arXiv subjects

Jessica A. Zebrowski

Publications and source records attributed to Jessica A. Zebrowski.

4 recordsLinked to original sources

arXiv2026

Little Red Dot Cosmology: A Matter-Era Baryon Acoustic Oscillations Probe of $\Lambda$CDM

The discovery of Little Red Dots (LRDs) with JWST provides a new source population for cosmology in a largely unmapped period of cosmic history. LRDs are most numerous at $4\lesssim z\lesssim9$, thereby bridging existing low-redshift large-scale-structure measurements and the cosmic microwave background. In this epoch, the Universe is deep in the matter-dominated era, where dark energy is dynamically negligible and the expansion history is tightly predicted in $\Lambda$CDM, making these redshifts a clean test of the standard cosmological model. Recent measurements indicate that LRDs have number densities of $\bar n\sim10^{-4}$ $h^3$ Mpc$^{-3}$, a bias rising from $b\sim 3$ to $\sim8$ over this interval, and distinctive spectrophotometric signatures -- a remarkably favorable combination for baryon acoustic oscillation (BAO) measurements. Using a Fisher forecast with these fiducial inputs, we find that a wide-field spectroscopic survey of LRDs over a DESI-like (14,000 deg$^2$) footprint delivers a percent-level isotropic distance scale measurement of $D_V/r_d$ across four bins spanning $4\lesssim z\lesssim9$. LRDs are therefore a compelling target for future wide-field near- to mid-infrared spectroscopy aimed at mapping large-scale structure deep into the matter-dominated era.

astro-ph.CO↗

arXiv2026

A New Window into the Baryon Cycle at Cosmic Noon with Line Intensity Mapping: Forecasts for auto- and cross-correlations in [CII]-158$μ$m, HI 21 cm, CO$_{J+1\rightarrow J}$, and H$α$ galaxies

Across the peak of cosmic star formation at $z\sim1-2$, inflow, processing, and feedback drive rapid changes in the spatial distribution and chemical composition of baryons in galaxies and surrounding reservoirs; this baryon cycle can be tomographically mapped by line intensity mapping (LIM) of atomic hydrogen, ionized carbon, and carbon monoxide. We present a simulation-based forecasting framework for detecting auto- and cross-power spectra between spectroscopic surveys of four such tracers at $z\sim0.5-1.7$ mapping the same deep field - TIM, EoRSpec/FYST, MeerKAT, & Euclid. We forward-model 3-D distributions for these tracers from magnetohydrodynamic simulations, directly capturing the two-halo, one-halo, and shot statistics without relying on analytical decompositions. We further detail a signal-to-noise formalism, tailored to LIM surveys with highly anisotropic geometries and Fourier-space coverage. We demonstrate that galaxy cross-correlations will be the dominant discovery channel for current-generation surveys. These instruments will detect the auto-spectra for CO and HI 21 cm and the CO $\times$ 21 cm cross-spectrum at modest S/N $\sim 1-10$, while placing upper limits on the [CII]-158$μ$m signals. [CII], CO, and HI LIM will be $\sim3-30\times$ ($0.5-1.5$ dex) more sensitive to cross-correlation with the Euclid survey, however, than their respective auto-correlations, constraining all three models of line emission at high significance (S/N $\sim 10-40$) within this decade. Finally, we formulate a staged instrumental trajectory with planned or reasonable improvements, including the as-proposed SKA-Mid. We forecast advancing the per-$k$-mode sensitivities of each auto-, galaxy-line, and line-line spectrum by several orders of magnitude, enabling new percent- and sub-percent level constraints on cosmology and the redshift evolution of star formation and the baryon cycle.

astro-ph.CO↗

arXiv2026

Forecasting the cross correlation of Terahertz Intensity Mapper [CII] line intensity maps with Euclid galaxies

We forecast that the Terahertz Intensity Mapper (TIM) cross-correlated with Euclid's Fornax deep field (EDF-F), TIM$\times$EDF-F, will detect the [CII]-galaxy cross-power spectrum at a median redshift of 1.1 with $\gtrsim 7 σ$ confidence. The Poisson component of the cross-power spectrum at $0.1 \leq k \leq 10$ hMpc$^{-1}$ (i.e. cross-shot noise) will be detected at $\gtrsim 3 σ$ in 4 bins spanning $0.5 < z< 1.7$. This measurement will constrain the mean [CII] specific intensity over half of cosmic history and assess the degree to which Euclid-selected galaxies account for the [CII] intensity observed by TIM. We find that TIM can detect the cross-power spectrum across a wide range of [CII] intensity models.

astro-ph.GA↗

arXiv2026

First constraints on causal sources of primordial gravitational waves from BICEP/Keck, SPTpol, SPT-3G, Planck and WMAP $B$-mode data

Non-inflationary sources of gravitational waves in the early Universe generically predict causality-limited tensor power spectra at low frequencies. We report the first-ever constraints on such sources based on cosmic microwave background (CMB) $B$-mode polarization measurements. Using data from BICEP/Keck, SPTpol, SPT-3G, Planck, and WMAP, we constrain the amplitude of an early causal tensor (ECT) power spectrum parameterized by $r_{ect}$, the ratio of causal tensor power to total scalar power at $k~=~0.01$ Mpc$^{-1}$, and obtain a 95% CL upper limit of $r_{ect}<$ 0.0077. Since $r_{ect}$ can easily be related to the parameters of a given theory, our bound robustly constrains a broad class of well-motivated gravitational wave sources in the early universe, including first-order cosmological phase transitions, enhanced small-scale density perturbations, and various topological defects. Finally, we translate our limit into a bound on the present-day energy density in gravitational waves at ultra-low frequencies otherwise inaccessible to traditional gravitational wave detection strategies, including pulsar timing arrays, interferometers, and resonant cavities.

astro-ph.CO↗