arXiv subjects

William Bowman

Publications and source records attributed to William Bowman.

5 recordsLinked to original sources

arXiv2026

Verifying Provenance of Digital Media: Why the C2PA Specifications Fall Short

The rapid rise of generative AI has made it easy to create convincing fake media at scale. In response, an industrial coalition has developed the Coalition for Content Provenance and Authenticity (C2PA), a system intended to provide verifiable provenance for digital content. Our research team conducted the first comprehensive, independent security analysis of C2PA. Our study includes the first formal-methods analysis of C2PA's core protocols. We find that the current C2PA specifications fail to achieve their claimed security goals. Furthermore, they also fail to achieve key additional goals, which all such provenance systems require for trustworthy deployment. As a result, C2PA may mislead users, platforms, and policymakers if relied upon prematurely. C2PA is a promising idea, but it should not yet be relied upon for high-stakes uses such as financial disclosures, journalism, or legal evidence.

cs.CR↗

arXiv2025

Quantitative Morphology of Galactic Cirrus in Deep Optical Imaging

Imaging of optical Galactic cirrus, the spatially resolved form of diffuse Galactic light, provides important insights into the properties of the diffuse interstellar medium (ISM) in the Milky Way. While previous investigations have focused mainly on the intensity characteristics of optical cirrus, their morphological properties remain largely unexplored. In this study, we employ several complementary statistical approaches -- local intensity statistics, angular power spectrum / $\Delta$-variance analysis, and wavelet scattering transform analysis -- to characterize the morphology of cirrus in deep optical imaging data. We place our investigation of optical cirrus into a multi-wavelength context by comparing the morphology of cirrus seen with the Dragonfly Telephoto Array to that seen with space-based facilities working at longer wavelengths (Herschel 250 $\mu m$, WISE 12 $\mu m$, and Planck radiance), as well as with structures seen in the DHIGLS HI column density map. Our statistical methods quantify the similarities and the differences of cirrus morphology in all these datasets. The morphology of cirrus at visible wavelengths resembles that of far-infrared cirrus more closely than that of mid-infrared cirrus; on small scales, anisotropies in the cosmic infrared background and systematics may lead to differences. Across all dust tracers, cirrus morphology can be well described by a power spectrum with a common power-law index $\gamma\sim-2.9$. We demonstrate quantitatively that optical cirrus exhibits filamentary, coherent structures across a broad range of angular scales. Our results offer promising avenues for linking the analysis of coherent structures in optical cirrus to the underlying physical processes in the ISM that shape them. Furthermore, we demonstrate that these morphological signatures can be leveraged to distinguish and disentangle cirrus from extragalactic light.

astro-ph.GA↗

arXiv2021

Stellar, Gas, and Dust Emission of Star Forming Galaxies out to z~2

While dust is a major player in galaxy evolution, its relationship with gas and stellar radiation in the early universe is still not well understood. We combine 3D-HST emission line fluxes with far-UV through far-IR photometry in a sample of 669 emission-line galaxies (ELGs) between 1.2 < z < 1.9 and use the MCSED spectral energy distribution fitting code to constrain the galaxies' physical parameters, such as their star formation rates (SFRs), stellar masses, and dust masses. We find that the assumption of energy balance between dust attenuation and emission is likely unreasonable in many cases. We highlight a relationship between the mass-specific star formation rate (sSFR), stellar mass, and dust mass, although its exact form is still unclear. Finally, a stacking of H$α$ and H$β$ fluxes shows that nebular attenuation increases with stellar mass and SFR for IR-bright ELGs.

astro-ph.GA↗

arXiv2021

Measuring Stellar Masses of Emission Line Galaxies at 1.2<z<1.9

The accurate measurement of stellar masses over a wide range of galaxy properties is essential for better constraining models of galaxy evolution. Emission line galaxies (ELGs) tend to have better redshift estimates than continuum-selected objects and have been shown to span a large range of physical properties, including stellar mass. Using data from the 3D-HST Treasury program, we construct a carefully vetted sample of 4350 ELGs at redshifts 1.16<z<1.90. We combine the 3D-HST emission line fluxes with far-UV through near-IR photometry and use the MCSED spectral energy distribution fitting code to constrain the galaxies' physical parameters, such as their star formation rate (SFRs) and stellar masses. Our sample is consistent with the z~2 mass-metallicity relation. More importantly, we show there is a simple but tight correlation between stellar mass and absolute magnitude in a near-IR filter that will be particularly useful in quickly calculating accurate stellar masses for millions of galaxies in upcoming missions such as Euclid and the Nancy Grace Roman Space Telescope.

astro-ph.GA↗

arXiv2016

The Rest-Frame Optical Morphology of Emission Line Galaxies at 2 < z < 3: Evidence for Inside-Out Formation in Low-Mass Galaxies

We compare the rest-frame ultraviolet and rest-frame optical morphologies of 2 < z < 3 star-forming galaxies in the GOODS-S field using Hubble Space Telescope WFC3 and ACS images from the CANDELS, GOODS, and ERS programs. We show that the distribution of sizes and concentrations for 1.90 < z < 2.35 galaxies selected via their rest-frame optical emission-lines are statistically indistinguishable from those of Lyman-alpha emitting systems found at z ~ 2.1 and z ~ 3.1. We also show that the z > 2 star-forming systems of all sizes and masses become smaller and more compact as one shifts the observing window from the UV to the optical. We argue that this offset is due to inside-out galaxy formation over the first ~ 2 Gyr of cosmic time.

astro-ph.GA↗