arXiv subjects

Evan C. Mayer

Publications and source records attributed to Evan C. Mayer.

8 recordsLinked to original sources

arXiv2026

TIME Commissioning Observations: II. On-sky Characterization and the 2D Map Data Processing Pipeline

The Tomographic Ionized-carbon Mapping Experiment (TIME) is a line intensity mapping (LIM) instrument that is designed to observe the power spectrum of the [CII] $158$~$\mu$m emission line during the Epoch of Reionization. TIME completed a commissioning run in 2022 at the Arizona Radio Observatory onboard the 12-M Radio Telescope at Kitt Peak, where it observed galactic sources for the first time. In this paper we report on an analysis of observations of the Orion Molecular Cloud (OMC) and G49.5 (a local HII region). The OMC observations were taken at least once a day to assess the stability of the instrument and demonstrate its on-sky performance. We describe a spectral image processing pipeline to make calibrated maps of raster scans of these sources, incorporating planet observations for gain calibration. We show with G49.5 that, when compared to the Bolocam Galactic Plane Survey, we are able to achieve a $< 3\%$ calibration difference. Based on the outcomes from this commissioning phase of TIME, we have demonstrated preliminary performance, and identified sources of improvement necessary for pursuing a LIM measurement.

astro-ph.IM↗

arXiv2026

A New Window into the Baryon Cycle at Cosmic Noon with Line Intensity Mapping: Forecasts for auto- and cross-correlations in [CII]-158$\mu$m, HI 21 cm, CO$_{J+1\rightarrow J}$, and H$\alpha$ 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$\mu$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 $\gtrsim 7 \sigma$ 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 $\gtrsim 3 \sigma$ 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↗

arXiv2025

TIME Commissioning Observations: I. Mapping Dust and Molecular Gas in the Sgr A Molecular Cloud Complex at the Galactic Center

We present the processing of an observation of Sagittarius A (Sgr A) with the Tomographic Ionized-carbon Mapping Experiment (TIME), part of the 2021-2022 commissioning run to verify TIME's hyperspectral imaging capabilities for future line-intensity mapping. Using an observation of Jupiter to calibrate detector gains and pointing offsets, we process the Sgr A observation in a purpose-built pipeline that removes correlated noise through common-mode subtraction with correlation-weighted scaling, and uses map-domain principal component analysis to identify further systematic errors. The resulting frequency-resolved maps recover strong 12CO(2-1) and 13CO(2-1) emission, and a continuum component whose spectral index discriminates free-free emission in the circumnuclear disk (CND) versus thermal dust emission in the 20 km s$^{-1}$ and 50 km s$^{-1}$ molecular clouds. Broadband continuum flux comparisons with the Bolocam Galactic Plane Survey (BGPS) show agreement to within $\sim$5% in high-SNR molecular clouds in the Sgr A region. From the CO line detections, we estimate a molecular hydrogen mass of between $5.4 \times 10^5 M_\odot$ and $5.7 \times 10^5 M_\odot$, consistent with prior studies. These results demonstrate TIME's ability to recover both continuum and spectral-line signals in complex Galactic fields, validating its readiness for upcoming extragalactic CO and [C II] surveys.

astro-ph.IM↗

arXiv2025

Development of a planar cable-driven parallel robot for submillimeter and terahertz beam mapping measurements

The spatial sensitivity pattern of millimeter-wavelength receivers is an important diagnostic of performance and is affected by the alignment of coupling optics. Characterization can be challenging in the field, particularly in the decentered and tightly packed optical configurations that are employed for many astronomical millimeter-wave cameras. In this paper, we present the design and performance of a lightweight and reconfigurable beam mapper, consisting of a bank of thermal sources positioned by a planar cable-driven robot. We describe how the measurement requirements and mechanical constraints of the Tomographic Ionized-carbon Mapping Experiment (TIME) optical relay drive the design of the mapper. To quantify the positioning performance, we predict the beam patterns at each surface to derive requirements and use a non-contact computer-vision based method built on OpenCV to track the payload position with an accuracy better than 1.0 mm. We achieve an in-plane absolute payload position error of 2.7 mm (RMSE) over a $\sim$400 mm $\times$ 400 mm workspace and an in-plane repeatability of 0.81 mm, offering substantial improvements in accuracy and speed over traditional handheld techniques.

astro-ph.IM↗

arXiv2025

TES Bolometer Design and Testing for the Tomographic Ionized-carbon Mapping Experiment Millimeter Array

Transition Edge Sensor (TES) bolometers are a well-established technology with a strong track record in experimental cosmology, making them ideal for current and future radio astronomy instruments. The Tomographic Ionized-carbon Mapping Experiment (TIME), in collaboration with JPL, has developed advanced silicon nitride leg isolated superconducting titanium detectors for 200 to 300 GHz observations of the Epoch of Reionization. Compared to their MHz counterparts, bolometers operating in this frequency range are less common because of their large absorber size and fragility. TIME aims to fabricate a total of 1920 high frequency (HF) and low frequency (LF) detectors to fully populate the focal plane. TIME has successfully developed HF (230 to 325 GHz) and LF (183 to 230 GHz) wafers that are physically robust and perform well at cryogenic temperatures (300 mK). Recent laboratory tests have shown high optical efficiencies for the LF wafers (30 to 40%), but low device yield for the HFs. To address this, new HF modules have been designed with improved cabling and a reduced backshort distance, and are expected to perform similarly to LFs in a similar lab setting. We report on the development of these detectors as well as recent laboratory and on sky tests conducted at the Arizona Radio Observatory's (ARO) 12 meter prototype antenna at Kitt Peak National Observatory.

astro-ph.IM↗

arXiv2025

The Arizona Molecular ISM Survey with the SMT: Survey Overview and Public Data Release

The CO(1-0) line has been carefully calibrated as a tracer of molecular gas mass. However, recent studies often favor higher J transitions of the CO molecule which are brighter and accessible for redshift ranges where CO(1-0) is not. These lines are not perfect analogues for CO(1-0), owing to their more stringent excitation conditions, and must be calibrated for use as molecular gas tracers. Here we introduce the Arizona Molecular ISM Survey with the SMT (AMISS), a multi-CO line survey of z~0 galaxies conducted to calibrate the CO(2-1) and CO(3-2) lines. The final survey includes CO(2-1) spectra of 176 galaxies and CO(3-2) spectra for a subset of 45. We supplement these with archival CO(1-0) spectra from xCOLD GASS for all sources and additional CO(1-0) observations with the Kitt Peak 12m Telescope. Targets were selected to be representative of the galaxy population in the stellar mass range of $10^9$ to $10^{11.5}$ M$_\odot$. Our project emphasized careful characterization of statistical and systematic uncertainties to enable studies of trends in CO line ratios. We show that optical and CO disk sizes are on average equal, for both the CO(1-0) and CO(2-1) line. We measure the distribution of CO line luminosity ratios, finding medians (16th-84th percentile) of 0.71 (0.51-0.96) for the CO(2-1)-to-CO(1-0) ratio, 0.39 (0.24-0.53) for the CO(3-2)-to-CO(1-0) ratio, and 0.53 (0.41-0.74) for the CO(3-2)-to-CO(2-1) ratio. A companion paper presents our study of CO(2-1)'s applicability as a molecular gas mass tracer and search for trends in the CO(2-1)-to-CO(1-0) ratio. Our catalog of CO line luminosities will be publicly available with the published version of this article.

astro-ph.GA↗

arXiv2024

Cosmic ray susceptibility of the Terahertz Intensity Mapper detector arrays

We report on the effects of cosmic ray interactions with the Kinetic Inductance Detector (KID) based focal plane array for the Terahertz Intensity Mapper (TIM). TIM is a NASA-funded balloon-borne experiment designed to probe the peak of the star formation in the Universe. It employs two spectroscopic bands, each equipped with a focal plane of four $\sim\,$900-pixel, KID-based array chips. Measurements of an 864-pixel TIM array shows 791 resonators in a 0.5$\,$GHz bandwidth. We discuss challenges with resonator calibration caused by this high multiplexing density. We robustly identify the physical positions of 788 (99.6$\,$%) detectors using a custom LED-based identification scheme. Using this information we show that cosmic ray events occur at a rate of 2.1$\,\mathrm{events/min/cm^2}$ in our array. 66$\,$% of the events affect a single pixel, and another 33$\,$% affect $<\,$5 KIDs per event spread over a 0.66$\,\mathrm{cm^2}$ region (2 pixel pitches in radius). We observe a total cosmic ray dead fraction of 0.0011$\,$%, and predict that the maximum possible in-flight dead fraction is $\sim\,$0.165$\,$%, which demonstrates our design will be robust against these high-energy events.

astro-ph.IM↗