A5028428608- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Impact of Light on Environment and Health
- Adaptive optics and wavefront sensing
- Scientific Research and Discoveries
- Astrophysical Phenomena and Observations
- Advanced Statistical Methods and Models
- Astrophysics and Cosmic Phenomena
- Remote Sensing in Agriculture
- CCD and CMOS Imaging Sensors
- Advanced Image Processing Techniques
- Plant Water Relations and Carbon Dynamics
- Geological and Geochemical Analysis
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Advanced Vision and Imaging
- Relativity and Gravitational Theory
- High-pressure geophysics and materials
- Reservoir Engineering and Simulation Methods
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
Yale University
2014-2023
Max Planck Institute for Astronomy
2018-2023
Whitney Museum of American Art
2014-2016
We report the discovery of 47 low surface brightness objects in deep images a 3° × field centered on Coma cluster, obtained with Dragonfly Telephoto Array. The have central μ(g, 0) ranging from 24–26 mag arcsec−2 and effective radii reff = 3''–10'', as measured archival Canada–France–Hawaii Telescope images. From their spatial distribution we infer that most or all are galaxies cluster. This relatively large distance is surprising it implies very large: 1.5–4.6 kpc sizes similar to those L*...
Recently a population of large, very low surface brightness, spheroidal galaxies was identified in the Coma cluster. The apparent survival these Ultra Diffuse Galaxies (UDGs) rich cluster suggests that they have high masses. Here we present stellar kinematics Dragonfly 44, one largest UDGs, using 33.5 hr integration with DEIMOS on Keck II telescope. We find velocity dispersion 47 km/s, which implies dynamical mass M_dyn=0.7x10^10 M_sun within its deprojected half-light radius r_1/2=4.6 kpc....
We present the unexpected discovery of four ultra diffuse galaxies (UDGs) in a group environment. recently identified seven extremely low surface brightness vicinity spiral galaxy M101, using data from Dragonfly Telephoto Array. The have effective radii $10"-38"$ and central brightnesses $25.6-27.7$ mag arcsec$^{-2}$ g-band. subsequently obtained follow-up observations with $HST$ to constrain distances these galaxies. Four remain persistently unresolved even spatial resolution $HST$/ACS,...
We use a new telescope concept, the Dragonfly Telephoto Array, to study low surface brightness outskirts of spiral galaxy M101. The radial profile is measured down mu_g ~ 32 mag/arcsec^2, depth that approaches sensitivity star count studies in Local Group. convert mass density using g-r color profile. shows no significant upturn at large radius and well-approximated by simple bulge + disk model out R = 70 kpc, corresponding 18 scale lengths. Fitting halo we find best-fitting M_halo 1.7 x...
Galaxies are thought to grow through accretion; as less massive galaxies disrupted and merge over time, their debris results in diffuse, clumpy stellar halos enveloping the central galaxy. Here we present a study of variation galaxies, using data from Dragonfly Nearby Survey (DNGS). The survey consists wide field, deep ($μ_{g} > 31$ mag arcsec$^{-2}$) optical imaging nearby Telephoto Array. Our sample includes eight spiral with masses similar that Milky Way, inclinations $16-90$ degrees...
We present Hubble Space Telescope imaging of two ultra diffuse galaxies (UDGs) with measured stellar velocity dispersions in the Coma cluster. The galaxies, Dragonfly 44 and DFX1, have effective radii 4.7 kpc 3.5 $47^{+8}_{-6}$ km/s $30^{+7}_{-7}$ km/s, respectively. Both are associated a striking number compact objects, tentatively identified as globular clusters: $N_{\rm gc}=74\pm 18$ for gc}=62\pm 17$ DFX1. clusters is far higher than expected from luminosities but consistent expectations...
Dwarf satellite galaxies are a key probe of dark matter and galaxy formation on small scales the halo masses their central galaxies. They have very low surface brightness, which makes it difficult to identify study them outside Local Group. We used brightness-optimized telescope, Dragonfly Telephoto Array, search for dwarf in field massive spiral M101. seven large, brightness objects this field, with effective radii 10–30 arcseconds brightnesses μg ∼ 25.5–27.5 mag arcsec−2. Given large...
We recently identified a population of low surface brightness objects in the field z = 0.023 Coma cluster, using Dragonfly Telephoto Array. Here we present Keck spectroscopy one largest these "ultra-diffuse galaxies" (UDGs), confirming that it is member cluster. The galaxy has prominent absorption features, including Ca ii H+K lines and G-band, no detected emission lines. Its radial velocity cz 6280 ± 120 km s−1 within 1σ dispersion an effective radius 4.3 0.3 kpc Sérsic index 0.89 0.06, as...
Abstract A large population of ultra-diffuse galaxies (UDGs) was recently discovered in the Coma cluster. Here we present optical spectra three such UDGs, DF 7, 44, and 17, which have central surface brightnesses μ g ≈ 24.4–25.1 mag arcsec −2 . The were acquired as part an ancillary program within SDSS-IV MaNGA Survey. We stacked 19 fibers regions from larger integral field units (IFUs) per source. With over 13.5 hr on-source integration, achieved a mean signal-to-noise ratio 9.5 Å −1 , 7.9...
Abstract We recently found an ultra diffuse galaxy (UDG) with a half-light radius of R e = 2.2 kpc and little or no dark matter. The total mass NGC1052–DF2 was measured from the radial velocities bright compact objects that are associated galaxy. Here, we analyze these using combination Hubble Space Telescope ( HST ) imaging Keck spectroscopy. Their average size is pc their ellipticity . From stacked spectrum derive age ≳9 Gyr metallicity [Fe/H] −1.35 ± 0.12. properties similar to ω...
We obtained follow-up HST observations of the seven low surface brightness galaxies discovered with Dragonfly Telephoto Array in field massive spiral galaxy M101. Out galaxies, only three were resolved into stars and are potentially associated M101 group at $D=7\text{ Mpc}$. Based on ACS photometry broad F606W F814W filters, we use a maximum likelihood algorithm to locate Tip Red Giant Branch (TRGB) color-magnitude diagrams. Distances $6.38^{+0.35}_{-0.35}, 6.87^{+0.21}_{-0.30}$...
We present a description of the Dragonfly Wide Field Survey (DWFS), deep photometric survey wide area sky. The DWFS covers 330 $\mathrm{deg}^2$ in equatorial GAMA fields and Stripe 82 SDSS $g$ $r$ bands. It is carried out with 48-lens Telephoto Array, telescope that optimized for detection low surface brightness emission. main goal to study dwarf galaxy population beyond Local Group. In this paper, we describe design show early results. reach $1\sigma$ depths $\mu_g\approx 31$ mag...
Low surface brightness galactic stellar halos provide a challenging but promising path towards unraveling the past assembly histories of individual galaxies. Here, we present detailed comparisons between Milky Way-mass disk galaxies observed as part Dragonfly Nearby Galaxies Survey (DNGS) and mass-matched in TNG100 run IllustrisTNG project. We produce mass maps well mock $g$ $r$-band images for randomly oriented simulated galaxies, convolving latter with PSF taking care to match background...
Two ultra diffuse galaxies in the same group, NGC1052-DF2 and NGC1052-DF4, have been found to little or no dark matter host unusually luminous globular cluster populations. Such low mass objects a group environment are easily disrupted expected show evidence of tidal distortions. In this work we present deep new imaging NGC1052 obtained with Dragonfly Telephoto Array, test hypothesis. We find that both strong position angle twists significantly more elongated at their outskirts than...
We present HST/ACS imaging of twenty-three very low surface brightness ($\mu_{e,V}$=25-27.5) galaxies detected in the fields four nearby galaxy groups. These objects were selected from deep optical obtained with Dragonfly Telephoto Array. Seven are new discoveries, while most others had been identified previously visual surveys photographic plates and more recent surveys. Few have studied detail. From ACS images, we measure distances to using both tip red giant branch method fluctuations...
Abstract In 2008 it was reported that the stellar stream of edge-on spiral NGC 5907 loops twice around galaxy, enveloping in a giant corkscrew-like structure. Here we present imaging this iconic object with Dragonfly Telephoto Array, reaching 1 σ surface brightness level μ g = 30.3 mag arcsec −2 on spatial scales 1′ (the approximate width stream). We find qualitatively different morphology from study. The data do not show two but single curved total length 45′ (220 kpc). ranges ≈ 27.6 to...
Abstract We present the primary results from Dragonfly Edge-on Galaxies Survey, an exploration of stellar halos twelve nearby ( d < 25 Mpc) edge-on disk galaxies with Telephoto Array. The orientation these allows their to be explored minimal obscuration by or confusion much brighter light. in sample span a range masses 10 9.68 10.88 M ⊙ . confirm that wide halo mass fractions previously seen for Milky Way–mass is also found among less massive spiral galaxies. scatter fraction large, but...
We study the presence of tidal features associated with ultra diffuse galaxies (UDGs) in galaxy clusters. Specifically, we stack deep Subaru images UDGs Coma cluster to determine whether they show position angle twists at large radii. Selecting central surface brightness (g-band) >24 magarcsec^{-2} and projected half-light radius >1.5 kpc, identify 287 Yagi et al. 2016 catalog low objects. The have apparent spheroidal shapes median Sersic index ~ 0.8 axis-ratio 0.7. are processed by masking...
We recently published velocity measurements of luminous globular clusters in the galaxy NGC1052-DF2, concluding that it lies far off canonical stellar mass - halo relation. Here we present a revised for one clusters, GC-98, and dispersion measurement galaxy. find intrinsic $\sigma=5.6^{+5.2}_{-3.8}$ km/s using Approximate Bayesian Computation, or $\sigma=7.8^{+5.2}_{-2.2}$ likelihood. The expected from stars alone is ~7 km/s. Responding to request Editors ApJ Letters RNAAS, also briefly...
Abstract The stellar content of the intracluster light (ICL) provides unique insight into hierarchical assembly process galaxy clusters. We present optical spectra three ICL regions ( μ g ≈ 25.3–26.2 mag arcsec −2 ) in Coma cluster, located between 100 and 180 kpc from their nearest brightest cluster galaxies (BCGs): NGC 4889 4874. Integral-field unit (IFU) spectroscopy with 13.5 hr on-source integration was acquired an ancillary program within Sloan Digital Sky Survey-IV MaNGA survey....
We describe an empirical, self-contained method to isolate faint, large-scale emission in imaging data of low spatial resolution. Multi-resolution filtering (MRF) uses independent superior resolution and point source depth create a model for all compact high surface brightness objects the field. This is convolved with appropriate kernel subtracted from image. The halos bright stars are removed separate step artifacts masked. resulting image only contains extended fainter than pre-defined...
Abstract Uncertainty in the wide-angle point-spread function (PSF) at large angles (tens of arcseconds and beyond) is one dominant sources error a number important quantities observational astronomy. Examples include stellar mass shape galactic halos maximum extent starlight disks nearby galaxies. However, modeling PSF has long been challenge astronomical imaging. In this paper, we present self-consistent method to model images. Scattered light from multiple bright stars fitted...
We present the discovery of a giant cloud ionized gas in field starbursting galaxy M82. Emission from is seen H$\alpha$ and [NII]$\lambda$6583 data obtained though small pathfinder instrument used to test key ideas that will be implemented Dragonfly Spectral Line Mapper, an upcoming ultranarrow-bandpass imaging version Telephoto Array. The discovered has shell-like morphology with linear extent $0.8^{\circ}$ positioned $0.6^{\circ}$ northwest At heliocentric distance M81 group, cloud's...
Abstract We present deep g - and r -band imaging of the well-known edge-on galaxy NGC 4565 (the “Needle Galaxy”), observed as part Dragonfly Edge-on Galaxies Survey. The 3 σ local surface brightness contrast limit on 10″ scales is 28.616 ± 0.005 mag arcsec −2 for image 28.936 image. trace galaxy’s starlight in narrow slice profiles spanning over 90 kpc along major axis (with bin sizes ranging from 1.7 × 0.5 to 7.8 kpc) brightnesses below 29 . confirm previously asymmetric disk truncation...