We investigate the kinematics of ionized gas within the nuclear starburst of NGC 253 with observations of the Brackett $α$ recombination line at 4.05 $μ$m. The goal is to distinguish motions driven by star-formation feedback from gravitational motions induced by the central mass structure. Using NIRSPEC on Keck II, we obtained 30 spectra through a $0''.5$ slit stepped across the central $\sim$5$''\times 25''$ (85 $\times$ 425 pc) region to produce a spectral cube. The Br$α$ emission resolves into four nuclear sources: S1 at the infrared core (IRC), N1 at the radio core near nonthermal source TH2, and the fainter sources N2 and N3 in the northeast. The line profile is characterized by a primary component with $Δv_{\mathrm{primary}}$$\sim$90-130 km s$^{-1}$ (FWHM) on top of a broad {blue} wing with $Δv_{\mathrm{broad}}$$\sim$300-350 km s$^{-1}$, and an additional redshifted narrow component in the west. The velocity field generated from our cube reveals several distinct patterns. A mean NE-SW velocity gradient of +10 km s$^{-1}$ arcsec$^{-1}$ along the major axis traces the solid-body rotation curve of the nuclear disk. At the radio core, isovelocity contours become S-shaped, indicating the presence of secondary nuclear bar of total extent $\sim$5$''$ (90 pc). The symmetry of the bar places the galactic center near the radio peak TH2 of the galaxy rather than the IRC, and makes this the most likely location of a SMBH. A third kinematic substructure is formed by blueshifted gas on the southeast side of the IRC. This feature provides evidence for a $\sim$100-250 km s$^{-1}$ starburst-driven outflow potentially responsible for powering the kpc-scale galactic wind of NGC 253.
We present a CO(3-2) study of four systems composed of six (ultra) luminous infrared galaxies (U/LIRGs), located at 0.28 < z < 0.44, that straddle the transition region between regular star forming galaxies and starbursts. These galaxies benefit from previous multi-wavelength analysis allowing in depth exploration of an understudied population of U/LIRGs at a time when the universe is experiencing a rapid decline in star formation rate density. We detect CO(3-2) emission in four targets and these galaxies fall between the loci of regular star forming galaxies and starbursts on the Kennicutt-Sc…
4C 71.07 is a high-redshift blazar whose optical radiation is dominated by quasar-like nuclear emission. We here present the results of a spectroscopic monitoring of the source to study its unbeamed properties. We obtained 24 optical spectra at the Nordic Optical Telescope (NOT) and William Herschel Telescope (WHT) and 3 near-infrared spectra at the Telescopio Nazionale Galileo (TNG). They show no evidence of narrow emission lines. The estimate of the systemic redshift from the H$β$ and H$α$ broad emission lines leads to $z_{\rm sys}=2.2130 \pm 0.0004$. Notwithstanding the nearly face-on orien…
The nuclear starburst within the central $\sim 15^{\prime\prime}$ ($\sim 250$ pc; $1^{\prime\prime} \simeq 17$ pc) of NGC253 has been extensively studied as a prototype for the starburst phase in galactic evolution. Atacama Large Millimeter/submillimeter Array (ALMA) imaging within receiver Bands 6 and 7 have been used to investigate the dense gas structure, kinetic temperature, and heating processes which drive the NGC253 starburst. Twenty-nine transitions from fifteen molecular species/isotopologues have been identified and imaged at $1.^{\prime\prime}5$ to $0.^{\prime\prime}4$ resolution, a…
We present an 8 pc x 5 pc resolution view of the central ~ 200 pc region of the nearby starburst galaxy NGC 253, based on ALMA Band 7 (λ ~ 0.85 mm or ν ~ 350 GHz) observations covering 11 GHz. We resolve the nuclear starburst of NGC 253 into eight dusty star-forming clumps, 10 pc in scale, for the first time. These clumps, each of which contains (4-10) x 10^4 M_sun of dust (assuming that the dust temperature is 25 K) and up to 6 x 10^2 massive (O5V) stars, appear to be aligned in two parallel ridges, while they have been blended in previous studies. Despite the similarities in sizes and dust m…
NGC 2915 is a unique nearby galaxy that is classified as an isolated blue compact dwarf based on its optical appearance but has an extremely extended H i gas disk with prominent Sd-type spiral arms. To unveil the starburst-triggering mystery of NGC 2915, we performed a comprehensive analysis of deep VLT/MUSE integral field spectroscopic observations that cover the star-forming region in the central kiloparsec of the galaxy. We find that episodes of bursty star formation have recurred in different locations throughout the central region, and the most recent one peaked around 50 Myr ago. The bur…
Radio recombination lines (RRLs) are powerful, extinction-free diagnostics of the ionized gas in young, star-forming regions. Unfortunately, these lines are difficult to detect in external galaxies. We present the results of EVLA observations of the RRL and radio continuum emission at 33 GHz from NGC 253, a nearby nuclear starburst galaxy. We detect the previously unobserved H58a and H59a RRLs and make simultaneous sensitive measurements of the continuum. We measure integrated line fluxes of $44.3 \pm 0.7$ W m$^{-2}$ and $39.9 \pm 0.8$ W m$^{-2}$ for the H58a and H59a lines, respectively. The …
We have used the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) to obtain the first spatially resolved, mid-infrared (mid-IR) images of IIZw096, a merging luminous infrared galaxy (LIRG) at $z = 0.036$. Previous observations with the Spitzer Space Telescope suggested that the vast majority of the total IR luminosity (LIR) of the system originated from a small region outside of the two merging nuclei. New observations with JWST/MIRI now allow an accurate measurement of the location and luminosity density of the source that is responsible for the bulk of the IR emission.…
We present rest-frame far-infrared (FIR) and optical size measurements of AGN hosts and star-forming galaxies in the COSMOS field, enabled by high-resolution ALMA/1 mm (0.1 arcsec - 0.4 arcsec) and HST/F814W imaging (~ 0.1 arcsec). Our sample includes 27 galaxies at z<2.5, classified as infrared-selected AGN (3 sources), X-ray selected AGN (4 sources), and non-AGN star-forming galaxies (20 sources), for which high-resolution Band 6/7 ALMA images are available at 1 mm from our own observing program as well as archival observations. The sizes and SFR surface densities measured from both ALMA/1 m…
IC883 is a luminous infrared galaxy (LIRG) classified as a starburst-active galactic nucleus (AGN) composite. In a previous study we detected a low-luminosity AGN (LLAGN) radio candidate. Here we report on our radio follow-up at three frequencies which provides direct and unequivocal evidence of the AGN activity in IC883. Our analysis of archival X-ray data, together with the detection of a transient radio source with luminosity typical of bright supernovae, give further evidence of the ongoing star formation activity, which dominates the energetics of the system. At sub-parsec scales, the rad…
We discuss integral field spectra of the compact star-forming complex that is the brightest near-infrared (NIR) source in the central regions of the starburst galaxy NGC 253. The spectra cover the H and K passbands and were recorded with the Gemini NIR Spectrograph during sub-arcsec seeing conditions. Absorption features in the spectrum of the star-forming complex are weaker than in the surroundings. An absorption feature is found near 1.78um that coincides with the location of a C2 bandhead. Emission lines of Brgamma, [FeII], and HeI2.06um do not track the NIR continuum light. Pockets of star…
Compact star formation appears to be generally common in dusty star-forming galaxies (SFGs). However, its role in the framework set by the scaling relations in galaxy evolution remains to be understood. In this work we follow up on the galaxy sample from the GOODS-ALMA 2.0 survey, an ALMA blind survey at 1.1mm covering a continuous area of 72.42arcmin$^2$ using two array configurations. We derived physical properties, such as star formation rates, gas fractions, depletion timescales, and dust temperatures for the galaxy sample built from the survey. There exists a subset of galaxies that exhib…
(Abridged) Heating of the interstellar medium by multiple supernovae (SNe) explosions is at the heart of producing galaxy-scale outflows. We use hydrodynamical simulations to study the efficiency of multiple SNe in heating the interstellar medium (ISM) and filling the volume with gas of high temperatures. We argue that it is important for SNe remnants to have a large filling factor {\it and} a large heating efficiency. For this, they have to be clustered in space and time, and keep exploding until the hot gas percolates through the whole region, in order to compensate for the radiative loss. I…
Overdense fireworks in GOODS-N: Unveiling a record number of massive dusty star forming galaxies at z$\sim$5.2 with the N2CLS
Aix Marseille Univ, CNRS, CNES, LAM (Laboratoire d’Astrophysique de Marseille)（艾克斯马赛大学）；Department of Astronomy, University of Geneva（日内瓦大学天文学系）；Institut de Radioastronomie Millimétrique (IRAM)（毫米波射电天文研究所）；Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学）；School of Physics and Astronomy, Cardiff University（卡迪夫大学物理与天文学学院）；Université Paris Cité, Université Paris-Saclay, CEA, CNRS, AIM（巴黎西岱大学、巴黎萨克雷大学）
High-resolution (0."03 - 0."09) (9 - 26 pc)) ALMA (100 - 350 GHz (3 - 0.8 mm)) and VLA 45 GHz measurements have been used to image continuum and spectral line emission from the inner region of the nearby infrared luminous galaxy IC 860. We detect compact (r=8-10 pc), luminous, mm continuum emission in the core of IC 860, with brightness temperatures $T_{\rm B}>$ 280 K. The 45 GHz continuum is equally compact, but fainter in flux. We suggest that the 3 to 0.8 mm continuum is opaque at mm-wavelengths, implying a very large H$_2$ column density $N$(H$_2$) of 1e26 cm-2, and that it emerges from ho…
Little Red Dot $-$ Host Galaxy $=$ Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot
MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理与空间研究所）；Institute of Science and Technology Austria (ISTA)（奥地利科学与技术研究所）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；The University of Texas at Austin（德克萨斯大学奥斯汀分校）；Princeton University（普林斯顿大学）；University of Geneva（日内瓦大学）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）
