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NASA NTRS2018

The Large UV/Optical/Infrared Surveyor (LUVOIR): Decadal Mission Study Update

NASA commissioned the study of four large mission concepts, including the Large Ultraviolet / Optical / Infrared (LUVOIR) Surveyor, to be evaluated by the 2020 Decadal Survey in Astrophysics. In response, the Science and Technology Definition Team (STDT) identified a broad range of science objectives for LUVOIR that include the direct imaging and spectral characterization of habitable exoplanets around sun-like stars, the study of galaxy formation and evolution, the exchange of matter between galaxies, star and planet formation, and the remote sensing of Solar System objects. To meet these objectives, the LUVOIR Study Office, located at NASA’s Goddard Space Flight Center (GSFC), completed the first design iteration of a 15-m segmented-aperture observatory that would be launched by the Space Launch System (SLS) Block 2 configuration. The observatory includes four serviceable instruments: the Extreme Coronagraph for Living Planetary Systems (ECLIPS), an optical / near-infrared coronagraph capable of delivering 10^-10contrast at inner working angles as small as 2 O/D; the LUVOIR UV Multi-object Spectrograph (LUMOS), which will provide low- and medium-resolution UV (100 – 400 nm) multi-object imaging spectroscopy in addition to far-UV imaging; the High Definition Imager (HDI), a high-resolution wide-field-of-view NUV-Optical-NIR imager; and Pollux, a high-resolution UV spectro-polarimeter being contributed by Centre National d’Etudes Spatiales (CNES).The study team has executed a second design iteration to further improve upon the 15-m concept, while simultaneously studying an 8-m concept. In these proceedings, we provide an update on these two architectures.

space telescopes↗
NASA NTRS1990

HI and FIR emission from S0 galaxies

A large body of work has accumulated in recent years which throws into disarray the traditional assumption that S0 systems are inert, non-starforming galaxies with uniform, old stellar populations. The copious 21-cm data have been recently reviewed and assessed by Wardle and Knapp (1986). This work showed that roughly a third of the several hundred observed S0's contain detectable amounts of neutral hydrogen (HI). More recently, Pogge and Eskridge (1987) have shown that a significant fraction of HI-rich systems also exhibit H alpha emission. Thronson et al. (1989) report detection of CO line emission from two thirds of the S0's in their sample. Both of these last papers, however, report on fairly small data sets (approx. 20 objects each). From co-added Infrared Astronomy Satellite (IRAS) data, Knapp et al. (1989) report that roughly two thirds of a sample of several hundred S0's are detected at 60 and 100 microns. Work by Bally and Thronson (1989) and Walsh et al. (1989) has shown that, while a large number of S0's follow a relation between radio continuum and far infrared radiation (FIR) emission similar to that found for spirals, significant numbers of both radio-bright, and FIR-bright S0's exist. Clearly, a large number of factors are involved in determining the state of the interstellar medium in S0 galaxies. The class is probably heterogeneous, suggesting that large data samples are required to sort out various sorts of objects. The 21 cm and FIR samples are the two largest currently available. It is therefore of interest to compare the two and see where this leads. The following results are already clear: HI and FIR flux data can be used to isolate strong candidates for systems which have gained their HI gas via accretion; a rough power-law relationship exists for galaxies which are undergoing relatively normal star-forming activity; a heterogeneous class of galaxies with strong FIR emission compared to their HI emission exists. Further work is required to determine the various physical processes responsible for this last class.

Eskridge, Paul B.↗
NASA NTRS1990

A model for the infrared emission from an OB star cluster environment

Researchers developed an interactive radiative transfer code that predicts the infrared emission from an HII region containing diffuse ionized and atomic gas and dense molecular clouds. This model complements the investigation of the redistribution of OB star luminosity in the interstellar medium (Leisawitz and Hauser 1988, Ap. J., 332, 954). The model can be used as a diagnostic tool to probe the radiation field and matter density in an HII region, place constraints on the proximity and orientation of an illuminated molecular cloud with respect to the ionizing stars, test for the presence of small, transiently heated dust grains, and determine whether the dust-to-gas ratio is normal. Predictions of the model agree qualitatively and quantitatively with observations of blister-type HII regions ionized by well-studied OB clusters in which the distribution of dense neutral material is known. This is illustrated by a model for Infrared Astronomy Satellite (IRAS) observations of the region around NGC 7380 (S142). Researchers plan to use the model in a survey of regions of massive star formation in the outer Galaxy to study OB stars embedded to various degrees in their parental molecular clouds.

Leisawitz, D.↗
NASA NTRS1992

158 micrometers (CII) mapping of the Orion molecular cloud

Data from the inner regions of the Orion nebula in the 157.7409 micrometers (CII) fine structure line is investigated. Large scale strip maps in (CII) across the face of the Orion molecular cloud, and CO spectra at selected positions in the Orion HII region/molecular cloud interface were obtained. The total (CII) luminosity from the Orion molecular cloud is estimated to be approximately 1500 of the solar luminosity or 0.3 of the far infrared luminosity. The overall properties of the Orion molecular cloud deduced are: the photodissociated gas to molecular gas mass fraction, the (CII) line to far infrared continuum intensity ratio and the (CII)/CO(12) (1 to 0) line intensity ratio are the same for the Orion molecular cloud and the nuclei of non-starburst galaxies. The observations provide an important link between (CII) emission from galactic molecular clouds and the nuclei of external galaxies.

Stacey, G. J.↗
NASA NTRS2016

Disk Detective: Discovery of New Circumstellar Disk Candidates Through Citizen Science

The Disk Detective citizen science project aims to find new stars with 22 micron excess emission from circumstellar dust using data from NASAs Wide-field Infrared Survey Explorer (WISE) mission. Initial cuts on the AllWISE catalog provide an input catalog of 277,686 sources. Volunteers then view images of each source online in 10different bands to identify false positives (galaxies, interstellar matter, image artifacts, etc.). Sources that survive this online vetting are followed up with spectroscopy on the FLWO Tillinghast telescope. This approach should allow us to unleash the full potential of WISE for finding new debris disks and proto planetary disks. We announce a first list of 37 new disk candidates discovered by the project, and we describe our vetting and follow-up process. One of these systems appears to contain the first debris disk discovered around a star with a white dwarf companion: HD 74389. We also report four newly discovered classical Be stars (HD 6612, HD 7406, HD 164137,and HD 218546) and a new detection of 22 micron excess around the previously known debris disk host star HD 22128.

NASAs Wide-field Infrared Survey Explorer (WISE) m↗
NASA NTRS1994

Spectroscopy of dwarf elliptical galaxies in the Fornax cluster

We present the results of spectroscopic observations of 10 nucleated dwarf elliptical galaxies (dE's) in the Fornax cluster. The blue spectra of Fornax dE galaxies indicate a wide range of metallicities at a given luminosity, similar to those of intermediate to metal-rich globular clusters. Metal abundances derived in this paper are well correlated with optical colors and agree with previous spectroscopic results. A discrepancy with metallicities inferred from infrared colors is evident; possible causes include an intermediate age population and dilution of spectral features by a blue light excess. Dwarf ellipticals exhibit a wide variation of hydrogen line strength which points to a complex star formation history. Prominent Balmer absorption lines are the signature of a young stellar population in the nuclei of some (but not all) dE's, while moderately strong Balmer lines in relatively metal-rich dE's are more consistent with an extended main sequence. In a few metal-poor dE galaxies, the hydrogen lines are consisent with, or perhaps weaker than, those found in Galactic globulars of similar metallicity. In the limited magnitude range of this sample, there is no apparent correlation of metallicity either with effective and central surface brightness, or with total and nuclear magnitudes. The velocity distribution of the Fornax dwarfs is flatter than that of brighter galaxies at the 75% confidence level, possibly indicating a difference in the kinematics of the two samples.

Held, Enrico V.↗
NASA NTRSDate not supplied

Nancy Grace Roman Space Telescope Observatory Implementation and Challenges

NASA’s Nancy Grace Roman Space Telescope (Roman) is a deep space infrared observatory with a Hubble-sized telescope and wide field of regard with a boresight view greater than 200 times that of the Hubble Wide Field Camera 3infrared field of view, that will conduct a suite of science surveys to characterize dark energy and expand the census of exoplanets in our galaxy. Roman will also demonstrate exoplanet coronagraphy with active wavefront control technology and provide general investigator opportunities for the science community. Roman is finishing the critical design phase and is planning for launch in 2026. It will operate at the second Sun-Earth-Moon Lagrange for a five-year primary mission life. The Observatory features a telescope with an existing, repurposed 2.4m primary mirror, a Wide Field Instrument with a near-infrared detector focal plane array and optical elements for imaging and spectroscopy, as well as a Coronagraph instrument technology demonstration for direct imaging and spectroscopy of exoplanets. The telescope and instruments are mounted to an Instrument Carrier for optical metering and isolation from Spacecraft-induced disturbances. The Spacecraft includes a Bus, Solar Array Sunshield, Deployable Aperture Cover, Outer Barrel Assembly, and Star Tracker/Inertial Reference Unit Bench. When fully integrated, Roman will be the largest Observatory assembled and tested at NASA’s Goddard Space Flight Center. The development of scientific satellites is challenging and pushes engineering boundaries to broaden scientific knowledge. The Roman mission implementation is a prime example and expected challenges have been amplified by the foundational decision to use existing, repurposed telescope components. Other unique aspects of the Roman mission, including its survey nature, large data volume, and Observatory packaging, create constrained design spaces that drive competing requirements across Observatory subsystems. Given these challenges, systems engineering has been a critical discipline in balancing implementation decisions and will continue to play a key role in the development of the Roman mission. This paper will discuss details of the Roman Observatory configuration, systems engineering challenges and the decision-making process used to mature the Roman Space Telescope from preliminary design to implementation.

Lisa M L Bartusek↗
NASA NTRS1980

Far-infrared forbidden O III line emission from the galactic center

The forbidden O III 51.8 micron fine-structure line has been detected in Sgr A West. It appears that the emission arises from the same compact clouds within the central parsec of the Galaxy which are observed in forbidden Ne II. The line intensity is used to derive an effective temperature of 32,000-40,000 K for the radiation field that ionizes the clouds. An upper limit is also reported for the forbidden O III 88.4 micron fine-structure line in Sgr A West. From this upper limit, one can conclude that the average electron density outside the known ionized clouds and within 30 arcsec of the galactic center is less than 40 per cu cm.

Watson, D. M.↗
NASA NTRS2015

Reconstructing Emission from Pre-Reionization Sources with Cosmic Infrared Background Fluctuation Measurements by the JWST

We present new methodology to use cosmic infrared background (CIB) fluctuations to probe sources at 10 less than or approx. equal to z less than or approx. equal to 30 from a James Webb Space Telescope (JWST) NIRCam configuration that will isolate known galaxies to 28 AB mag at 0.55 m. At present significant mutually consistent source-subtracted CIB fluctuations have been identified in the Spitzer and AKARI data at 25 m, but we demonstrate internal inconsistencies at shorter wavelengths in the recent CIBER data. We evaluate CIB contributions from remaining galaxies and show that the bulk of the high-z sources will be in the confusion noise of the NIRCam beam, requiring CIB studies. The accurate measurement of the angular spectrum of the fluctuations and probing the dependence of its clustering component on the remaining shot noise power would discriminate between the various currently proposed models for their origin and probe the flux distribution of its sources. We show that the contribution to CIB fluctuations from remaining galaxies is large at visible wavelengths for the current instruments precluding probing the putative Lyman-break of the CIB fluctuations. We demonstrate that with the proposed JWST configuration such measurements will enable probing the Lyman-break. We develop a Lyman-break tomography method to use the NIRCam wavelength coverage to identify or constrain, via the adjacent two-band subtraction, the history of emissions over 10 less than or approx. equal to z less than or approx. equal to 30 as the universe comes out of the Dark Ages. We apply the proposed tomography to the current SpitzerIRAC measurements at 3.6 and 4.5 m, to find that it already leads to interestingly low upper limit on emissions at z greater than or approx. equal to 30.

NIRCam beam↗
DOE OSTI2022

The Nascent Milliquasar VT J154843.06+220812.6: Tidal Disruption Event or Extreme Accretion State Change?

We present a detailed multiwavelength follow-up of the nuclear radio flare VT J154843.06+220812.6, hereafter VT J1548. VT J1548 was selected as a ~1 mJy radio flare in 3 GHz observations from the Very Large Array Sky Survey. It is located in the nucleus of a low-mass ($\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\odot }\sim 6$) host galaxy with weak or no past active galactic nuclei (AGN) activity. VT J1548 is associated with a slow rising (multiple year), bright mid-IR flare in the Wide-field Infrared Survey Explorer survey, peaking at ~10%L edd. . No associated optical transient is detected, although we cannot rule out a short, early optical flare given the limited data available. Constant late-time (~3 yr post-flare) X-ray emission is detected at ~10 42 erg s –1 . The radio spectral energy distribution is consistent with synchrotron emission from an outflow incident on an asymmetric medium. A follow-up, optical spectrum shows transient, bright, high-ionization coronal line emission ([Fe xi] λ6375, [Fe xi] λ7894, [S xii] λ7612). Transient broad Hα is also detected but without corresponding broad Hβ emission, suggesting high nuclear extinction. We interpret this event as either a tidal disruption event or an extreme flare of an AGN, in both cases obscured by a dusty torus. Although these individual properties have been observed in previous transients, the combination is unprecedented. This event highlights the importance of searches across all wave bands for assembling a sample of nuclear flares that spans the range of observable properties and possible triggers.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Limitations on thermal and nonthermal models for the radiation from extragalactic sources.

Both thermal and nonthermal models for the radiation from QSOs and Seyfert galaxies are discussed in terms of the size limitations imposed by the models. It is concluded that if daily fluctuations in the luminosity of Seyfert galaxies are confirmed and do represent a maximum size for the sources, then neither dust models nor ordinary synchrotron models can explain the radiation. Colgate's proposal involving the production of infrared radiation by a nonthermal plasma is considered, and a more detailed theory is derived which indicates that the process cannot produce infrared radiation.

Jones, T. W.↗
NASA NTRS1997

An Investigation of the Cold Interstellar Medium of the Outer Galaxy

The primary objective of this proposal was to determine the relationship between the molecular gas and dust components of the interstellar medium of the Outer Galaxy. It made use of the High Resolution IRAS Galaxy Atlas and the FCRAO CO Survey of the Outer Galaxy. These HIRES images greatly augment the spatial dynamic range of the IRAS Survey data and the ability to discriminate multiple point sources within a compact region. Additionally, the HIRES far infrared images allow for more direct comparisons with molecular line data observed at 45 sec resolution. From funding of this proposal, we have completed two papers for publication in a refereed journal.

Heyer, Mark H.↗
DOE OSTI2020

Prescriptions for Correcting Ultraviolet-based Redshifts for Luminous Quasars at High Redshift

High-redshift quasars typically have their redshift determined from rest-frame ultraviolet (UV) emission lines. However, these lines, and more specifically the prominent C IV λ1549 emission line, are typically blueshifted yielding highly uncertain redshift estimates compared to redshifts determined from rest-frame optical emission lines. We present near-infrared spectroscopy of 18 luminous quasars at 2.15 < z < 3.70 that allows us to obtain reliable systemic redshifts for these sources. Together with near-infrared spectroscopy of an archival sample of 44 quasars with comparable luminosities and redshifts, we provide prescriptions for correcting UV-based redshifts. Our prescriptions reduce velocity offsets with respect to the systemic redshifts by ~140 km s -1 and reduce the uncertainty on the UV-based redshift by ~25% with respect to the best method currently used for determining such values. We also find that the redshifts determined from the Sloan Digital Sky Survey Pipeline for our sources suffer from significant uncertainties, which cannot be easily mitigated. In conclusion, we discuss the potential of our prescriptions to improve UV-based redshift corrections given a much larger sample of high-redshift quasars with near-infrared spectra.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

XMM–Newton study of the Sculptor dwarf spheroidal galaxy

ABSTRACT We analysed observations with XMM–Newton in the field of the Sculptor dwarf spheroidal galaxy (dSph). The aim of the study was the classification of X-ray binaries and accreting white dwarfs belonging to the Sculptor dSph. Using different methods of X-ray timing and spectral analyses, together with an extensive multiwavelength study of the optical and infrared counterparts of the X-ray sources, we classified the sources detected with XMM–Newton in the field of the Sculptor dSph. The long-term variability of the sources has been studied over two XMM–Newton observations. None of the members of the Sculptor dSph show significant long-term variability over these two observations. We also searched for periodicity and pulsation using the Lomb–Scargle and Rayleigh Z$^{2}_{n}$ techniques. No signals of pulsation or periodicity have been found for the X-ray sources. The results show the presence of a noticeable number of background X-ray sources in the field of this galaxy. We classified 43 sources as active galactic nuclei, galaxies, and galaxy candidates. Three Galactic foreground stars have been identified in the field of the Sculptor dSph, and one of them is an M-dwarf candidate. Moreover, we classified four symbiotic-star candidates and three quiescent low-mass X-ray binary candidates in the Sculptor dSph. The luminosity of these X-ray sources is ∼1033−35 erg s−1.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Discovery of two bright high-redshift gravitationally lensed quasars revealed by Gaia

We present the discovery and preliminary characterisation of two high-redshift gravitationally lensed quasar systems in Gaia Data Release 2 (DR2). Candidates with multiple close-separation Gaia detections and quasar-like colours in WISE, Pan-STARRS, and DES are selected for follow-up spectroscopy with the New Technology Telescope. We confirm DES J215028.71-465251.3 as a $z$ = 4.130 ± 0.006 asymmetric, doubly imaged lensed quasar system and model the lensing mass distribution as a singular isothermal sphere. The system has an Einstein radius of 1.202 ± 0.005 arcsec and a predicted time delay of ~122.0 d between the quasar images, assuming a lensing galaxy redshift of $z$ = 0.5, making this a priority system for future optical monitoring. We confirm PS J042913.17+142840.9 as a $z$ = 3.866 ± 0.003 four-image quasar system in a cusp configuration, lensed by two foreground galaxies. The system is well modelled using a singular isothermal ellipsoid for the primary lens and a singular isothermal sphere for the secondary lens with Einstein radii 0.704 ± 0.006 and 0.241 ± 0.030 arcsec, respectively. A maximum predicted time delay of 9.6 d is calculated, assuming lensing galaxy redshifts of $z$ = 1.0. Furthermore, PS J042913.17+142840.9 exhibits a large flux ratio anomaly, up to a factor of 2.66 ± 0.37 in i band, that varies across optical and near-infrared wavelengths. We discuss LSST and its implications for future high-redshift lens searches and outline an extension to the search using supervised machine learning techniques.

Astronomy & Astrophysics↗
DOE OSTI2025

Constraints on f ( R ) gravity from thermal-Sunyaev-Zel’dovich-effect-selected SPT galaxy clusters and weak lensing mass calibration from DES and HST

We present constraints on the f ( R ) gravity model using a sample of 1005 galaxy clusters in the redshift range 0.25–1.78 that have been selected through the thermal Sunyaev-Zel’dovich effect from South Pole Telescope data and subjected to optical and near-infrared confirmation with the multicomponent matched filter algorithm. We employ weak gravitational lensing mass calibration from the Dark Energy Survey Year 3 data for 688 clusters at z < 0.95 and from the Hubble Space Telescope for 39 clusters with 0.6 < z < 1.7 . Our cluster sample is a powerful probe of f ( R ) gravity, because this model predicts a scale-dependent enhancement in the growth of structure, which impacts the halo mass function (HMF) at cluster mass scales. To account for these modified gravity effects on the HMF, our analysis employs a semianalytical approach calibrated with numerical simulations. Combining calibrated cluster counts with primary cosmic microwave background temperature and polarization anisotropy measurements from the Planck 2018 release, we derive robust constraints on the f ( R ) parameter f R 0 . Our results, log 10 | f R 0 | < − 5.32 at the 95% credible level, are the tightest current constraints on f ( R ) gravity from cosmological scales. This upper limit rules out f ( R ) -like deviations from general relativity that result in more than a ∼ 20 % enhancement of the cluster population on mass scales M 200 c > 3 × 10 14 M ⊙ . Published by the American Physical Society 2025

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1981

The diffuse galactic gamma radiation: The Compton contribution and component separation by energy interval and galactic coordinates

The radiation to be expected from cosmic ray interactions with matter and photons was examined. Particular emphasis is placed on the Compton emission. Both the photon density in and near the visible region and that in the region are deduced from the estimates of the emission functions throughout the Galaxy. The blackbody radiation is also included in the estimate of the total Compton emission. The result suggests that the gamma ray Compton radiation from cosmic ray ineractions with galactic visible and infrared photons is substantially larger than previously believed.

Kniffen, D. A.↗
NASA NTRS1990

Ar/S

Near-infrared spectroscopy at high altitude and low humidity has been carried out to accurately measure (Ar III) lambda 7136 and (S III) lambda 9069 in the extreme metal-poor dwarf irregular galaxy IZw18. The ratio of the abundance of argon to the abundance of sulfur is within about 0.2 dex of the value for the solar neighborhood. Since n(Ar)/n(S) appears to be a universal constant, the line ratio (AR III) lambda 7136/(S III) lambda 9069 may be a useful diagnostic of temperature in cool, metal-rich HII regions.

Mccall, Marshall L.↗