An Inner Disk in the Large Gap of the Transition Disk SR 24S

We report new Atacama Large Millimeter/sub-millimeter Array (ALMA) Band 3 observations at 2.75 mm of the TD around SR 24S with an angular resolution of $\sim$0.11''$\times$ 0.09'' and a peak signal-to-noise ratio of $\sim24$. We detect an inner disk and a mostly symmetric ring-like structure that peaks at $\sim$0.32'', that is $\sim$37 au at a distance of $\sim$114.4 pc. The full width at half maximum of this ring is $\sim$28 au. We analyze the observed structures by fitting the dust continuum visibilities using different models for the intensity profile, and compare with previous ALMA observations of the same disk at 0.45 mm and 1.30 mm. We qualitatively compare the results of these fits with theoretical predictions of different scenarios for the formation of a cavity or large gap. The comparison of the dust continuum structure between different ALMA bands indicates that photoevaporation and dead zone can be excluded as leading mechanisms for the cavity formation in SR 24S disk, leaving the planet scenario (single or multiple planets) as the most plausible mechanism. We compared the 2.75 mm emission with published (sub-)centimeter data and find that the inner disk is likely tracing dust thermal emission. This implies that any companion in the system should allow dust to move inwards throughout the gap and replenish the inner disk. In the case of one single planet, this puts strong constraints on the mass of the potential planet inside the cavity and the disk viscosity of about $\lesssim$5 $M_{\rm{Jup}}$ and $\alpha\sim10^{-4}-10^{-3}$, respectively.Comment: Accepted to Ap

Revealing signatures of planets migrating in protoplanetary discs with ALMA multi-wavelength observations

Recent observations show that rings and gaps are ubiquitous in protoplanetary discs. These features are often interpreted as being due to the presence of planets; however, the effect of planetary migration on the observed morphology has not been investigated hitherto. In this work we investigate whether multiwavelength mm/submm observations can detect signatures of planet migration, using 2D dusty hydrodynamic simulations to model the structures generated by migrating planets and synthesising ALMA continuum observations at 0.85 and 3 mm. We identify three possible morphologies for a migrating planet: a slowly migrating planet is associated with a single ring outside the planet's orbit, a rapidly migrating planet is associated with a single ring inside the planet's orbit while a planet migrating at intermediate speed generates one ring on each side of the planet's orbit. We argue that multiwavelength data can distinguish multiple rings produced by a migrating planet from other scenarios for creating multiple rings, such as multiple planets or discs with low viscosity. The signature of migration is that the outer ring has a lower spectral index, due to larger dust grains being trapped there. Of the recent ALMA observations revealing protoplanetary discs with multiple rings and gaps, we suggest that Elias 24 is the best candidate for a planet migrating in the intermediate speed regime.Comment: Accepted for publication in MNRA

Observing planet formation

Planets are thought to form in the circumstellar disks orbiting young stars in formation. According to the core-accretion model, a candidate scenario for Earth-like planets, the interstellar sub-$\mu$m-sized dust particles grow thanks to collisions to mm/cm size and then form km-sized planetesimals via dynamical encounters. Eventually, the rocky planetary cores accrete gas and, depending on the total gas mass attained, a terrestrial planet or a gas giant forms. Modern sub-mm/mm/radio interferometers such as ALMA and VLA detect the thermal emission of dust grains and provide us with an unprecedented sharp view of protoplanetary disks at the spatial scales where planet formation occurs. In recent years, evidence of grain growth in disks has been obtained by extensive sub-mm/mm photometric studies, but so far they only provided disk-averaged estimates of the dust properties. Moreover, the derivation of dust properties from the observed spectral index was done under reasonable - but simplifying - assumptions rather than with a proper modeling of the disk emission. The thesis presents an analysis method that enables - for the first time - the disk structure and the dust properties to be constrained simultaneously by fitting multi-wavelength observations with a self-consistent physical model. The thesis presents also an accelerated version of the computer code that uses modern graphics cards and provides the computational breakthrough needed to exploit the new wealth of information now available. Applying the multi-wavelength analysis to observations of three disks in the Taurus and Ophiuchus star-forming regions, a key result is a radial gradient in the grain-size distribution, with large grains of up to $1\,\mathrm{cm}$ size confined to the inner disk and smaller grains of size $\ll 1\,\mathrm{mm}$ populating the whole disk. Similar results hold for another disk, HD~163296, where in addition the grain size radial profile supports the scenario of enhanced grain growth at the snowline location of the second most abundant volatile in disks, CO. The tool developed in the thesis is also designed to accelerate the analysis of high-resolution observations for demographic studies. By applying the analysis tool to an ALMA disk survey in the Lupus star-forming region, the physical structure of more than 20 disks is obtained, in particular the disks's size and dust mass among other physical parameters. To date, this is the largest sample of disks of the same star-forming region fitted homogeneously with a self-consistent model. Remarkably, the sample is complete in the mass range of 0.7$M_\odot$ to one $M_\odot$. The results are compatible with previous studies based on simpler analyses but also highlight a consistent difference in the disks's luminosity-size correlation between the older ($\sim3\,\mathrm{Myr}$) Lupus and the younger ($\sim1-2\,\mathrm{Myr}$ old) Taurus-Auriga region. The application of the analysis developed in this thesis to multi-wavelength observations of large samples of disks with ALMA will allow us to spatially resolve the early growth of solids in numerous protoplanetary disks, and therefore to provide measurements that will be crucial to inform, test, and refine theoretical models of planet formation.Die Entstehung von Planeten und Sternen ist eng miteinander verknüpft. Der Stern bildet sich im Zentrum einer rotierenden Materiescheibe. Die Planeten entstehen wiederum in der zirkumstellaren Scheibe. Das Kern-Akkretions-Modell beschreibt die allmähliche Entstehung von Planeten in folgender Weise: Interstellare Staubteilchen mit Größen im Submillimeterbereich wachsen durch Kollisionen auf eine Größe von Millimetern bzw. Zentimetern heran. Sie stoßen wieder zusammen und bilden im weiteren kilometergroße Planetesimale. Schließlich akkretieren die felsartigen Planetenkerne Gas und bilden dann, je nach akkretierter Gasmasse, einen erdähnlichen Planeten oder einen Gasriesen. Moderne Interferometer mit Wellenlängen von Submillimeter über Millimeter bis in den Radiobereich wie das Atacama Large Millimetre Array (ALMA) oder das Very Large Array (VLA) detektieren die thermische Emission von Staubkörnern und erlauben eine nie dagewesene Auflösung von protoplanetaren Scheiben bis auf Längenskalen, auf denen sich die Planetenbildung ereignet. In den letzten Jahren haben ausführliche photometrische Studien im Submilli\-meter- und Millimeter-Wellenlängenbereich Hinweise auf Kornwachstum in Scheiben geliefert, allerdings nur gemittelt über die gesamte Scheibe. Zudem wurde die Ableitung der Staubeigenschaften vom beobachteten spektralen Index unter plausiblen, aber stark vereinfachenden, Annahmen durchgeführt. In Rahmen dieser Dissertation wurde eine Analysemethode entwickelt, die es zum ersten Mal erlaubt, gleichzeitig die Struktur der Scheibe und die Eigenschaften des Staubs durch eine Anpassung eines selbstkonsistenten, physikalischen Modells an die Beobachtungen in mehreren Wellenlängenbereichen zu ermitteln. Außerdem wird eine neue Version eines Computercodes präsentiert, die durch die Verwendung moderner Grafikkarten viel schneller ist. Das stellt einen Durchbruch in der Rechenleistung dar, der erforderlich ist, um die riesigen, aktuell verfügbaren Datenmengen zu bewältigen. In der Anwendung der Multiwellenlängen-Analyse auf Beobachtungen dreier Scheiben in Sternentstehungsregionen der Sternbilder Stier (Taurus) und Schlangenträger (Ophiuchus) zeigt sich ein radialer Gradient in der Verteilung der Korngröße. Dabei sind große Körner von bis zu einem Zentimeter Größe auf die innere Scheibe beschränkt. Dagegen sind Körner, die viel kleiner sind als ein Millimeter, in der gesamten Scheibe zu finden. Ähnliche Ergebnisse betreffen eine andere analysierte Scheibe in HD 163296. Dort gilt zusätzlich, dass das Radialprofil der Korngröße ein Szenario unterstützt, in dem verstärktes Kornwachstum genau dort auftritt, wo der zweithäufigste, flüchtige Stoff in Scheiben, nämlich Kohlenmonoxid (CO), gefriert. Das Computerprogramm, das im Rahmen der Dissertation entwickelt wurde, dient auch zur Beschleunigung der zwölf Analysen von hochaufgelösten Beobachtungen in Studien ganzer Populationen von Sternen mit protoplanetaren Scheiben. Konkret wurde das Programm auf mit ALMA beobachtete Scheiben in einer Sternentstehungsregion im Sternbild Wolf (Lupus) angewendet. Daraus wurde die physikalische Struktur von mehr als zwanzig Scheiben abgeleitet. Neben anderen physikalischen Parametern wurden ihre Größen und Staubmassen bestimmt. Bis jetzt ist dies die größte Anzahl von Scheiben aus der gleichen Sternentstehungsregion, die je einheitlich mit einem selbstkonsistenten Modell betrachtet wurde. Es ist bemerkenswert, dass dieser Satz an Scheiben im Massenbereich von 0,7 bis 1 Sonnenmassen und im Strahlungsfluss --- integriert über den Submillimeterbereich --- vollständig ist. Die Ergebnisse sind im Einklang mit vorherigen Arbeiten, die auf einfacheren Analysen beruhten. Allerdings zeigen sie auch einen klaren Unterschied in der Korrelation zwischen der Leuchtkraft und der Größe der Scheiben aus der älteren, ca. drei Millionen Jahre alten Region im Sternbild Wolf und der jüngeren, ca. 1-2 Millionen Jahre alten Population aus dem Grenzgebiet zwischen Stier und Fuhrmann (Auriga). Die Anwendung der Analyse dieser Dissertation auf Multiwellenlängen\--Be\-ob\-achtungen einer großen Zahl von Scheiben, die mit ALMA beobachtet wurden, wird es erlauben, das Wachstum fester Körper im frühen Stadium vieler protoplanetarer Scheiben räumlich aufzulösen. Diese Messungen werden von zentraler Bedeutung sein, um theoretische Modelle der Planetenentstehung aufzustellen, zu testen und sie weiter zu verbessern

IMMUNOLOGICAL SIGNATURE IN NAÏVE AND SUNITINIB-TREATED SOFT TISSUE SARCOMA PATIENTS: ROLE OF MYELOID CELLS

Although designed to directly target cancer cells and tumor associated-vasculature, anti-angiogenic drugs (e.g. sunitinib), have been described to influence tumor-host interactions. Sunitinib is currently in use at our Institute for the treatment of progressive, advanced soft tissue sarcomas (STS) of different histology. However, the systemic and local immune responses and their modulation by anti-angiogenic therapies are unknown in these neoplasms, namely solitary fibrous tumors (SFTs), clear cell sarcoma (CCS) and alveolar soft part sarcoma (ASPS). This thesis aims to shed light on the immunological status of these STS patients and to address the question to which extent sunitinib induces immune modulation in these patients. Thus, my research focused on the characterization of both tumor-infiltrating and circulating immune cells of STS patients. Fine analysis of the immune contexture at the tumor site in na\uefve and in sunitinib-treated tumors revealed that myeloid cells, namely tumor-associated macrophages, represent a key component of the tumor microenvironment and that their reprogramming is part of the response to sunitinib treatment. Immune monitoring of circulating cells in these STS patients indicated that circulating myeloid suppressor cells were associated to disease progression and were the major player in mediating the immune-suppressive status in na\uefve and in sunitinib-treated SFT patients. Moreover, evidence have been provided that, in sunitinib-treated SFT patients, myeloid suppressor cells may be part of acquired resistance, thus supporting the notion that myeloid cells are the most relevant hurdle in the efficacy of anti-angiogenic treatments. Collectively the results of this thesis shed light on an unappreciated phenomenon of immune dysfunction in STS patients and indicate that in SFTs sunitinib transiently relieves systemic immunosuppression and reprograms the immune microenvironment. Moreover, for the first time, an antigen-specific T cell response has been evidenced in CCS, and, this tumor-specific response has occurred in association to sunitinib-induced immune modulation. Overall, this thesis poses the rationale for the development of immune-based clinical approaches aimed at achieving a more durable disease control in these cancer patients, for which effective medical therapies are still needed

A super-resolution analysis of the DSHARP survey: Substructure is common in the inner 30 au

The DSHARP survey evidenced the ubiquity of substructure in the mm dust distribution of large, bright protoplanetary discs. Intriguingly, these datasets have yet higher resolution information that is not recovered in a CLEAN image. We first show that the intrinsic performance of the CLEAN algorithm is resolution-limited. Then analyzing all 20 DSHARP sources using the 1D, super-resolution code Frankenstein (frank), we accurately fit the 1D visibilities to a mean factor of 4.3 longer baseline than the Fourier transform of the CLEAN images and a factor of 3.0 longer baseline than the transform of the CLEAN component models. This yields a higher resolution brightness profile for each source, identifying new substructure interior to 30 au in multiple discs; resolving known gaps to be deeper, wider, and more structured; and known rings to be narrower and brighter. Across the survey, high contrast gaps are an average 14% wider and 44% deeper in the frank profiles relative to CLEAN, and high contrast rings are an average 26% narrower. Categorizing the frank brightness profiles into trends, we find that the relative scarcity of features interior to 30 au in the survey's CLEAN images is an artifact of resolving power, rather than an intrinsic rarity of inner disc (or compact disc) substructure. Finally the rings in the frank profiles are narrower than the previously inferred deconvolved widths, indicating smaller alpha / St ratios in the local gas disc

Detecting the halo heating from AGN feedback with ALMA

The Sunyaev-Zel'dovich (SZ) effect can potentially be used to investigate the heating of the circumgalactic medium and subsequent suppression of cold gas accretion onto the host galaxy caused by quasar feedback. We use a deep ALMA observation of HE0515-4414 in band 4, the most luminous quasar known at the peak of cosmic star formation (z=1.7), to search for the SZ signal tracing the heating of the galaxy's halo. ALMA's sensitivity to a broad range of spatial scales enables us to disentangle emitting compact sources from the negative, extended SZ signal. We obtain a marginal S-Z detection (~3.3$\sigma$) on scales of about 300 kpc (30-40 arcsec), at the 0.2 mJy level, 0.5 mJy after applying a correction factor for primary beam attenuation and flux that is resolved out by the array. We show that our result is consistent with a simulated ALMA observation of a similar quasar in the FABLE cosmological simulations. We emphasise that detecting an SZ signal is more easily achieved in the visibility plane than in the (inferred) images. We also confirm a marginal detection (3.2$\sigma$) of a potential SZ dip on smaller scales (<100 kpc) already claimed by other authors, possibly highlighting the complex structure of the halo heating. Finally, we use SZ maps from the FABLE cosmological simulations, convolved with ALMA simulations, to illustrate that band 3 observations are much more effective in detecting the SZ signal with higher significance, and discuss the optimal observing strategy.Comment: 13 pages, 16 figures. Accepted for publication by MNRA

An Inner Disk in the Large Gap of the Transition Disk SR 24S

We report new Atacama Large Millimeter/sub-millimeter Array (ALMA) Band 3 observations at 2.75 mm of the TD around SR 24S with an angular resolution of $\sim$0.11''$\times$ 0.09'' and a peak signal-to-noise ratio of $\sim24$. We detect an inner disk and a mostly symmetric ring-like structure that peaks at $\sim$0.32'', that is $\sim$37 au at a distance of $\sim$114.4 pc. The full width at half maximum of this ring is $\sim$28 au. We analyze the observed structures by fitting the dust continuum visibilities using different models for the intensity profile, and compare with previous ALMA observations of the same disk at 0.45 mm and 1.30 mm. We qualitatively compare the results of these fits with theoretical predictions of different scenarios for the formation of a cavity or large gap. The comparison of the dust continuum structure between different ALMA bands indicates that photoevaporation and dead zone can be excluded as leading mechanisms for the cavity formation in SR 24S disk, leaving the planet scenario (single or multiple planets) as the most plausible mechanism. We compared the 2.75 mm emission with published (sub-)centimeter data and find that the inner disk is likely tracing dust thermal emission. This implies that any companion in the system should allow dust to move inwards throughout the gap and replenish the inner disk. In the case of one single planet, this puts strong constraints on the mass of the potential planet inside the cavity and the disk viscosity of about $\lesssim$5 $M_{\rm{Jup}}$ and $\alpha\sim10^{-4}-10^{-3}$, respectively

Estimating the fossil disc mass during supermassive black hole mergers: The importance of torque implementation

In this paper, we revisit the issue of estimating the "fossil" disc mass in the circumprimary disc, during the merger of a supermassive black hole binary. As the binary orbital decay speeds up due to the emission of gravitational waves, the gas in the circumprimary disc might be forced to accrete rapidly and could in principle provide a significant electromagnetic counterpart to the gravitational wave emission. Since the luminosity of such flare is proportional to the gaseous mass in the circumprimary disc, estimating such mass accurately is important. Previous investigations of this issue have produced contradictory results, with some authors estimating super-Eddington flares and large disc mass, while others suggesting that the "fossil" disc mass is very low, even less than a Jupiter mass. Here, we perform simple 1D calculations to show that such very low estimates of the disc mass are an artifact of the specific implementation of the tidal torque in 1D models. In particular, for moderate mass ratios of the binary, the usual formula for the torque used in 1D models significantly overestimates the width of the gap induced by the secondary and this artificially leads to a very small leftover circumprimary disc. Using a modified torque, calibrated to reproduce the correct gap width as estimated by 3D models, leads to fossil disc masses of the order of one solar mass. The rapid accretion of the whole circumprimary disc would produce peak luminosities of the order of 1-20 times the Eddington luminosity. Even if a significant fraction of the gas escapes accretion by flowing out the secondary orbit during the merger (an effect not included in our calculations), we would still predict close to Eddington luminosities that might be easily detected