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NASA NTRS2020

Atacama Cosmology Telescope: Component-separated maps of CMB temperature and the thermal Sunyaev-Zel'dovich effect

Optimal analyses of many signals in the cosmic microwave background (CMB) require map-level extraction of individual components in the microwave sky, rather than measurements at the power spectrum level alone. To date, nearly all map-level component separation in CMB analyses has been performed exclusively using satellite data. In this paper, we implement a component separation method based on the internal linear combination (ILC) approach which we have designed to optimally account for the anisotropic noise (in the 2D Fourier domain) often found in ground-based CMB experiments. Using this method, we combine multi-frequency data from the Planck satellite and the Atacama Cosmology Telescope Polarimeter (ACTPol) to construct the first wide area (≈2100 sq. deg.), arcminute-resolution component-separated maps of the CMB temperature anisotropy and the thermal Sunyaev-Zel'dovich (tSZ) effect sourced by the inverse-Compton scattering of CMB photons off hot, ionized gas. Our ILC pipeline allows for explicit deprojection of various contaminating signals, including a modified blackbody approximation of the cosmic infrared background (CIB) spectral energy distribution. The cleaned CMB maps will be a useful resource for CMB lensing reconstruction, kinematic SZ cross-correlations, and primordial non-Gaussianity studies. The tSZ maps will be used to study the pressure pro les of galaxies, groups, and clusters through cross-correlations with halo catalogs, with dust contamination controlled via CIB deprojection. The data products described in this paper are available on LAMBDA.

Mathew S. Madhavacheril↗
NASA NTRS2019

A New Class of Changing-look LINERs

We report the discovery of six active galactic nuclei (AGNs) caught "turning on" during the first nine months of the Zwicky Transient Facility (ZTF) survey. The host galaxies were classified as low-ionization nuclear emission-line region galaxies (LINERs) by weak narrow forbidden line emission in their archival SDSS spectra, and detected by ZTF as nuclear transients. In five of the cases, we found via follow-up spectroscopy that they had transformed into broad-line AGNs, reminiscent of the changing-look LINER iPTF16bco. In one case, ZTF18aajupnt/AT2018dyk, follow-up Hubble Space Telescope ultraviolet and ground-based optical spectra revealed the transformation into a narrow-line Seyfert 1 with strong [Fe vii, x, xiv] and He ii λ 4686 coronal lines. Swift monitoring observations of this source reveal bright UV emission that tracks the optical flare, accompanied by a luminous soft X-ray flare that peaks ~60 days later. Spitzer follow-up observations also detect a luminous mid-infrared flare, implying a large covering fraction of dust. Archival light curves of the entire sample from CRTS, ATLAS, and ASAS-SN constrain the onset of the optical nuclear flaring from a prolonged quiescent state. Here we present the systematic selection and follow-up of this new class of changing-look LINERs, compare their properties to previously reported changing-look Seyfert galaxies, and conclude that they are a unique class of transients well-suited to test the uncertain physical processes associated with the LINER accretion state.

Sara Frederick↗
NASA NTRS1983

Large Deployable Reflector (LDR) - A concept for an orbiting submillimeter-infrared telescope for the 1990s

The history and background of the Large Deployable Reflector (LDR) are reviewed. The results of the June 1982 Asilomar (CA) workshop are incorporated into the LDR science objectives and telescope concept. The areas where the LDR may have the greatest scientific impact are in the study of star formation and planetary systems in the own and nearby galaxies and in cosmological studies of the structure and evolution of the early universe. The observational requirements for these and other scientific studies give rise to a set of telescope functional requirements. These, in turn, are satisfied by an LDR configuration which is a Cassegrain design with a 20 m diameter, actively controlled, segmented, primary reflector, diffraction limited at a wavelength of 30 to 50 microns. Technical challenges in the LDR development include construction of high tolerance mirror segments, surface figure measurement, figure control, vibration control, pointing, cryogenics, and coherent detectors. Project status and future plans for the LDR are discussed.

Swanson, P. N.↗
NASA NTRS1975

The effect of suprathermal protons on the physical conditions in Seyfert galaxy nuclei II

The radiative transfer of Ly-alpha, Ly-beta, and H-alpha in a hydrogen gas containing dust was considered with application to the nuclear gas in Seyfert galaxies. By neglecting the direct escape of line radiation and by averaging over the gas, the radiation transfer in space is suppressed and the frequency transfer only is considered. The dust degrades the line radiation via frequency-independent absorption, converting the energy to infrared luminosity. The source functions in the lines were solved, using appropriate approximations, in order to determine under what conditions the narrow component of the Balmer line radiation from the gas can be self-absorbed and degraded without similar degradation of the broad component, which originates from the suprathermals themselves. The results are used to find self-consistent values for the temperature and ionization of the gas for various amounts of dust and various concentrations of suprathermal particles.

Stoner, R.↗
NASA NTRS1977

Spectrum and isotropy of the submillimeter background radiation

Infrared evidence referable to the spectrum and isotropy of the background radiation of the universe is considered, along with theoretical implications. Difficulties in the submillimeter region are indicated. Two types of anisotropy are treated: small-scale granularity (attributable to discrete sources such as galaxies or to condensation in the primordial plasma) and large-scale anisotropies; the anisotropies are discussed as possible indicators of the early history of the universe, and in relation to future possible generalized Michelson-Morley experiments (to detect effects on local physics of the existence of a universal rest frame). A complete blackbody spectrum is seen as the clear signature of the primordial fireball, and slight deviations from a perfect thermal spectrum (or perfect isotropy) are to be sought and scrutinized.

Muehlner, D.↗
NASA NTRS1990

Space Infrared Telescope Facility (SIRTF) implementation plans

This paper describes the Space Infrared Telescope Facility (SIRFT) mission planned by NASA for a launch by a Titan IV launch vehicle near the end of this decade. Special attention is given to the SIRFT's scientific goals, instruments, and technology. The cryogenically cooled SIRFT will utilize three scientific instruments, the Infrared Array Camera, the Infrared Spectrograph, and the Multiband Imaging Photometer for SIRFT and will achieve sensitivities 100 to 10,000 times greater than previous space telescope missions. During its five or six years of operation, SIRFT is expected to yield information on the formation and evolution of galaxies and stars and the solar-system phenomena and supernovae, as well as on the formation of other solar systems.

Spehalski, Richard J.↗
NASA NTRS1993

(abstract) Supernova Remnant and Molecular Clouds

Upon impact of the shockwaves generated by a supernova remnant, molecular gas and the associated dust grains are substantially excited and become prominent sources of infrared emission. Recent studies of such interactions, utilizing the infrared data and information from other wavelengths, have revealed many details of the physical processes in the interstellar medium. In particluar, the understanding of the temperature and ionization structures in the postshock material is helpful in modeling the star-gas cycles in the Galaxy, and probing the circumstances of star formation.

medium molecular gas↗
NASA NTRS2009

A Smoking Gun in the Carina Nebula

The Carina Nebula is one of thc youngest, most active sites of massive star formation in our Galaxy. In this nebula, we have discovered a bright X-ray source that has persisted for approx.30 years. The soft X-ray spectrum. consistent with kT approx.130 eV blackbody radiation with mild extinction, and no counterpart in the near- and mid-infrared wavelengths indicate that it is a, approx. 10(exp 6)-year-old neutron star housed in the Carina Nebula. Current star formation theory does not suggest that the progenitor of the neutron star and massive stars in the Carina Nebula, in particular (eta)Car, are coeval. This result demonstrates that the Carina Nebula experienced at least two major episodes of massive star formation. The neutron star would be responsible for remnants of high energy activity seen in multiple wavelengths.

Hamaguchi, Kenji↗
NASA NTRS2013

Is There a Metallicity Ceiling to Form Carbon Stars? - A Novel Technique Reveals a Scarcity of C-Stars in the Inner M31 Disk

We use medium-band near-infrared (NIR) Hubble Space Telescope WFC3 photometry with model NIR spectra of Asymptotic Giant Branch (AGB) stars to develop a new tool for efficiently distinguish- ing carbon-rich (C-type) AGB stars from oxygen-rich (M-type) AGB stars in galaxies at the edge of and outside the Local Group. We present the results of a test of this method on a region of the inner disk of M31, where we nd a surprising lack of C stars, contrary to the ndings of previous C star searches in other regions of M31. We nd only 1 candidate C star (plus up to 6 additional, less certain C stars candidates), resulting in an extremely low ratio of C to M stars (C=M = (3.3(sup +20)(sub - 0.1) x 10(sup -4)) that is 1-2 orders of magnitude lower than other C/M estimates in M31. The low C/M ratio is likely due to the high metallicity in this region which impedes stars from achieving C/O > 1 in their atmospheres. These observations provide stringent constraints to evolutionary models of metal-rich AGB stars and suggest that there is a metallicity threshold above which M stars are unable to make the transition to C stars, dramatically affecting AGB mass loss and dust production and, consequently, the observed global properties of metal-rich galaxies.

Metallicity↗
DOE OSTI2022

The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar, and APOGEE-2 Data

This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1986

Abundance studies of oxygen and nitrogen in nebulae - Uses of the far-infrared emission lines

The potential of infrared forbidden emission lines for studying nebular abundances is discussed, with emphasis on the far-infrared fine-structure lines of oxygen and nitrogen. Observations of these transitions provide fundamentally new diagnostics of the physical conditions in ionized nebulae, and make it possible for the first time to study the abundances of these species in the inner parts of the Galaxy. These new tools for nebular abundance studies are only beginning to be exploited. The results derived so far from such studies are reviewed, and future prospects and applications of these techniques are discussed.

Dinerstein, Harriet L.↗
NASA NTRS1994

Arm structure in normal spiral galaxies, 1: Multivariate data for 492 galaxies

Multivariate data have been collected as part of an effort to develop a new classification system for spiral galaxies, one which is not necessarily based on subjective morphological properties. A sample of 492 moderately bright northern Sa and Sc spirals was chosen for future statistical analysis. New observations were made at 20 and 21 cm; the latter data are described in detail here. Infrared Astronomy Satellite (IRAS) fluxes were obtained from archival data. Finally, new estimates of arm pattern radomness and of local environmental harshness were compiled for most sample objects.

Magri, Christopher↗
NASA NTRS2007

CALISTO: A Cryogenic Far-Infrared/Submillimeter Observatory

We present a design for a cryogenically cooled large aperture telescope for far-infrared astronomy in the wavelength range 30 micrometers to 300 micrometers. The Cryogenic Aperture Large Infrared Space Telescope Observatory, or CALISTO, is based on an off-axis Gregorian telescope having a 4 m by 6 m primary reflector. This can be launched using an Atlas V 511, with the only optical deployment required being a simple hinged rotation of the secondary reflector. The off-axis design, which includes a cold stop, offers exceptionally good performance in terms of high efficiency and minimum coupling of radiation incident from angles far off the direction of maximum response. This means that strong astronomical sources, such as the Milky Way and zodiacal dust in the plane of the solar system, add very little to the background. The entire optical system is cooled to 4 K to make its emission less than even this low level of astronomical emission. Assuming that detector technology can be improved to the point where detector noise is less than that of the astronomical background, we anticipate unprecedented low values of system noise equivalent power, in the vicinity of 10(exp -19) WHz(exp -0.5), through CALISTO's operating range. This will enable a variety of new astronomical investigations ranging from studies of objects in the outer solar system to tracing the evolution of galaxies in the universe throughout cosmic time.

Cryogenic Aperture Large Infrared Space Telescope ↗
DOE OSTI2023

Limited impact of jet-induced feedback in the multi-phase nuclear interstellar medium of 4C12.50

4C12.50 (IRAS 13451+1232) at z = 0.122 is an ultraluminous infared radio galaxy that has often been proposed as a prime candidate for the link between ultraluminous infared galaxies and young radio galaxies. It is also an interesting target to investigate whether and how radio-induced feedback affects the evolution of galaxies in the early phases of radio activity. We study, in detail for the first time, the hot (≥1500 K) molecular gas in 4C12.50. The potential impact of the radio jet on this gas phase, as well as on the star formation activity, are investigated. We also study the ionised (including coronal) gas as traced by the near-infrared lines. Using near-infrared long slit spectroscopy obtained with EMIR on GTC and X-shooter on VLT, we analyse the emission line spectrum of the ionised, coronal, and, specially, the hot molecular gas in the western nucleus hosting the compact radio jet. Based on high spatial resolution ALMA CO(2–1) data, we also revise the location of 4C12.50 in the Kennicutt-Schmidt diagram in order to investigate whether star formation is suppressed. 4C12.50 hosts (2.1 ± 0.4) × 10 4 M ⊙ of hot molecular gas. An unusually high rotational temperature T rot = 3020 ± 160 K is inferred. The molecular gas mass obeys a power-law temperature distribution, dM H2 /dT ∝ T –5 , from T ~300 K and up to ~3000 K. Both results support the idea that shocks (probably induced by the radio jet) contribute to the heating and excitation of the hot molecular gas. A molecular outflow is not detected. The coupling of the outflowing ionised and neutral outflows with the hot molecular gas is poor. Contrary to other studies, we claim that there is no evidence for star formation suppression in this object. If radio-induced feedback can regulate the star formation activity in galaxies, 4C12.50 is a promising candidate to reveal this phenomenon in action. However, we find no solid evidence for a current or past impact of this mechanism on the evolution of this system, neither by clearing out the dusty central cocoon efficiently, nor by suppressing the star formation activity.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1997

Mid-Infrared Observations of the Galactic Center

Under this grant, Susan Stolovy completed her thesis work and performed an analysis of the galactic center. For her thesis Susan analyzed observations of the galactic center obtained with the KAO using the KEGS spectrograph, built at Cornell. These observations present a study of the distribution and kinematics of the atomic gas in the inner few parsecs of the Galaxy as traced by the forbidden [SiII] line at 34.814 microns. The integrated [SiII] emission peaks near Sgr A* and extends past the inner edge of the Circumnuclear Disk (CND), passing through a gap in the dense molecular material to the northwest. The [SiII] maps have a spatial resolution of 15" and a spectral resolution of 50 km/s. The spectra, which are characterized by broad linewidths of order 100 km/s, are kinematically consistent with the CND rotation to the southwest but not to the north. The northern extension may be experiencing shocks and is likely to be infalling along the Northern Arm. Observations of high [Sill]/ [OI] and [SiII]/dust continuum ratios support the conjecture that turbulent motions and shocks in the inner few parsecs of the Galaxy are destroying dust grains, thus elevating the abundance of atomic silicon.

Stolovy, Susan↗
NASA NTRS1982

A technology program for the development of the large deployable reflector for space based astronomy

Technologies for the development of the Large Deployable Reflector (LDR), a NASA project for the 1990's, for infrared and submillimeter astronomy are presented. The proposed LDR is a 10-30 diameter spaceborne observatory operating in the spectral region from 30 microns to one millimeter, where ground observations are nearly impossible. Scientific rationales for such a system include the study of ancient signals from galaxies at the edge of the universe, the study of star formation, and the observation of fluctuations in the cosmic background radiation. System requirements include the ability to observe faint objects at large distances and to map molecular clouds and H II regions. From these requirements, mass, photon noise, and tolerance budgets are developed. A strawman concept is established, and some alternate concepts are considered, but research is still necessary in the areas of segment, optical control, and instrument technologies.

Kiya, M. K.↗
NASA NTRS1988

Observations of supernova SN1987a

Supernova SN1987a was discovered on February 23, 1987, in the Large Magellanic Cloud, a nearby galaxy that is visible only from the Southern Hemisphere. The NASA program for observations of SN1987a, which was developed rapidly after the discovery of the explosion, was designed to be implemented through a series of coordinated campaigns of gamma-ray, X-ray, ultraviolet, and infrared observations from spacecraft, rockets, balloons, aircraft and the ground. The author summarizes models for supernovae, recent results for SN1987a, and the NASA plans for further observations.

Riegler, Guenter R.↗
NASA NTRS1993

Supernova 1993J as a spectroscopic link between type II and type Ib supernovae

Supernova 1993J in the nearby galaxy M81 is one of the closest - and hence brightest - supernovae to be witnessed this century. The early spectrum of SN1993J showed the characteristic hydrogen signature of type II supernovae, but its subsequent evolution is atypical for this class of supernova. Here we present optical and infrared spectra of SN1993J up to 43 days after outburst, which reveal the onset of the helium absorption and emission features more commonly associated with hydrogen-free type Ib supernovae. Corresponding model spectra show that the progenitor star must have possessed an unusually thin (for type II supernovae) hydrogen-rich envelope overlying a helium-rich mantle. Moreover, the supernova ejecta must have remained compositionally stratified, with little transport of the hydrogen-rich material down into the underlying helium layer or mixing of heavier elements outwards. SN1993J therefore represents a transition object between hydrogen-dominated type II supernovae, and hydrogen-free, helium-dominated type Ib supernovae.

Swartz, D. A.↗