We present the detection of Ly-alpha, [OIII] and H-alpha emission associated with an extremely strong DLA system (N(HI) = 10^22.10 cm^-2) at z=2.207 towards the quasar SDSS J113520-001053. This is the largest HI column density ever measured along a QSO line of sight, though typical of what is seen in GRB-DLAs. This absorption system also classifies as ultrastrong MgII system with W2796_r=3.6 A. The mean metallicity of the gas ([Zn/H]=-1.1) and dust depletion factors ([Zn/Fe]=0.72, [Zn/Cr]=0.49) are consistent with (and only marginally larger than) the mean values found in the general QSO-DLA population. The [OIII]-Ha emitting region has a very small impact parameter with respect to the QSO line of sight, b=0.1", and is unresolved. From the Ha line, we measure SFR=25 Msun/yr. The Ly-a line is double-peaked and is spatially extended. More strikingly, the blue and red Ly-a peaks arise from distinct regions extended over a few kpc on either side of the star-forming region. We propose that this is the consequence of Ly-a transfer in outflowing gas. The presence of starburst-driven outflows is also in agreement with the large SFR together with a small size and low mass of the galaxy (Mvir~10^10 Msun). From the stellar UV continuum luminosity of the galaxy, we estimate an age of at most a few 10^7 yr, again consistent with a recent starburst scenario. We interpret the data as the observation of a young, gas rich, compact starburst galaxy, from which material is expelled through collimated winds powered by the vigorous star formation activity. We substantiate this picture by modelling the radiative transfer of Ly-a photons in the galactic counterpart. Though our model (a spherical galaxy with bipolar outflowing jets) is a simplistic representation of the true gas distribution and velocity field, the agreement between the observed and simulated properties is particularly good. [abridged]
The kinematics of damped Lyman alpha absorbers (DLAs) are difficult to reproduce in hierarchical galaxy formation models, particularly the preponderance of wide systems. We investigate DLA kinematics at z=3 using high-resolution cosmological hydrodynamical simulations that include a heuristic model for galactic outflows. Without outflows, our simulations fail to yield enough wide DLAs, as in previous studies. With outflows, predicted DLA kinematics are in much better agreement with observations. Comparing two outflow models, we find that a model based on momentum-driven wind scalings provides …
X-ray properties of hot interstellar gas in a starburst galaxy NGC 253 were investigated to gain a further understanding of starburst-driven outflow activity by XMM-Newton and Suzaku. Spectroscopic analysis for three regions of the galaxy characterized by multiwavelength observations was conducted. The hot gas was represented by two thin thermal plasmas with temperatures of kT ~0.2 and ~0.6 keV. Abundance ratios i.e., O/Fe, Ne/Fe, Mg/Fe and Si/Fe, are consistent between three regions, which suggests the common origin of the hot gas. The abundance patterns are consistent with those of type II s…
(Abridged) Star formation-driven outflows are a critical phenomenon in theoretical treatments of galaxy evolution, despite the limited ability of observations to trace them across cosmological timescales. If the strongest MgII absorption-line systems detected in the spectra of background quasars arise in such outflows, "ultra-strong" MgII (USMgII) absorbers would identify significant numbers of galactic winds over a huge baseline in cosmic time, in a manner independent of the luminous properties of the galaxy. To this end, we present the first detailed imaging and spectroscopic study of the fi…
We study the kinematically narrow, low-ionization line emission from a bright, starburst galaxy at z = 0.69 using slit spectroscopy obtained with Keck/LRIS. The spectrum reveals strong absorption in MgII and FeII resonance transitions with Doppler shifts of -200 to -300 km/s, indicating a cool gas outflow. Emission in MgII near and redward of systemic velocity, in concert with the observed absorption, yields a P Cygni-like line profile similar to those observed in the Ly alpha transition in Lyman Break Galaxies. Further, the MgII emission is spatially resolved, and extends significantly beyond…
We obtained medium-resolution ultraviolet (UV) spectra between 1150 and 1450 Angstroms of the four UV-bright, infrared (IR)-luminous starburst galaxies IRAS F08339+6517, NGC 3256, NGC 6090, and NGC 7552 using the Cosmic Origins Spectrograph onboard the Hubble Space Telescope. The selected sightlines towards the starburst nuclei probe the properties of the recently formed massive stars and the physical conditions in the starburst-driven galactic superwinds. Despite being metal-rich and dusty, all four galaxies are strong Lyman-alpha emitters with equivalent widths ranging between 2 and 13 Angst…
Galactic outflows can be powered either by nuclear starbursts (SB) or active galactic nuclei (AGN). It has been argued that extreme starbursts can power extreme outflows, without the need to invoke AGN feedback. However, contributions from past and/or hidden AGN activity cannot be ruled out. Here, we constrain the potential role of the central black hole in driving powerful outflows in starburst galaxies (with no sign of ongoing AGN activity). We examine whether the galactic outflows can be explained by AGN luminosity evolution in the framework of our AGN `radiative dusty feedback' scenario. W…
Neutral outflows have been detected in many ultraluminous infrared galaxies (ULIRGs) via the Na I D $λλ5890, 5896$ absorption-line doublet. For the first time, we have mapped and analyzed the 2-D kinematics of a cool neutral outflow in a ULIRG, F10565+2448, using the integral field unit (IFU) on Gemini North to observe the Na I D feature. At the same time we have mapped the ionized outflow with the [NII] and H$α$ emission lines. We find a systemic rotation curve that is consistent with the rotation of the molecular disk determined from previous CO observations. The absorption lines show eviden…
Spectropolarimetry results for the starburst galaxy M82 are presented. The optical emission lines of the filaments in the energetic outflow ("superwind") from the nuclear starburst region of M82 are substantially polarized. The H-alpha polarization degrees and angles measured by our study are consistent with previous narrowband imaging polarimetry data. The polarized emission lines are redshifted with respect to the emission lines in the total light and systemic motion of the galaxy. The emission line intensity ratios [NII]/H-alpha and [SII]/H-alpha in the polarized light are similar to those …
We successfully detected a molecular outflow with a scale of 370-450 pc in the central region of the starburst galaxy NGC 3628 through deep CO(1-0) observations by using the Nobeyama Millimeter Array (NMA). The mass of the outflowing molecular gas is ~2.8x10^7 M_sun, and the outflow velocity is ~90(+/-10) km s^{-1}. The expansion timescale of the outflow is 3.3-6.8 Myr, and the molecular gas mass flow rate is 4.1-8.5 M_sun yr^{-1}. It requires mechanical energy of (1.8-2.8)x10^{54} erg to create this sub-kpc scale molecular outflow. In order to understand the evolution of the molecular outflow…
We propose a model of starburst--driven galactic outflows whose dynamics depends on both radiation and thermal pressure. Standard models of thermal pressure--driven winds fail to explain some key observations of outflows at low and high redshift galaxies. We discuss a scenario in which radiation pressure from massive stars in a stellar population drive a shell of gas and dust. Subsequent supernova (SN) explosions from the most massive stars in this population then drive stellar ejecta outward in a rarefied medium, making it collide with the radiation pressure driven shell. The collision impart…
We study the properties of massive, galactic-scale outflows of molecular gas and investigate their impact on galaxy evolution. We present new IRAM PdBI CO(1-0) observations of local ULIRGs and QSO hosts: clear signature of massive and energetic molecular outflows, extending on kpc scales, is found in the CO(1-0) kinematics of four out of seven sources, with measured outflow rates of several 100 Msun/yr. We combine these new observations with data from the literature, and explore the nature and origin of massive molecular outflows within an extended sample of 19 local galaxies. We find that sta…
Magnetic fields are a good tracer for gas compression by shock waves, which can be caused by interaction of star-formation driven outflows from individual star formation sites as described in the chimney model. We study the magnetic field structure in the central part of the nuclear starburst galaxy NGC 253 with spatial resolutions between 40 and 150 pc to detect any filamentary emission associated with the nuclear outflow. New VLA observations at 3 cm with 7.5" resolution were combined with archive data at 20 and 6 cm. We find filamentary radio continuum emission in a geometrical distribution…
An important property of star-forming galaxies at z~1-2 is the high local star-formation intensities they maintain over tens of kiloparsecs at levels that are only observed in the nearby Universe in the most powerful nuclear starbursts. To investigate how these high star-formation intensities affect the warm ionized medium, we present an analysis of the average spectra of about 50 such galaxies at z~1.2-2.6 and of subsamples selected according to their local and global star-formation intensity. Stacking allows us to probe relatively weak lines like [SII]λλ6716,6731 and [OI]λ6300, which are tra…
We searched for star formation activity associated with high-z Damped Lyman-alpha systems (DLAs) with Subaru telescope. We used a set of narrow-band (NB) filters whose central wavelengths correspond to the redshifted Lyman-alpha emission lines of targeted DLA absorbers at 3<z<4.5. We detected one apparent NB-excess object located 3.80 arcsec (~28kpc) away from the quasar SDSS J031036.84+005521.7. Follow-up spectroscopy revealed an asymmetric Lyman-alpha emission at z_em=3.115+/-0.003, which perfectly matches the sub-DLA trough at z_abs=3.1150 with logN(HI)/cm^-2=20.05. The Lyman-alpha luminosi…
Post-Starburst Quasars (PSQs) are hypothesized to represent a stage in the evolution of massive galaxies in which the star formation has been recently quenched due to the feedback of the nuclear activity. In this paper our goal is to test this scenario with a resolved stellar population study of the PSQ J0210-0903, as well as of its emitting gas kinematics and excitation. We have used optical Integral Field Spectroscopy obtained with the Gemini GMOS instrument at a velocity resolution of ~120 km/s and spatial resolution of ~0.5 kpc. We find that old stars dominate the luminosity (at 4700 Å) in…
Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\ge 10^5$ (corresponding to a star formation rate (SFR)$\ge 1$ M$_{\odot}$ yr$^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\sim 200\hbox{--}1000$ cm$^{-3}$ and scale height $z_0\ge 200 (n_0/10^2 \, {…
Recent well resolved numerical simulations of AGN feedback have shown that its effects on the host galaxy may be not only negative but also positive. In the late gas poor phase, AGN feedback blows the gas away and terminates star formation. However, in the gas-rich phase(s), AGN outflows trigger star formation by over-compressing cold dense gas and thus provide positive feedback on their hosts. In this paper we study this AGN-triggered starburst effect. We show that star formation rate in the burst increases until the star formation feedback counteracts locally the AGN outflow compression. Glo…
We report the discovery of the first 'ghostly' damped Ly$α$ absorption system (DLA), which is identified by the presence of absorption from strong low-ion species at $z_{\rm abs}=1.70465$ along the line of sight to the quasar SDSSJ113341.29$-$005740.0 with $z_{\rm em}=1.70441$. No Ly$α$ absorption trough is seen associated with these absorptions because the DLA trough is filled with the leaked emission from the broad emission line region of the quasar. By modeling the quasar spectrum and analyzing the metal lines, we derive log$N$(HI)(cm$^{-2}$)$\sim$21.0 $\pm$ 0.3. The DLA cloud is small ($\l…
We present a spectroscopic catalogue of 40 luminous starburst galaxies at z=0.7--1.7 (median z=1.3). 19 of these are submillimetre galaxies (SMGs) and 21 are submillimetre-faint radio galaxies (SFRGs). This sample helps to fill in the redshift desert at z=1.2--1.7 in previous studies as well as probing a lower luminosity population of galaxies. Radio fluxes are used to determine star-formation rates for our sample which range from around 50 to 500 M$_\odot$ yr$^{-1}$ and are generally lower than those in z$\sim$2 SMGs. We identify nebular [OII] 3727 emission in the rest-UV spectra and use the …
What is the contribution of mass, metals and energy from starburst galaxies to the Intergalactic Medium? Starburst galaxies drive galactic-scale outflows or "superwinds" that may be responsible for removing metals from galaxies and polluting the Intergalactic Medium (IGM). In the last decade tremendous progress was made in mapping cool entrained gas in superwinds through UV/optical imaging and absorption line spectroscopy. These studies demonstrated that superwinds are ubiquitous in galaxies forming stars at high surface densities and that the most powerful starbursts can drive outflows near e…
We present results on the nature of extreme ejective feedback episodes and the physical conditions of a population of massive ($\rm M_* \sim 10^{11} M_{\odot}$), compact starburst galaxies at z = 0.4-0.7. We use data from Keck/NIRSPEC, SDSS, Gemini/GMOS, MMT, and Magellan/MagE to measure rest-frame optical and near-IR spectra of 14 starburst galaxies with extremely high star formation rate surface densities (mean $\rm Σ_{SFR} \sim 3000 \,M_{\odot} yr^{-1} kpc^{-2}$) and powerful galactic outflows (maximum speeds v$_{98} \sim$ 1000-3000 km s$^{-1}$). Our unique data set includes an ensemble of …
We analyze the physical conditions in the low-ionization component of starburst outflows (in contrast to the high-ionization wind fluid observed in X-rays), based on new Keck/LRIS spectroscopy of partially resolved absorption troughs in near-ultraviolet and optical spectra of Ultraluminous Infrared Galaxies. The large velocity width and blueshift present in seven, atomic transitions indicate a macroscopic velocity gradient within the outflowing gas. The \mgII 2796, 2803 (and \feII 2587, 2600) doublet lines in these data constrains the gas kinematics better than the heavily blended \nad 5892, 9…
We performed spectral analysis of Suzaku data of the galactic disk and outflow regions of the starburst galaxy M82. Thermal modeling of the central disk regions requires at least three temperature components. The Ly$β$ line fluxes of O VIII and Ne X exceed those expected from a plasma in collisional ionization equilibrium. The ratios of Ly$β$/Ly$α$ lines for O VIII and Ne X are higher than those of collisional ionization equilibrium, which may be caused by the process of charge exchange. In the outflow wind region, the spectra are well reproduced with two-temperature thermal models, and we hav…
NGC 2992 is an intermediate Seyfert 1 galaxy showing outflows on kilo parsec scales which might be due either to AGN or starburst activity. We therefore aim at investigating its central region for a putative starburst in the past and its connection to the AGN and the outflows. Observations were performed with the adaptive optics near infrared integral field spectrograph SINFONI on the VLT, complemented by longslit observations with ISAAC on the VLT, as well as N- and Q-band data from the Spitzer archive. The spatial and spectral resolutions of the SINFONI data are 50 pc and 83 km/s, respective…
We present the first Keck/OSIRIS infrared IFU observations of a high redshift damped Lyman-alpha (DLA) galaxy detected in the line of sight to a background quasar. By utilizing the Laser Guide Star Adaptive Optics (LGSAO) to reduce the quasar PSF to FWHM~0.15 arcsec, we were able to search for and map the foreground DLA emission free from the quasar contamination. We present maps of the H-alpha and [OIII] $λλ$ 5007, 4959 emission of DLA 2222-0946 at a redshift of z ~ 2.35. From the composite spectrum over the H-alpha emission region we measure a star formation rate of 9.5 $\pm$ 1.0 M$_{\odot}$…
Mass outflows driven by stars and active galactic nuclei are a key element in many current models of galaxy evolution. They may produce the observed black hole-galaxy mass relation and regulate and quench both star formation in the host galaxy and black hole accretion. However, observational evidence of such feedback processes through outflows of the bulk of the star forming molecular gas is still scarce. Here we report the detection of massive molecular outflows, traced by the hydroxyl molecule (OH), in far-infrared spectra of ULIRGs obtained with Herschel-PACS as part of the SHINING key proj…
We present optical to far-infrared photometry of 31 reddened QSOs that show evidence for radiatively driven outflows originating from AGN in their rest-frame UV spectra. We use these data to study the relationships between the AGN-driven outflows, and the AGN and starburst infrared luminosities. We find that FeLoBAL QSOs are invariably IR-luminous, with IR luminosities exceeding 10^{12} Solar luminosities in all cases. The AGN supplies 76% of the total IR emission, on average, but with a range from 20% to 100%. We find no evidence that the absolute luminosity of obscured star formation is affe…
The under-abundance of very massive galaxies in the universe is frequently attributed to the effect of galactic winds. Although ionized galactic winds are readily observable most of the expelled mass is likely in cooler atomic and molecular phases. Expanding molecular shells observed in starburst systems such as NGC 253 and M 82 may facilitate the entrainment of molecular gas in the wind. While shell properties are well constrained, determining the amount of outflowing gas emerging from such shells and the connection between this gas and the ionized wind requires spatial resolution <100 pc cou…
ALMA observations have revealed that many high redshift galaxies are surrounded by extended (10-15 kpc) [CII]-emitting halos which are not predicted by even the most advanced zoom-in simulations. Using a semi-analytical model, in a previous work we suggested that such halos are produced by starburst-driven, catastrophically cooling outflows. Here, we further improve the model and compare its predictions with data from 7 star-forming ($10\lesssim \rm SFR/ M_\odot \rm yr^{-1}<100$) galaxies at z=4-6, observed in the ALPINE survey. We find that (a) detected [CII] halos are a natural by-product of…
We present the first attempt to detect outflows from galaxies approaching the Epoch of Reionization (EoR) using a sample of 9 star-forming ($\rm SFR=31\pm 20~M_{\odot}~yr^{-1}$) $z\sim 5.5$ galaxies for which the [CII]158$μ$m line has been previously obtained with ALMA. We first fit each line with a Gaussian function and compute the residuals by subtracting the best fitting model from the data. We combine the residuals of all sample galaxies and find that the total signal is characterised by a flux excess of $\sim 0.5$ mJy extended over $\sim 1000$ km~s$^{-1}$. Although we cannot exclude that …
Tracing ionized gas kinematics in Lyman-Break Analogs. Implications for star formation compactness and outflow properties
Universidad de La Serena（拉塞雷纳大学）；Instituto de Astrofísica de Andalucía (CSIC)（安达卢西亚天体物理研究所）；Centro de Estudios de Física del Cosmos de Aragón (CEFCA)（阿拉贡宇宙物理学研究中心）；INAF - Osservatorio Astronomico di Roma（意大利国家天文台罗马天文台）；Michigan Institute for Data Science, University of Michigan（密歇根大学数据科学研究所）
We present three-dimensional, adaptive mesh simulations of dwarf galaxy out- flows driven by supersonic turbulence. Here we develop a subgrid model to track not only the thermal and bulk velocities of the gas, but also its turbulent velocities and length scales. This allows us to deposit energy from supernovae directly into supersonic turbulence, which acts on scales much larger than a particle mean free path, but much smaller than resolved large-scale flows. Unlike previous approaches, we are able to simulate a starbursting galaxy modeled after NGC 1569, with realistic radiative cooling throu…
