We present spatially-resolved spectroscopy from the Keck Cosmic Web Imager (KCWI) of a star-forming galaxy at z=0.6942, which shows emission from the Mg II 2796, 2803 Angstrom doublet in the circumgalactic medium (CGM) extending ~37 kpc at 3-sigma significance in individual spaxels (1-sigma detection limit 4.8 x 10^{-19} erg s^-1 cm^-2 arcsec^-2). After deconvolution with the seeing, we obtain 5-sigma detections extending for ~31 kpc measured in 7-spaxel (1.1 arcsec^2) apertures. Spaxels covering the galaxy stellar regions show clear P-Cygni-like emission/absorption profiles with the blueshifted absorption extending to relative velocities of v = -800 km/s; however, the P-Cygni profiles give way to pure emission at large radii from the central galaxy. We have performed three-dimensional radiative transfer modeling to infer the geometry and velocity and density profiles of the outflowing gas. Our observations are most consistent with an isotropic outflow rather than biconical wind models with half-opening angles phi <= 80 deg. Furthermore, our modeling suggests that a wind velocity profile that decreases with radius is necessary to reproduce the velocity widths and strengths of Mg II line emission profiles at large circumgalactic radii. The extent of the Mg II emission we measure directly is further corroborated by our modeling, where we rule out outflow models with extent <30 kpc.
Motivated by the recent discovery of the near-ubiquity of Ly$α$ emission around $z \gtrsim 3$ QSOs, we performed a systematic study of QSO circumgalactic Ly$α$ emission at $z\approx2$, utilizing the unique capability of the Keck Cosmic Web Imager (KCWI) -- a new wide-field, blue sensitive integral-field spectrograph (IFU). In this paper, we present KCWI observations on a sample of 16 ultraluminous Type-I QSOs at $z=2.1-2.3$ with ionizing luminosities of $L_{\rm{ν_{\rm{LL}}}}=10^{31.1-32.3}$ erg s$^{-1}$ Hz$^{-1}$. We found that 14 out of 16 QSOs are associated with Ly$α$ nebulae with projected…
The Circumgalactic Medium of Extreme Emission Line Galaxies at z ~ 2: Resolved Spectroscopy and Radiative Transfer Modeling of Spatially Extended Lyman-alpha Emission in the KBSS-KCWI Survey
本研究通过 KCWI 积分场观测和辐射转移模拟，揭示了 z~2 极端发射线星系中延展 Lyα 发射的径向变化，提出团块状多相外流模型，调和了外流速度测量，并指出非径向运动和外晕 HI 柱密度变化。
Revealing the Gas Recycling in the Circumgalactic Medium (CGM) Utilizing a Luminous Ly$α$ Nebula Around a Type-II Quasar at z=2.6 with the Keck Cosmic Web Imager (KCWI)
Enormous Ly$α$ nebulae (ELANe) represent the extrema of Ly$α$ nebulosities. They have detected extents of $>200$ kpc in Ly$α$ and Ly$α$ luminosities $>10^{44}$ erg s$^{-1}$. The ELAN population is an ideal laboratory to study the interactions between galaxies and the intergalactic/circumgalactic medium (IGM/CGM) given their brightness and sizes. The current sample size of ELANe is still very small, and the few $z\approx2$ ELANe discovered to date are all associated with local overdensities of active galactic nuclei (AGNs). Inspired by these results, we have initiated a survey of ELANe associat…
Observing the circumgalactic medium (CGM) in emission provides 3D maps of the spatial and kinematic extent of the gas that fuels galaxies and receives their feedback. We present mock emission-line maps of highly resolved CGM gas from the FOGGIE project (Figuring Out Gas & Galaxies in Enzo) and link these maps back to physical and spatial properties of the gas. By increasing the spatial resolution alone, the total luminosity of the line emission increases by an order of magnitude. This increase arises in the abundance of dense small-scale structure resolved when the CGM gas is simulated to < 10…
We present the first results from our CGM at Cosmic Noon with KCWI program to study gas flows in the circumgalactic medium (CGM) at $z=2-3$. Combining the power of a high-resolution VLT/UVES quasar spectrum, an HST/ACS image, and integral field spectroscopy with Keck/KCWI, we detected Lya emission from a $1.7L_{\ast}$ galaxy at $z_{\rm gal}=2.0711$ associated with a Lyman limit system with weak MgII ($W_r(2796)=0.24$ Ang) in quasar field J143040$+$014939. The galaxy is star-forming (${\rm SFR}_{\rm FUV}=37.8$ M$_{\odot}$ yr$^{-1}$) and clumpy: either an edge-on disk ($i=85^{\circ}$) or, less l…
We present a survey of the central region of the nearest starburst galaxy, IC 10, using the W. M. Keck Observatory Keck Cosmic Web Imager (KCWI) at high spectral and spatial resolution. We map the central starburst of IC 10 to sample the kinematic and ionization properties of the individual star-forming regions. Using the low spectral resolution mode of KCWI we map the oxygen abundance and with the high spectral resolution mode we identify 46 individual H II regions. These H II regions have an average radius of 4.0 pc, star formation rate $\sim1.3\times10^{-4}$ M$_\odot$ yr$^{-1}$, and velocit…
We present Atacama Large Millimeter/submillimeter Array (ALMA) 870um observations of 29 bright Herschel sources near high-redshift QSOs. The observations confirm that 20 of the Herschel sources are submillimeter-bright galaxies (SMGs) and identify 16 new SMG-QSO pairs that are useful to studies of the circumgalactic medium (CGM) of SMGs. Eight out of the 20 SMGs are blends of multiple 870um sources. The angular separations for six of the Herschel-QSO pairs are less than 10", comparable to the sizes of the Herschel beam and the ALMA primary beam. We find that four of these six "pairs" are actua…
We outline theoretical predictions for extended emission from MgII, tracing cool ~10^4 K gas in the circumgalactic medium (CGM) of star-forming galaxies in the high-resolution TNG50 cosmological magnetohydrodynamical simulation. We synthesize surface brightness maps of this strong rest-frame ultraviolet metal emission doublet (2796, 2803), adopting the assumption that the resonant scattering of MgII can be neglected and connecting to recent and upcoming observations with the Keck/KCWI, VLT/MUSE, and BlueMUSE optical integral field unit spectrographs. Studying galaxies with stellar masses 7.5 <…
The Two Component Circumgalactic Medium Emission around z~2 Radio-loud Quasars
University of Arizona（亚利桑那大学）；University of California San Diego（加州大学圣地亚哥分校）；Florida Gulf Coast University（佛罗里达海湾海岸大学）；California Institute of Technology（加州理工学院）；Canadian Institute for Theoretical Astrophysics, University of Toronto（多伦多大学加拿大理论天体物理研究所）；Carnegie Science（卡内基科学）；University of Maryland Baltimore County（马里兰大学巴尔的摩郡分校）
Red quasars may represent a young stage of galaxy evolution that provide important feedback to their host galaxies. We are studying a population of extremely red quasars (ERQs) with exceptionally fast and powerful outflows, at median redshift $z$ = 2.6. We present Keck/KCWI integral field spectra of 11 ERQs, which have a median color $i-W3$ = 5.9~mag, median $\left\langle L_{\text{bol}} \right\rangle$ $\approx$ 5 $\times$ $10^{47}$ erg s$^{-1}$, Ly$α$ halo luminosity $\left\langle L_{\text{halo}} \right\rangle$ $=$ 5 $\times$ $10^{43}$ erg s$^{-1}$, and maximum linear size $>128$ kpc. The ERQ …
The discovery of giant quasar Ly$α$ nebulae at $z>2$ has opened up the possibility to directly study in emission the Circumgalactic and Intergalactic Medium (CGM/IGM). However, the resonant nature of the Ly$α$ line and its different emission mechanisms hamper the ability to constrain both the kinematics and physical properties of the CGM/IGM. Here, we present results of a pilot project aiming at the detection of CGM H$α$ emission, a line which does not suffer from these limitations. To this end, we first used KCWI to detect Ly$α$ emission around three bright quasars with $2.25<z<2.27$, a range…
The multi-phase circumgalactic medium (CGM) arises within the complex environment around a galaxy, or collection of galaxies, and possibly originates from a wide range of physical mechanisms. In this paper, we attempt to disentangle the origins of these multi-phase structures and present a detailed analysis of the quasar field Q0122-003 field using Keck/KCWI galaxy observations and HST/COS spectra probing the CGM. Our re-analysis of this field shows that there are two galaxies associated with the absorption. We have discovered a dwarf galaxy, G_27kpc ($M_{\star}=10^{8.7}$ M$_{\odot}$), at z=0.…
Constraining the nature of active galactic nuclei through circumgalactic Lya emission at z=2-3
Tsinghua University（清华大学）；University of Milan Bicocca（米兰比可卡大学）；Universität Heidelberg（海德堡大学）；National Astronomical Observatory of Japan（日本国立天文台）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；Xi’an Jiaotong-Liverpool University（西交利物浦大学）
Ninety per cent of baryons are located outside galaxies, either in the circumgalactic or intergalactic medium. Theory points to galactic winds as the primary source of the enriched and massive circumgalactic medium. Winds from compact starbursts have been observed to flow to distances somewhat greater than ten kiloparsecs, but the circumgalactic medium typically extends beyond a hundred kiloparsecs. Here we report optical integral field observations of the massive but compact galaxy SDSS J211824.06+001729.4. The oxygen [O II] lines at wavelengths of 3726 and 3729 angstroms reveal an ionized ou…
Dusty quasars might be in a young stage of galaxy evolution with prominent quasar feedback. A recently discovered population of luminous, extremely red quasars at $z\sim$~2--4 has extreme spectral properties related to exceptionally powerful quasar-driven outflows. We present Keck/KCWI observations of the reddest known ERQ, at $z=$\,2.3184, with extremely fast [\ion{O}{III}]~$λ$5007 outflow at $\sim$6000~km~s$^{-1}$. The Ly$α$ halo spans $\sim$100~kpc. The halo is kinematically quiet, with velocity dispersion $\sim$300~km~s$^{-1}$ and no broadening above the dark matter circular velocity down …
Motivated by integral field units (IFUs) on large ground telescopes and proposals for ultraviolet-sensitive space telescopes to probe circumgalactic medium (CGM) emission, we survey the most promising emission lines and how such observations can inform our understanding of the CGM and its relation to galaxy formation. We tie our emission estimates to both HST/COS absorption measurements of ions around $z\approx 0.2$ Milky Way mass halos and models for the density and temperature of gas. We also provide formulas that simplify extending our estimates to other samples and physical scenarios. We f…
We develop a new method to infer the temporal, geometric, and energetic properties of galaxy outflows, by combining stellar spectral modeling to infer starburst ages, and absorption lines to measure velocities. If winds are accelerated with time during a starburst event, then these two measurements enable us to solve for the wind radius, similarly to length scales and the Hubble parameter in Big Bang cosmology. This wind radius is the vital, but hard-to-constrain parameter in wind physics. We demonstrate the method using spectra of 87 starburst galaxies at z=0.05-0.44, finding that winds accel…
In major galaxy mergers, the orbits of stars are violently perturbed, and gas is torqued to the centre, diluting the gas metallicity and igniting a starburst. In this paper, we study the gas dynamics in and around merging galaxies using a series of cosmological magneto-hydrodynamical (MHD) zoom-in simulations. We find that the gas bridge connecting the merging galaxies pre-coalescence is dominated by turbulent pressure, with turbulent Mach numbers peaking at values of 1.6-3.3. This implies that bridges are dominated by supersonic turbulence, and are thus ideal candidates for studying the impac…
We present Keck Cosmic Web Imager (KCWI) integral field spectroscopy (IFS) observations of rest-frame UV emission lines $\rm Lyα$, C IV $λλ$ 1548 Å, 1550Åand He II 1640 Åobserved in the circumgalactic medium (CGM) of two $z=2$ radio-loud quasar host galaxies. We detect extended emission on 80-90 kpc scale in $\rm Lyα$ in both systems with C IV, and He II emission also detected out to 30-50 kpc. All emission lines show kinematics with a blue and redshifted gradient pattern consistent with velocities seen in massive dark matter halos and similar to kinematic patterns of inflowing gas seen in hyd…
Winds are predicted to be ubiquitous in low-mass, actively star-forming galaxies. Observationally, winds have been detected in relatively few local dwarf galaxies, with even fewer constraints placed on their timescales. Here, we compare galactic outflows traced by diffuse, soft X-ray emission from Chandra Space Telescope archival observations to the star formation histories derived from Hubble Space Telescope imaging of the resolved stellar populations in six starburst dwarfs. We constrain the longevity of a wind to have an upper limit of 25 Myr based on galaxies whose starburst activity has a…
Large-scale outflows from starburst galaxies are multi-phase, multi-component fluids. Charge-exchange lines which originate from the interfacing surface between the neutral and ionised components are a useful diagnostic of the cold dense structures in the galactic outflow. From the charge-exchange lines observed in the nearby starburst galaxy M82, we conduct surface-to-volume analyses and deduce that the cold dense clumps in its galactic outflow have flattened shapes, resembling a hamburger or a pancake morphology rather than elongated shapes. The observed filamentary H$α$ features are therefo…
The recent discovery by Cantalupo et al. (2014) of the largest (~500 kpc) and luminous Ly-alpha nebula associated with the quasar UM287 (z=2.279) poses a great challenge to our current understanding of the astrophysics of the halos hosting massive z~2 galaxies. Either an enormous reservoir of cool gas is required $M\simeq10^{12}$ $M_{\odot}$, exceeding the expected baryonic mass available, or one must invoke extreme gas clumping factors not present in high-resolution cosmological simulations. However, observations of Ly-alpha emission alone cannot distinguish between these two scenarios. We ha…
Constraining the density distribution of the cold Circumgalactic Medium of quasars at z>2 through Lya, HeII and Ha emission
INAF – Osservatorio Astronomico di Trieste（意大利国家天体物理研究所的里雅斯特天文台）；Dipartimento di Fisica "G. Occhialini", Università degli Studi di Milano-Bicocca（米兰比可卡大学G. Occhialini物理系）；Department of Physics and Astronomy, University of California, Riverside（加州大学河滨分校物理与天文学系）；Cahill Center for Astrophysics, California Institute of Technology（加州理工学院卡希尔天体物理学中心）；Institute for Cosmic Ray Research, The University of Tokyo（东京大学宇宙射线研究所）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia（摩德纳和雷焦艾米利亚大学物理、信息学与数学系）
A deep 400-ksec ACIS-S observation of the nearest quasar known, Mrk 231, is combined with archival 120-ksec data obtained with the same instrument and setup to carry out the first ever spatially resolved spectral analysis of a hot X-ray emitting circumgalactic nebula around a quasar. The 65 x 50 kpc X-ray nebula shares no resemblance with the tidal debris seen at optical wavelengths. One notable exception is the small tidal arc 3.5 kpc south of the nucleus where excess soft X-ray continuum emission and Si XIII 1.8 keV line emission are detected, consistent with star formation and its associate…
We present the first detailed dissection of the circumgalactic medium (CGM) of massive starburst galaxies at z > 2. Our target is a submillimeter galaxy (SMG) at z = 2.674 that has a star formation rate of 1200 $M_\odot$/yr and a molecular gas reservoir of $1.3\times10^{11} M_\odot$. We characterize its CGM with two background QSOs at impact parameters of 93 kpc and 176 kpc. We detect strong HI and metal-line absorption near the redshift of the SMG towards both QSOs, each consisting of three main subsystems spanning over 1500 km/s. The absorbers show remarkable kinematic and metallicity cohere…
We present multi-band Hubble Space Telescope imaging that spans rest-frame near-ultraviolet through near-infrared wavelengths (0.3-1.1 $μ$m) for 12 compact starburst galaxies at z=0.4-0.8. These massive galaxies (M_stellar ~ 10^11 M_Sun) are driving very fast outflows ($v_{max}$=1000-3000 km/s), and their light profiles are dominated by an extremely compact starburst component (half-light radius ~ 100 pc). Our goal is to constrain the physical mechanisms responsible for launching these fast outflows by measuring the physical conditions within the central kiloparsec. Based on our stellar popula…
We analyze relative abundances and ionization conditions in a strong absorption system at z=6.84, seen in the spectrum of the z=7.54 background quasar ULAS J134208.10+092838.61. Singly ionized C, Si, Fe, Mg, and Al measurements are consistent with a warm neutral medium that is metal-poor but not chemically pristine. Firm non-detections of C IV and Si IV imply that any warm ionized phase of the IGM or CGM has not yet been enriched past the ultra-metal-poor regime (<0.001Z_{solar}), unlike lower redshift DLAs where these lines are nearly ubiquitous. Relative abundances of the heavy elements 794 …
A Post-starburst Galaxy Undergoing Ram-pressure Stripping at Redshift 3.06
Tsinghua University（清华大学）；National Radio Astronomy Observatory（国家射电天文台）；University of Alabama in Huntsville（阿拉巴马大学亨茨维尔分校）；European Southern Observatory（欧洲南方天文台）；Cosmic Dawn Center (DAWN), Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔学院宇宙黎明中心(DAWN)）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo（东京大学前沿研究综合科学中心 Kavli宇宙物理数学研究所(WPI)）；Center for Data-Driven Discovery, Kavli IPMU (WPI), UTIAS, The University of Tokyo（东京大学 UTIAS Kavli IPMU 数据驱动发现中心）
Deep XMM-Newton observation reveals hot gaseous outflow in NGC 5746
Dr. Karl Remeis-Observatory, Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg（弗里德里希·亚历山大大学埃尔朗根天体粒子物理中心卡尔·雷米斯天文台）
Clumpy Disk, Interloper, or Merger? Nature of a Distant Galaxy Pair at 5 kpc Projected Separation
University of California, Irvine（加州大学尔湾分校）；University of California, Riverside（加州大学河滨分校）；California Institute of Technology（加州理工学院）；The University of Texas at Austin（德克萨斯大学奥斯汀分校）；Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）
We present new GALEX images and optical spectroscopy of J1229+02, a dwarf post-starburst galaxy located 81 kpc from the 1585 km/s absorber in the 3C 273 sight line. The absence of Hα emission and the faint GALEX UV fluxes confirm that the galaxy's recent star formation rate is $<10^{-3} M_{\odot}$/yr. Absorption-line strengths and the UV-optical SED give similar estimates of the acceptable model parameters for its youngest stellar population where $f_m$ < 60% of its total stars (by mass) formed in a burst $t_sb$ = 0.7-3.4 Gyr ago with a stellar metallicity of -1.7 < [Fe/H] < +0.2; we also esti…
The GECKOS Survey: Extraplanar ionised gas in star-forming galaxies from eDIG to galaxy-scale winds
Swinburne University of Technology（斯威本科技大学）；ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)（ARC三维全天空天体物理学卓越中心）；European Southern Observatory（欧洲南方天文台）；University of Oklahoma（俄克拉荷马大学）；Liverpool John Moores University（利物浦约翰摩尔斯大学）；University of New South Wales（新南威尔士大学）
A dense, metal-rich absorber driven by a heavily dust-obscured galaxy: The direct evidence of CGM enrichment at $z\sim7$
University of Toronto（多伦多大学）；Dunlap Institute for Astronomy and Astrophysics（邓普天文学与天体物理研究所）；University of Copenhagen（哥本哈根大学）；Niels Bohr Institute（尼尔斯·玻尔研究所）；Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）；MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理学与空间研究学院）；Massachusetts Institute of Technology（麻省理工学院）
