A5043639808- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- Particle Accelerators and Free-Electron Lasers
- Cosmology and Gravitation Theories
- Scientific Research and Discoveries
- Spectroscopy and Laser Applications
- Particle accelerators and beam dynamics
- CCD and CMOS Imaging Sensors
- Superconducting and THz Device Technology
- Antenna Design and Optimization
- Data Analysis and Archiving
- Methane Hydrates and Related Phenomena
- Engineering Education and Pedagogy
- Genetics, Bioinformatics, and Biomedical Research
- Radio Wave Propagation Studies
University of Groningen
2017-2025
Netherlands Institute for Radio Astronomy
2016-2025
University of Glasgow
2023
Catalyst
2023
Chandler–Gilbert Community College
2020
Cornell University
2009-2018
The Netherlands Cancer Institute
2018
Children's Heart Center Nevada
2017
University of Nevada, Las Vegas
2017
University of California, San Diego
2005
We present a current catalog of 21 cm HI line sources extracted from the Arecibo Legacy Fast L-band Feed Array (ALFALFA) survey over ~2800 square degrees sky: alpha.40 catalog. Covering 40% final area, contains 15855 in regions 07h30m < R.A. 16h30m, +04 deg Dec. +16 and +24 +28 22h 03h, +14 +32 deg. Of those, 15041 are certainly extragalactic, yielding source density 5.3 galaxies per degree, factor 29 improvement Parkes All Sky Survey. In addition to centroid positions, flux densities,...
The precise localization of the repeating fast radio burst (FRB 121102) has provided first unambiguous association (chance coincidence probability $p\lesssim3\times10^{-4}$) an FRB with optical and persistent counterpart. We report on imaging spectroscopy counterpart find that it is extended ($0.6^{\prime\prime}-0.8^{\prime\prime}$) object displaying prominent Balmer [OIII] emission lines. Based spectrum line ratios, we classify as a low-metallicity, star-forming, $m_{r^\prime} = 25.1$ AB...
Abstract We present optical, near-infrared, and mid-infrared imaging of the host galaxy FRB 121102 with Gemini North telescope, Hubble Space Telescope , Spitzer . The is resolved, revealing a bright star-forming region located in outskirts irregular, low-metallicity dwarf galaxy. has half-light radius 0.68 kpc ( ), encompassing projected location compact pc), persistent radio source that associated 121102. diameter 5–7 kpc, broadband spectral energy distribution fitting indicates it total...
We present the catalog of ~31500 extragalactic HI line sources detected by completed ALFALFA survey out to z < 0.06 including both high signal-to-noise ratio (> 6.5) detections and ones lower quality which coincide in position recessional velocity with galaxies known redshift. review observing technique, data reduction pipeline, construction process, focusing on details particular relevance understanding catalog's compiled parameters. further describe make available digital spectra...
The discovery of a previously unknown 21cm HI line source identified as an ultra-compact high velocity cloud in the ALFALFA survey is reported. detection barely resolved by Arecibo 305m telescope ~4' beam and has narrow linewidth (HPFW 24 km/s). Further observations at with VLA corroborate detection, provide estimate radius, ~1' 5 x 10^19 cm^-2 isophote, show to exhibit rotation amplitude ~9.0 +/- 1.5 km/s. In other papers, Rhode et al. (2013) have stellar counterpart ongoing star forming...
We present KPNO 4-m and LBT/MODS spectroscopic observations of an HII region in the nearby dwarf irregular galaxy Leo P discovered recently Arecibo ALFALFA survey. In both observations, we are able to accurately measure temperature sensitive [O III] 4363 Angstrom line determine a "direct" oxygen abundance 12 + log(O/H) = 7.17 +/- 0.04. Thus, is extremely metal deficient (XMD) galaxy, and, indeed, one most star-forming galaxies ever observed. For its estimated luminosity, consistent with...
Leo P is a low-luminosity dwarf galaxy discovered through the blind HI Arecibo Legacy Fast ALFA (ALFALFA) survey. The and follow-up optical observations have shown that gas-rich with active star formation, an underlying older population, extremely low oxygen abundance. We obtained imaging Hubble Space Telescope to two magnitudes below red clump in order study evolution of P. refine distance measurement be 1.62+/-0.15 Mpc, based on luminosity horizontal branch stars 10 newly identified RR...
We study the gas kinematics traced by 21-cm emission of a sample six HI$-$rich low surface brightness galaxies classified as ultra-diffuse (UDGs). Using 3D kinematic modelling code $\mathrm{^{3D}}$Barolo we derive robust circular velocities, revealing startling feature: UDGs are clear outliers from baryonic Tully-Fisher relation, with velocities much lower than similar mass. Notably, baryon fraction our UDG is consistent cosmological value: these compatible having no "missing baryons" within...
Abstract We present a sample of 115 very low optical surface brightness, highly extended, H i -rich galaxies carefully selected from the ALFALFA survey that have similar absolute magnitudes, brightnesses, and radii to recently discovered “ultra-diffuse” (UDGs). However, these systems are bluer more irregular morphologies than other UDGs, isolated, contain significant reservoirs . find while sources normal star formation rates for -selected stellar mass, they efficiencies. further deep...
ABSTRACT We study the gas kinematics of a sample six isolated gas-rich low surface brightness galaxies, class called ultra-diffuse galaxies (UDGs). These have recently been shown to be outliers from baryonic Tully–Fisher relation (BTFR), as they rotate much slower than expected given their mass, and baryon fraction similar cosmological mean. By means 3D kinematic modelling fitting technique, we show that H i in our UDGs is distributed ‘thin’ regularly rotating discs determine rotation...
ABSTRACT We present new H i interferometric observations of the gas-rich ultra-diffuse galaxy AGC 114905, which previous work, based on low-resolution data, identified as an outlier baryonic Tully–Fisher relation. The observations, at a spatial resolution ∼2.5 times higher than before, reveal regular disc rotating about 23 km s−1. Our kinematic parameters, recovered with robust 3D modelling fitting technique, show that flat part rotation curve is reached. Intriguingly, can be explained...
The MHONGOOSE (MeerKAT H I Observations of Nearby Galactic Objects: Observing Southern Emitters) survey maps the distribution and kinematics neutral atomic hydrogen (H ) gas in around 30 nearby star-forming spiral dwarf galaxies to extremely low column densities. density sensitivity (3 σ over 16 km s −1 ranges from ∼5 × 10 17 cm −2 at 90″ resolution ∼4 19 highest 7″. mass 50 is ∼5.5 5 M ⊙ a distance Mpc (the median sample galaxies). velocity data 1.4 . One main science goals detection cold...
We present first results from the "Survey of HI in Extremely Low-mass Dwarfs" (SHIELD), a multi-configuration EVLA study neutral gas contents and dynamics galaxies with masses 10^6-10^7 Solar mass range detected by Arecibo Legacy Fast ALFA (ALFALFA) survey. describe survey motivation concept demonstration using VLA imaging 6 low-mass early ALFALFA data products. then primary scientific goals SHIELD preliminary WIYN 3.5m 12 galaxies. With only few exceptions, distributions these extremely are...
We present a catalog of 59 ultra-compact high velocity clouds (UCHVCs) extracted from the 40% complete ALFALFA HI-line survey. The UCHVCs have median flux densities 1.34 Jy km/s, angular diameters 10', and widths 23 km/s. show that full UCHVC population cannot easily be associated with known populations clouds. Of presented here, only 11 are also in compact cloud commensal GALFA-HI survey, demonstrating utility this separate dataset analysis. Based on their sky distribution observed...
The MIGHTEE large survey project will four of the most well-studied extragalactic deep fields, totalling 20 square degrees to $\mu$Jy sensitivity at Giga-Hertz frequencies, as well an ultra-deep image a single ~1 degree MeerKAT pointing. observations provide radio continuum, spectral line and polarisation information. As such, MIGHTEE, along with excellent multi-wavelength data already available in these allow range science be achieved. Specifically, is designed significantly enhance our...
We present results from ground-based optical imaging of a low-mass dwarf galaxy discovered by the ALFALFA 21-cm HI survey. Broadband (BVR) data obtained with WIYN 3.5-m telescope at Kitt Peak National Observatory (KPNO) are used to construct color-magnitude diagrams galaxy's stellar population down V_0 ~ 25. also use narrowband H-alpha KPNO 2.1-m identify an HII region in galaxy. these constrain distance be between 1.5 and 2.0 Mpc. This places Leo P within Local Volume but beyond Group. Its...
We present VLA HI spectral line imaging of 5 sources discovered by ALFALFA. These targets are drawn from a larger sample systems that were not uniquely identified with optical counterparts during ALFALFA processing, and as such have unusually high mass to light ratios. candidate "Almost Dark" objects fall into 4 categories: 1) nearby neighbors likely tidal origin; 2) appear be part system multiple sources, but which may in 3) isolated detections, located near gas-poor early-type galaxy; 4)...
We present the H I emission project within MIGHTEE survey, currently being carried out with newly commissioned MeerKAT radio telescope. This is one of first deep, blind, medium-wide interferometric surveys for neutral hydrogen (H ) ever undertaken, extending our knowledge to z = 0.6. The science goals this medium-deep, survey are extensive, including evolution gas content galaxies over past 5 billion years. Simulations predict nearly 3000 0 < 0.4 will be detected directly in , statistical...
Repeating fast radio bursts (FRBs) present excellent opportunities to identify FRB progenitors and host environments, as well decipher the underlying emission mechanism. Detailed studies of repeating FRBs might also hold clues origin a population. We aim detect first two FRBs: 121102 (R1) 180814.J0422+73 (R2), characterise their repeat statistics. want significantly improve sky localisation R2. use Westerbork Synthesis Radio Telescope conduct extensive follow-up these FRBs. The new...
(Abridged) Specific angular momentum is one of the key parameters that control evolution galaxies. We derive baryonic specific disc galaxies and study its relation with dark matter momentum. Using a combination high-quality HI rotation curves HI/near-IR surface densities, we homogeneously measure stellar ($j_{\rm *}$) gas gas}$) momenta for large sample local This allows us to determine bar}$) high accuracy across very wide range masses. The $j_{\ast}-M_\ast$ an unbroken power-law from $7...
ABSTRACT We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part Survey H i in Extremely Low-Mass Dwarfs project, which a multi-wavelength study galaxies with masses range 10 6 –10 7.2 M ⊙ , discovered by Arecibo Legacy Fast ALFA (ALFALFA) survey. have obtained spectra lone ii region 198691 new high-throughput KPNO Ohio State Multi-Object Spectrograph on Mayall 4 m, as well Blue Channel spectrograph MMT 6.5 m telescope. These enable measurement...
We describe the APERture Tile In Focus (Apertif) system, a phased array feed (PAF) upgrade of Westerbork Synthesis Radio Telescope that transforms this telescope into high-sensitivity, wide-field-of-view L -band imaging and transient survey instrument. Using novel PAF technology, up to 40 partially overlapping beams are formed on sky simultaneously, significantly increasing speed telescope. With upgraded instrument, an covering area 2300 deg 2 is being performed will deliver both continuum...
The relations between the specific angular momenta ( j ) and masses M of galaxies are often used as a benchmark in analytic models hydrodynamical simulations they considered to be amongst most fundamental scaling relations. Using accurate measurements stellar * ), gas baryonic bar for large sample disc galaxies, we report discovery tight correlations , cold fraction interstellar medium f ). At fixed follow parallel power laws 2D spaces, with gas-rich having larger (but lower than gas-poor...