A5061573398- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Scientific Research and Discoveries
- Remote Sensing in Agriculture
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Plant Water Relations and Carbon Dynamics
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- Statistics Education and Methodologies
- Mathematics and Applications
- Spectroscopy and Laser Applications
- Advanced Vision and Imaging
York University
2018-2024
Tufts University
2014-2017
Here we present a sample of 12 massive quiescent galaxy candidates at [Formula: see text] observed with the James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec). These galaxies were pre-selected from Hubble imaging and 10 our sources unable to be spectroscopically confirmed by ground based spectroscopy. By combining spectroscopic data NIRSpec multi-wavelength JWST Camera (NIRCam), analyse their stellar populations formation histories. We find that all classify as on...
We present spectra of the most massive quiescent galaxy yet discovered at $z>3$, spectroscopically confirmed via detection Balmer absorption features in $H-$ and $K-$bands Keck/MOSFIRE. The confirm a with no significant ongoing star formation, consistent lack rest-frame UV flux overall photometric spectral energy distribution. With stellar mass $3.1^{+0.1}_{-0.2} \times 10^{11} ~\rm{M}_\odot$ $z = 3.493$, this is nearly three times more than highest redshift absorption-line identified known....
Abstract We present near-infrared spectroscopic confirmations of a sample 16 photometrically selected galaxies with stellar masses <?CDATA $\mathrm{log}({M}_{* }/{M}_{\odot })$?> >11 at redshift z > 3 from the XMM-VIDEO and COSMOS-UltraVISTA fields using Keck/MOSFIRE as part Massive Ancient Galaxies At NEar-infrared (MAGAZ3NE) survey. Eight ultramassive (UMGs) have specific star formation rates (sSFR) < 0.03 Gyr −1 , negligible emission lines. Another seven UMGs show lines...
We report the discovery of MAGAZ3NE J095924+022537, a spectroscopically-confirmed protocluster at $z = 3.3665^{+0.0009}_{-0.0012}$ around $UVJ$-quiescent ultra-massive galaxy (UMG; $M_{\star}=2.34^{+0.23}_{-0.34}\times10^{11} {\rm M}_\odot$) in COSMOS UltraVISTA field. present total 38 members (14 spectroscopic and 24 photometric), including UMG. Notably, marked contrast to protoclusters previously reported this epoch which have been found contain predominantly star-forming members, we...
Using the UltraVISTA catalogs, we investigate evolution in 11.4 Gyr since z = 3 of progenitors local ultra-massive galaxies (log (Mstar/M☉) ≈ 11.8; UMGs), providing a complete and consistent picture how most massive at 0 have assembled. By selecting with semi-empirical approach using abundance matching, infer growth stellar mass 0.56 dex, 0.45 0.27 dex from 3, 2, 1, respectively, to 0. At < UMGs constitute homogeneous population only quiescent old populations. > contribution star-forming...
We present the census of massive (log(M$_{*}$/M$_{\odot}$)$\geq 11$) galaxies at $3<z<6$ identified over COSMOS/UltraVISTA Ultra-Deep field stripes: consisting $\approx100$ and $\approx20$ high-confidence candidates $3<z<4$ $4<z<6$, respectively. The population is comprised post-starburst, UV star-forming dusty-star forming in roughly equal fractions, while UV-star-forming dominate $4<z<6$ . account for various sources biases SED modelling, finding that treatment emission line contamination...
We present a new rest-frame color-color selection method using "synthetic $u_s-g_s$ and $g_s-i_s$'', $(ugi)_s$ colors to identify star-forming quiescent galaxies. Our is similar the widely-used $U-V$ versus $V-J$ ($UVJ$) diagram. However, $UVJ$ suffers known systematics. Spectroscopic campaigns have shown that $UVJ$-selected samples at $z \gtrsim 3$ include $\sim 10-30\%$ contamination from galaxies with dust-obscured star formation strong emission lines. Moreover, $z>3$, are extrapolated...
We present spectroscopic confirmation of an ultra-massive galaxy (UMG) with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo>log</mml:mo><mml:mrow><mml:mo stretchy="true" form="prefix">(</mml:mo><mml:msub><mml:mi>M</mml:mi><mml:mo>⋆</mml:mo></mml:msub><mml:mi>/</mml:mi><mml:msub><mml:mi>M</mml:mi><mml:mo>⊙</mml:mo></mml:msub><mml:mo...
We present the analysis and results of a spectroscopic follow-up program mass-selected sample six galaxies at 3 < z 4 using data from Keck-NIRSPEC VLT-Xshooter. confirm > redshifts for half through detection strong nebular emission lines, improve zphot accuracy remainder combination photometry spectra. The modeling emission-line-corrected spectral energy distributions (SEDs) adopting improved confirms very large stellar masses (M_* ~ 1.5-4 x 10^11 Msun) in first 2 Gyrs cosmic history, with...
Abstract How massive early-type galaxies (ETGs) assembled their mass, on which timescales the star formation quenched, and when supersolar metallicity has been established are still open debated issues. Thanks to very deep spectroscopic observations carried out at Large Binocular Telescope, we simultaneously measured stellar age, metallicity, velocity dispersion for C1-23152, an ETG redshift z = 3.352, corresponding epoch universe was ∼1.8 Gyr old. The analysis of its spectrum shows that...
Abstract In this work, we publish stellar velocity dispersions, sizes, and dynamical masses for eight ultramassive galaxies (UMGs; <?CDATA $\mathrm{log}({M}_{* }/{M}_{\odot })$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mo>*</mml:mo> </mml:msub> stretchy="true">/</mml:mo> <mml:mo>⊙</mml:mo> stretchy="false">)</mml:mo> </mml:math> > 11), z ≳...
Abstract The measured ages of massive, quiescent galaxies at z ∼ 3–4 imply that massive quench as early 6. While the number spectroscopic confirmations < 3 has increased over years, there are only a handful > 3.5. We report redshifts one secure ( = 3.757) and two tentative 3.336 4.673) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow>...
Abstract Despite the ubiquity of clumpy star-forming galaxies at high-redshift, origin clumps are still largely unconstrained due to limited observations that can validate mechanisms for clump formation. We postulate if form accretion metal-poor gas leads violent disk instability, should have lower gas-phase metallicities compared nonclumpy galaxies. In this work, we obtain near-infrared spectrum 42 and similar masses, star formation rates, colors z ≈ 0.7 using Gemini Near-Infrared...
Using a sample of 98 galaxy clusters recently imaged in the near infra-red with ESO NTT, WIYN and WHT telescopes, supplemented 33 from archive, we measure how stellar mass most massive galaxies universe, namely Brightest Cluster Galaxies (BCG), increases time. Most BCGs this new lie redshift range $0.2<z<0.6$, which has been noted recent works to mark an epoch over growth stalls. From 132 clusters, create subsample 102 systems that includes only those have estimates cluster mass. We combine...
Abstract We present a study of the influence galaxy mergers on star formation at 0.3 < z 2.5. Major are selected from CANDELS/3D- HST catalog using peak-finding algorithm. Mergers have projected nucleus separation their members between 3 and 15 kpc. compare activity in merging nonmerging galaxies find no significant differences. that only 12% major (in which both <?CDATA $\mathrm{log}\,({M}_{\star }/{M}_{\odot })\geqslant 10$?> ) starbursting (i.e., with rate (SFR) above main sequence...
Abstract We present the formation histories of 19 massive (≳3 × 10 M ⊙ ) quiescent (specific star rate, sSFR < 0.15 Gyr −1 galaxy candidates at z ~ 3.0–4.5 observed using JWST/NIRSpec. This completes spectroscopic confirmation 24 K -selected sample from ZFOURGE and 3DHST surveys. Utilizing Prism 1–5 μ m spectroscopy, we confirm that all 12 sources eluded by ground-based spectroscopy lie > 3, resulting in a spectroscopically confirmed number density ~1.4 −5 Mpc −3 between 3 4....
We present the first spectroscopic confirmation of an ultramassive galaxy at redshift using data from Keck-NIRSPEC, VLT-X-shooter, and GTC-Osiris. detect strong [O iii] Lyα emission, weak ii], C iv, He ii, placing C1-23152 a . The modeling emission-line-corrected spectral energy distribution (SED) results in best-fit stellar mass , star formation rate <7 yr−1, negligible dust extinction. stars appear to have formed short intense burst ∼300–500 Myr prior observation epoch, setting this z ∼...
Abstract We present rest-frame optical spectra from Keck/MOSFIRE and Keck/NIRES of 16 candidate ultramassive galaxies targeted as part the Massive Ancient Galaxies at z > 3 Near-Infrared Survey (MAGAZ3NE). These candidates were selected to have photometric redshifts ≲ phot <4, stellar masses <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">log</mml:mi> </mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:msub>...
Abstract One of the challenges in understanding quenching processes for galaxies is connecting progenitor star-forming populations to their descendant quiescent over cosmic time. Here we attempt a novel approach this challenge by assuming that underlying stellar mass distribution not significantly altered during environmental-quenching solely affect gas content cluster galaxies, such as strangulation and ram pressure stripping. Using deep, high-resolution photometry Hubble Frontier Fields,...
The measured ages of massive, quiescent galaxies at $z\sim 3-4$ imply that massive quench as early 6$. While the number spectroscopic confirmations $z < 3$ has increased over years, there are only a handful > 3.5$. We report redshifts one secure ($z=3.757$) and two tentative ($z = 3.336$, $z=4.673$) ($\log(M_\ast/M_\odot) 10.3$) with 11 hours Keck/MOSFIRE $K$-band observations. Our candidates were selected from FENIKS survey, which uses deep Gemini/Flamingos-2 $K_b$ $K_r$ imaging optimized...
The formation of galaxies by gradual hierarchical co-assembly baryons and cold dark matter halos is a fundamental paradigm underpinning modern astrophysics predicts strong decline in the number massive at early cosmic times. Extremely quiescent (stellar masses $>10^{11}$ M$_\odot$) have now been observed as 1-2 billions years after Big Bang; these are extremely constraining on theoretical models they form 300-500 Myr earlier only some can this early. Here we report spectroscopic observations...
Abstract The resolved mass assembly of Milky Way–mass galaxies has been previously studied in simulations, the local Universe, and at higher redshifts using infrared (IR) light profiles. To better characterize Way analogs (MWAs), as well their changes star formation rate (SFR) color gradients, we construct stellar SFR maps MWA progenitors selected with abundance matching techniques up to z ∼2 deep, multiwavelength imaging data from Hubble Frontier Fields. Our results profiles agree previous...
Abstract We present the construction of a deep multiwavelength point-spread-function-matched photometric catalog in Ultra-Deep Survey (UDS) field following final UKIDSS UDS release. The includes photometry 24 filters, from MegaCam- uS 0.38 μ m band to Spitzer-IRAC 8 band, over ∼0.9 deg 2 and with 5 σ depth 25.3 AB K -band detection image. catalog, containing ≈188,564 (136,235) galaxies at 0.2 < z 8.0 stellar mass <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">...
Abstract We examine the quiescent fractions of massive galaxies in six z ≳ 3 spectroscopically confirmed protoclusters COSMOS field, one which is newly and presented here. report spectroscopic confirmation MAGAZ3NE J100143+023021 at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>3.122</mml:mn> </mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.004</mml:mn> <mml:mo>+</mml:mo> <mml:mn>0.007</mml:mn>...