of the lighter fragment M3. Such effect could be expected if the scattered fragment looks like a di-nuclear system destroying due to inelastic scattering on the Ti nucleus. A mean flight time between the Cf source and the foil does not exceed 0.1 ns. It can be regarded as a low limit for the life time of the di-nuclear system (shape isomer).

We introduce a force correction term to better model the dynamical friction (DF) experienced by a supermassive black hole (SMBH) as it orbits within its host galaxy. This new approach accurately follows the orbital decay of a SMBH and drastically improves over commonly used advection methods. The force correction introduced here naturally scales with the force resolution of the simulation and converges as resolution is increased. In controlled experiments we show how the orbital decay of the SMBH closely follows analytical predictions when particle masses are significantly smaller than that of the SMBH. In a cosmological simulation of the assembly of a small galaxy, we show how our method allows for realistic black hole orbits. This approach overcomes the limitations of the advection scheme, where black holes are rapidly and artificially pushed toward the halo center and then forced to merge, regardless of their orbits. We find that SMBHs from merging dwarf galaxies can spend significant time away from the center of the remnant galaxy. Improving the modeling of SMBH orbital decay will help in making robust predictions of the growth, detectability, and merger rates of SMBHs, especially at low galaxy masses or at high redshift., 8 pages, 4 figure, Accepted by MNRAS