[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-128684-en":3,"doc-seo-128684-105":31,"detail-sidebar-cat-0-en-105":92},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":20,"is_deleted":4,"is_public":21,"is_downloadable":21,"audit_status":21,"page_count":22,"language":23,"language_code":24,"site_id":25,"html_lang":24,"table_of_contents":26,"faqs":27,"seo_title":28,"seo_description":14,"update_tm":29,"read_time":30},128684,962084928432,"Emma Wilson","https://ap-avatar.wpscdn.com/davatar_155a257f0dc6eb9ab79c44ca47cae57d",8,"Research & Report","CASBI: Chemical Abundance Simulation Based Inference - Master Degree in Physics of Data","Galaxies assemble hierarchically and the stellar “remnants” of accretion events preserve information about their assembly history, yet extracting the properties of the accreted systems remains difficult. This thesis introduces CASBI (Chemical Abundance Simulation Based Inference), a simulation-based inference pipeline for Galactic Archaeology. It exploits the mass-metallicity relation and multidimensional chemical abundances of halo stars to infer key merger-building-block properties, demonstrating accurate and precise posteriors for phase-mixed dwarf galaxy stellar masses from abundance distributions in the iron–oxygen plane.","Universit`a degli Studi di Padova Physics and Astronomy Department ”Galileo Galilei”  \nMaster Degree in Physics of Data  \nCASBI: Chemical Abundance Simulation  \nBased Inference  \nSupervisor:  \nProf. Antonino Milone Co-Supervisor:  \nDr. Tobias Buck Co-Supervisor:  \nDr. Giuliano Iorio  \nCandidate:  \nGiuseppe Viterbo  \nAcademic Year 2023/2024  \n“Home is behind, the world ahead And there are many paths to tread Through shadow, to the edge of night Until the stars are all alight.”  \n—J.R.R. Tolkien, The Lord of the Rings  \n2  \nContents  \n1 Abstract 5  \n2 Introduction 7  \n2.1 Morphology of the Milky Way: disk and halo ...................... 7  \n2.2 Galactic Archaeology .................................... 8  \n3 Previous work 15  \n3.1 The reconstruction of the Assembly history of the Milky Way ............. 15  \n3.2 Simulation Based Inference ................................ 18  \n4 CASBI: Chemical Abundance Simulation Based Inference 23  \n4.1 Simulator and Preprocessing ............................... 23  \n4.2 Realistic halo and one step Inference ........................... 27  \n5 Results 31  \n5.1 Calibration ......................................... 31  \n5.2 Test set ........................................... 35  \n5.3 A first step toward inference on observations ...................... 38  \n5.4 Subhalo level accuracy and uncertainty .......................... 39  \n5.5 Galactic halo reconstruction ................................ 41  \n6 Conclusion 43  \nA Early Test 45  \nA.1 Free Form Flow as a surrogate simulator ......................... 45  \nA.2 Two step Inference ..................................... 48  \nB Accuracy 51  \nC Coverage 55  \nD TARP 59  \nBibliography 63  \nChapter 1  \nAbstract  \nGalaxies evolve hierarchically through merging with lower-mass systems, and the “remnants” of these events are a key indicator of their past assembly history. These “remnants” are star systems that, during their lifetime, were captured by the gravitational potential of a larger galaxy, and ended up in the star halo of their host. Accurately measuring the properties of the accreted galaxies and hence unraveling the Milky Way (MW) formation history is a challenging task. In this work I present CASBI (Chemical Abundance Simulation Based Inferece), a novel inference pipeline for Galactic Archaeology based on Simulation Based Inference methods. CASBI leverages on the fact that thereis a well defined mass-metallicity relation for galaxies. CASBI performs inference of key galaxy properties based on multidimensional chemical abundances of stars in the stellar halo. Hence, I recast the task of unraveling the merger history of the MW into a SBI problem to recover the properties ([e.g. total](e.g. total) stellar mass and infall time) of the halo building blocks using the multidimensional chemical abundances of stars in the stellar halo as observable. I highlight CASBI’s potential by inferring posteriors for the stellar masses of completely phase mixed dwarf galaxies solely from the 2d-distributions of stellar abundance in the iron vs. oxygen plane and find accurate and precise inference results.  \n6 1. Abstract  \nChapter 2  \nIntroduction  \n2.1 Morphology of the Milky Way: disk and halo  \nThis section in inspired by [BT08] . The majority of stars in the Milky Way lies in a flattened, roughly axisymmetric structure known as the Galactic disk. The midplane of this disk is called the Galactic plane. In the direction z perpendicular to the Galactic plane the density of stars follows an exponential,  \nρ (R, z) = ρ(R,0)e−|z|/zd (R) , (2 . 1)  \nwhere zd (R) is the scale height at radius R. A good representation of the vertical structure of the disk is obtained by superimposing two populations described by different scale heights: the thin disk with zd (R) ≃ 300 pc and the thick disk with zd (R) ≃ 1 kpc. Age-wise the stars in the thin disk are younger. The thick disk is characterized by stars with lower metallicity and, at a given metallicity, they have higher abu","cbCaifgMPoDZiBRm","https://ap.wps.com/l/cbCaifgMPoDZiBRm","pdf",11846961,3,1,75,"English","en",105,"# Abstract\n# Introduction\n## Morphology of the Milky Way: disk and halo\n## Galactic Archaeology\n# Previous work\n## The reconstruction of the Assembly history of the Milky Way\n## Simulation Based Inference\n# CASBI: Chemical Abundance Simulation Based Inference\n## Simulator and Preprocessing\n## Realistic halo and one step Inference\n# Results\n## Calibration\n## Test set\n## A first step toward inference on observations\n## Subhalo level accuracy and uncertainty\n## Galactic halo reconstruction\n# Conclusion\n# Early Test\n## Free Form Flow as a surrogate simulator\n## Two step Inference\n# Accuracy\n# Coverage\n# TARP\n# Bibliography","[{\"question\":\"What does CASBI aim to infer in Galactic Archaeology?\",\"answer\":\"CASBI infers key properties of Milky Way halo building blocks, such as total stellar mass and infall time, using multidimensional chemical abundances of halo stars as observables.\"},{\"question\":\"Which observational inputs does CASBI rely on?\",\"answer\":\"CASBI leverages multidimensional chemical abundance distributions of stars in the stellar halo, highlighting results using 2D distributions in the iron versus oxygen plane.\"},{\"question\":\"Why are the “remnants” of accretion events important for the Milky Way assembly history?\",\"answer\":\"Accretion remnants are star systems captured by a larger galaxy’s gravitational potential and deposited in the stellar halo, preserving measurable signals of past merger events.\"}]","CASBI: Chemical Abundance Simulation Based Inference - Master Degree in Physics of Data | PDF",1786002634,189,{"code":4,"msg":32,"data":33},"ok",{"site_id":25,"language":24,"slug":34,"title":13,"keywords":35,"description":14,"schema_data":36,"social_meta":87,"head_meta":89,"extra_data":91,"updated_unix":29},"casbi-chemical-abundance-simulation-based-inference-master-degree-in-physics-of-data","",{"@graph":37,"@context":86},[38,54,69],{"@type":39,"itemListElement":40},"BreadcrumbList",[41,45,49,51],{"item":42,"name":43,"@type":44,"position":21},"https://docshare.wps.com","Home","ListItem",{"item":46,"name":47,"@type":44,"position":48},"https://docshare.wps.com/document/","Document",2,{"item":50,"name":12,"@type":44,"position":20},"https://docshare.wps.com/document/research-report/",{"item":52,"name":13,"@type":44,"position":53},"https://docshare.wps.com/document/casbi-chemical-abundance-simulation-based-inference-master-degree-in-physics-of-data/128684/",4,{"url":52,"name":13,"@type":55,"author":56,"headline":13,"publisher":58,"fileFormat":61,"inLanguage":24,"description":14,"dateModified":62,"datePublished":63,"encodingFormat":61,"isAccessibleForFree":64,"interactionStatistic":65},"DigitalDocument",{"name":9,"@type":57},"Person",{"url":42,"name":59,"@type":60},"DocShare","Organization","application/pdf","2026-08-25","2026-08-06",true,{"@type":66,"interactionType":67,"userInteractionCount":20},"InteractionCounter",{"@type":68},"ViewAction",{"@type":70,"mainEntity":71},"FAQPage",[72,78,82],{"name":73,"@type":74,"acceptedAnswer":75},"What does CASBI aim to infer in Galactic Archaeology?","Question",{"text":76,"@type":77},"CASBI infers key properties of Milky Way halo building blocks, such as total stellar mass and infall time, using multidimensional chemical abundances of halo stars as observables.","Answer",{"name":79,"@type":74,"acceptedAnswer":80},"Which observational inputs does CASBI rely on?",{"text":81,"@type":77},"CASBI leverages multidimensional chemical abundance distributions of stars in the stellar halo, highlighting results using 2D distributions in the iron versus oxygen plane.",{"name":83,"@type":74,"acceptedAnswer":84},"Why are the “remnants” of accretion events important for the Milky Way assembly history?",{"text":85,"@type":77},"Accretion remnants are star systems captured by a larger galaxy’s gravitational potential and deposited in the stellar halo, preserving measurable signals of past merger events.","https://schema.org",{"og:url":52,"og:type":88,"og:title":13,"og:site_name":59,"og:description":14},"article",{"robots":90,"canonical":52},"index,follow",{"doc_id":7,"site_id":25},{"code":4,"msg":5,"data":93},[94,98,102,106,111,116,121,124,129,132,136],{"id":21,"doc_module":4,"doc_module_name":47,"category_name":95,"show_sort_weight":96,"slug":97},"Story & Novel",90,"story-novel",{"id":48,"doc_module":4,"doc_module_name":47,"category_name":99,"show_sort_weight":100,"slug":101},"Literature",80,"literature",{"id":53,"doc_module":4,"doc_module_name":47,"category_name":103,"show_sort_weight":104,"slug":105},"Exam",70,"exam",{"id":107,"doc_module":4,"doc_module_name":47,"category_name":108,"show_sort_weight":109,"slug":110},5,"Comic",60,"comic",{"id":112,"doc_module":4,"doc_module_name":47,"category_name":113,"show_sort_weight":114,"slug":115},6,"Technology",50,"technology",{"id":117,"doc_module":4,"doc_module_name":47,"category_name":118,"show_sort_weight":119,"slug":120},7,"Healthcare",40,"healthcare",{"id":11,"doc_module":4,"doc_module_name":47,"category_name":12,"show_sort_weight":122,"slug":123},30,"research-report",{"id":125,"doc_module":4,"doc_module_name":47,"category_name":126,"show_sort_weight":127,"slug":128},9,"Religion & Spirituality",20,"religion-spirituality",{"id":127,"doc_module":4,"doc_module_name":47,"category_name":130,"show_sort_weight":127,"slug":131},"World Cup","world-cup",{"id":133,"doc_module":4,"doc_module_name":47,"category_name":134,"show_sort_weight":133,"slug":135},10,"Lifestyle","lifestyle",{"id":137,"doc_module":4,"doc_module_name":47,"category_name":138,"show_sort_weight":107,"slug":139},19,"General","general"]