arXiv subjects

Johannes Staguhn

Publications and source records attributed to Johannes Staguhn.

34 records · Page 2Linked to original sources

arXiv2019

Review: Far-Infrared Instrumentation and Technology Development for the Next Decade

Far-infrared astronomy has advanced rapidly since its inception in the late 1950's, driven by a maturing technology base and an expanding community of researchers. This advancement has shown that observations at far-infrared wavelengths are important in nearly all areas of astrophysics, from the search for habitable planets and the origin of life, to the earliest stages of galaxy assembly in the first few hundred million years of cosmic history. The combination of a still developing portfolio of technologies, particularly in the field of detectors, and a widening ensemble of platforms within which these technologies can be deployed, means that far-infrared astronomy holds the potential for paradigm-shifting advances over the next decade. In this review, we examine current and future far-infrared observing platforms, including ground-based, sub-orbital, and space-based facilities, and discuss the technology development pathways that will enable and enhance these platforms to best address the challenges facing far-infrared astronomy in the 21st century.

astro-ph.IM↗

arXiv2019

HAWC+/SOFIA Multiwavelength Polarimetric Observations of OMC-1

We report new polarimetric and photometric maps of the massive star-forming region OMC-1 using the HAWC+ instrument on the Stratospheric Observatory for Infrared Astronomy (SOFIA). We present continuum polarimetric and photometric measurements of this region at 53, 89, 154, and 214 microns at angular resolutions of 5.1, 7.9, 14.0, and 18.7 arcseconds for the four bands, respectively. The photometric maps enable the computation of improved SEDs for the region. We find that at the longer wavelengths, the inferred magnetic field configuration matches the `hourglass' configuration seen in previous studies, indicating magnetically-regulated star formation. The field morphology differs at the shorter wavelengths. The magnetic field inferred at these wavelengths traces the bipolar structure of the explosive Becklin-Neugebauer (BN)/Kleinman-Low (KL) outflow emerging from OMC-1 behind the Orion Nebula. Using statistical methods to estimate the field strength in the region, we find that the explosion dominates the magnetic field near the center of the feature. Farther out, the magnetic field is close to energetic equilibrium with the ejecta and may be providing confinement to the explosion. The correlation between polarization fraction and the local polarization angle dispersion indicates that the depolarization as a function of unpolarized intensity is a result of intrinsic field geometry as opposed to decreases in grain alignment efficiency in denser regions.

astro-ph.GA↗

arXiv2018

SOFIA Far Infrared Imaging Polarimetry of M82 and NGC 253: Exploring the Super-Galactic Wind

We present Far-Infrared polarimetry observations of M82 at 53 and $154~μ\rm{m}$ and NGC 253 at $89~μ\rm{m}$, which were taken with HAWC+ in polarimetry mode on the Stratospheric Observatory for Infrared Astronomy (SOFIA). The polarization of M82 at $53~μ\rm{m}$ clearly shows a magnetic field geometry perpendicular to the disk in the hot dust emission. For M82 the polarization at $154~μ\rm{m}$ shows a combination of field geometry perpendicular to the disk in the nuclear region, but closer to parallel to the disk away from the nucleus. The fractional polarization at $53~μ\rm{m}$ $(154~μ\rm{m})$ ranges from 7% (3%) off nucleus to 0.5% (0.3%) near the nucleus. A simple interpretation of the observations of M82 invokes a massive polar outflow, dragging the field along, from a region $\sim 700$~pc in diameter that has entrained some of the gas and dust, creating a vertical field geometry seen mostly in the hotter $(53~μ\rm{m})$ dust emission. This outflow sits within a larger disk with a more typical planar geometry that more strongly contributes to the cooler $(154~μ\rm{m})$ dust emission. For NGC 253, the polarization at $89~μ\rm{m}$ is dominated by a planar geometry in the tilted disk, with weak indication of a vertical geometry above and below the plane from the nucleus. The polarization observations of NGC 253 at $53~μ\rm{m}$ were of insufficient S/N for detailed analysis.

astro-ph.GA↗

arXiv2018

The Origins Space Telescope

The Origins Space Telescope, one of four large Mission Concept studies sponsored by NASA for review in the 2020 US Astrophysics Decadal Survey, will open unprecedented discovery space in the infrared, unveiling our cosmic origins. We briefly describe in this article the key science themes and architecture for OST. With a sensitivity gain of up to a factor of 1,000 over any previous or planned mission, OST will open unprecedented discovery space, allow us to peer through an infrared window teeming with possibility. OST will fundamentally change our understanding of our cosmic origins - from the growth of galaxies and black holes, to uncovering the trail of water, to life signs in nearby Earth-size planets, and discoveries never imagined. Built to be highly adaptable, while addressing key science across many areas of astrophysics, OST will usher in a new era of infrared astronomy.

astro-ph.IM↗

arXiv2018

SOFIA/HAWC+ detection of a gravitationally lensed starburst galaxy at $z$ = 1.03

We present the detection at 89 $μ$m (observed frame) of the {\it Herschel}-selected gravitationally lensed starburst galaxy HATLASJ1429-0028 (also known as G15v2.19) in 15 minutes with the High-resolution Airborne Wideband Camera-plus (HAWC+) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The spectacular lensing system consists of an edge-on foreground disk galaxy at $z$ = 0.22 and a nearly complete Einstein ring of an intrinsic ultra-luminous infrared galaxy at $z$ = 1.03. Is this high IR luminosity powered by pure star formation (SF) or also an active galactic nucleus (AGN)? Previous nebular line diagnostics indicate that it is star-formation dominated. We perform a 27-band multi-wavelength spectral energy distribution modeling (SED) including the new SOFIA/HAWC+ data to constrain the fractional AGN contribution to the total IR luminosity. The AGN fraction in the IR turns out to be negligible. In addition, J1429-0028 serves as a testbed for comparing SED results from different models/templates and SED codes (MAGPHYS, SED3FIT, and CIGALE). We stress that star formation history is the dominant source of uncertainty in the derived stellar mass (as high as a factor of $\sim$ 10) even in the case of extensive photometric coverage. Furthermore, the detection of a source at $z$ $\sim$ 1 with SOFIA/HAWC+ demonstrates the potential of utilizing this facility for distant galaxy studies including the decomposition of SF/AGN components, which cannot be accomplished with other current facilities.

astro-ph.GA↗

arXiv2018

An Analysis of ALMA Deep Fields and the Perceived Dearth of High-z Galaxies

Deep, pencil-beam surveys from ALMA at 1.1-1.3mm have uncovered an apparent absence of high-redshift dusty galaxies, with existing redshift distributions peaking around $z\sim1.5-2.5$. This has led to a perceived dearth of dusty systems at $z>4$, and the conclusion, according to some models, that the early Universe was relatively dust-poor. In this paper, we extend the backward evolution galaxy model described by Casey et al. (2018) to the ALMA regime (in depth and area) and determine that the measured number counts and redshift distributions from ALMA deep field surveys are fully consistent with constraints of the infrared luminosity function (IRLF) at $z<2.5$ determined by single-dish submillimeter and millimeter surveys conducted on much larger angular scales ($\sim1-10$deg$^{2}$). We find that measured 1.1-1.3mm number counts are most constraining for the measurement of the faint-end slope of the IRLF at $z<2.5$ instead of the prevalence of dusty galaxies at $z>4$. Recent studies have suggested that UV-selected galaxies at $z>4$ may be particularly dust-poor, but we find their millimeter-wave emission cannot rule out consistency with the Calzetti dust attenuation law even by assuming relatively typical, cold-dust ($T_{\rm dust}\approx30\,$K) SEDs. Our models suggest that the design of ALMA deep fields requires substantial revision to constrain the prevalence of $z>4$ early Universe obscured starbursts. The most promising avenue for detection and characterization of such early dusty galaxies will come from future ALMA 2mm blank field surveys covering a few hundred arcmin$^{2}$ and the combination of existing and future dual-purpose 3mm datasets.

astro-ph.GA↗

arXiv2018

The Brightest Galaxies in the Dark Ages: Galaxies' Dust Continuum Emission During the Reionization Era

Though half of cosmic starlight is absorbed by dust and reradiated at long wavelengths (3$μ$m-3mm), constraints on the infrared through millimeter galaxy luminosity function (the `IRLF') are poor in comparison to the rest-frame ultraviolet and optical galaxy luminosity function, particularly at z>2.5. Here we present a backward evolution model for interpreting number counts, redshift distributions, and cross-band flux density correlations in the infrared and submillimeter sky, from 70$μ$m-2mm, using a model for the IRLF out to the epoch of reionization. Mock submillimeter maps are generated by injecting sources according to the prescribed IRLF and flux densities drawn from model spectral energy distributions that mirror the distribution of SEDs observed in $0 4$, and an alternate dust-rich early Universe model, where DSFGs dominate $\sim$90% of $z>4$ star-formation. We find that current submm/mm datasets do not clearly rule out either of these extreme models. We suggest that future surveys at 2mm will be crucial to measuring the IRLF beyond $z\sim4$. The model framework developed in this paper serves as a unique tool for the interpretation of multiwavelength IR/submm extragalactic datasets and will enable more refined constraints on the IRLF than can be made from direct measurements of individual galaxies' integrated dust emission.

astro-ph.GA↗

arXiv2015

Submillimeter Observations of CLASH 2882 and the Evolution of Dust in this Galaxy

Two millimeter observations of the MACS J1149.6+2223 cluster have detected a source that was consistent with the location of the lensed MACS1149-JD galaxy at z=9.6. A positive identification would have rendered this galaxy as the youngest dust forming galaxy in the universe. Follow up observation with the AzTEC 1.1 mm camera and the IRAM NOrthern Extended Millimeter Array (NOEMA) at 1.3 mm have not confirmed this association. In this paper we show that the NOEMA observations associate the 2 mm source with [PCB2012] 2882 ([PCB2012] 2882 is the NED-searchable name for this source.), source number 2882 in the Hubble Space Telescope ( HST) Cluster Lensing and Supernova (CLASH) catalog of MACS J1149.6+2223. This source, hereafter referred to as CLASH 2882, is a gravitationally lensed spiral galaxy at z=0.99. We combine the GISMO 2 mm and NOEMA 1.3 mm fluxes with other (rest frame) UV to far-IR observations to construct the full spectral energy distribution (SED) of this galaxy, and derive its star formation history, and stellar and interstellar dust content. The current star formation rate of the galaxy is 54/mu Msun yr-1, and its dust mass is about 5 10^7/mu Msun, where mu is the lensing magnification factor for this source, which has a mean value of 2.7. The inferred dust mass is higher than the maximum dust mass that can be produced by core collapse supernovae (CCSN) and evolved AGB stars. As with many other star forming galaxies, most of the dust mass in CLASH 2882 must have been accreted in the dense phases of the ISM.

astro-ph.GA↗

arXiv2014

Characterizing Extragalactic Anomalous Microwave Emission in NGC 6946 with CARMA

Using 1 cm and 3 mm CARMA and 2 mm GISMO observations, we follow up the first extragalactic detection of anomalous microwave emission (AME) reported by Murphy et al. 2010 in an extranuclear region (Enuc. 4) of the nearby face-on spiral galaxy NGC 6946. We find the spectral shape and peak frequency of AME in this region to be consistent with models of spinning dust emission. However, the strength of the emission far exceeds the Galactic AME emissivity given the abundance of polycyclic aromatic hydrocarbons (PAHs) in that region. Using our galaxy-wide 1 cm map (21" resolution), we identify a total of eight 21"x21" regions in NGC 6946 that harbour AME at >95% significance at levels comparable to that observed in Enuc. 4. The remainder of the galaxy has 1 cm emission consistent with or below the observed Galactic AME emissivity per PAH surface density. We probe relationships between the detected AME and dust surface density, PAH emission, and radiation field, though no environmental property emerges to delineate regions with strong versus weak or non-existent AME. On the basis of these data and other AME observations in the literature, we determine that the AME emissivity per unit dust mass is highly variable. We argue that the spinning dust hypothesis, which predicts the AME power to be approximately proportional to the PAH mass, is therefore incomplete.

astro-ph.GA↗

arXiv2014

Dust formation, evolution, and obscuration effects in the very high-redshift universe

The evolution of dust at redshifts z>9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally-condensed dust. Because of the low initial dust-to-gas mass ratio, grain destruction rates are low, so that CCSNe are net producers of interstellar dust. Galaxies with large initial gas mass or high mass infall rate will therefore have a more rapid net rate of dust production comported to galaxies with lower gas mass, even at the same star formation rate. The dust composition is dominated by silicates, which exhibit a strong rise in the UV opacity near the Lyman break. This "silicate-UV break" may be confused with the Lyman break, resulting in a misidentification of a galaxies' photometric redshift. In this paper we demonstrate these effects by analyzing the spectral energy distribution (SED) of MACS1149-JD, a lensed galaxy at z=9.6. A potential 2mm counterpart of MACS1149-JD has been identified with GISMO. While additional observations are required to corroborate this identification, we use this possible association to illustrate the physical processes and the observational effects of dust in the very high redshift universe.

astro-ph.GA↗

arXiv2012

SOFIA observations of S106: Dynamics of the warm gas

Context. The HII region/PDR/molecular cloud complex S106 is excited by a single O-star. The full extent of the warm and dense gas close to the star has not been mapped in spectrally resolved high-J CO or [CII] lines, so the kinematics of the warm, partially ionized gas, are unknown. Whether the prominent dark lane bisecting the hourglass-shaped nebula is due solely to the shadow cast by a small disk around the exciting star or also to extinction in high column foreground gas was an open question until now. Aims. To disentangle the morphology and kinematics of warm neutral and ionized gas close to the star, study their relation to the bulk of the molecular gas, and to investigate the nature of the dark lane. Methods. We use the heterodyne receiver GREAT on board SOFIA to observe velocity resolved spectral lines of [C II] and CO 11-10 in comparison with so far unpublished submm continuum data at 350 micron (SHARC-II) and complementary molecular line data. Results. The high angular and spectral resolution observations show a very complex morphology and kinematics of the inner S106 region, with many different components at different excitation conditions contributing to the observed emission. The [C II] lines are found to be bright and very broad, tracing high velocity gas close to the interface of molecular cloud and HII region. CO 11-10 emission is more confined, both spatially and in velocity, to the immediate surroundings of S106 IR showing the presence of warm, high density (clumpy) gas. Our high angular resolution submm continuum observations rule out the scenario where the dark lane separating the two lobes is due solely to the shadow cast by a small disk close to the star. The lane is clearly seen also as warm, high column density gas at the boundary of the molecular cloud and HII region.

astro-ph.GA↗

arXiv2009

On the nature of the first galaxies selected at 350 microns

[abridged] We present constraints on the nature of the first galaxies selected at 350 microns. The sample includes galaxies discovered in the deepest blank-field survey at 350 microns (in the Bootes Deep Field) and also later serendipitous detections in the Lockman Hole. Spectral energy distribution templates are fit to identified counterparts, and the sample is found to comprise IR-luminous galaxies at 1<z<3 predominantly powered by star formation. The first spectrum of a 350-micron-selected galaxy provides an additional confirmation, showing prominent dust grain features typically associated with star-forming galaxies. Compared to submillimeter galaxies selected at 850 and 1100 microns, galaxies selected at 350 microns have a similar range of far-infrared color temperatures. However, no 350-micron-selected sources are reliably detected at 850 or 1100 microns. Galaxies in our sample with redshifts 1<z<2 show a tight correlation between the far- and mid-infrared flux densities, but galaxies at higher redshifts show a large dispersion in their mid- to far-infrared colors. The 350-micron flux densities (15<S(350)<40 mJy) place these objects near the Herschel/SPIRE 350-micron confusion threshold, with the lower limit on the star formation rate density suggesting the bulk of the 350-micron contribution will come from less luminous infrared sources and normal galaxies.

astro-ph.CO↗

arXiv2007

ExoPTF Science Uniquely Enabled by Far-IR Interferometry: Probing the Formation of Planetary Systems, and Finding and Characterizing Exoplanets

By providing sensitive sub-arcsecond images and integral field spectroscopy in the 25 - 400 micron wavelength range, a far-IR interferometer will revolutionize our understanding of planetary system formation, reveal otherwise-undetectable planets through the disk perturbations they induce, and spectroscopically probe the atmospheres of extrasolar giant planets in orbits typical of most of the planets in our solar system. The technical challenges associated with interferometry in the far-IR are greatly relaxed relative to those encountered at shorter wavelengths or when starlight nulling is required. A structurally connected far-IR interferometer with a maximum baseline length of 36 m can resolve the interesting spatial structures in nascent and developed exoplanetary systems and measure exozodiacal emission at a sensitivity level critical to TPF-I mission planning. The Space Infrared Interferometric Telescope was recommended in the Community Plan for Far-IR/Submillimeter Space Astronomy, studied as a Probe-class mission, and estimated to cost 800M dollars. The scientific communities in Europe, Japan, and Canada have also demonstrated a keen interest in far-IR interferometry through mission planning workshops and technology research, suggesting the possibility of an international collaborative effort.

astro-ph↗

arXiv2007

The Space Infrared Interferometric Telescope (SPIRIT): High-resolution imaging and spectroscopy in the far-infrared

We report results of a recently-completed pre-Formulation Phase study of SPIRIT, a candidate NASA Origins Probe mission. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their inhomogeneous composition; (2) characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with SPIRIT will be complementary to those of the James Webb Space Telescope and the ground-based Atacama Large Millimeter Array. All three observatories could be operational contemporaneously.

astro-ph↗

arXiv2004

350 micron Galactic Center Dust Observations with SHARC II

We present first and preliminary submillimeter continuum images of the Galactic Center region obtained with the new Caltech Submillimeter Observatory facility camera SHARC II. The instrument allows 350 micron observations with unprecedented sensitivity and instantaneous spatial coverage. The stability of the SHARC II detectors combined with the large number of available pixels allows a non-differential scanning mode that does not require the observation of a reference off-source position. Here we present large-scale 350 micron dust continuum images from the Sgr A and Sgr C regions, as well as the detection of sub-mm dust continuum emission from the IRAS 25 micron source AFGL5376. This source is produced in a large-scale shock that extends well above the Galactic plane.

astro-ph↗

arXiv2000

The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)

AST/RO, a 1.7 m diameter telescope for astronomy and aeronomy studies at wavelengths between 200 and 2000 microns, was installed at the South Pole during the 1994-1995 Austral summer. The telescope operates continuously through the Austral winter, and is being used primarily for spectroscopic studies of neutral atomic carbon and carbon monoxide in the interstellar medium of the Milky Way and the Magellanic Clouds. The South Pole environment is unique among observatory sites for unusually low wind speeds, low absolute humidity, and the consistent clarity of the submillimeter sky. Four heterodyne receivers, an array receiver, three acousto-optical spectrometers, and an array spectrometer are installed. A Fabry-Perot spectrometer using a bolometric array and a Terahertz receiver are in development. Telescope pointing, focus, and calibration methods as well as the unique working environment and logistical requirements of the South Pole are described.

astro-ph↗