Mass determination of supermassive black holes in nearby galaxies

This thesis focusses on the measure of the mass of supermassive black holes (SBH) lurking in the center of nearby quiescent galaxies. Increasing the demography of SBHs allows to study the correlations between their mass and the properties of their host to get insights about the joint evolution of SBHs and galaxies. New stringent limits on the SBH mass of 7 nearby galaxies are obtained by modeling the central width of the nebular emission lines measured over subarcsecond apertures with the Hubble Space Telescope (HST). The central stellar velocity dispersion of each galaxy is derived from new long-slit spectra from ground-based observations and the bulge effective radius is derived from a two-dimensional photometric decomposition of the i-band images from the Sloan Digital Sky Survey. The SBH-mass limits run parallel and above the relation between the SBH mass and the stellar velocity dispersion with no systematic trend depending on the galaxy distance or morphology. This gives further support to previous findings suggesting that the nuclear gravitational potential is remarkably well traced by the nebular-line width when the gas is centrally peaked. With this investigation, the number of galaxies with SBH-mass stringent limits obtained from nebular-line width increases to 114. These galaxies are further analyzed to more tightly constrain their SBH mass by taking into account the stellar mass contribution in the galaxy nucleus. To this aim the surface brightness distribution is measured from HST images and the mass-to-light ratio of an old and metal-rich stellar population is adopted for 100 nearby galaxies (D<103 Mpc) spanning a wide range of Hubble types (E-Sc) and central velocity dispersions (58-419 km/s). The shape of the profile of the emission lines and of the radial profile of emission-line flux are analysed to verify that nongravitational forces have a minor impact on the SBH-mass estimate. On average the stellar mass contribution is larger for galaxies with low effective velocity dispersion partly due to the presence of a nuclear stellar cluster or disk. Moreover, the stellar mass contribution is negligible in ellipticals and depends on the aperture size rather than on galaxy distance. These new SBH-mass limits run parallel to the relation between the SBH mass and the stellar velocity dispersion and they exceed the expected values by a median factor of 1.7. This is a striking result, since the dynamical analysis does not rely on spatially-resolved gas distribution and kinematics. Finally, new stellar velocity dispersions within subarcsecond apertures are obtained for the nuclei of a sample of 28 nearby galaxies. HST spectra obtained with the G750M grating are fitted using a library of single stellar population models and Gaussian emission lines, while constraining in most cases the stellar population content from an initial fit to HST G430L spectra. These measurements are useful for constraining the SBH mass as illustrated by the cases of the lenticular galaxies NGC 4435 and NGC 4459. These are characterized by similar ground-based stellar velocity dispersions but remarkably different SBH masses, where in particular NGC 4435 appears to host a significantly undermassive SBH compared to what expected from the relation between the SBH mass and stellar velocity dispersion. Jeans axisymmetric dynamical models are built to match the ground-based stellar kinematics obtained with integral-field spectroscopy assuming a SBH mass as predicted from the relation with the velocity dispersion and using high-resolution images as a base for constructing the stellar-mass model. Such reference models are used to make a prediction for the nuclear velocity dispersion. Whereas it agrees with the nuclear measurement for NGC 4459, for NGC 4435 the observed velocity dispersion is remarkably smaller than the predicted one, which further suggests that this galaxy hosts an undermassive SBH

A catalogue of nuclear stellar velocity dispersions of nearby galaxies from \u2009H\u3b1 STIS spectra to constrain supermassive black hole masses

We present new measurements for the nuclear stellar velocity dispersion \u3c3* within sub-arcsecond apertures for 28 nearby galaxies. Our data consist of Space Telescope Imaging Spectrograph (STIS) long-slit spectra obtained with the G750M grating centred on the H\u3b1 spectral range. We fit the spectra using a library of single stellar population models and Gaussian emission lines, while constraining in most cases the stellar-population content from an initial fit to G430L STIS spectra. We illustrate how these \u3c3* measurements can be useful for constraining the mass M\u2022 of supermassive black holes (SBHs) by concentrating on the cases of the lenticular galaxies NGC 4435 and NGC 4459. These are characterized by similar ground-based half-light radii stellar velocity dispersion \u3c3e values but remarkably different M\u2022 as obtained from modelling their central ionized-gas kinematics, where NGC 4435 appears to host a significantly undermassive SBH compared to what is expected from the M\u2022 - \u3c3e relation. For both galaxies, we build Jeans axisymmetric dynamical models to match the ground-based stellar kinematics obtained with Spectrographic Areal Unit for Research on Optical Nebulae integral-field spectrograph, including an SBH with M\u2022 value as predicted by the M\u2022 - \u3c3e relation and using high-resolution HST images taken with the Advanced Camera for Surveys to construct the stellar-mass model. By mimicking the HST observing conditions we use such reference models to make a prediction for the nuclear \u3c3* value. Whereas this was found to agree with our nuclear \u3c3* measurement for NGC 4459, for NGC 4435 the observed \u3c3* is remarkably smaller than the predicted one, which further suggests that this galaxy could host an undermassive SBH

Kinematic and stellar population properties of the counter-rotating components in the S0 galaxy NGC 1366

Context. Many disk galaxies host two extended stellar components that rotate in opposite directions. The analysis of the stellar populations of the counter-rotating components provides constraints on the environmental and internal processes that drive their formation. Aims. The S0 NGC 1366 in the Fornax cluster is known to host a stellar component that is kinematically decoupled from the main body of the galaxy. Here we successfully separated the two counter-rotating stellar components to independently measure the kinematics and properties of their stellar populations. Methods. We performed a spectroscopic decomposition of the spectrum obtained along the galaxy major axis and separated the relative contribution of the two counter-rotating stellar components and of the ionized-gas component. We measured the line-strength indices of the two counter-rotating stellar components and modeled each of them with single stellar population models that account for the \u3b1/Fe overabundance. Results. We found that the counter-rotating stellar component is younger, has nearly the same metallicity, and is less \u3b1/Fe enhanced than the corotating component. Unlike most of the counter-rotating galaxies, the ionized gas detected in NGC 1366 is neither associated with the counter-rotating stellar component nor with the main galaxy body. On the contrary, it has a disordered distribution and a disturbed kinematics with multiple velocity components observed along the minor axis of the galaxy. Conclusions. The different properties of the counter-rotating stellar components and the kinematic peculiarities of the ionized gas suggest that NGC 1366 is at an intermediate stage of the acquisition process, building the counter-rotating components with some gas clouds still falling onto the galaxy. \ua9 ESO 2017

Neuroactive Steroids in First-Episode Psychosis: A Role for Progesterone?

Neuroactive steroids may play a role in the pathophysiology of psychotic disorders, but few studies examined this issue. We compared serumlevels of cortisol, testosterone, dehydroepiandrosterone, and progesterone between a representative sample of firstepisode psychosis (FEP) patients and age- and gender-matched healthy subjects. Furthermore, we analyzed the associations between neuroactive steroids levels and the severity of psychotic symptom dimensions.Male patients had lower levels of progesterone than controls

Analysis of cavitation artifacts in Magnetic Resonance Imaging Thermometry during laser ablation monitoring

: Magnetic Resonance Thermometry Imaging (MRTI) holds great potential in laser ablation (LA) monitoring. It provides the real-time multidimensional visualization of the treatment effect inside the body, thus enabling accurate intraoperative prediction of the thermal damage induced. Despite its great potential., thermal maps obtained with MRTI may be affected by numerous artifacts. Among the sources of error producing artifacts in the images., the cavitation phenomena which could occur in the tissue during LA induces dipole-structured artifacts. In this work., an analysis of the cavitation artifacts occurring during LA in a gelatin phantom in terms of symmetry in space and symmetry of temperature values was performed. Results of 2 Wand 4 W laser power were compared finding higher symmetry for the 2 W case in terms of both dimensions of artifact-lobes and difference in temperature values extracted in specular pixels in the image. This preliminary investigation of artifact features may provide a step forward in the identification of the best strategy to correct and avoid artifact occurrence during thermal therapy monitoring. Clinical Relevance- This work presents an analysis of cavitation artifacts in MRTI from LA which must be corrected to avoid error in the prediction of thermal damage during LA monitoring

Efficacy of very low-calorie ketogenic diet with the Pronokal® method in obese women with polycystic ovary syndrome: a 16-week randomized controlled trial

Objective: The aim of this study isto assess the efficacy of a very low-calorie ketogenic diet (VLCKD) method vs a Mediterranean low-calorie diet (LCD) in obese polycystic ovary syndrome (PCOS) women of a reproductive age.Design: Randomized controlled open-label trial was performed in this study. The treatment period was 16 weeks; VLCKD for 8 weeks then LCD for 8 weeks, according to the Pronokal (R) method (experimental group; n = 15) vs Mediterranean LCD for 16 weeks (control group; n = 15). Ovulation monitoring was carried out at baseline and after 16 weeks, while a clinical exam, bioelectrical impedance analysis (BIA), anthropometry, and biochemical analyses were performed at baseline, at week 8, and at week 16.Results: BMI decreased significantly in both groups and to a major extent in the experimental group (-13.7% vs -5.1%, P = 0.0003). Significant differences between the experimental and the control groups were also observed in the reduction of waist circumference (-11.4% vs -2.9%), BIA-measured body fat (-24.0% vs -8.1%), and free testosterone (-30.4% vs -12.6%) after 16 weeks (P = 0.0008, P = 0.0176, and P = 0.0009, respectively). Homeostatic model assessment for insulin resistance significantly decreased only in the experimental group (P = 0.0238) but without significant differences with respect to the control group (-23% vs -13.2%, P &gt; 0.05). At baseline, 38.5% of participants in the experimental group and 14.3% of participants in the control group had ovulation, which increased to 84.6% (P = 0.031) and 35.7% (P &gt; 0.05) at the end of the study, respectively.Conclusion: In obese PCOS patients, 16 weeks of VLCKD protocol with the Pronokal (R) method was more effective than Mediterranean LCD in reducing total and visceral fat, and in ameliorating hyperandrogenism and ovulatory dysfunction.Significance statements: To the best of our knowledge, this is the first randomized controlled trial on the use of the VLCKD method in obese PCOS. It demonstrates the superiority of VLCKD with respect to Mediterranean LCD in reducing BMI with an almost selective reduction of fat mass and a unique effect of VLCKD in reducing visceral adiposity, insulin resistance, and in increasing SHBG with a consequent reduction of free testosterone. Interestingly, this study also demonstrates the superiority of the VLCKD protocol in improving ovulation, whose occurrence increased by 46.1% in the group treated by the VLCKD method against a rise of 21.4% in the group treated by Mediterranean LCD. This study extends the therapeutic approach possibilities in obese PCOS women

Shorter androgen receptor polyQ alleles protect against life-threatening COVID-19 disease in European males

Background: While SARS-CoV-2 similarly infects men and women, COVID-19 outcome is less favorable in men. Variability in COVID-19 severity may be explained by differences in the host genome. Methods: We compared poly-amino acids variability from WES data in severely affected COVID-19 patients versus SARS-CoV-2 PCR-positive oligo-asymptomatic subjects. Findings: Shorter polyQ alleles (≤22) in the androgen receptor (AR) conferred protection against severe outcome in COVID-19 in the first tested cohort (both males and females) of 638 Italian subjects. The association between long polyQ alleles (≥23) and severe clinical outcome (p = 0.024) was also validated in an independent cohort of Spanish men <60 years of age (p = 0.014). Testosterone was higher in subjects with AR long-polyQ, possibly indicating receptor resistance (p = 0.042 Mann-Whitney U test). Inappropriately low serum testosterone level among carriers of the long-polyQ alleles (p = 0.0004 Mann-Whitney U test) predicted the need for intensive care in COVID-19 infected men. In agreement with the known anti-inflammatory action of testosterone, patients with long-polyQ and age ≥60 years had increased levels of CRP (p = 0.018, not accounting for multiple testing). Interpretation: We identify the first genetic polymorphism that appears to predispose some men to develop more severe disease. Failure of the endocrine feedback to overcome AR signaling defects by increasing testosterone levels during the infection leads to the polyQ tract becoming dominant to serum testosterone levels for the clinical outcome. These results may contribute to designing reliable clinical and public health measures and provide a rationale to test testosterone as adjuvant therapy in men with COVID-19 expressing long AR polyQ repeats. Funding: MIUR project "Dipartimenti di Eccellenza 2018-2020" to Department of Medical Biotechnologies University of Siena, Italy (Italian D.L. n.18 March 17, 2020) and "Bando Ricerca COVID-19 Toscana" project to Azienda Ospedaliero-Universitaria Senese. Private donors for COVID-19 research and charity funds from Intesa San Paolo

Mass determination of supermassive black holes in nearby galaxies

This thesis focusses on the measure of the mass of supermassive black holes (SBH) lurking in the center of nearby quiescent galaxies. Increasing the demography of SBHs allows to study the correlations between their mass and the properties of their host to get insights about the joint evolution of SBHs and galaxies. New stringent limits on the SBH mass of 7 nearby galaxies are obtained by modeling the central width of the nebular emission lines measured over subarcsecond apertures with the Hubble Space Telescope (HST). The central stellar velocity dispersion of each galaxy is derived from new long-slit spectra from ground-based observations and the bulge effective radius is derived from a two-dimensional photometric decomposition of the i-band images from the Sloan Digital Sky Survey. The SBH-mass limits run parallel and above the relation between the SBH mass and the stellar velocity dispersion with no systematic trend depending on the galaxy distance or morphology. This gives further support to previous findings suggesting that the nuclear gravitational potential is remarkably well traced by the nebular-line width when the gas is centrally peaked. With this investigation, the number of galaxies with SBH-mass stringent limits obtained from nebular-line width increases to 114. These galaxies are further analyzed to more tightly constrain their SBH mass by taking into account the stellar mass contribution in the galaxy nucleus. To this aim the surface brightness distribution is measured from HST images and the mass-to-light ratio of an old and metal-rich stellar population is adopted for 100 nearby galaxies (D<103 Mpc) spanning a wide range of Hubble types (E-Sc) and central velocity dispersions (58-419 km/s). The shape of the profile of the emission lines and of the radial profile of emission-line flux are analysed to verify that nongravitational forces have a minor impact on the SBH-mass estimate. On average the stellar mass contribution is larger for galaxies with low effective velocity dispersion partly due to the presence of a nuclear stellar cluster or disk. Moreover, the stellar mass contribution is negligible in ellipticals and depends on the aperture size rather than on galaxy distance. These new SBH-mass limits run parallel to the relation between the SBH mass and the stellar velocity dispersion and they exceed the expected values by a median factor of 1.7. This is a striking result, since the dynamical analysis does not rely on spatially-resolved gas distribution and kinematics. Finally, new stellar velocity dispersions within subarcsecond apertures are obtained for the nuclei of a sample of 28 nearby galaxies. HST spectra obtained with the G750M grating are fitted using a library of single stellar population models and Gaussian emission lines, while constraining in most cases the stellar population content from an initial fit to HST G430L spectra. These measurements are useful for constraining the SBH mass as illustrated by the cases of the lenticular galaxies NGC 4435 and NGC 4459. These are characterized by similar ground-based stellar velocity dispersions but remarkably different SBH masses, where in particular NGC 4435 appears to host a significantly undermassive SBH compared to what expected from the relation between the SBH mass and stellar velocity dispersion. Jeans axisymmetric dynamical models are built to match the ground-based stellar kinematics obtained with integral-field spectroscopy assuming a SBH mass as predicted from the relation with the velocity dispersion and using high-resolution images as a base for constructing the stellar-mass model. Such reference models are used to make a prediction for the nuclear velocity dispersion. Whereas it agrees with the nuclear measurement for NGC 4459, for NGC 4435 the observed velocity dispersion is remarkably smaller than the predicted one, which further suggests that this galaxy hosts an undermassive SBH.Questo lavoro di tesi è dedicato alla misura della massa dei buchi neri supermassicci (SBH) che si celano al centro delle galassie quiescenti vicine. Aumentare il campione di SBH di massa nota permette di studiarne le relazioni con le altre proprietà delle galassie per poterne investigare l'evoluzione congiunta. Nuovi limiti stringenti sulla massa del SBH di 7 galassie sono stati fissati dalla misura della larghezza delle righe nebulari del gas ionizzato in spettri presi con l'Hubble Space Telescope (HST) entro aperture di dimensioni inferiori al secondo d'arco. La dispersione di velocità delle stelle è stata misurata con spettri a fenditura lunga presi da terra e il raggio efficace è stato ricavato dalla decomposizione fotometrica di immagini della Sloan Digital Sky Survey. Questi limiti di massa si dispongono parallelamente e al di sopra della relazione tra la massa del SBH e la dispersione di velocità delle stelle e non dipendono dalla morfologia o dalla distanza delle galassie. Questo suggerisce che il potenziale gravitazionale nei nuclei galattici è ben tracciato dalla larghezza delle righe di emissione se il gas si concentra verso il centro. Il numero delle galassie con un limite sulla massa del SBH ricavato dalla larghezza delle righe di emissione sale così a 114 oggetti. Queste galassie sono state ulteriormente analizzate includendo nel modello dinamico il contributo della massa stellare per ottenere limiti ancora più stringenti sulla massa del SBH. A tale scopo la brillanza superficiale misurata da immagini HST e il rapporto massa-luminosità tipico di una popolazione stellare vecchia e ricca in metalli sono stati usati per 100 galassie vicine (D<100 Mpc) e con un'ampia varietà di morfologie (E-Sc) e dispersioni di velocità (58-419 km/s). La forma dei profili delle righe di emissione e dell'andamento radiale del loro flusso sono stati studiati per escludere che le forze non gravitazionali giocassero un ruolo rilevante nella stima della massa del SBH. Il contributo stellare è maggiore per galassie con bassa dispersione di velocità, anche per la presenza di un ammasso/disco stellare nucleare, e trascurabile per le ellittiche. Esso dipende dalle dimensioni dell'apertura ma non dalla distanza della galassia. I nuovi limiti di massa si dispongono parallelamente alla relazione tra la massa del SBH e la dispersione di velocità ed eccedono il valore predetto dalla medesima solo di un fattore 1.7. Questo è un risultato notevole visto che il modello dinamico si basa su una distribuzione e cinematica del gas non spazialmente risolte. Infine, sono state ottenute nuove misure di dispersione di velocità stellare nel nucleo di 28 galassie. Gli spettri HST ottenuti con il reticolo G750M sono stati interpolati con modelli di popolazioni stellari e varie righe di emissione gaussiane, vincolando la popolazione stellare nel nucleo delle galassie grazie a spettri presi con il reticolo G430L. Queste misure permettono di porre dei forti vincoli sulla massa del SBH come mostrano i casi di NGC 4435 e NGC 4459. Si tratta di due galassie lenticolari caratterizzate da valori simili di dispersione di velocità stellare ma con masse di SBH molto diverse. In particolare, quella di NGC 4435 è molto più bassa rispetto a quanto predetto dalla relazione tra la massa del SBH e la dispersione di velocità stellare. Grazie a modelli dinamici stellari assisimmetrici è stata riprodotta la cinematica ottenuta da spettroscopia a campo integrale usando immagini HST e adottando come massa del SBH quella predetta dalla relazione con la dispersione di velocità. Questi modelli permettono di predire il valore centrale di dispersione di velocità e di confrontarlo con il valore osservato. Mentre per NGC 4459 il valore teorico e quello osservato sono in accordo, il valore misurato per NGC 4435 è molto più basso rispetto che a quello del modello dinamico indicando che la galassia ospita un SBH meno massiccio del normale