- Department of Physics
University of Crete
GR-71003, Heraklion, Greece
Phone: +30-2810-394216
Fax: +30-2810-394301
E-mail: vassilis@physics.uoc.gr - +30-2810-394216
Vassilis Charmandaris
University of Crete, Physics, Faculty Member
- Foundation for Research and Technology - Hellas, Institute of Astrophysics, Department MemberObservatoire de Paris, LERMA, Department Memberadd
- Dr. Charmandaris completed his undergraduate studies in Physics at the University of Thessaloniki. He continued his g... moreDr. Charmandaris completed his undergraduate studies in Physics at the University of Thessaloniki. He continued his graduate studies in the US and obtained his PhD in Astrophysics at Iowa State University. After a postdoctoral fellowship with the ISO/CAM group at the Astrophysics section of CEA/Saclay (France) he was awarded a Marie Curie fellowship at the Observatoire de Paris, (France). In 1999 he moved back to the US and spent 6 years at the Astronomy Department of Cornell University. There he worked with the group who developed the Infrared Spectrograph of the Spitzer Space Telescope, which was launched by NASA in August 2003. In February 2005, Dr. Charmandaris joined the faculty of the Department of Physics of the University of Crete and he is currently a Professor of Observational Astrophysics. From September 2013 until September 2018 he served as the Director of the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing (IAASARS) of the National Observatory of Athens. Since March 2019 he is the Director of the Institute of Astrophysics at FORTH.edit
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IR spectra will measure the 2 main energy-generating processes by which galactic nuclei shine: black hole accretion and star formation. Both of these play roles in galaxy evolution, and they appear connected. To obtain a complete sample... more
IR spectra will measure the 2 main energy-generating processes by which galactic nuclei shine: black hole accretion and star formation. Both of these play roles in galaxy evolution, and they appear connected. To obtain a complete sample of AGN, covering the range of luminosities and column-densities, we will combine 2 complete all-sky samples with complementary selections, minimally biased by dust
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Research Interests: Physics, Organic Chemistry, Physical Chemistry, Astrophysical Plasma, Spectroscopy, and 15 moreLuminous Infrared Galaxies, Astrophysics, Planetary and Space Science, Nuclear, Molecular, Galaxy, Background Subtraction, Electron Density, High Resolution, Seyfert galaxies, Active Galaxies, Atomic, Starburst Galaxies, Theoretical and Computational High Energy & Nuclear Physics, and new combination
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Research Interests: Organic Chemistry, Astrophysical Plasma, Star Formation, Active Galactic Nuclei, Statistical Analysis, and 13 moreLuminous Infrared Galaxies, Galaxy evolution, Galaxy, Polycyclic Aromatic Hydrocarbon, Radial Velocity, Black Hole, Spatial Distribution, Mid-Infrared, Fine Structure Constant, Spectrum, Infrared, Interactive Monitoring System, and Interactive system
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Research Interests: Physics, Organic Chemistry, Astrophysical Plasma, Active Galactic Nuclei, Luminous Infrared Galaxies, and 15 moreNearby Galaxies, Galaxy Formation and Evolution, Astrophysics, Color, Galaxy evolution, Galaxy, Scaling up, Luminosity, Polycyclic Aromatic Hydrocarbon, Infrared, Active Galaxies, Lower Bound, Continuum, Low Resolution, and Continuo
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Research Interests: Physics, Star Formation, Astrophysics, Astronomy, Galaxy, and 3 moreLuminosity, Stars, and Astronomical
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Research Interests: Physics, Infrared Astronomy, Galaxy Formation and Evolution, Astrophysics, Near Infrared Spectroscopy, and 13 moreGalaxy, Polycyclic Aromatic Hydrocarbon, Mid-Infrared, High Resolution, Infrared, Interactive Monitoring System, Infrared imaging, Star Clusters, Starburst Galaxies, Energy Source, Hubble Space Telescope Images, Astronomical, and Interactive system
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Research Interests: Physics, Star Formation, Active Galactic Nuclei, Mechanism Design, Galactic Astronomy, and 15 moreAstrophysics, Molecular Clouds, Astronomy, Galaxy, Galaxies, Passive Cooling, Mission Planning, Astronomical instrumentation, Disks, ISM, Space Missions, Star Clusters, Field of View, Experimental Astronomy, and Spectral Resolution
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Research Interests: Physics, Star Formation, Active Galactic Nuclei, Luminous Infrared Galaxies, Nearby Galaxies, and 15 moreGalaxy Formation and Evolution, Herschel Space Observatory, Astrophysics, Astronomy, X Rays, Galaxy, Dwarf Galaxies, Power Law, Polycyclic Aromatic Hydrocarbon, Infrared, Far Infrared, Gaussian distribution, Active Galaxies, Spectral Energy Distribution, and Principal Investigator
We present new GALEX and Spitzer Imaging, and IRS spectroscopy of a small sample of collision ring galaxies, including the Cartwheel ring galaxy. When combined with X-ray and optical imaging, where available, we will explore 1) The nature... more
We present new GALEX and Spitzer Imaging, and IRS spectroscopy of a small sample of collision ring galaxies, including the Cartwheel ring galaxy. When combined with X-ray and optical imaging, where available, we will explore 1) The nature and excitation of the ULX/HLX sources in the Cartwheel ring, 2) the mid-IR dust properties of regions of powerful star formation in the rings and spokes, and 3) the dependence of PAH emission line strength on the metallicity and UV properties of the massive star formation regions. ...
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Abstract: To help understand the effects of galaxy interactions on star formation, we analyze Spitzer infrared and GALEX ultraviolet images of the interacting galaxy pair Arp 82 (NGC 2535/6), and compare to a numerical simulation of the... more
Abstract: To help understand the effects of galaxy interactions on star formation, we analyze Spitzer infrared and GALEX ultraviolet images of the interacting galaxy pair Arp 82 (NGC 2535/6), and compare to a numerical simulation of the interaction. We investigate the UV and IR properties of several star forming regions (clumps). Using the FUV/NUV colors of the clumps we constrain the ages. The 8 micron and 24 micron luminosities are used to estimate the far-infrared luminosities and the star formation rates of the clumps. We investigate ...
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We present Spitzer IRS Mid-IR spectroscopy of a sub-set of collisional ring galaxies from a larger sample being observed with the imaging cameras on Spitzer, and in the UV with Galex. The paper will concentrate on three systems that have... more
We present Spitzer IRS Mid-IR spectroscopy of a sub-set of collisional ring galaxies from a larger sample being observed with the imaging cameras on Spitzer, and in the UV with Galex. The paper will concentrate on three systems that have been studied in detail: Arp 143, LT 41 and NGC 985. In Arp 143 and LT 41 we investigate the variations in PAH strength with underlying UV/opt/IR continuum, and discuss the discovery of powerful molecular hydrogen emission from the nucleus and inter-ring region in Arp 143. In the X- ...
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ABSTRACT
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The short-low module of the Infrared Spectrograph (IRS), on-board the Spitzer Space Telescope, has serendipitously imaged sky positions in the Peak-Up (PU) fields for targeted short-low spectral observations. The resulting imaging and... more
The short-low module of the Infrared Spectrograph (IRS), on-board the Spitzer Space Telescope, has serendipitously imaged sky positions in the Peak-Up (PU) fields for targeted short-low spectral observations. The resulting imaging and photometric data at 16 and 22 µm provide coverage between the IRAC 8 µm and MIPS 24 µm bands (although not every PU field has existing coverage from these instruments). We are analyzing these PU data with the goal of eventually releasing to the community a photometric catalog of both stellar and extragalactic point sources obtained from our measurements. Our scientific interests are to search for stars with excess infrared emission from dust and investigate both main-sequence star debris disks, indicative of planetary formation, and circumstellar shells of evolved objects. We will also study galaxy evolution through deep source counts at 16 µm. These source counts will let us measure the evolution of the spectral energy distributions of galaxies, particularly in PAH emission and silicate absorption features. This work is based on archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.
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We have obtained images of 26 Hickson Compact Groups of galaxies with sensitivities up to 22 mag/arcsec2 in the J, H, and Ks bands with the Wide-field Infrared Camera at the Hale 5 m telescope at Palomar Observatory. Near infrared imaging... more
We have obtained images of 26 Hickson Compact Groups of galaxies with sensitivities up to 22 mag/arcsec2 in the J, H, and Ks bands with the Wide-field Infrared Camera at the Hale 5 m telescope at Palomar Observatory. Near infrared imaging data can be used to map out the history of star formation and gravitational interactions and the relationship of this progression to the striking morphological disturbances of the galaxies of our sample. We have examined and correlated characteristics in the near infrared of the isophotal profiles and color distributions and compared these observations with those in optical and infrared wavelengths. A number of faint dwarf galaxies have also been identified in our images, allowing us to place stringent limits on their presence and permitting significantly better statistics on the faint end of the luminosity function of compact groups.
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Mid-IR spectroscopy has detected the signatures of star-formation (PAH emission) in high redshift (z>1) ultra- and hyper-luminous infrared galaxies. However, the study of the dominant population of IR-luminous galaxies (10^{11} - 10^{12}... more
Mid-IR spectroscopy has detected the signatures of star-formation (PAH emission) in high redshift (z>1) ultra- and hyper-luminous infrared galaxies. However, the study of the dominant population of IR-luminous galaxies (10^{11} - 10^{12} Lsun at 1<z<3), requires observation of sources a at the 0.1 mJy level. We present the deepest spectra taken to date in the Long-Low module of the the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. We targeted two faint (˜ 0.15 mJy) sources in the Southern GOODS field at z=1.09 and z=2.69 as likely star-forming galaxies. Spectra of the lower redshift target were taken in 8-21 micron range (short-low first order and long-low second order), while the higher redshift target was observed from 21-37 microns (long-low first order). Observing times were 3 and 9 hours on-source for SL-1 and LL-2, respectively, and 12 hours for LL-1. We also present the spectra of two serendipitous sources. We detect strong PAH emission in four targets. We compare the spectra to those of local galaxies observed by the IRS. The z=1.09 source appears to be a typical, star-formation dominated LIRG, while the z=2.69 source is a composite source with strong star formation and a prominent AGN. The AGN component dominates the IRAC colors of this source, obscuring the 1.6 micron ``bump.'' Such sources would be excluded from IRAC surveys for starbursts which might then underestimate the star formation density.
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I will present a review on the mid-IR (5--16 microns) spectral imaging of a sequence of nearby interacting galaxies observed by ISOCAM, the mid-IR camera on board ISO. The galaxies are part of the well known Toomre's ``merger sequence''... more
I will present a review on the mid-IR (5--16 microns) spectral imaging of a sequence of nearby interacting galaxies observed by ISOCAM, the mid-IR camera on board ISO. The galaxies are part of the well known Toomre's ``merger sequence'' which was defined as a sample of galaxies depicting progressive snapshots in the time evolution of a merging event. It will be shown that the ratio of the 15 to 7 micron flux correlates well with the IRAS colors of the galaxies, and that using it in conjunction with the [NeII] and [NeIII] lines one can trace the intensity of the radiation field in a starburst. This suggests that even though the bolometric luminosity of merging luminous infrared galaxies is dominated by emission at wavelengths longer than 40 microns, the study of the mid-IR spectral energy distribution is a powerful tool in understanding their global star formation history.
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We present the deepest spectra taken to date by the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. We targeted two faint ( ˜ 0.15 mJy) sources in the Southern GOODS field, at z=1.09 and z=2.69, as likely star-forming... more
We present the deepest spectra taken to date by the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. We targeted two faint ( ˜ 0.15 mJy) sources in the Southern GOODS field, at z=1.09 and z=2.69, as likely star-forming galaxies. Spectra of the lower redshift target were taken in 8-21 micron range (short-low first order and long-low second order), while the higher redshift target was observed from 21-37 microns (long-low first order). Observing times were 3 and 9 hours on-source for SL-1 and LL-2, respectively, and 12 hours for LL-1. We detect strong PAH emission in both targets. We compare the spectra to those of local galaxies observed by the IRS.
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Ultraluminous Infrared Galaxies (ULIRGs) have the power output of quasars, yet they emit nearly all of their energy in the mid to far-infrared. While rare in the local Universe, ULIRGs play an increasingly important role in the evolving... more
Ultraluminous Infrared Galaxies (ULIRGs) have the power output of quasars, yet they emit nearly all of their energy in the mid to far-infrared. While rare in the local Universe, ULIRGs play an increasingly important role in the evolving star formation rate density at high redshift, and they may account for a major fraction of the far-infrared background. Nearly 200 low-redshift ULIRGs have been observed with the IRS on Spitzer during the cryogenic phase of the mission. The IRS spectra of ULIRGs show a great diversity in their properties (slopes, emission line ratios, PAH strengths, extinction), and when coupled with near-infrared and far-infrared photometry, they have been used to quantify the amount of energy produced by AGN and starbursts. The 2-5 micron window is critical for measuring the contribution of hot (~1000K) AGN-heated dust to the emerging SED, yet nearly half of the ULIRGs observed with the IRS have no existing IRAC photometry to cover this wavelength range. Here we propose to complete the Spitzer observations of this important population by observing 83 ULIRGs and 23 PG QSOs (used as templates to understand the hot dust contribution in ULIRGs) with IRAC at 3.6 and 4.5 microns to fill in the missing part of their SEDs, and provide a lasting mid-infrared legacy for studies of ULIRGs and AGN at high-redshift with future generations of IR facilties.
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We present new diagnostics to distinguish and classify in the mid-infrared active galactic nuclei (AGN) from starbursts. We identify in the mid-infrared emission of late type galaxies three different components associated with HII... more
We present new diagnostics to distinguish and classify in the mid-infrared active galactic nuclei (AGN) from starbursts. We identify in the mid-infrared emission of late type galaxies three different components associated with HII regions, diffuse/photo-dissociation regions (PDRs), and AGNs. Based on this decomposition, our diagnostic diagram provides a quantitative estimate of the AGN and starburst contribution in a given mid-infrared spectrum, as well as the star formation efficiency of active galaxies. Each component has characteristic mid-infrared signatures that can be identified in our spectra. We show that UIB emission is very faint or absent in regions harboring the intense and hard radiation fields of AGNs or ``pure'' HII regions where particules emitting UIBs are destroyed by photo-dissociation. However, contrary to starburst galaxies, typical AGN spectra present a strong continuum below 9 microns originating from hot dust heated by the AGN radiation field. Finally, we show that this diagnostic diagram can be used to reveal the presence of very obscured active nuclei embedded in a large concentration of dust. The use of this diagnostic in future mid-infrared observations with the New Generation Space Telescope (NGST) is briefly discussed.
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We present VLA H I and optical spectra of the peculiar galaxy Arp~10. Originally believed to be an example of a classical colliding ring galaxy with multiple rings, the new observations show a large disturbed neutral hydrogen disk... more
We present VLA H I and optical spectra of the peculiar galaxy Arp~10. Originally believed to be an example of a classical colliding ring galaxy with multiple rings, the new observations show a large disturbed neutral hydrogen disk extending 2.7 times the diameter of the bright optical ring. We also present evidence for optical shells or ripples in the outer optical isophotes of the galaxy reminiscent of the ripples seen in some early type systems. The H I disk comprises of two main parts: a very irregular outer structure, containing peculiar loops and filaments and a more regular inner disk associated with the main bright optical ring. In both cases, the H I structures do not exactly trace the optical morphology. This effect is most apparent in the outer parts, where the HI emission resembles the H I loops seen in some shell elliptical galaxies. Even the inner H I disk does not correspond well morphologically nor kinematically to the optical rings. These peculiarities lead us to believe that the potential in which the H I disk resides is significantly out of equilibrium -- a situations which would inherently produce rings of star formation. We suggest that Arp 10 is either i) the late stages of a merger between a large H I rich disk and an SO galaxy or ii) the final stages in the formation of a single gas-rich disk system.
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The IRS Peak-Up arrays are read out in parallel to every Short-Low spectrum taken during the Spitzer mission. We propose to mine this extensive set of more than 170,000 Peak-Up images, which are amply distributed across the sky. We... more
The IRS Peak-Up arrays are read out in parallel to every Short-Low spectrum taken during the Spitzer mission. We propose to mine this extensive set of more than 170,000 Peak-Up images, which are amply distributed across the sky. We propose to use these images for two main programs: (i) to study galaxy counts in moderately deep 16 micron images over a wide area; and (ii) to search for infrared excesses from stars. The 16 micron Peak-Up images include almost a square degree of low-background data at exposure times of at least 100 sec. Of these, about 300 square arcmin have exposure times greater than 15 minutes. These data will include 5,000--10,000 galaxies with 16-micron flux densities > 120 micro-Jy. This deep survey is unique because such coverage cannot be achieved in dedicated pointed observations, due to the small Peak-Up field of view. The IRS Peak-Up blue and red filters sample the SEDs of stellar sources at 16 and 22 microns. The stellar systems we will study are main-sequence and evolved stars. We expect to detect at least several hundred stars in the Peak-Up images, and expect to find excesses in about 10% of main-sequence stars, plus a higher percentage of dust shells around evolved stars. The intended goal of this study is the detection of new and unique phenomenology in main-sequence and evolved stars. We propose to release catalogs of point sources, as added-value products for the community. Through this program we will expand the impact of Spitzer observations for ancillary discoveries.
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Even though the dust constitutes less than one hundredth of the mass of the interstellar medium it is now widely accepted that its influence on the energetics of galaxies, due to the heating of the gas via photoelectrons, as well as on... more
Even though the dust constitutes less than one hundredth of the mass of the interstellar medium it is now widely accepted that its influence on the energetics of galaxies, due to the heating of the gas via photoelectrons, as well as on their obscuration/extinction properties and overall morphology is profound. Interactions between galaxies cause instabilities and lead to massive star formation over extended spatial scales where the properties of interstellar radiation field, gas and dust content vary substantially. I will present a review of our current knowledge on the warm dust content of interacting galaxies in the local universe. An emphasis will be given on the interpretation of their mid-IR properties using the results obtained over the past 4 years with the Infrared Space Observatory (ISO) and how we can improve upon them using the Space Infrared Telescope Facility (SIRTF).
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The Spitzer Infrared Spectrometer (IRS) offers a new Peak Up Imaging (PUI) mode for the upcoming Cycle 2. PUI mode observations are taken in simultaneous 54''x81'' fields of view in the Red (22 microns) and Blue (16 micron) filters, with... more
The Spitzer Infrared Spectrometer (IRS) offers a new Peak Up Imaging (PUI) mode for the upcoming Cycle 2. PUI mode observations are taken in simultaneous 54''x81'' fields of view in the Red (22 microns) and Blue (16 micron) filters, with a pixel scale of 1.8 arcseconds per pixel. Images are diffraction limited, implying a FWHM=2 pixels at 16 microns. All PUI observations are background-limited. We describe the use of this new mode, including observation planning and proposal preparation. We present validation observations of a variety of targets including faint extragalactic objects and imaging of an extended nearby galaxy. We discuss the sensitvity and saturation limits of this new mode. Preliminary observations suggest a 1-sigma sensitivity of 50 microJy in a 30 second exposure in the lowest background regions of the sky.
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We have developed a method to decompose mid-infrared spectra into a single PAH component and several silicate-graphite dust components, performing a least-squares fit to obtain the temperature and optical depth of each. Here, we use this... more
We have developed a method to decompose mid-infrared spectra into a single PAH component and several silicate-graphite dust components, performing a least-squares fit to obtain the temperature and optical depth of each. Here, we use this method to analyze the set of ultraluminous infrared galaxy (ULIRG) spectra obtained with the IRS onboard the Spitzer Space Telescope as part of the GTO program. ULIRGs are defined as galaxies with infrared (8-1000 μm) luminosities in excess of 1012 LSun. This energy is produced by both AGN and starburst activity, with the fraction of energy produced by each process varying from galaxy to galaxy. The parameters returned by the fit procedure reveal the physical composition of ULIRGs but do not necessarily constrain their geometric structure. We find that the luminosity of the PAH component increases and the ratio of the PAH to dust continuum luminosity decreases as the total mid-infrared luminosity of a galaxy increases.
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We propose to obtain deep IRS spectra of the outer disk of the nearby edge on spiral galaxy NGC 891. Our primary goal is to investigate the physical state, mass, and heating processes in the molecular ISM through investigations of four... more
We propose to obtain deep IRS spectra of the outer disk of the nearby edge on spiral galaxy NGC 891. Our primary goal is to investigate the physical state, mass, and heating processes in the molecular ISM through investigations of four pure rotational lines of H2. Pioneering work in the S(0) and S(1) lines with ISO indicate large quantities of warm (T ~ 120 K) molecular clouds along the disk of the galaxy ? fully half of the cold H2 component traced in CO. Furthermore, the ISO results suggest vast quantities of cool (T < 90 K) molecular gas at radii beyond 8 kpc ? 5 to 15 times the mass of the atomic gas, and perhaps enough to solve the missing mass problem within the disk of the galaxy! These are exciting results that need to be verified. The key element, however, is that the large masses depend on an assumed ortho to para H2 ratio, and uncertain gas excitation due to limited lines. For example, GTO time spectra in the S(1) and S(0) lines are consistent with the ISO results, but adding in the S(2) line leads to an interpretation invoking a small ortho to para ratio (~ 0.65), and larger gas temperatures, resulting in 1/10 the mass of warm molecular gas! Unfortunately, our spectra are not deep enough to detect the S(2) line in the outer galaxy, so we are unable to properly model the gas excitation there. This proposal is to go at least 5 times deeper in the most interesting regions of the outer galaxy to strongly detect the S(2) line. We also plan to scour the outer regions (R > 12 kpc) for cool molecular gas by deep integrations in the S(1) and S(0) lines. Finally, we plan a sparse map of most of the disk to detect the S(3) line using the Short-Lo spectrometer. The S(0), S(2), and S(1) and S(3) transitions constrain the excitation of para and ortho H2 respectively, and together yield the o/p ratio. The four lines will therefore solidly establish the mass of warm and cool molecular gas in NGC 891. Are there massive quantities of cool gas in the outer disks of galaxies?
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High-resolution images of the molecular gas in the Antennae galaxies (NGC 4038/39) have revealed a population of ~ 100 massive concentrations of molecular gas. These supergiant molecular complexes have masses which range over three orders... more
High-resolution images of the molecular gas in the Antennae galaxies (NGC 4038/39) have revealed a population of ~ 100 massive concentrations of molecular gas. These supergiant molecular complexes have masses which range over three orders of magnitude and maximum masses approaching 109 solar masses. The slope of the mass function of 1.4+/- 0.1 agrees very well with the slope of the mass function of giant molecular clouds and cores observed in the Milky Way. However, the mass range of the complexes lies well above that of typical giant molecular clouds. I will compare the mass function of the molecular complexes with the observed mass function for the super star clusters in the Antennae, as well as with the mass function derived from similar observations of NGC 5248, a more isolated spiral galaxy that contains a few luminous star clusters.
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The Great Observatory All-sky LIRG Survey (GOALS) targets a complete sample of 203 LIRGS in the local Universe, selected from the IRAS Revised Bright Galaxy Sample (RBGS). The RBGS is a complete sample of 629 galaxies with IRAS 60-micron... more
The Great Observatory All-sky LIRG Survey (GOALS) targets a complete sample of 203 LIRGS in the local Universe, selected from the IRAS Revised Bright Galaxy Sample (RBGS). The RBGS is a complete sample of 629 galaxies with IRAS 60-micron flux densities above 5.24 Jy, covering the full sky above Galactic latitudes |b| > 5 degrees. The RBGS objects are the brightest 60-micron sources in the extragalactic sky, and they span a wide range in morphologies from normal, isolated gas-rich spirals to full mergers. The sample includes numerous nuclear starbursts, Type 1 and 2 Seyfert nuclei, and LINERS. These systems are the best local analogs for comparisons with infrared and sub-mm selected galaxies at high redshift. In Cycles 1 and 3 we were awarded time to image the GOALS sample with IRAC and MIPS, and to obtain nuclear spectra with the IRS. The cycle-3 observations formed the core of a Spitzer Legacy program to obtain and make available IRS nuclear spectra of the GOALS targets. Here we propose to extend and enhance the Spitzer observations of the GOALS sample by obtaining IRS maps in the low-resolution SL and LL slits of 81 LIRGs (in 61 systems) which are close, bright, and highly resolved with IRAC. The primary goals of this proposal are to construct IRS spectral maps which will enable us to (1) explore the ionization state, small and large grain dust properties, and warm molecular gas over the full extent of LIRGs covering a wide range in luminosity and interaction state, and (2) create globally integrated SEDs which, when combined with the existing Spitzer, HST, VLA, NIR, ground-based optical, and proposed Herschel imaging data, will allow us to extend the photometry and spectra from the UV through the radio on matched spatial scales. These spectral maps will complete an unprecedented mid-infrared spectroscopic and photometric survey of luminous infrared galaxies in the local Universe. The total requested time for this program, including all overheads, is 111 hrs.
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We have surveyed a field covering 8.4 degrees2 within the NOAO Deep Wide Field Survey region in Boötes with the Multiband Imaging Photometer on the Spitzer Space Telescope to a limiting 24 um flux density of 0.3 mJy, identifying ˜ 22,000... more
We have surveyed a field covering 8.4 degrees2 within the NOAO Deep Wide Field Survey region in Boötes with the Multiband Imaging Photometer on the Spitzer Space Telescope to a limiting 24 um flux density of 0.3 mJy, identifying ˜ 22,000 point sources. Thirty one sources from this survey with F(24 um) > 0.75 mJy , which are optically ``invisible'' (R > 26) or very faint (I > 24) have been observed with the low-resolution modules of the Infrared Spectrograph on SST. The spectra were extracted using the IRS SMART spectral analysis package in order to optimize their signal to noise. A suite of mid-IR spectral templates of well known galaxies, observed as part of the IRS GTO program, is used to perform formal fits to the spectral energy distribution of the Boötes sources. These fits enable us to measure their redshift, to calculate the depth of the 9.7 um silicate feature along with the strength of 7.7 um PAH, as well as to estimate their bolometric luminosities. We compare the mid-IR slope, the measured PAH luminosity, and the optical depth of these sources with those of galaxies in the local Universe. As a result we are able to estimate the contribution of a dust enshrouded active nucleus to the mid-IR and bolometric luminosity of these systems. This work is based [in part] on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through Contract Number 1257184 issued by JPL/Caltech.
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The Great Observatories All-Sky LIRG Survey (GOALS 20) combines data from NASA's Spitzer Space Telescope, Chandra X-Ray Observatory, Hubble Space Telescope (HST), and Galaxy Evolution Explorer (GALEX) observatories, together with... more
The Great Observatories All-Sky LIRG Survey (GOALS 20) combines data from NASA's Spitzer Space Telescope, Chandra X-Ray Observatory, Hubble Space Telescope (HST), and Galaxy Evolution Explorer (GALEX) observatories, together with ground-based data, into a comprehensive imaging and spectroscopic survey of over 200 low-redshift (z < 0:088), Luminous Infrared Galaxies (LIRGs). The LIRGs are a complete subset of the IRAS Revised Bright Galaxy Sample (RBGS), which comprises 629 extragalactic objects with 60 μm flux densities above 5.24 Jy, and Galactic latitudes above five degrees. The LIRGs targeted in GOALS span the full range of nuclear spectral types defined via traditional optical line-ratio diagrams (type-1 and type-2 AGN, LINERs, and starbursts) as well as interaction stages (major mergers, minor mergers, and isolated galaxies). They provide an unbiased picture of the processes responsible for enhanced infrared emission in galaxies in the local Universe. As an example of the analytic power of the multiwavelength GOALS data set, we present Spitzer, Chandra, HST, and GALEX images and spectra for the interacting system VV 340 (IRAS F14547 þ 2449). The Spitzer MIPS imaging data indicates that between 80–95% of the total far-infrared emission (or about 5 × 10 11 L ⊙) originates in VV 340 north. While the Spitzer IRAC colors of VV 340 north and south are consistent with star-forming galaxies, both the Spitzer IRS and Chandra ACIS data indicate the presence of an AGN in VV 340 north. The observed line fluxes, without correction for extinction, imply that the AGN accounts for less than 10%–20% of the observed infrared emission. The X-ray data are consistent with a heavily absorbed (N H ≥ 10 24 cm À2) AGN. The GALEX far and near-UV fluxes imply a extremely large infrared " excess " (IRX) for the system (F IR =F fuv ∼ 81) which is well above the correlation seen in starburst galaxies. Most of this excess is driven by VV 340 N, which has an IR excess of nearly 400. The VV 340 system seems to be comprised of two very different galaxies: an infrared luminous edge-on galaxy (VV 340 north) that dominates the long-wavelength emission from the system, which hosts a buried AGN; and a face-on starburst (VV 340 south) that dominates the short-wavelength emission.
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An analysis of data from the Spitzer Space Telescope, Hubble Space Telescope, Chandra X-ray Observatory, and AKARI Infrared Astronomy Satellite is presented for the z = 0.036 merging galaxy system II Zw 096 (CGCG 448-020). Because II Zw... more
An analysis of data from the Spitzer Space Telescope, Hubble Space Telescope, Chandra X-ray Observatory, and AKARI Infrared Astronomy Satellite is presented for the z = 0.036 merging galaxy system II Zw 096 (CGCG 448-020). Because II Zw 096 has an infrared luminosity of log(L IR /L) = 11.94, it is classified as a Luminous Infrared Galaxy (LIRG), and was observed as part of the Great Observatories All-sky LIRG Survey (GOALS). The Spitzer data suggest that 80% of the total infrared luminosity comes from an extremely compact, red source not associated with the nuclei of the merging galaxies. The Spitzer mid-infrared spectra indicate no high-ionization lines from a buried active galactic nucleus in this source. The strong detection of the 3.3 μm and 6.2 μm polycyclic aromatic hydrocarbon emission features in the AKARI and Spitzer spectra also implies that the energy source of II Zw 096 is a starburst. Based on Spitzer infrared imaging and AKARI near-infrared spectroscopy, the star formation rate is estimated to be 120 M yr −1 and >45 M yr −1 , respectively. Finally, the high-resolution B-, I-, and H-band images show many star clusters in the interacting system. The colors of these clusters suggest at least two populations—one with an age of 1–5 Myr and one with an age of 20–500 Myr, reddened by 0–2 mag of visual extinction. The masses of these clusters span a range between 10 6 and 10 8 M. This starburst source is reminiscent of the extranuclear starburst seen in NGC 4038/9 (the Antennae Galaxies) and Arp 299 but approximately an order of magnitude more luminous than the Antennae. The source is remarkable in that the off-nuclear infrared luminosity dominates the entire system.