CCAPP Fellows Symposium 2021

Ashley Ross

Producing Large-scale structure maps with the Dark Energy Spectroscopic Instrument

The Dark Energy Spectroscopic Instrument (DESI) began obtaining galaxy spectra for the purpose of creating 3D maps of large-scale structure last March. Over its five year survey, it will obtain more than 30 million galaxy and quasar redshifts distributed over 14,000 deg2 of sky coverage. In the four months of operation (March-July) it obtained approximately as many galaxy and quasar redshifts as previously known to humans. I will explain the basics of how large-scale structure maps are created using DESI data and some of what we hope to learn from the maps.

Naim Karacayli

1D Lyman-α Power Spectrum

The Lyα forest technique can probe matter in vast volumes far into the past (2 < z < 5) and at smaller scales than galaxy surveys (r < 1 Mpc) through absorption lines in quasar spectra. 1D power spectrum of the Lyα forest (P1D) has emerged as a competitive framework to study new physics, but also has come with various challenges and systematic errors in analysis. In this talk, I will go over the optimal quadratic estimator for P1D, share simple forecasts for the upcoming Dark Energy Spectroscopic Instrument (DESI) and present the results from an application to the largest data set of high-resolution, high-S/N quasar spectra. A crude Fisher analysis estimates that these results will improve warm dark matter mass constraints by more than a factor of 2. If time allows, I will mention some preliminary results and possible extensions for DESI.

Andrei Cuceu

Cosmology from the 3D distribution of the Lyman-alpha forest

The Lyman-alpha (Lya) forest consists of a series of absorption lines in spectra of high-redshift quasars. These lines trace the underlying matter density field, and therefore the forest can be used as a probe of large scale structure in the Universe. So far, cosmological measurements of the Lyman-alpha forest have mostly focused on the baryon acoustic oscillation (BAO) feature. However, with recent advancements in modelling of the Lya correlation function, it is now possible to look beyond BAO. In this talk, I will discuss how the 3D distribution of the Lya forest can be used to extract more cosmological information through the Alcock-Paczynski (AP) effect and redshift space distortions (RSD). I will also show forecasts of such a measurement for the Dark Energy Spectroscopic Instrument (DESI).

Yi-Kuan Chiang

Probing the Cosmic Inventory with Tomographic Intensity Mapping

The formation of stars, galaxies, and large-scale structures drives complex energy density flows over a wide range of temporal and spatial scales in the Universe. The net effect could be distilled by probing the evolution of the cosmic energy density inventory over time. To start piecing together this dynamical picture of cosmic constituents, we embark on a journey to quantify the aggregate amount of stars, dust, thermal, and gravitational energy as a function of cosmic time via tomographic intensity mapping---a new method to unlock the use of diffuse light in sky surveys across the electromagnetic spectrum.

Anna Porredon

Dark Energy Survey Year 3 multi-probe cosmological constraints with an optimized galaxy sample

The cosmological information obtained from imaging surveys is most robust when multiple probes are used. Two of the most sensitive probes of the large-scale structure of the universe are galaxy clustering and weak gravitational lensing. I will present cosmological results from the Dark Energy Survey first three years of observations combining those two probes, using an optimized lens sample of 11 million galaxies for the clustering measurements.

Jack Elvin-Poole

Testing Dark Energy with Galaxy Clustering and Lensing

Galaxy surveys are fundamental tools of cosmology allowing us to measure the geometry and growth of structure in the universe. Using weak gravitational lensing and galaxy clustering from these surveys, we can directly trace the dark matter distribution and infer from this the properties of Dark Energy and Dark Matter. Recent measurements of this kind from the Dark Energy Survey (DES) have taken a major step towards understanding these phenomena. I will present these results, both using the combination of lensing and clustering (the so-called “3x2pt” analysis) and from measurement of the Baryonic Acoustic Oscillation from galaxy clustering. We find our results to be consistent with predictions from the Cosmic Microwave Background within the Lambda-CDM model. When combining with external data we can provide a 3% measurement of the Dark Energy Equation of state, consistent with the Lambda-CDM value. Our BAO measurement is a 2.7% measurement of the angular diameter distance at a redshift of 0.835, competitive with the transverse measurements of spectroscopic surveys. As well as providing statistically powerful tests of Dark Energy and the LCDM model, DES will be a major testbed for the methodological developments required for the next generation of experiments Euclid, LSST, DESI, to be successful.

Chun-Hao To

Multi-probe cluster cosmology analyses with photometric surveys

Three cosmic tracer fields are measured from photometric surveys: galaxy density, weak gravitation lensing shear, and cluster density. The joint analysis of the auto and cross correlations of the first two fields, often referred to as the 3x2pt analysis, has become a popular and competitive cosmological test of the standard cosmological model. The abundances and spatial distributions of galaxy clusters, which are associated with the highest peaks in the matter density field, provide another powerful probe of cosmic structure formation and evolution. In this talk, I will present the first cosmological constraints from the joint analysis of the auto/cross correlations of these three cosmic tracer fields and cluster abundances using data taken in the first season of the Dark Energy Survey (DES-Y1). Further, I will show that this analysis gives a precise constraint on the mass of galaxy clusters and compare this constraint with results from other techniques. Finally, improvements of this analysis in both simulations and modeling in the on-going analysis of DES-Y3 datasets will be presented. I will further discuss prospects of this analysis with ten years of data from the Legacy Survey of Space and Time (LSST).

Subhash Bose

Exploring the unexplored regime of Supernova diversity

In the past few years we found some peculiar and luminous hydrogen-rich SNe (LSNe-II), like ASASSN-15nx and ASASSN-18am, having a peak luminosity mag, which is in between normal ccSNe and SLSNe. Some previous studies hinted a possible `gap’ in luminosity (M_V ~ -18 and -20 mag)between CCSNe and SLSNe. A normal SN can easily attain this luminosity by means of ejecta-CSM interaction. However, in LSNe-II the lack of any interaction signatures in spectra or X-ray luminosity makes them unique with unknown powering mechanism. Some of the possible scenarios are – magnetar spin-down, large synthesized mass, or a very contrived ejecta-CSM interaction configuration somehow hiding interaction signatures in spectra. Detailed studies of more such objects are needed to weave a consistent picture of ccSNe diversity and to understand possible powering mechanisms that are beyond standard neutrino-driven explosion models.

Sumit K. Sarbadhicary

Unravelling supernova progenitors from radio surveys of supernovae and supernova remnants

Connecting supernovae with their progenitor stars is a major challenge in astrophysics. Some of the important open questions include: are thermonuclear supernovae mostly explosions of white dwarfs with a main-sequence, evolved giant or white dwarf companion? Is the explosion driven by accretion, merger, or collision with the companion? How often do the white dwarfs explode below the Chandrasekhar limit? For core-collapse supernovae, whose progenitors are massive stars, the precise mass range of stars that explode is presently unclear as a result of uncertainties in binary stellar evolution and the stellar structure of evolved massive stars. I will discuss addressing these topics with two unique strategies: (1) Studying the circumstellar material around the progenitor with radio observations. Radio serves as a clean tracer of circumstellar material produced by mass-loss from the progenitor prior to explosion. I will discuss new ongoing projects to observe radio supernovae very early and very late after the explosion to probe a wide-variety of circumstellar material. (2) Measuring the delay-time distribution of supernovae from supernova remnant surveys and star-formation history maps in the Local Group galaxies, which is a powerful way to constrain the age-distribution of supernova progenitors and directly connect with stellar population model predictions. I will finally discuss the ongoing VLA Local Group Survey — the most sensitive radio survey of six northern star-forming Local Group galaxies — M31, M33, NGC6822, IC10, IC1613, WLM — to uncover the deepest sample of radio supernova remnants, HII regions and atomic ISM in these galaxies, with exciting prospects for progenitor and stellar feedback studies.

Amy Sardone

Detecting Diffuse HI Around Nearby Galaxies

The circumgalactic medium (CGM) is host to large reservoirs of gas around galaxies, providing the fuel for galactic star formation. As gas flows from the intergalactic medium (IGM) and on into the CGM, we should be able to detect it as cold gas accretion. Much of this cold gas is too diffuse for easy detection. However, given the right observational set up, we should be able to see it. I will be focusing on recent results from our program to map the CGM of 18 galaxies in the MHONGOOSE survey in neutral hydrogen (HI) with the Green Bank Telescope. For this program we obtained deep observations with high HI column density sensitivity, and focused on the diffuse HI detected outside the disks of each galaxy, as this is the reservoir of gas expected to fuel star formation galaxies.

Samantha Benincasa

BESPOKE Galaxy Samples: A tailor-made approach to galaxy simulations

Feedback from massive stars shapes the ISM and galaxy evolution and yet the nature of star formation in the galactic context holds many as yet unsolved questions. With a growing compendium of high fidelity data from surveys with instruments like ALMA, HST and optical IFUS, we have an unprecedented view of dense gas, star clusters and star formation in galaxies spanning the star-forming main sequence. To contextualize these observational studies, there is a deep need for comparable theoretical work and, specifically, commensurate samples of simulated galaxies. I will discuss results from the BESPOKE (Better Extragalactic Simulation Physics on Known Examples) project. BESPOKE is creating an expanding survey of simulated galaxies that structurally match galaxies in the THINGS and PHANGS survey samples. The BESPOKE galaxies provide us with an unprecedented opportunity: to study the interplay between the ISM and stellar feedback across multiple scales and environments in simulated galaxies with the ability to truly benchmark against matched galaxy observations. I will present intriguing first results on this exciting new front.

David Martin

Small Circumbinary Planets - Do They Exist And How Do We Find Them?

A dozen transiting circumbinary planets have been discovered and they are all large and gaseous (> 3 Earth radii). It is natural to pose the question: do small circumbinary planets exist? I will attempt to answer this in two ways. First, observationally, I will show the first results from a new search using the STANLEY algorithm, which was custom-built to account for three-body geometry and dynamics. Second, I will complement this with a theoretical study on the plausibility of small circumbinary planets, investigating whether they are imperiled by slow migration speeds through treacherous mean motion resonances.

Mathieu Vrard

Red giant evolutionary status determination with Kepler data

The launch of the space missions CoRoT and Kepler brought a very important amount of long stellar light-curves. These long duration data allowed us to analyze with precision the variation of the luminosity of stars as a function of time, thus permitting us to obtain informations on the waves that are going through the star. This technique, called asteroseismology, is currently the only way to directly decipher the interior of stars through observations. Among the observed stars, the red giants showed peculiar oscillation waves, allowing us to sound their core. With this technique we can distinguish clump stars (burning their Helium in their core) from RGB stars (Burning their Hydrogen around an inert Helium core). Here I will present the last catalog of those objects that was constructed with the latest data from the Kepler satellite by merging different seismic evolutionary status determination techniques. The characteristics of the different objects for which a determination is possible or not will be presented. Finally, I will present a few new results we obtained on the red giant star evolution and characteristics by using this new catalog.

Fiorenzo Vincenzo

CNO dredge-up in a sample of APOGEE/Kepler red giants: Tests of stellar models and Galactic evolutionary trends of N/O and C/N

Surface abundances of C, N, and O in red giants are affected by processed material mixed into the stars' convective envelopes. Using a sample of ∼5100 stars with elemental abundances from APOGEE and asteroseismic masses from Kepler, we test theoretical stellar models that predict this mixing, then apply these models to derive birth C, N, and O abundances for these stars. Our models with standard mixing can reproduce the observed trends to within plausible uncertainties in the birth abundances. Some models with ''extra'' mixing processes fail, predicting trends with surface gravity or evolutionary state that are not observed. Applying mixing corrections to the APOGEE abundances removes the observed age-dependence of log(N/O) and log(C/N), but it leaves trends of log(N/O) and log(C/N) with metallicity, as expected based on nucleosynthesis models. The stellar N/O trend agrees well with Dopita et al.'s calibration of gas phase log(N/O) with metallicity, and with gas phase trends in the MaNGA integral field survey of nearby galaxies. We also find a substantial separation in birth [N/Mg] ratios between high-[α/Fe] (''thick disc'') stars and low-[α/Fe] (''thin disc'') stars. We find a smaller but still clear separation for [C/Mg]. The trends of birth C and N abundances with [Fe/H] and [α/Fe] could affect spectroscopic age estimates for red giants that rely on the observed C/N ratio as a diagnostic of stellar mass.

- Link to the paper: https://arxiv.org/abs/2106.03912

William Luszczak

Not Your Grandparent's Astronomy: Searching for the Origins of the Astrophysical Neutrino Flux

While the existence of the high energy astrophysical neutrino flux has been known since 2013, its precise origins remain a mystery. This is a particularly interesting problem, as identifying astrophysical neutrino point sources would allow us to examine regions of the universe typically inaccessible to more traditional photon-based astronomy. While the first hints of astrophysical neutrino point sources have potentially been seen in multi-messenger analyses of the blazars TXS 0506+056 and NGC 1068, a definitive explanation of the origins of the entire astrophysical neutrino flux has yet to be solidified. This talk will outline past efforts and future prospects for further exploring the origins of the astrophysical neutrino flux using both existing neutrino detectors (IceCube, ARA), as well as experiments planned for the near future (PUEO).

Steven Prohira

Toward detection of UHE neutrinos with the Radar Echo Telescope

Detecting ultra-high-energy (UHE) neutrinos is key to understanding the most energetic processes in the universe: the astrophysical sources of UHE cosmic rays which have been detected at earth with energies exceeding 1 Joule per nucleon. As UHE cosmic messengers, neutrinos are unparalleled for their ability to travel from source to Earth unimpeded, therefore pointing back to their origins. Unfortunately, however, they are very difficult to detect, owing to their low flux and small interaction cross section. In this talk I will discuss a novel, forthcoming experimental effort: the Radar Echo Telescope, which uses well-established radar technology to detect the cascade produced by these elusive neutrinos as they interact in polar ice. I'll discuss the theory and storied history of the radar echo method, recent laboratory work that validated the method, our current experimental efforts in service of UHE neutrino detection with radar, and future prospects.

Keith McBride

HELIX design and status

The High Energy Light Isotope eXperiment (HELIX) is a balloon-borne mass spectrometer optimized to measure the isotopes of Beryllium in cosmic rays. These secondary isotopes measurements at high energy (30 GeV) are important probes of cosmic ray propagation timescale in the Milky Way. HELIX is designed to measure these and other isotopes using a superconducting magnet, drift chamber tracker, and a Ring-Imaging Cherenkov detector. OSU plays a leading role in operations and design of the tracker and magnet subsystems along with the Data Acquisition. I will present a brief overview of HELIX which is aiming for a flight in the next year.

Marco Montella

Online Physics at the ATLAS experiment: an alternative approach to physics analysis at collider experiments

The ATLAS experiment is one of the four major collaborations purposed with the collection and analysis of the collisional data delivered by the Large Hadron Collider at CERN. The ATLAS Trigger and Data Acquisition system (TDAQ) stands at the core of the data processing chain, singling out potentially interesting events to be recorded for later analysis if a series of baseline kinematic requirements are met. The existing constraints in bandwidth, processing power and storage capabilities, which limit the ATLAS TDAQ output event rate, are reflected onto the kinematic thresholds an event has to meet to be written out for analysis. This in turn affects and limits the reach of the ALTAS physics programme, most severely with respect to valuable but unspectacular signatures such as low-mass resonances decaying into hadrons. We wish to present the Trigger-Level Analysis (TLA) framework, an alternative data acquisition and analysis workflow that partially mitigates the aforementioned ATLAS TDAQ limitations. Our goal is accomplished by recording and storing not the full detector-read out, as is standard practice for events passing the TDAQ criteria, but instead only a minimal kinematic description of each selected event. This strategy allows to increase the rate of written-out events by several orders of magnitudes without saturating the available bandwidth, unlocking new and exciting opportunities for physics research which lie beyond the reach of the traditional ATLAS offline analysis. In this talk we will cover the core principles, advantages and drawbacks of the TLA framework, present highlights from the previously published Trigger-Level research at ATLAS and lastly provide an overview of the ongoing work at ATLAS to improve and extend the TLA programme to a wider array of theoretically motivated physics signatures in view of the upcoming LHC Run 3 data-taking campaign.

Ivan Esteban

Neutrino interactions from the cosmos

Do neutrinos have sizable self-interactions? They might. Laboratory constraints are weak, so strong effects are possible in astrophysical environments and the early universe. In this talk, I will explore how neutrino self-interactions change our picture of the early universe and of high-energy astrophysical neutrino propagation. This leads to unique signatures that will be tested in next-generation observations, with potential links to measurements of neutrino masses and the Hubble constant.

Takahiro Sudoh

Multi-messenger Approach to Understanding Extreme Accelerators of Cosmic Rays

Recent gamma-ray observations have started to revolutionize our understanding of the high-energy sky. One major success is the discovery of mysterious sources around nearby pulsars, named “TeV Halos”. Another milestone is the detection of multiple sources with photon energies of more than 100 TeV. We discuss theoretical insights of these new observations. First, the TeV gamma-ray sky is dominated by sources powered by pulsars. Second, energetic pulsars are likely to accelerate electrons beyond PeV-scale energies. Finally, gamma-ray observations also suggest that recycled pulsars can significantly contribute to non-thermal emission from massive galaxies, modifying the famous radio—star-formation-rate correlation. Taking various messengers together, we will tackle the origin of cosmic-ray electrons and positrons.

Jung-Tsung Li

Dynamics of millicharged dark matter in supernova remnants

Milli-charged dark matter (mDM) is a leading DM candidate and has been extensively searched in the terrestrial DM experiments. It possesses fractional electric charge and allows DM to have electromagnetic interaction with baryons. In this work, we provide a mechanism for mDM to scatter efficiently with Standard Model particles in supernova remnants. The idea is that in the frame of the expanding supernova remnant, the ambient mDM represents a beam flowing into the remnant and may drive plasma waves, which in turn scatters them. Our work reveals that the supernova shocks could sweep up and thermalize the ambient mDM via plasma instability. However, these mDM particles return to having roughly the original/ambient DM velocity in the end due to the adiabatic decompression. We also address the difficulty of getting Fermi-accelerated mDM owing to an ultra-slow instability at the upstream of the shock. Our result implies that the detectability of terrestrial experiments to charged DM is, in fact, not strongly affected by supernova shocks, despite prior claims.