We study the relationship between dense gas and star formation in the Antennae galaxies by comparing ALMA observations of dense gas tracers (HCN, HCO$^+$, and HNC $\mathrm{J}=1-0$) to the total infrared luminosity ($\mathrm{L_{TIR}}$) calculated using data from the \textit{Herschel} Space Observatory and the \textit{Spitzer} Space Telescope. We compare the luminosities of our SFR and gas tracers using aperture photometry and employing two methods for defining apertures. We taper the ALMA dataset to match the resolution of our $\mathrm{L_{TIR}}$ maps and present new detections of dense gas emission from complexes in the overlap and western arm regions. Using OVRO CO $\mathrm{J}=1-0$ data, we compare with the total molecular gas content, $\mathrm{M(H_2)_{tot}}$, and calculate star formation efficiencies and dense gas mass fractions for these different regions. We derive HCN, HCO$^+$ and HNC upper limits for apertures where emission was not significantly detected, as we expect emission from dense gas should be present in most star-forming regions. The Antennae extends the linear $\mathrm{L_{TIR}-L_{HCN}}$ relationship found in previous studies. The $\mathrm{L_{TIR}-L_{HCN}}$ ratio varies by up to a factor of $\sim$10 across different regions of the Antennae implying variations in the star formation efficiency of dense gas, with the nuclei, NGC 4038 and NGC 4039, showing the lowest SFE$_\mathrm{dense}$ (0.44 and 0.70 $\times10^{-8}$ yr$^{-1}$). The nuclei also exhibit the highest dense gas fractions ($\sim 9.1\%$ and $\sim7.9\%$).
The formation mechanism of super star clusters (SSCs), a present-day analog of the ancient globulars, still remains elusive. The major merger, the Antennae galaxies is forming SSCs and is one of the primary targets to test the cluster formation mechanism. We reanalyzed the archival ALMA CO data of the Antennae and found three typical observational signatures of a cloud-cloud collision toward SSC B1 and other SSCs in the overlap region; i. two velocity components with $\sim$100 km s$^{-1}$ velocity separation, ii. the bridge features connecting the two components, and iii. the complementary spa…
The Antennae Galaxies is one of the starbursts in major mergers. Tsuge et al. (2020) showed that the five giant molecular complexes in the Antennae Galaxies have signatures of cloud-cloud collisions based on the ALMA archival data at 60 pc resolution. In the present work we analyzed the new CO data toward the super star cluster (SSC) B1 at 14 pc resolution obtained with ALMA, and confirmed that two clouds show complementary distribution with a displacement of $\sim$70 pc as well as the connecting bridge features between them. The complementary distribution shows a good correspondence with the …
We present a high-resolution smoothed particle hydrodynamics simulation of the Antennae galaxies (NGC 4038/4039) and follow the evolution $3$ Gyrs beyond the final coalescence. The simulation includes metallicity dependent cooling, star formation, and both stellar feedback and chemical enrichment. The simulated best-match Antennae reproduces well both the observed morphology and the off-nuclear starburst. We also produce for the first time a simulated two-dimensional metallicity map of the Antennae and find good agreement with the observed metallicity of off-nuclear stellar clusters, however t…
We present a direct determination of the stellar metallicity in the close pair galaxy NGC~4038 (D = 20 Mpc) based on the quantitative analysis of moderate resolution KMOS/VLT spectra of three super star clusters (SSCs). The method adopted in our analysis has been developed and optimised to measure accurate metallicities from atomic lines in the $J$-band of single red supergiant (RSG) or RSG-dominated star clusters. Hence, our metallicity measurements are not affected by the biases and poorly understood systematics inherent to strong line HII methods which are routinely applied to massive data …
We present 1" (<100 pc) resolution maps of millimeter emission from five molecules-CN, HCN, HCO+, CH3OH, and HNCO-obtained towards NGC 4038, which is the northern galaxy of the mid-stage merger, Antennae galaxies, with the Atacama Large Millimeter/submillimeter Array. Three molecules (CN, CH3OH, and HNCO) were detected for the first time in the nuclear region of NGC 4038. High-resolution mapping reveals a systematic difference in distributions of different molecular species and continuum emission. Active star forming regions identified by the 3 mm and 850 um continuum emission are offset from …
We present a ~ 1" (100 pc) resolution 12CO (3-2) map of the nearby intermediate stage interacting galaxy pair NGC 4038/9 (the Antennae galaxies) obtained with the Submillimeter Array. We find that half the CO (3-2) emission originates in the overlap region where most of the tidally induced star formation had been previously found in shorter wavelength images, with the rest being centered on each of the nuclei. The gross distribution is consistent with lower resolution single dish images, but we show for the first time the detailed distribution of the warm and dense molecular gas across this ga…
We present observations of the dense molecular gas tracers HCN, HNC, and HCO+ in the J=1-0 transition using ALMA. We supplement our datasets with previous observations of CO J=1-0, which traces the total molecular gas content. We separate the Antennae into 7 bright regions in which we detect emission from all three molecules, including the nuclei of NGC 4038 and NGC 4039, 5 super giant molecular complexes in the overlap region and 2 additional bright clouds. We find that the ratio of L(HCN)/L(CO), which traces the dense molecular gas fraction, is greater in the two nuclei (L(HCN)/L(CO) ~ 0.07 …
In optical images, the not amply studied isolated interacting galaxy pair KPG 486 (NGC 6090) displays similar features to the galaxy pair The Antennae (NGC 4038/39). To compare the distribution of ionized hydrogen gas, morphology and kinematic and dynamic behaviour between both galaxy pairs, we present observations in the H$α$ emission line of NGC 6090 acquired with the scanning Fabry-Perot interferometer, PUMA. For each galaxy in NGC 6090 we obtained several kinematic parameters, its velocity field and its rotation curve, we also analysed some of the perturbations induced by their encounter. …
We used the Gemini Multi-Object Spectrograph Integral Field Unit to map the gas distribution, excitation and kinematics within the inner kiloparsec of four nearby low-luminosity active galaxies: NGC3982, NGC4501, NGC2787 and NGC4450. The observations cover the spectral range 5600-7000Å at a velocity resolution of 120km/s and spatial resolution ranging from 50 to 70pc at the galaxies. Extended emission in Hα, [NII]λλ6548,6583, [SII]λλ6716,6730 over most of the field-of-view is observed for all galaxies, while only NGC3982 shows [OI]λ6300 extended emission. The Hα equivalent widths combined with…
Kogakuin University（工学府大学）；Shizuoka University（静冈大学）；Shunan University（周南大学）；Shibaura Institute of Technology（芝浦工业大学）；RIKEN（理化学研究所）；The University of Tokyo（东京大学）；National Astronomical Observatory of Japan（日本国立天文台）；Kagawa University（香川大学）；Osaka Electro-Communication University（大阪电波大学）；SOKENDAI（综合研究大学院大学）
We observed the nuclear region of the galaxy NGC 1365 with the integral field unit of the Gemini Multi Object Spectrograph mounted on the GEMINI-South telescope. The field of view covers $13^{\prime\prime} \times 6^{\prime\prime}$ ($1173 \times 541$ pc$^{2}$) centered on the nucleus, at a spatial resolution of $52$ pc. The spectral coverage extends from $5600$ Å to $7000$ Å, at a spectral resolution $R=1918$. NGC 1365 hosts a Seyfert 1.8 nucleus, and exhibits a prominent bar extending out to $100^{\prime\prime}$ (9 kpc) from the nucleus. The field of view lies within the inner Lindblad resonan…
We here study the multi-band properties of a kiloparsec-size superbubble in the late-type spiral galaxy NGC628. The superbubble is the largest of many holes seen in the early release images using JWST/MIRI filters that trace the Polycyclic Aromatic Hydrocarbon (PAH) emissions. The superbubble is located in the interarm region ~3 kpc from the galactic center in the south-east direction. The shell surrounding the superbubble is detected in HI, CO, and Halpha with an expansion velocity of 12 km/s, and contains as much as 2x10^7 Msun of mass in gas that is mostly in molecular form. We find a clear…
We present Atacama Large Millimeter/submillimeter Array observations at $\approx100$ GHz with $0.05$ arcsec (3 pc) resolution of the kiloparsec-scale jet seen in the nearby Seyfert galaxy NGC 1068, and we report the presence of parsec-scale blobs at the head of the jet. The combination of the detected radio flux ($\approx0.8$ mJy), spectral index ($\approx0.5$), and the blob size ($\approx10$ pc) suggests a strong magnetic field of $B\approx240\,μ$G. Such a strong magnetic field most likely implies magnetic field amplification by streaming cosmic rays. The estimated cosmic-ray power by the jet…
We study a gas rich merging dwarf system KUG 0200-096. Deep optical image reveals an optically faint tail with a length of 20 kpc, giving a visual impression of tidal antenna similar to NGC 4038/39. The interacting dwarf galaxies have B-band absolute magnitudes -18.06 and -16.63 mag. We identify a young stellar clump of stellar mass of 2$\times$10$^{7}$ M$_{\sun}$ at the tip of the antenna, possibly a Tidal Dwarf Galaxy (TDG). The putative TDG candidate is quite blue with $g-r$ color index of -0.07 mag, whereas the interacting dwarf galaxies have $g-r$ color indices 0.29 and 0.19 mag. The TDG …
We present the analysis of archival Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) observations of the interacting galaxies NGC 4038/39 (a.k.a. the Antennae) at a distance of 18.1 Mpc. Up to 38 young star-forming complexes with evident contribution from Wolf-Rayet (WR) stars are unveiled. We use publicly available templates of Galactic WR stars in conjunction with available photometric extinction measurements to quantify and classify the WR population in each star-forming region, on the basis of its nearly Solar oxygen abundance. The total estimated number of WR stars in t…
We present new radio observations of the z = 0.029 radio galaxy NGC 6109, a member of the 3CRR sample. We find the radio morphology of the counter-jet to be highly distorted, showing a unique 'doughnut' structure ~6 kpc in diameter. The doughnut is overpressured compared with the surrounding atmosphere as measured with Chandra. We investigate the polarisation properties of the source and find evidence for an interaction between the doughnut and the external environment. This may cause the extreme jet bend. Alternatively, while providing no explanation for the rotation-measure and magnetic fiel…
Active galactic nucleus (AGN) feedback is postulated as a key mechanism for regulating star formation within galaxies. Studying the physical properties of the outflowing gas from AGN is thus crucial for understanding the co-evolution of galaxies and supermassive black holes. Here we report 55 pc resolution ALMA neutral atomic carbon [CI] $^3P_1\text{-}^3P_0$ observations toward the central 1 kpc of the nearby type-2 Seyfert galaxy NGC 1068, supplemented by 55 pc resolution CO($J=1\text{-}0$) observations. We find that [CI] emission within the central kpc is strongly enhanced by a factor of $>$…
We employ optical spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE) combined with X-ray and radio data to study the highly-ionized gas (HIG) phase of the feedback in a sample of five local nearby Active Galactic Nuclei (AGN). Thanks to the superb field of view and sensitivity of MUSE, we found that the HIG, traced by the coronal line [FeVII] $λ$6089, extends to scales not seen before, from 700 pc in Circinus and up to ~2 kpc in NGC5728 and NGC3393. The gas morphology is complex, following closely the radio jet and the X-ray emission. Emission line ratios suggest gas excitation by …
The ACS and NICMOS have been used to obtain new HST images of NGC 4038/4039 ("The Antennae"). These new observations allow us to better differentiate compact star clusters from individual stars, based on both size and color. We use this ability to extend the cluster luminosity function by approximately two magnitudes over our previous WFPC2 results, and find that it continues as a single power law, dN/dL propto L^alpha with alpha=-2.13+/-0.07, down to the observational limit of Mv~-7. Similarly, the mass function is a single power law dN/dM propto M^beta with beta=-2.10+/-0.20 for clusters wit…
We present Herschel SPIRE-FTS observations of the Antennae (NGC 4038/39), a well studied, nearby ($22$ Mpc) ongoing merger between two gas rich spiral galaxies. We detect 5 CO transitions ($J=4-3$ to $J=8-7$), both [CI] transitions and the [NII]$205μm$ transition across the entire system, which we supplement with ground based observations of the CO $J=1-0$, $J=2-1$ and $J=3-2$ transitions, and Herschel PACS observations of [CII] and [OI]$63μm$. Using the CO and [CI] transitions, we perform both a LTE analysis of [CI], and a non-LTE radiative transfer analysis of CO and [CI] using the radiative…
Symmetric kiloparsec-scale radio knots in NGC 7213: evidence for a confined weak jet and recurrent nuclear activity
INAF – Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所）；Cahill Center for Astronomy & Astrophysics, California Institute of Technology（加州理工学院）；CSIRO Astronomy and Space Science（澳大利亚联邦科学与工业研究组织天文与空间科学部）；INAF – Istituto di Radioastronomia（意大利国家天体物理研究所射电天文台）；Dipartimento di Fisica, Universitá di Roma Tor Vergata（罗马托尔维加塔大学）；Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre（罗马第三大学）；INAF – Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）
We present the discovery of highly-collimated radio jets spanning a total of 355 kpc around the nearby elliptical galaxy NGC 2663, and the possible first detection of recollimation on kiloparsec scales. The small distance to the galaxy (~28.5 Mpc) allows us to resolve portions of the jets to examine their structure. We combine multiwavelength data: radio observations by the Murchison Widefield Array (MWA), the Australian Square Kilometre Array Pathfinder (ASKAP) and the Australia Telescope Compact Array (ATCA), and X-ray data from Chandra, Swift and SRG/eROSITA. We present intensity, rotation …
We have modelled the stellar and nebular continua and emission-line intensity ratios of massive stellar populations in the Antennae galaxy using high resolution and self-consistent libraries of model HII regions around central clusters of aging stars. The model libraries are constructed using the stellar population synthesis code, Starburst99, and photoionisation model, Cloudy. The Geneva and PARSEC stellar evolutionary models are plugged into Starburst99 to allow comparison between the two models. Using a spectrum-fitting methodology that allows the spectral features in the stellar and nebula…
The understating of the origin of the H2 line emission from the central regions of galaxies represent an important key to improve our knowledge about the excitation and ionization conditions of the gas in these locations. Usually these lines can be produced by Starburts, shocks and/or radiation from an active galactic nucleus (AGN). Luminous Infrared Galaxies (LIRG) represent ideal and challenging objects to investigate the origin of the H2 emission, as all processes above can be observed in a single object. In this work, we use K-band integral field spectroscopy to map the emission line flux …
Mass outflow generated by the dynamical feedback from massive stars is currently a topic of high interest. Using a purpose-developed analysis technique, and taking full advantage of the high kinematic and angular resolution of our instrument we have detected a number of expanding superbubbles in the interacting pair of galaxies Arp 244 (NGC 4038/9) commonly known as the Antennae. We use a Fabry-Pérot interferometer GHαFaS to measure the profile of Hα in emission over the full extent of the object, except for the extended HI tails. The superbubbles are found centred on most of the brightest HII…
We use the CARMA millimeter interferometer to map the Antennae Galaxies (NGC4038/39), tracing the bulk of the molecular gas via the 12CO(1-0) line and denser molecular gas via the high density transitions HCN(1-0), HCO+(1-0), CS(2-1), and HNC(1-0). We detect bright emission from all tracers in both the two nuclei and three locales in the overlap region between the two nuclei. These three overlap region peaks correspond to previously identified "supergiant molecular clouds". We combine the CARMA data with Herschel infrared (IR) data to compare observational indicators of the star formation effi…
Using the atomic carbon [CI](1$-$0) and [CI](2$-$1) emission maps observed with the $Herschel\ Space\ Observatory$, and CO(1$-$0), HI, infrared and submm maps from literatures, we estimate the [CI]-to-H$_2$ and CO-to-H$_2$ conversion factors of $α_\mathrm{[CI](1-0)}$, $α_\mathrm{[CI](2-1)}$, and $α_\mathrm{CO}$ at a linear resolution $\sim1\,$kpc scale for six nearby galaxies of M 51, M 83, NGC 3627, NGC 4736, NGC 5055, and NGC 6946. This is perhaps the first effort, to our knowledge, in calibrating both [CI]-to-H$_2$ conversion factors across the spiral disks at spatially resolved $\sim1\,$kp…
We aim to map the distribution and kinematics of molecular and ionized gas in a sample of active galaxies, to quantify the nuclear inflows and outflows. Here, we analyze the nuclear kinematics of NGC 1566 via ALMA observations of the CO J:2-1 emission at 24 pc spatial and $\sim$2.6 km s$^{-1}$ spectral resolution, and Gemini-GMOS/IFU observations of ionized gas emission lines and stellar absorption lines at similar spatial resolution, and 123 km s$^{-1}$ of intrinsic spectral resolution. The morphology and kinematics of stellar, molecular (CO) and ionized ([N II]) emission lines are compared t…
JWST reveals how black holes are fed: kiloparsec-scale multiphase filaments feed sub-kiloparsec circumnuclear disks
Université de Montréal（蒙特利尔大学）；University of Michigan（密歇根大学）；Princeton University（普林斯顿大学）；Michigan State University（密歇根州立大学）；Institut Trottier de recherche sur les exoplanètes（特鲁瓦耶系外行星研究所）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）；University of Portsmouth（朴茨茅斯大学）
The Luminous Infrared Galaxy NGC1614 hosts a prominent circumnuclear ring of star formation. However, the nature of the dominant emitting mechanism in its central ~100 pc is still under debate. We present sub-arcsecond angular resolution radio, mid-infrared, Pa-alpha, optical, and X-ray observations of NGC1614, aimed at studying in detail both the circumnuclear ring and the nuclear region. The 8.4 GHz continuum emission traced by the Very Large Array (VLA) and the Gemini/T-ReCS 8.7 micron emission, as well as the Pa-alpha line emission, show remarkable morphological similarities within the sta…
The CO-to-H$_2$ conversion factor ($α_\rm{CO}$) is critical to studying molecular gas and star formation in galaxies. The value of $α_\rm{CO}$ has been found to vary within and between galaxies, but the specific environmental conditions that cause these variations are not fully understood. Previous observations on $\sim$kpc scales revealed low values of $α_\rm{CO}$ in the centers of some barred spiral galaxies, including NGC 3351. We present new ALMA Band 3, 6, and 7 observations of $^{12}$CO, $^{13}$CO, and C$^{18}$O lines on 100 pc scales in the inner $\sim$2 kpc of NGC 3351. Using multi-lin…
We present a study of the magnetic field properties of NGC 4038/9 (the `Antennae' galaxies), the closest example of a late stage merger of two spiral galaxies. Wideband polarimetric observations were performed using the Karl G. Jansky Very Large Array between 2 and 4 GHz. Rotation measure synthesis and Faraday depolarization analysis was performed to probe the magnetic field strength and structure at spatial resolution of $\sim1$ kpc. Highly polarized emission from the southern tidal tail is detected with intrinsic fractional polarization close to the theoretical maximum ($0.62\pm0.18$), estim…
We present a coherent and homogeneous multi-line study of the CS molecule in nearby (D$<$10Mpc) galaxies. We include, from the literature, all the available observations from the $J=1-0$ to the $J=7-6$ transitions towards NGC 253, NGC 1068, IC 342, Henize~2-10, M~82, the Antennae Galaxies and M~83. We have, for the first time, detected the CS(7-6) line in NGC 253, M~82 (both in the North-East and South-West molecular lobes), NGC 4038, M~83 and tentatively in NGC 1068, IC 342 and Henize~2-10. We use the CS molecule as a tracer of the densest gas component of the ISM in extragalactic star-formin…
We present the highest spatial resolution (~0.5") CO (3-2) observations to date of the "overlap" region in the merging Antennae galaxies (NGC 4038/39), taken with the ALMA. We report on the discovery of a long (3 kpc), thin (aspect ratio 30/1), filament of CO gas which breaks up into roughly ten individual knots. Each individual knot has a low internal velocity dispersion (~10 km/s), and the dispersion of the ensemble of knots in the filament is also low (~10 km/s). At the other extreme, we find that the individual clouds in the Super Giant Molecular Cloud 2 region discussed by Wilson and coll…
The "Antennae Galaxy" (NGC 4038/39) is the closest major interacting galaxy system and therefore often taken as merger prototype. We present the first comprehensive integral field spectroscopic dataset of this system, observed with the MUSE instrument at the ESO VLT. We cover the two regions in this system which exhibit recent star-formation: the central galaxy interaction and a region near the tip of the southern tidal tail. In these fields, we detect HII regions and diffuse ionized gas to unprecedented depth. About 15% of the ionized gas was undetected by previous observing campaigns. This n…
We address the study of the \Ha\ vertical velocity field in a sample of four nearly face-on galaxies using long slit spectroscopy taken with the ISIS spectrograph attached to the WHT at the Roque de los Muchachos Observatory (Spain). The spatial structure of the velocity vertical component shows a radial corrugated pattern with spatial scales higher or within the order of { one} kiloparsec. The gas is mainly ionized by high-energy photons: only in some locations of NGC~278 and NGC~1058 is there some evidence of ionization by low-velocity shocks, which, in the case of NGC~278, could be due to m…
The properties of tidally induced arms provide a means to study molecular cloud formation and the subsequent star formation under environmental conditions which in principle are different from quasi stationary spiral arms. We report the properties of a newly discovered molecular gas arm of likely tidal origin at the south of NGC 4039 and the overlap region in the Antennae galaxies, with a resolution of 1"68 x 0"85, using the Atacama Large Millimeter/submillimeter Array science verification CO(2-1) data. The arm extends 3.4 kpc (34") and is characterized by widths of ~ 200 pc (2") and velocity …
We present HCN J=4-3 and HCO^+ J=4-3 maps of six nearby star-forming galaxies, NGC 253, NGC 1068, IC 342, M82, M83, and NGC 6946, obtained with the James Clerk Maxwell Telescope as part of the MALATANG survey. All galaxies were mapped in the central 2 arcmin $\times$ 2 arcmin region at 14 arcsec (FWHM) resolution (corresponding to linear scales of ~ 0.2-1.0 kpc). The L_IR-L'_dense relation, where the dense gas is traced by the HCN J=4-3 and the HCO^+ J=4-3 emission, measured in our sample of spatially-resolved galaxies is found to follow the linear correlation established globally in galaxies …
A multi-scale view of molecular gas and magnetic fields in the Antennae galaxies
Institute of Theoretical Astrophysics, University of Oslo（奥斯陆大学理论天体物理研究所）；University of South Carolina（南卡罗来纳大学）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Aix Marseille Univ, CNRS, CNES, LAM（艾克斯-马赛大学，法国国家科学研究中心，法国国家空间研究中心，拉姆实验室）
Initial Mass Functions of Young Stellar Clusters from the Gemini Spectroscopic Survey of Nearby Galaxies I. Young Massive Clusters in the Antennae galaxies
The complex physical, kinematic, and chemical properties of galaxy centres make them interesting environments to examine with molecular line emission. We present new $2-4$" (${\sim}75{-}150$ pc at $7.7$ Mpc) observations at 2 and 3 mm covering the central $50$" (${\sim}1.9$ kpc) of the nearby double-barred spiral galaxy NGC 6946 obtained with the IRAM Plateau de Bure Interferometer. We detect spectral lines from ten molecules: CO, HCN, HCO$^+$, HNC, CS, HC$_3$N, N$_2$H$^+$, C$_2$H, CH$_3$OH, and H$_2$CO. We complemented these with published 1mm CO observations and 33 GHz continuum observations…
The presence of multiple populations (MPs) with distinctive light element abundances is a widespread phenomenon in clusters older than 6 Gyr. Clusters with masses, luminosities, and sizes comparable to those of ancient globulars are still forming today. Nonetheless, the presence of light element variations has been poorly investigated in such young systems, even if the knowledge of the age at which this phenomenon develops is crucial for theoretical models on MPs. We use J-band integrated spectra of three young (7-40 Myr) clusters in NGC 4038 to look for Al variations indicative of MPs. Assumi…
We test claims that the power-law mass functions of young star clusters (ages $\lesssim\mbox{few}\times10^8$~yr) have physical upper cutoffs at $M_*\sim10^5~M_{\odot}$. Specifically, we perform maximum-likelihood fits of the Schechter function, $ψ(M)=dN/dM\propto M^β~\mbox{exp}(-M/M_*)$, to the observed cluster masses in eight well-studied galaxies (LMC, SMC, NGC 4214, NGC 4449, M83, M51, Antennae, and NGC 3256). In most cases, we find that a wide range of cutoff mass is permitted ($10^5~M_\odot \lesssim M_* < \infty$). We find a weak detection at $M_* \sim 10^5~M_\odot$ in one case (M51) and …
NGC 7469 is a well known Luminous IR Galaxy, with a circumnuclear star formation ring ($\sim 830$ pc radius) surrounding a Seyfert 1 AGN. Nuclear unresolved winds were previously detected in X-rays and UV, as well as an extended biconical outflow in IR coronal lines. We search for extended outflows by measuring the kinematics of the $\mathrm{Hβ}$ and [O III] $λ5007$ optical emission lines, in data of the VLT/MUSE integral field spectrograph. We find evidence of two outflow kinematic regimes: one slower regime extending across most of the star formation ring -- possibly driven by the massive st…
We present a model of the photodissociation regions of NGC 4038, which is part of the Antennae galaxies. We have considered one-dimensional slabs of uniform density all having a maximum $A_V=10\,{\rm mag}$, interacting with plane-parallel radiation. The density range in our simulations spans four orders of magnitude ($100\le n\le 10^6\,{\rm cm}^{-3}$) and the UV field strength spans more than three orders of magnitude ($10\leχ\le10^{4.5}$ multiples of the ${\rm Draine}$ field), from which we generated a grid of about 1400 simulations. We compare our results with Herschel SPIRE-FTS, CSO and ISO…
We present deep far-infrared observations of the nearby edge-on galaxy NGC 891 obtained with the Herschel Space Observatory and the Spitzer Space Telescope. The maps confirm the detection of thermal emission from the inner circumgalactic medium (halo) and spatially resolve a dusty superbubble and a dust spur (filament). The dust temperature of the halo component is lower than that of the disk but increases across a region of diameter ~8.0 kpc extending at least 7.7 kpc vertically from one side of the disk, a region we call a superbubble because of its association with thermal X-ray emission an…
Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content. Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows, it remains unclear how these outflows…
We examine the star formation in the outer halo of NGC~1275, the central galaxy in the Perseus cluster (Abell 426), using far ultraviolet and optical images obtained with the Hubble Space Telescope. We have identified a population of very young, compact star clusters with typical ages of a few Myr. The star clusters are organised on multiple-kiloparsec scales. Many of these star clusters are associated with "streaks" of young stars, the combination of which has a cometary appearance. We perform photometry on the star clusters and diffuse stellar streaks, and fit their spectral energy distribut…
The recent star formation histories (SFHs) of post-starburst galaxies have been determined almost exclusively from detailed modeling of their composite star light. This has provided important but limited information on the number, strength, and duration of bursts of star formation. In this work, we present a direct and independent measure of the recent SFH of S12 (plate-mjd-fiber for SDSS 623-52051-207; designated EAS12 in Smercina et al. 2018) from its star cluster population. We detect clusters from high resolution, $UBR$ optical observations from HST, and compare their luminosities and colo…
We present a panchromatic investigation of the partially-embedded, emerging massive cluster Source 26 (= S26) in NGC 4449 with optical spectra obtained at Apache Point Observatory and archival Hubble, Spitzer, and Herschel Space Telescope images. First identified as a radio continuum source with a thermal component due to ionized material, the massive cluster S26 also exhibits optical Wolf-Rayet (WR) emission lines that reveal a large evolved massive star population. We find that S26 is host to $\sim$240 massive stars, of which $\sim$18 are Wolf-Rayet stars; the relative populations are roughl…
