arXiv subjects

Benjamin Rose

Publications and source records attributed to Benjamin Rose.

16 recordsLinked to original sources

arXiv2025

Revisiting the Mass Step: Environmental Dependence of Type Ia Supernovae in Low-Metallicity Host Galaxies

Despite the tremendous impact of Type Ia supernovae (SNe Ia) on the field of cosmology, their underlying physics are still poorly understood. Studies have found an intriguing correlation between standardized Type Ia supernova (SN Ia) luminosities and host galaxy masses, commonly referred to as the "mass step". SNe Ia in massive galaxies appear systematically brighter than in lower-mass, star-forming hosts after standardization. However, previous analyses use host galaxy mass estimates derived largely from optical data alone and assume parametric forms for host star formation histories (SFHs), both of which are known to misestimate galaxy stellar masses. In this work, we re-examine the mass-step relation with a sample of SN Ia host galaxies complete in broadband optical (3000 Angstrom to 1 micron) and near-infrared (up to 1.8 micron) data, and in some cases including mid-infrared observations (up to 4.5 micron), using Prospector to derive nonparametric SFHs. We find that while the masses for these galaxies have indeed been underestimated, the overall trend in SN Ia luminosity versus host mass remains largely unchanged. We also uncover an environmental metallicity-dependent trend, in which low-metallicity galaxies (Z < -1 Zsol) may drive much of the observed SN Ia luminosity-mass correlation, suggesting that the chemical composition of the SN environment plays a central role in shaping the standardized brightness of SNe Ia.

astro-ph.CO↗

arXiv2025

Interacting bosonic dark energy and fermionic dark matter in Einstein scalar Gauss-Bonnet gravity

We explore a cosmological framework in which a Gauss-Bonnet (GB) coupled scalar field, acting as dark energy, interacts with a fermionic dark matter field through a coupling obtained from the point of view of particle physics. This setup is inspired by string/M-theory, and two representative scalar field potentials are investigated: exponential and power-law. A distinctive feature of the GB-coupled models is their potential to alter the propagation speed of gravitational waves (GWs), a property with significant implications in light of recent multi-messenger astrophysical observations. To account for this, we analyze models under two scenarios: one where the GW speed differs from that of light and the other where they are equal, but all consistent with current observational constraints. The dynamical evolution of the system is investigated by reformulating the field equations into an autonomous dynamical system, enabling a detailed analysis of the Universe's long-term behavior, including the radiation-, matter- and dark energy-dominated epochs. We constrain the model parameters using a broad set of recent observational data, including mock high-redshift measurements from the Roman Space Telescope. Our findings indicate that both potentials yield cosmologies that are in excellent agreement with current data, closely tracking the expansion history predicted by the standard $\Lambda$CDM model, while still allowing room for subtle deviations that could be tested by future observations.

astro-ph.CO↗

arXiv2025

Interacting Scalar Fields as Dark Energy and Dark Matter in Einstein scalar Gauss Bonnet Gravity

A Gauss-Bonnet (GB) coupled scalar field $\phi$, responsible for the late-time cosmic acceleration and interacting with a coherent scalar field $\psi$ through an interaction potential $W(\phi,\psi)$, is considered from the point of view of particle physics for two different models. The non-minimal coupling between the GB curvature term and the field $\phi$ leads to a time-dependent speed of gravitational waves (GWs), which is fixed to unity in order to be consistent with current GW observations, rendering the GB coupling function model-independent. We investigate the dynamical stability of the system by formulating it as an autonomous system, and provide a detailed discussion on the choice of initial conditions required to obtain stable background evolution of the models. We constrain the model parameters using various sets of observational data, including both early- and late-time probes. We incorporate the improved Dark Energy Survey (DES) 5-year Type Ia supernova sample (DES-SN5YR), referred to as DES-Dovekie, which exhibits substantially lower tension with the Pantheon+ supernova sample. We find that both models are physically viable and closely follow the $\Lambda$CDM trend for the Pantheon+ and DES samples. However, upon including the Roman mock data, a significant departure is observed at higher redshifts, yielding statistically strong preference over the flat $\Lambda$CDM model.

gr-qc↗

arXiv2025

Initial Characterization of Stellar Photometry of Roman images from the OpenUniverse Simulations

NASA's Nancy Grace Roman Space Telescope (Roman) will provide an opportunity to study dark energy with unprecedented precision and accuracy using several techniques, including measurements of high-$z$ Type Ia Supernovae (SNe Ia, $z \lesssim 3.0$) via the High-Latitude Time Domain Survey (HLTDS). In this work, we do an initial "benchmark" characterization of the photometric repeatability of stellar fluxes, which must be below $1\%$ when sky noise is subdominant in order to enable a number of calibration requirements. Achieving this level of flux precision requires attention to Roman's highly-structured, spatially-varying, undersampled PSF. In this work, we build a library of effective PSFs (ePSFs) compatible with the OpenUniverse HLTDS simulations. Using our library of ePSFs, we recover stellar flux to between $0.6 - 1.2\%$ photometric precision, finding that redder bands perform better by this metric. We also find that flux recovery is improved by up to $20\%$ when a chip (sensor chip assembly; SCA) is divided into 8 sub-SCAs in order to account for the spatial variation of the PSF. With our optimized algorithm, we measure non-linearity due to photometry (magnitude dependence) of $|s_{NL}| < 1.93 \times 10^{-3}$ per dex, which is still larger than stated requirements for detector effects and indicates that further work is necessary. We also measure the dependence of photometric residuals on stellar color, and find the largest possible dependence in R062, implying a color-dependent PSF model may be needed. Finally, we characterize the detection efficiency function of each OpenUniverse Roman filter, which will inform future studies.

astro-ph.IM↗

arXiv2024

Interacting Models of Dark Energy and Dark Matter in Einstein scalar Gauss Bonnet Gravity

We study the dynamics of the interacting models between the Gauss-Bonnet (GB) coupled scalar field and the dark matter fluid in a homogeneous and isotropic background. A key feature of GB coupling models is the varying speed of gravitational waves (GWs). We utilize recent constraints on the GW speed and conduct our analysis in two primary scenarios: model-dependent and model-independent. In the model-dependent scenario, where determining the GW speed requires a specific GB coupling functional form, we choose an exponential GB coupling. We adopt a dynamical system analysis to obtain the necessary constraints on the model parameters that describe different phases of the universe and produce a stable late-time accelerating solution following the GW constraint, and find that to satisfy all these constraints, fine-tuning of the free parameters involved in the models is often needed. In the model-independent scenario, the GW speed is fixed to one, and we construct the autonomous system to identify the late-time stable accelerating critical points. Furthermore, we adopt a Bayesian inference method using late-time observational data sets, including 31 data points from cosmic chronometer data (Hubble data) and 1701 data points from Pantheon+ and find that all the observational constraints can be satisfied without fine-tuning. In addition, we also utilize simulated binned Roman and LSST data to study the evolution of the universe in the model-independent scenario. We find that the model shows significant deviation at higher redshifts from $\Lambda$CDM and fits the current data much better than $\Lambda$CDM within the error bars.

gr-qc↗

arXiv2023

Roman CCS White Paper: Measuring Type Ia Supernovae Discovered in the Roman High Latitude Time Domain Survey

We motivate the cosmological science case of measuring Type Ia supernovae with the Nancy Grace Roman Space Telescope as part of the High Latitude Time Domain Survey. We discuss previously stated requirements for the science, and a baseline survey strategy. We discuss the various areas that must still be optimized and point to the other white papers that consider these topics in detail. Overall, the baseline case should enable an exquisite measurement of dark energy using SNe Ia from z=0.1 to z>2, and further optimization should only strengthen this once-in-a-generation experiment.

astro-ph.IM↗

arXiv2023

Roman CCS White Paper: Balanced Prism Plus Filter Cadence in the High Latitude Time Domain Survey Core Community Survey

The Nancy Grace Roman Space Telescope's (RST) Wide Field Imager (WFI) is equipped with a slitless prism that can be used for spectroscopic discovery and follow-up of explosive transients at high redshift as part of its High Latitude Time Domain Survey. This is new and unique spectroscopic capability, not only for its original purpose for cosmology, but also for other types of explosive transients. This white paper is intended to help make this new capability more clear to the community. The depth of the RST prism compared to ground-based spectrographs is explored, showing that the RST prism will be unrivaled in the observer-frame NIR. The influence of the selected sky locations on the speed and homogeneity of a RST prism survey is also estimated. This unique new capability should be considered when balancing the HLTDS time devoted to cadenced imaging and spectroscopy.

astro-ph.IM↗

arXiv2023

Roman CCS White Paper: Considerations for Selecting Fields for the Roman High-latitude Time Domain Core Community Survey

In this white paper, we review five top considerations for selecting locations of the fields of the Roman High-latitude Time Domain Survey. Based on these considerations, we recommend Akari Deep Field South (ADFS)/Euclid Deep Field South (EDFS) in the Southern Hemisphere has it avoids bright stars, has minimal Milky Way dust, is in Roman Continuous viewing zone, overlaps with multiple past and future surveys, and minimal zodiacal background variation. In the North, Extended Groth Strip (EGS) is good except for its zodiacal variation and Supernova/Acceleration Probe North (SNAP-N) and European Large Area Infrared Space Observatory Survey-North 1 (ELAIS N-1) are good except for their synergistic archival data.

astro-ph.IM↗

arXiv2023

Roman CCS White Paper: Options to Increase the Coverage Area of Prism Time Series in the High-Latitude Time Domain Core Community Survey

The current reference High-latitude time domain survey increases the completeness of transients with prism temporal time series data by adjusting the ratio of prism-to-imaging time. However, there are two other nobs that allow for a more complete prism coverage: prism cadence and exposure time. In this white paper, we discuss how changes to the prism cadence and exposure time -- in order to increase the fraction of observed transients with spectral time series -- affect supernova cosmology, transient typing and template building, and the study of rare transients.

astro-ph.IM↗

arXiv2023

Roman CCS White Paper: Tracing stellar mass assembly and emerging quiescence at cosmic noon -- the case for deep imaging with all of Roman's wide filters in the HLTDS

We present arguments for including observations with all of the Wide Field Instrument imaging filters, with the exception of F146, within the Nancy Grace Roman Space Telescope (\emph{Roman}) High Latitude Time Domain Survey (HLTDS). Our case is largely driven by the extragalactic deep field science that can be accomplished with HLTDS observations and also by the improvements in type Ia supernova (SN Ia) cosmology systematics that a wide wavelength coverage affords.

astro-ph.IM↗

arXiv2023

Roman CCS White Paper: Characterizing Superluminous Supernovae with Roman

Type-I Superluminous Supernovae (SLSNe) are an exotic class of core-collapse SN (CCSN) that can be up to 100 times brighter and more slowly-evolving than normal CCSNe. SLSNe represent the end-stages of the most massive stripped stars, and are thought to be powered by the spin-down energy of a millisecond magnetar. Studying them and measuring their physical parameters can help us to better understand stellar mass-loss, evolution, and explosions. Moreover, thanks to their high luminosities, SLSNe can be seen up to greater distances, allowing us to explore how stellar physics evolves as a function of redshift. The High Latitude Time Domain Survey (HLTDS) will provide us with an exquisite dataset that will discover 100s of SLSNe. Here, we focus on the question of which sets of filters and cadences will allow us to best characterize the physical parameters of these SLSNe. We simulate a set of SLSNe at redshifts ranging from z = 0.1 to z = 5.0, using six different sets of filters, and cadences ranging from 5 to 100 days. We then fit these simulated light curves to attempt to recover the input parameter values for their ejecta mass, ejecta velocity, magnetic field strength, and magnetar spin period. We find that four filters are sufficient to accurately characterize SLSNe at redshifts below $z = 3$, and that cadences faster than 20 days are required to obtain measurements with an uncertainty below 10\%, although a cadence of 70 days is still acceptable under certain conditions. Finally, we find that the nominal survey strategy will not be able to properly characterize the most distant SLSNe at $z = 5$. We find that the addition of 60-day cadence observations for 4 years to the nominal HLTDS survey can greatly improve the prospect of characterizing these most extreme and distant SNe, with only an 8\% increase to the time commitment of the survey.

astro-ph.HE↗

arXiv2022

The Dark Energy Survey Supernova Program results: Type Ia Supernova brightness correlates with host galaxy dust

Cosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between color and luminosity ($\beta$) and do not account for varying host-galaxy dust properties. However, from studies of dust in large samples of galaxies, it is known that dust attenuation can vary significantly. Here we take advantage of state-of-the-art modeling of galaxy properties to characterize dust parameters (dust attenuation $A_V$, and a parameter describing the dust law slope $R_V$) for the Dark Energy Survey (DES) SN Ia host galaxies using the publicly available \texttt{BAGPIPES} code. Utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact SN Ia cosmology: 1) there exists a large range ($\sim1-6$) of host $R_V$ 2) high stellar mass hosts have $R_V$ on average $\sim0.7$ lower than that of low-mass hosts 3) there is a significant ($>3\sigma$) correlation between the Hubble diagram residuals of red SNe Ia that when corrected for reduces scatter by $\sim13\%$ and the significance of the ``mass step'' to $\sim1\sigma$. These represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling ``mass step'' and intrinsic scatter ($\sigma_{\rm int}$) in SN Ia analyses. We also find that red-sequence galaxies have both lower and more peaked dust law slope distributions on average in comparison to non red-sequence galaxies. We find that the SN Ia $\beta$ and $\sigma_{\rm int}$ both differ by $>3\sigma$ when determined separately for red-sequence galaxy and all other galaxy hosts. The agreement between fitted host-$R_V$ and SN Ia $\beta$ \& $\sigma_{\rm int}$ suggests that host dust properties play a major role in SN Ia color-luminosity standardization and supports the claim that SN Ia intrinsic scatter is driven by $R_V$ variation.

astro-ph.CO↗

arXiv2022

High-Precision Redshifts for Type Ia Supernovae with the Nancy Grace Roman Space Telescope P127 Prism

We present results from simulating slitless spectroscopic observations with the Nancy Grace Roman Space Telescope's (Roman) Wide-Field Instrument (WFI) P127 prism spanning 0.75 $\mu m$ to 1.8 $\mu m$. We quantify the efficiency of recovered Type Ia supernovae (SNe Ia) redshifts, as a function of P127 prism exposure time, to guide planning for future observing programs with the Roman prism. Generating the two-dimensional dispersed images and extracting one-dimensional spectra is done with the slitless spectroscopy package pyLINEAR along with custom-written software. From the analysis of 1698 simulated SN Ia P127 prism spectra, we show the efficiency of recovering SN redshifts to $z\lesssim3.0$, highlighting the exceptional sensitivity of the Roman P127 prism. Redshift recovery is assessed by setting a requirement of $\sigma_z = (\left|z - z_\mathrm{true} \right|)/(1+z) \leq 0.01$. We find that 3 hr exposures are sufficient for meeting this requirement, for $\gtrsim 50\%$ of the sample of mock SNe Ia at $z\approx2$ and within $\pm5$ days of rest-frame maximum light in the optical. We also show that a 1 hr integration of Roman can achieve the same precision in completeness to a depth of $24.4 \pm 0.06$ AB mag (or $z\lesssim 1$). Implications for cosmological studies with Roman P127 prism spectra of SNe Ia are also discussed.

astro-ph.GA↗

arXiv2022

Connecting Infrared Surface Brightness Fluctuation Distances to Type Ia Supernova Hosts: Testing the Top Rung of the Distance Ladder

We compare infrared surface brightness fluctuation (IR SBF) distances measured in galaxies that have hosted type Ia supernovae (SNIa) to distances estimated from SNIa light curve fits. We show that the properties of SNIa found in IR SBF hosts are very different from those exploding in Cepheid calibrators, therefore, this is a direct test of systematic uncertainties on estimation of the Hubble constant (Ho) using supernovae. The IR SBF results from Jensen et al. (2021; arXiv:2105.08299) provide a large and uniformly measured sample of IR SBF distances which we directly compare with distances to 25 SNIa host galaxies. We divide the Hubble flow SNIa into sub-samples that best match the divergent supernova properties seen in the IR SBF hosts and Cepheid hosts. We further divide the SNIa into a sample with light curve widths and host masses that are congruent to those found in the SBF-calibrated hosts. We refit the light curve stretch and color correlations with luminosity, and use these revised parameters to calibrate the Hubble flow supernovae with IR SBF calibrators. Relative to the Hubble flow, the average calibrator distance moduli vary by 0.03mag depending on the SNIa subsamples examined and this adds a 1.8% systematic uncertainty to our Hubble constant estimate. Based on the IR SBF calibrators, Ho=74.6$\pm$0.9(stat)$\pm$ 2.7(syst) km/s/Mpc, which is consistent with the Hubble constant derived from supernovae calibrated from Cepheid variables. We conclude that IR SBF provides reliable calibration of SNIa with a precision comparable to Cepheid calibrators, and with a significant saving in telescope time.

astro-ph.CO↗

arXiv2019

Science from an Ultra-Deep, High-Resolution Millimeter-Wave Survey

Opening up a new window of millimeter-wave observations that span frequency bands in the range of 30 to 500 GHz, survey half the sky, and are both an order of magnitude deeper (about 0.5 uK-arcmin) and of higher-resolution (about 10 arcseconds) than currently funded surveys would yield an enormous gain in understanding of both fundamental physics and astrophysics. In particular, such a survey would allow for major advances in measuring the distribution of dark matter and gas on small-scales, and yield needed insight on 1.) dark matter particle properties, 2.) the evolution of gas and galaxies, 3.) new light particle species, 4.) the epoch of inflation, and 5.) the census of bodies orbiting in the outer Solar System.

astro-ph.CO↗

arXiv2014

High-Amplitude, Rapid Photometric Variation of the New Polar MASTER OT J132104.04+560957.8

We present photometric and spectroscopic observations of the cataclysmic variable MASTER OT J132104.04+560957.8 which strongly indicate that it is a polar with an orbital period of 91 minutes. The optical light curve shows two maxima and two minima per orbital cycle, with considerable variation in the strength of the secondary maximum and in the morphology and depth of the minima.

astro-ph.SR↗