eprintid: 37239
rev_number: 11
eprint_status: archive
userid: 9256
dir: disk0/00/03/72/39
datestamp: 2025-09-09 09:56:46
lastmod: 2025-09-09 09:56:57
status_changed: 2025-09-09 09:56:46
type: doctoralThesis
metadata_visibility: show
creators_name: Zhang, Xiangyu
title: On the Variation of Interstellar Dust Extinction
subjects: ddc-520
divisions: i-130001
adv_faculty: af-13
abstract: Dust obscures astronomical observations and plays a important role in the evolution of galaxies. Mapping dust in three dimensions not only allows accurate correction of observations but also constrains the evolution of the interstellar medium (ISM). Extinction is the central observable to trace the density and properties of dust, and is widely employed in dust mapping. Most existing dust maps assume a universal extinction curve, treating the properties of dust as uniform. This thesis
introduces variations in the slope of extinction curves, parameterized by R(V). I construct a data-driven forward model that predicts low-resolution spectra as a function of stellar parameters (effective temperature, surface gravity, and metallicity), parallax, and extinction properties. This model is applied to all 220 million Gaia XP spectra, yielding precise extinction curves for 130 million stars in the Milky Way, LMC, and SMC. From these, I construct the first 3D all-sky map of extinction curve variations. Unexpectedly, I find extinction curves steepen, rather than flatten, with increasing dust density in translucent dust clouds. I propose a theoretical explanation, attributing the steepening to the growth of polycyclic aromatic hydrocarbons (PAHs). The results also provide implications for future observations in the era of the JWST.
date: 2025
id_scheme: DOI
id_number: 10.11588/heidok.00037239
own_urn: urn:nbn:de:bsz:16-heidok-372390
date_accepted: 2025-07-03
advisor: HASH(0x5591101245a0)
language: eng
bibsort: ZHANGXIANGONTHEVARIA20250903
full_text_status: public
place_of_pub: Heidelberg
citation:   Zhang, Xiangyu  (2025) On the Variation of Interstellar Dust Extinction.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/37239/1/thesis_XiangyuZhang-1.pdf