Rolf A. Jansen
A5023960152- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- GaN-based semiconductor devices and materials
- Gamma-ray bursts and supernovae
- Microwave Engineering and Waveguides
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Advanced Antenna and Metasurface Technologies
- Radio Frequency Integrated Circuit Design
- Ga2O3 and related materials
- Astrophysical Phenomena and Observations
- Semiconductor materials and devices
- Semiconductor Quantum Structures and Devices
- Astrophysics and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Radio Astronomy Observations and Technology
- Electromagnetic Simulation and Numerical Methods
- Electromagnetic Compatibility and Noise Suppression
- Silicon Carbide Semiconductor Technologies
- ZnO doping and properties
- History and Developments in Astronomy
- Pulsars and Gravitational Waves Research
- Metal and Thin Film Mechanics
Arizona State University
2016-2025
Idaho State Department of Education
2024
Royal Society Te Apārangi
2016-2019
University of Arizona
2019
RWTH Aachen University
2005-2014
University of Duisburg-Essen
1986-2006
Center for Astrophysics Harvard & Smithsonian
2000-2005
Smithsonian Astrophysical Observatory
2005
Dutch Health Care Inspectorate
2004
John Innes Centre
1988-2003
We present early observations of the afterglow GRB 030329 and spectroscopic discovery its associated supernova SN 2003dh. obtained spectra each night from March 30.12 (0.6 days after burst) to April 8.13 (UT) (9.6 burst). The cover a wavelength range 350-850 nm. consist power-law continuum (Fν ∝ ν-0.9) with narrow emission lines originating H II regions in host galaxy, indicating low redshift z = 0.1687. However, our taken 2003 5 show broad peaks flux characteristic supernova. Correcting for...
We present 1210 Johnson/Cousins B, V, R, and I photometric observations of 22 recent Type Ia supernovae (SNe Ia): SNe 1993ac, 1993ae, 1994M, 1994S, 1994T, 1994Q, 1994ae, 1995D, 1995E, 1995al, 1995ac, 1995ak, 1995bd, 1996C, 1996X, 1996Z, 1996ab, 1996ai, 1996bk, 1996bl, 1996bo, 1996bv. Most the photometry was obtained at Fred Lawrence Whipple Observatory Harvard-Smithsonian Center for Astrophysics in a cooperative observing plan aimed improving database Ia. The redshifts sample range from cz =...
We investigate the [O II] emission line as a star formation rate (SFR) indicator using integrated spectra of 97 galaxies from Nearby Field Galaxies Survey (NFGS). The sample includes all Hubble types and contains SFRs ranging 0.01 to 100 M⊙ yr-1. compare Kennicutt Hα SFR calibrations show that there are two significant effects produce disagreement between SFR([O II]) SFR(Hα): reddening metallicity. Differences in ionization state interstellar medium do not contribute significantly observed...
The Wide Field Infrared Survey Telescope (WFIRST) is a 2.4m space telescope with 0.281 deg^2 field of view for near-IR imaging and slitless spectroscopy coronagraph designed > 10^8 starlight suppresion. As background information Astro2020 white papers, this article summarizes the current design anticipated performance WFIRST. While WFIRST does not have UV imaging/spectroscopic capabilities Hubble Space Telescope, wide surveys hundreds times more efficient. Some most ambitious multi-cycle...
We give an overview and describe the rationale, methods, first results from NIRCam images of JWST "Prime Extragalactic Areas for Reionization Lensing Science" ("PEARLS") project. PEARLS uses up to eight filters survey several prime extragalactic areas: two fields at North Ecliptic Pole (NEP); seven gravitationally lensing clusters; high redshift proto-clusters; iconic backlit VV 191 galaxy system map its dust attenuation. also includes NIRISS spectra one NEP NIRSpec high-redshift quasars....
Abstract We present an analysis of the ultraviolet luminosity function (UV LF) and star formation rate density distant galaxies (7.5 < z 13.5) in “blank” fields Prime Extragalactic Areas for Reionization Lensing Science (PEARLS) survey combined with Early Release data from CEERS, GLASS, NGDEEP surveys/fields first release JADES. use strict quality cuts on EAZY photometric redshifts to obtain a reliable selection characterization high-redshift ( > 6.5) consistently processed set deep,...
Abstract A Type Ia supernova (SN) at z = 1.78 was discovered in James Webb Space Telescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165; 0.35). The SN is situated 1.5–2 kpc from host-galaxy nucleus and appears three different locations as a result gravitational lensing by G165. These data can yield value for Hubble’s constant using time delays this multiply imaged that we call “SN H0pe.” Over cluster, identified 21 image multiplicities, confirmed five them...
Abstract Recent JWST observations at z > 6 may imply galactic ionizing photon production above prior expectations. Under observationally motivated assumptions about escape fractions, these suggest a ~ 8–9 end to reionization, in tension with the < required by Ly α forest. In this work, we use radiative transfer simulations understand what different tell us when reionization ended and it started. We consider model that ends too early ( ≈ 8) alongside two more realistic scenarios 5: one...
A closed-form expression is presented for the effective dielectric constant of single microstrip lines which valid with high accuracy up to mm-wave frequencies. The formula given has been designed use in MIC and MMIC CAD programs as well indirect measurement substrate permittivities by resonance techniques.
In this paper, closed-form expressions are presented which model the frequency-dependent even- and odd-mode characteristics of parallel coupled microstrip lines with hitherto unattained accuracy range validity. They include effective dielectric constants, characteristic impedances using power-current formulation, as well open-end equivalent lengths for two fundamental modes on microstrip. The formulas accurate into millimeter-wave region. based an extensive set numerical data were generated...
A survey is given of the so-called spectral-domain approach, an analytical and numerical technique particularly suited for solution boundary-value problems in microwave millimeter-wave integrated circuits, The mathematical formulation part that approach described a generalized notation two- three-dimensional strip slot-type fields. In similar way, treated, keeping always touch with physical background, as well respective applications. discussion different specific aspects presented outlines...
We present extensive optical and infrared photometry of the afterglow gamma-ray burst (GRB) 030329 its associated supernova (SN) 2003dh over first two months after detection (2003 March 30-May 29 UT). Optical spectroscopy from a variety telescopes is shown and, when combined with photometry, allows an unambiguous separation between SN contributions. The GRB initially power-law continuum but shows significant color variations during week that are unrelated to presence SN. early light curve...
A comprehensive method of designing a broadband Doherty power amplifier is presented in this paper. The essential limitations bandwidth extension are discussed based on the proposed structure amplifier, which also takes output matching networks both sub-amplifiers into account. realized by applying simplified real frequency technique with desired frequency-dependent optimum impedances. GaN transistors were selected to implement circuit structure.
A closed form expression for the equivalent line length associated with single microstrip open end is presented use in microwave CAD programs. The maximum relative error involved less than 2.5% and its effect can be shown to below physical tolerances.
We use 101 galaxies selected from the Nearby Field Galaxy Survey (NFGS) to investigate effect of aperture size on star formation rate, metallicity and reddening determinations for galaxies.Our sample includes all Hubble types except ellipticals with global SFRs ranging 0.01 100 M ⊙ yr -1 , metallicities between 7.9 log(O/H) + 12 9.0, 0 A(V ) 3.3.We compare derived nuclear spectra those integrated spectra.For apertures capturing < 20% B 26 light, differences metallicity, extinction rate are...
We combine wide and deep galaxy number-count data from GAMA, COSMOS/G10, HST ERS, UVUDF various near-, mid- far- IR datasets ESO, Spitzer Herschel. The combined range the far-UV (0.15microns) to far-IR (500microns), in all cases contribution integrated light (IGL) of successively fainter galaxies converges. Using a simple spline fit, we derive IGL extrapolated-IGL bands. argue undetected low surface brightness intra-cluster/group is modest, that our measurements are an accurate...
ABSTRACT We present results from a multi-chord Pluto stellar occultation observed on 2015 June 29 New Zealand and Australia. This occurred only two weeks before the NASA Horizons flyby of system serves as useful comparison between ground-based space results. find that Pluto's atmosphere is still expanding, with significant pressure increase 5 ± 2% since 2013 factor almost three 1988. trend rules out, today, an atmospheric collapse associated recession Sun. A central flash, rare occurrence,...
The first James Webb Space Telescope (JWST) data on the massive colliding cluster El Gordo allow for 23 known families of multiply lensed images to be confirmed and eight new members these identified. Based families, which have been spectroscopically by MUSE, we derived an initial lens model. This model guided identification 37 additional galaxies, among 28 are entirely systems, nine were previously known. determined geometric redshifts systems. agree reasonably well with spectroscopic or...
Abstract We present a multiwavelength analysis using the Submillimeter Array (SMA), James Clerk Maxwell Telescope, NOEMA, JWST, Hubble Space Telescope (HST), and Spitzer of two dusty strongly star-forming galaxies, 850.1 850.2, seen through massive cluster lens A 1489. These SMA-located sources both lie at z = 4.26 have bright dust continuum emission, but 850.2 is UV-detected Lyman-break galaxy, while undetected ≲ 2 μ m, even with deep JWST/NIRCam observations. investigate their stellar,...
We present an analysis of a sample robust high redshift galaxies selected photometrically from the `blank' fields Prime Extragalactic Areas for Reionization Science (PEARLS) survey and Early Release Observations (ERO) data James Webb Space Telescope (JWST) with aim selecting candidate active galactic nuclei (AGN). Sources were identified parent using threefold selection procedure, which includes spectral energy distribution (SED) fitting to identify sources that are best fitted by AGN SED...
Abstract We report the results of James Webb Space Telescope/NIRCam observations 19 (sub)millimeter sources detected by Atacama Large Millimeter Array (ALMA). The accurate ALMA positions allowed unambiguous identifications their NIRCam counterparts. Taking gravitational lensing into account, these represent 16 distinct galaxies in three fields and constitute largest sample its kind to date. counterparts’ spectral energy distributions cover from rest-frame ultraviolet near-IR provide...
Abstract Supernova (SN) SN H0pe is a gravitationally lensed, triply imaged, Type Ia (SN Ia) discovered in James Webb Space Telescope imaging of the PLCK G165.7+67.0 cluster galaxies. Well-observed multiply imaged SNe provide rare opportunity to constrain Hubble constant ( H 0 ), by measuring relative time delay between images and modeling foreground mass distribution. located at z = 1.783 first with sufficient light-curve sampling long enough delays for an inference. Here we present...
Abstract We utilize deep JWST Near Infrared Camera (NIRCam) observations for the first direct constraints on Galaxy Stellar Mass Function (GSMF) at z > 10. Our EPOCHS v1 sample includes 1120 galaxy candidates 6.5 < 13.5 taken from a consistent reduction and analysis of publicly available NIRCam data covering Prime Extragalactic Areas Reionization Science, CEERS, GLASS, JADES GOOD-S, NGDEEP, SMACS0723 surveys, totaling 187 arcmin 2 . investigate impact spectral energy distribution...
Abstract The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits primary Wide-Field Camera 3 Ultraviolet and VISible light F275W imaging with coordinated parallel Advanced for Surveys F435W imaging, on four five premier extragalactic fields: GOODS-N, GOODS-S, EGS, COSMOS. We introduce this by presenting comprehensive analysis absolute...
We investigate the Hα and infrared star formation rate (SFR) diagnostics for galaxies in Nearby Field Galaxy Survey (NFGS). For 81 our sample, we derive fluxes (included here) from integrated spectra. There is a strong correlation between ratio of far-infrared to optical luminosities L(FIR)/L(Hα) extinction E(B-V) measured with Balmer decrement. Before reddening correction, SFR(IR) SFR(Hα) are related each other by power law: = (2.7 ± 0.3)SFR(Hα)1.30±0.06. Correction using decrement...