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Sample records for nearby starburst galaxy

  1. Starburst outflows from nearby galaxies

    NASA Technical Reports Server (NTRS)

    Waller, William H.

    1990-01-01

    Starburst outflows from NGC 5461, 1569 and M82 are discussed. The Sc I galaxy, M101, is reknowned for the kpc-size superassociations of star clusters and HII regions that dominate its spiral arms. NGC 5461 is one of the brightest of these superassociations, rivaling the Large Magellanic Cloud in H alpha luminosity. The NGC 5461 superassociation is dominated by a single unresolved HII region of outstanding luminosity (approx. 1000 Orion nebulae). Detailed examination of corresponding continuum images indicates that only the southern plume has any sort of stellar counterpart. The other plumes are clearly diffuse with no underlying hot stars. An image of NGC 1569 is discussed. Besides showing the peculiar arm noted by Zwicky (1971) and the filamentary extensions to the North and South (as noted by Hodge 1974), this image also reveals two arc-like features of diffuse ionized gas to the South. Both arcs are concentric with the bright center of the galaxy - where the super star clusters, A and B are located. The inner arc (Arc 1) appears to follow the same curve as the SW arm thus suggesting that the two features represent limb-brightened fragments of vast superbubble that was blown out by a central starburst sometime in the past. As the classic starburst galaxy, M82 displays all the luminous hallmarks of intense high-mass star formation and outflow activity. The diffuse H alpha and x ray emitting gas along the minor axis provides especially good evidence for a bipolar outflow of hot gas which is shock heating the swept-up interstellar medium (ISM) to temperatures of approx. 10(exp 4) K. An image shows the H alpha emission within the disk and along the minor axis. Another image shows the same field in the light of near-infrared. Both figures are based on charge coupled device images taken with the McGraw-Hill 1.3 m telescope (Waller 1989). The longer wavelength emission clearly shows a more extended morphology along the major axis. The morphological discrepancy is most

  2. What Do Star Clusters in Nearby Starburst Galaxies Tell Us?

    NASA Astrophysics Data System (ADS)

    Lim, Sungsoon; Lee, M.; Hwang, N.

    2014-01-01

    Nearby starburst galaxies are a good laboratory for the study of starburst processes. M82, one of the most famous starburst galaxies, has been a target for numerous studies of starburst events. Especially, many studies have used star clusters as starburst tracers in M82, but they usually investigated a only small central region. We present a photometric study of star clusters in M82 using wide-field UBVI, YJ, and H band images in the Hubble Space Telescope archive. We find ˜1100 star clusters in 12’x8’ field, and estimate ages and masses of about 630 star clusters using spectral energy distribution fitting method. Young star clusters are located in the disk region, while old star clusters are found in both disk and halo regions. Age distribution of star clusters shows three distinguished populations: young (≦ 5 Myr), intermediate-age (about 500 Myr), and old (≧10 Gyr) star clusters. Several massive young star clusters (≥˜105M⊙) are found in the nuclear region, which are regarded as a result of recent starburst. Interestingly, we also find very massive star clusters (≥˜106M⊙) with intermediate-age in the nuclear region, which indicates another starburst event at about 500 Myr ago. This suggests that there are at least two starburst events: 5 Myr and 500 Myr ago, and that the earlier starburst at about 500 Myr ago may be more violent than the recent one. We also find about 30 star clusters in the halo region of M82. They are probably metal-poor old globular clusters belonging to M82 halo. It suggests that starburst galaxies may also be enshrouded by old stellar populations.

  3. THE NATURE OF STARBURSTS. I. THE STAR FORMATION HISTORIES OF EIGHTEEN NEARBY STARBURST DWARF GALAXIES

    SciTech Connect

    McQuinn, Kristen B. W.; Skillman, Evan D.; Stark, David; Weisz, Daniel; Cannon, John M.; Dalcanton, Julianne; Williams, Benjamin; Dolphin, Andrew; Hidalgo-RodrIguez, Sebastian

    2010-09-20

    We use archival Hubble Space Telescope observations of resolved stellar populations to derive the star formation histories (SFHs) of 18 nearby starburst dwarf galaxies. In this first paper, we present the observations, color-magnitude diagrams (CMDs), and the SFHs of the 18 starburst galaxies, based on a homogeneous approach to the data reduction, differential extinction, and treatment of photometric completeness. We adopt a star formation rate (SFR) threshold normalized to the average SFR of the individual system as a metric for classifying starbursts in SFHs derived from resolved stellar populations. This choice facilitates finding not only the currently bursting galaxies but also 'fossil' bursts increasing the sample size of starburst galaxies in the nearby (D < 8 Mpc) universe. Thirteen of the eighteen galaxies are experiencing ongoing bursts and five galaxies show fossil bursts. From our reconstructed SFHs, it is evident that the elevated SFRs of a burst are sustained for hundreds of Myr with variations on small timescales. A long >100 Myr temporal baseline is thus fundamental to any starburst definition or identification method. The longer lived bursts rule out rapid 'self-quenching' of starbursts on global scales. The bursting galaxies' gas consumption timescales are shorter than the Hubble time for all but one galaxy confirming the short-lived nature of starbursts based on fuel limitations. Additionally, we find that the strength of the H{alpha} emission usually correlates with the CMD-based SFR during the last 4-10 Myr. However, in four cases, the H{alpha} emission is significantly less than what is expected for models of starbursts; the discrepancy is due to the SFR changing on timescales of a few Myr. The inherently short timescale of the H{alpha} emission limits identifying galaxies as starbursts based on the current characteristics which may or may not be representative of the recent SFH of a galaxy.

  4. The Nature of Starbursts. I. The Star Formation Histories of Eighteen Nearby Starburst Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Cannon, John M.; Dalcanton, Julianne; Dolphin, Andrew; Hidalgo-Rodríguez, Sebastian; Holtzman, Jon; Stark, David; Weisz, Daniel; Williams, Benjamin

    2010-09-01

    We use archival Hubble Space Telescope observations of resolved stellar populations to derive the star formation histories (SFHs) of 18 nearby starburst dwarf galaxies. In this first paper, we present the observations, color-magnitude diagrams (CMDs), and the SFHs of the 18 starburst galaxies, based on a homogeneous approach to the data reduction, differential extinction, and treatment of photometric completeness. We adopt a star formation rate (SFR) threshold normalized to the average SFR of the individual system as a metric for classifying starbursts in SFHs derived from resolved stellar populations. This choice facilitates finding not only the currently bursting galaxies but also "fossil" bursts increasing the sample size of starburst galaxies in the nearby (D < 8 Mpc) universe. Thirteen of the eighteen galaxies are experiencing ongoing bursts and five galaxies show fossil bursts. From our reconstructed SFHs, it is evident that the elevated SFRs of a burst are sustained for hundreds of Myr with variations on small timescales. A long >100 Myr temporal baseline is thus fundamental to any starburst definition or identification method. The longer lived bursts rule out rapid "self-quenching" of starbursts on global scales. The bursting galaxies' gas consumption timescales are shorter than the Hubble time for all but one galaxy confirming the short-lived nature of starbursts based on fuel limitations. Additionally, we find that the strength of the Hα emission usually correlates with the CMD-based SFR during the last 4-10 Myr. However, in four cases, the Hα emission is significantly less than what is expected for models of starbursts; the discrepancy is due to the SFR changing on timescales of a few Myr. The inherently short timescale of the Hα emission limits identifying galaxies as starbursts based on the current characteristics which may or may not be representative of the recent SFH of a galaxy. Based on observations made with the NASA/ESA Hubble Space Telescope

  5. Ionized Gas Observation Toward a Nearby Starburst Galaxy NGC 253

    NASA Astrophysics Data System (ADS)

    Nakanishi, K.; Sorai, K.; Nakai, N.; Kuno, N.; Matsubayashi, K.; Sugai, H.; Takano, S.; Kohno, K.; Nakajima, T.

    2015-12-01

    ALMA observation of a hydrogen recombination emission line toward NGC 253 was performed. NGC 253 is a prototypical starburst galaxy in the nearby universe. The recombination line was clearly detected in the central region of NGC 253 with a spatial resolution of few dozens of parsecs at the galaxy. The line and thermal free-free continuum emission show quite similar spatial distribution, and this fact shows the recombination line certainly traces ionized gas formed by young massive stars. Estimated electron temperature (6500-9000K) from the data are similar to those of Galactic HII regions. The recombination line has large velocity width at the center of the galaxy, and the velocity structure is quite different from that of molecular emission line.

  6. (12)CO (3-2) & (1-0) emission line observations of nearby starburst galaxy nuclei

    NASA Technical Reports Server (NTRS)

    Devereux, Nicholas; Taniguchi, Yoshiaki; Sanders, D. B.; Nakai, N.; Young, J. S.

    1994-01-01

    New measurements of the (12)CO (1-0) and (12)CO (3-2) line emission are presented for the nuclei of seven nearby starburst galaxies selected from a complete sample of 21 nearby starburst galaxies for which the nuclear star formation rates are measured to be comparable to the archetype starburst galaxies M82 and NGC 253. The new observations capitalize on the coincidence between the beam size of the 45 m Nobeyama telescope at 115 GHz and that of the 15 m James Clerk Maxwell Telescope at 345 GHz to measure the value of the (12)CO (3-2)/(1-0) emission line ratio in a 15 sec (less than or equal to 2.5 kpc) diameter region centered on the nuclear starburst. In principle, the (12)CO (3-2)/(1-0) emission line ratio provides a measure of temperature and optical depth for the (12)CO gas. The error weighted mean value of the (12)CO (3-2)/(1-0) emission line ratio measured for the seven starburst galaxy nuclei is -0.64 +/- 0.06. The (12)CO (3-2)/(1-0) emission line ratio measured for the starburst galaxy nuclei is significantly higher than the average value measured for molecular gas in the disk of the Galaxy, implying warmer temperatures for the molecular gas in starburst galaxy nuclei. On the other hand, the (12)CO (3-2)/(1-0) emission line ratio measured for the starburst galaxy nuclei is not as high as would be expected if the molecular gas were hot, greater than 20 K, and optically thin, tau much less than 1. The total mass of molecular gas contained within the central 1.2-2.8 kpc diameter region of the starburst galaxy nuclei ranges from 10(exp 8) to 10(exp 9) solar mass. While substantial, the molecular gas mass represents only a small percentage, approximately 9%-16%, of the dynamical mass in the same region.

  7. PROPERTIES OF NEARBY STARBURST GALAXIES BASED ON THEIR DIFFUSE GAMMA-RAY EMISSION

    SciTech Connect

    Paglione, Timothy A. D.; Abrahams, Ryan D.

    2012-08-20

    The physical relationship between the far-infrared and radio fluxes of star-forming galaxies has yet to be definitively determined. The favored interpretation, the 'calorimeter model', requires that supernova generated cosmic-ray (CR) electrons cool rapidly via synchrotron radiation. However, this cooling should steepen their radio spectra beyond what is observed, and so enhanced ionization losses at low energies from high gas densities are also required. Further, evaluating the minimum energy magnetic field strength with the traditional scaling of the synchrotron flux may underestimate the true value in massive starbursts if their magnetic energy density is comparable to the hydrostatic pressure of their disks. Gamma-ray spectra of starburst galaxies, combined with radio data, provide a less ambiguous estimate of these physical properties in starburst nuclei. While the radio flux is most sensitive to the magnetic field, the GeV gamma-ray spectrum normalization depends primarily on gas density. To this end, spectra above 100 MeV were constructed for two nearby starburst galaxies, NGC 253 and M82, using Fermi data. Their nuclear radio and far-infrared spectra from the literature are compared to new models of the steady-state CR distributions expected from starburst galaxies. Models with high magnetic fields, favoring galaxy calorimetry, are overall better fits to the observations. These solutions also imply relatively high densities and CR ionization rates, consistent with molecular cloud studies.

  8. OBSERVATIONAL CONSTRAINTS ON THE MOLECULAR GAS CONTENT IN NEARBY STARBURST DWARF GALAXIES

    SciTech Connect

    McQuinn, Kristen B. W.; Skillman, Evan D.; Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F.; Dolphin, Andrew E.; Cannon, John M.; Holtzman, Jon

    2012-06-01

    Using star formation histories derived from optically resolved stellar populations in 19 nearby starburst dwarf galaxies observed with the Hubble Space Telescope, we measure the stellar mass surface densities of stars newly formed in the bursts. By assuming a star formation efficiency (SFE), we then calculate the inferred gas surface densities present at the onset of the starbursts. Assuming an SFE of 1%, as is often assumed in normal star-forming galaxies, and assuming that the gas was purely atomic, translates to very high H I surface densities ({approx}10{sup 2}-10{sup 3} M{sub Sun} pc{sup -2}), which are much higher than have been observed in dwarf galaxies. This implies either higher values of SFE in these dwarf starburst galaxies or the presence of significant amounts of H{sub 2} in dwarfs (or both). Raising the assumed SFEs to 10% or greater (in line with observations of more massive starbursts associated with merging galaxies), still results in H I surface densities higher than observed in 10 galaxies. Thus, these observations appear to require that a significant fraction of the gas in these dwarf starbursts galaxies was in the molecular form at the onset of the bursts. Our results imply molecular gas column densities in the range 10{sup 19}-10{sup 21} cm{sup -2} for the sample. In the galaxies where CO observations have been made, these densities correspond to values of the CO-H{sub 2} conversion factor (X{sub CO}) in the range >(3-80) Multiplication-Sign 10{sup 20} cm{sup -2} (K km s{sup -1}){sup -1}, or up to 40 Multiplication-Sign greater than Galactic X{sub CO} values.

  9. A New Database of observed SEDs of Nearby Starburst Galaxies from the UV to the FIR

    NASA Astrophysics Data System (ADS)

    Wu, W.; Clayton, G. C.; Gordon, K. D.; Misselt, K. A.; Smith, T. L.

    2000-12-01

    We present a new database of UV to FIR data of about 50 nearby starburst galaxies. The galaxies are selected based upon the availability of IUE data. We have recalibrated the IUE UV spectra for these galaxies by incorporating the most recent improvements in the IUE data calibration. For the spectra in optical range, we include the data from the atlas by Kinney et al. and the results of our own long-slit observations with the Bok telescope (Steward Observatory), complemented by the photometric data from the HST/WFPC2 observations. The NIR data are from the literature, our new observations at CTIO, NASA/IRTF and the Mount Laguana Observatory. In addition, the ISO archive has provided mid-IR spectra for some of the galaxies. The optical to IR data are matched to the IUE aperture. In conjunction with IRAS and ISO FIR fluxes, all these data form a set of observed spectral energy distributions (SEDs) of the nucleus regions of nearby starburst galaxies, which should be useful in studying star formation and dust/gas attenuation in galaxies.

  10. Dynamics of starbursting dwarf galaxies. III. A H I study of 18 nearby objects

    NASA Astrophysics Data System (ADS)

    Lelli, Federico; Verheijen, Marc; Fraternali, Filippo

    2014-06-01

    We investigate the dynamics of starbursting dwarf galaxies, using both new and archival H I observations. We consider 18 nearby galaxies that have been resolved into single stars by HST observations, providing their star formation history and total stellar mass. We find that 9 objects have a regularly rotating H I disk, 7 have a kinematically disturbed H I disk, and 2 show unsettled H I distributions. Two galaxies (NGC 5253 and UGC 6456) show a velocity gradient along the minor axis of the H I disk, which we interpret as strong radial motions. For galaxies with a regularly rotating disk we derive rotation curves, while for galaxies with a kinematically disturbed disk, we estimate the rotation velocities in their outer parts. We derive baryonic fractions within about 3 optical scale lengths and find that, on average, baryons constitute at least 30% of the total mass. Despite the star formation having injected ~1056 ergs in the ISM in the past ~500 Myr, these starbursting dwarfs have both baryonic and gas fractions similar to those of typical dwarf irregulars, suggesting that they did not eject a large amount of gas out of their potential wells. Appendices are available in electronic form at http://www.aanda.orgH I datacubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A71

  11. Starburst galaxies

    NASA Technical Reports Server (NTRS)

    Weedman, Daniel W.

    1987-01-01

    The infrared properties of star-forming galaxies, primarily as determined by the Infrared Astronomy Satellite (IRAS), are compared to X-ray, optical, and radio properties. Luminosity functions are reviewed and combined with those derived from optically discovered samples using 487 Markarian galaxies with redshifts and published IRAS 60 micron fluxes, and 1074 such galaxies in the Center for Astrophysics redshift survey. It is found that the majority of infrared galaxies which could be detected are low luminosity sources already known from the optical samples, but non-infrared surveys have found only a very small fraction of the highest luminosity sources. Distributions of infrared to optical fluxes and available spectra indicate that the majority of IRAS-selected galaxies are starburst galaxies. Having a census of starburst galaxies and associated dust allow severl important global calculations. The source counts are predicted as a function of flux limits for both infrared and radio fluxes. These galaxies are found to be important radio sources at faint flux limits. Taking the integrated flux to z = 3 indicates that such galaxies are a significant component of the diffuse X-ray background, and could be the the dominant component depending on the nature of the X-ray spectra and source evolution.

  12. THEORETICAL EXPLANATION OF THE COSMIC-RAY PERPENDICULAR DIFFUSION COEFFICIENT IN THE NEARBY STARBURST GALAXY NGC 253

    SciTech Connect

    Buffie, K.; Shalchi, A.; Heesen, V. E-mail: v.heesen@soton.ac.uk

    2013-02-10

    Diffusion coefficients are usually used to describe the propagation of cosmic rays through the universe. Whereas such transport parameters can be obtained from experiments in the solar system, it is difficult to determine diffusion coefficients in the Milky Way or in external galaxies. Recently, a value for the perpendicular diffusion coefficient in the nearby starburst galaxy NGC 253 has been proposed. In the present paper, we reproduce this value theoretically by using an advanced analytical theory for perpendicular diffusion.

  13. Dense gas in nearby galaxies. XIII. CO submillimeter line emission from the starburst galaxy M 82

    NASA Astrophysics Data System (ADS)

    Mao, R. Q.; Henkel, C.; Schulz, A.; Zielinsky, M.; Mauersberger, R.; Störzer, H.; Wilson, T. L.; Gensheimer, P.

    2000-06-01

    12CO J = 1-0, 2-1, 4-3, 7-6, and 13CO 1-0, 2-1, and 3-2 line emission was mapped with angular resolutions of 13'' - 22'' toward the nuclear region of the archetypical starburst galaxy M 82. There are two hotspots on either side of the dynamical center, with the south-western lobe being slightly more prominent. Lobe spacings are not identical for all transitions: For the submillimeter CO lines, the spacing is ~ 15''; for the millimeter lines (CO J = 2-1 and 1-0) the spacing is ~ 26'', indicating the presence of a `low' and a `high' CO excitation component. A Large Velocity Gradient (LVG) excitation analysis of the submillimeter lines leads to inconsistencies, since area and volume filling factors are almost the same, resulting in cloud sizes along the lines-of-sight that match the entire size of the M 82 starburst region. Nevertheless, LVG column densities agree with estimates derived from the dust emission in the far infrared and at submillimeter wavelengths. 22'' beam averaged total column densities are N(CO) ~ 5 1018 and N(H_2) ~ 1023 \\cmsq; the total molecular mass is a few 108 \\solmass. Accounting for high UV fluxes and variations in kinetic temperature and assuming that the observed emission arises from photon dominated regions (PDRs) resolves the problems related to an LVG treatment of the radiative transfer. Spatial densities are as in the LVG case (\

  14. CONSTRAINING STELLAR FEEDBACK: SHOCK-IONIZED GAS IN NEARBY STARBURST GALAXIES

    SciTech Connect

    Hong, Sungryong; Calzetti, Daniela; Gallagher, John S. III; Martin, Crystal L.; Conselice, Christopher J.; Pellerin, Anne

    2013-11-01

    We investigate the properties of feedback-driven shocks in eight nearby starburst galaxies using narrow-band imaging data from the Hubble Space Telescope. We identify the shock-ionized component via the line diagnostic diagram [O III] (λ5007)/Hβ versus [S II] (λλ6716, 6731) (or [N II] (λ6583))/Hα, applied to resolved regions 3-15 pc in size. We divide our sample into three sub-samples: sub-solar, solar, and super-solar, for consistent shock measurements. For the sub-solar sub-sample, we derive three scaling relations: (1) L{sub shock}∝SFR{sup 0.62}, (2) L{sub shock}∝Σ{sub SFR,{sub HL}} {sup 0.92}, and (3) L{sub shock}/L{sub tot}∝(L{sub H} /L{sub ☉,{sub H}}){sup –0.65}, where L{sub shock} is the Hα luminosity from shock-ionized gas, Σ{sub SFR,{sub HL}} the star formation rate (SFR) per unit half-light area, L{sub tot} the total Hα luminosity, and L{sub H} /L{sub ☉,{sub H}} the absolute H-band luminosity from the Two Micron All Sky Survey normalized to solar luminosity. The other two sub-samples do not have enough number statistics, but appear to follow the first scaling relation. The energy recovered indicates that the shocks from stellar feedback in our sample galaxies are fully radiative. If the scaling relations are applicable in general to stellar feedback, our results are similar to those by Hopkins et al. for galactic superwinds. This similarity should, however, be taken with caution at this point, as the underlying physics that enables the transition from radiative shocks to gas outflows in galaxies is still poorly understood.

  15. THE STAR CLUSTER SYSTEM IN THE NEARBY STARBURST GALAXY M82

    SciTech Connect

    Lim, Sungsoon; Lee, Myung Gyoon; Hwang, Narae E-mail: mglee@astro.snu.ac.kr

    2013-03-20

    We present a photometric study of star clusters in the nearby starburst galaxy M82 based on the UBVI-, YJ- and H-band Hubble Space Telescope images. We find 1105 star clusters with V < 23 mag. Of those, 1070 are located in the disk region, while 35 star clusters are in the halo region. The star clusters in the disk are composed of a dominant blue population with a color peak at (B - V){sub 0} Almost-Equal-To 0.45, and a weaker red population. The luminosity function of the disk clusters shows a power-law distribution with a power-law index {alpha} = -2.04 {+-} 0.03, and the scale height of their distribution is h{sub z} = 9.''64 {+-} 0.''40 (164 {+-} 7 pc), similar to that of the stellar thin disk of M82. We have derived the ages of {approx}630 star clusters using the spectral energy distribution fit method by comparing UBVI(YJ)H-band photometric data with the simple stellar population models. The age distribution of the disk clusters shows that the most dominant cluster population has ages ranging from 100 Myr to 1 Gyr, with a peak at about 500 Myr. This suggests that M82 has undergone a disk-wide star formation about 500 Myr ago, probably through the interaction with M81. The brightest star clusters in the nuclear region are much brighter than those in other regions, indicating that more massive star clusters are formed in the denser environments. On the other hand, the colors of the halo clusters are similar to those of globular clusters in the Milky Way, and their ages are estimated to be older than 1 Gyr. These are probably genuine old globular clusters in M82.

  16. THE GREEN BANK TELESCOPE MAPS THE DENSE, STAR-FORMING GAS IN THE NEARBY STARBURST GALAXY M82

    SciTech Connect

    Kepley, Amanda A.; Frayer, David; Leroy, Adam K.; Usero, Antonio; Walter, Fabian

    2014-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO{sup +}. Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope (GBT)—the largest single-dish millimeter radio telescope—for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO{sup +} in the starburst galaxy M82. The HCN and HCO{sup +} in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO{sup +} emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and traces the eastern edge of the hot outflowing gas. The central starburst region has a higher ratio of star formation to dense gas than the outer regions, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies, a capability that will increase further with the 16 element feed array under construction.

  17. Spatially Resolved Stellar Populations Of Nearby Post-Starburst Galaxies In SDSS-IV MaNGA

    NASA Astrophysics Data System (ADS)

    Liu, Charles; Betances, Ashley; Bonilla, Alaina Marie; Gonzalez, Andrea; Migliore, Christina; Goddard, Daniel; Masters, Karen; SDSS-IV MaNGA Team

    2016-01-01

    We have selected five galaxies in the Mapping Nearby Galaxies at APO (MaNGA) project of the latest generation of the Sloan Digital Sky Survey (SDSS-IV) identified as post-starburst (E+A) systems, in the transition between "blue cloud" and "red sequence" galaxies. We measure the equivalent widths of the Balmer series, D4000 break, and metal lines across each galaxy, and produce maps of the stellar age, stellar mass, and metallicities of each galaxy using FIREFLY, a full spectral analysis code. We have found that the measured properties of the galaxies overall generally matches well with single-aperture SDSS spectra from which the original post-starburst identifications were made. The variation in the spatial distributions of the stellar populations, in particular the A-stars, give us insight into the details of the transitional E+A quenching phase. This work was supported by the Alfred P. Sloan Foundation via the SDSS-IV Faculty and Student Team (FAST) initiative, ARC Agreement No. SSP483 to the CUNY College of Staten Island.

  18. Starbursts in colliding galaxies.

    NASA Astrophysics Data System (ADS)

    Mirabel, I. F.; Duc, P. A.

    Global starbursts are a consequence of rapid changes in the dynamics of the interstellar gas. The most violent starbursts take place in the nuclear regions of galaxies, when galaxy-galaxy encounters cause a sudden reduction of angular momentum, with the subsequent infall to the central regions of a large fraction of the overall interstellar gas. Although starbursts are also observed in the central regions of isolated barred spiral galaxies, most of the starbursts with bolometric luminosities above 1012Lsun occur in mergers. Super-starbursts in galactic nuclei seem to require high infall rates of interstellar gas that can only be produced during mergers. The authors discuss the phenomenon of extranuclear starbursts in relation to the formation of dwarf galaxies during galaxy-galaxy collisions. As a consequence of tidal interactions a fraction of the less gravitationally bound atomic hydrogen that populates the outskirts of disk galaxies may escape into the intergalactic medium. It is found that the ejected gas may assemble again and collapse, leading to the formation of intergalactic starbursts, namely, tidal dwarf galaxies.

  19. Cosmic ray interactions in starbursting galaxies

    NASA Astrophysics Data System (ADS)

    Yoast-Hull, Tova M.

    High quality gamma-ray and radio observations of nearby galaxies offer an unprecedented opportunity to quantitatively study the properties of their cosmic ray populations. Accounting for various interactions and energy losses, I developed a multi-component, single-zone model of the cosmic ray populations in the central molecular zones of star-forming galaxies. Using observational knowledge of the interstellar medium and star formation, I successfully predicted the radio, gamma-ray, and neutrino spectra for nearby starbursts. Using chi-squared tests to compare the models with observational radio and gamma-ray data, I placed constraints on magnetic field strengths, cosmic ray energy densities, and galactic wind (advection) speeds. The initial models were applied to and tested on the prototypical starburst galaxy M82. To further test the model and to explore the differences in environment between starbursts and active galactic nuclei, I studied NGC 253 and NGC 1068, both nearby giant spiral galaxies which have been detected in gamma-rays. Additionally, I demonstrated that the excess GeV energy gamma-ray emission in the Galactic Center is likely not diffuse emission from an additional population of cosmic rays accelerated in supernova remnants. Lastly, I investigated cosmic ray populations in the starburst nuclei of Arp 220, a nearby ultraluminous infrared galaxy which displays a high-intensity mode of star formation more common in young galaxies, and I showed that the nuclei are efficient cosmic-ray proton calorimeters.

  20. Starburst Galaxy NGC 3310

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Scientists using NASA's Hubble Space Telescope are studying the colors of star clusters to determine the age and history of starburst galaxies, a technique somewhat similar to the process of learning the age of a tree by counting its rings.

    This month's Hubble Heritage image showcases the galaxy NGC 3310. It is one of several starburst galaxies, which are hotbeds of star formation, being studied by Dr. Gerhardt Meurer and a team of scientists at Johns Hopkins University, Laurel, Md.

    The picture, taken by Hubble's Wide Field and Planetary Camera 2, is online at http://heritage.stsci.edu and http://oposite.stsci.edu/pubinfo/pr/2001/26 and http://www.jpl.nasa.gov/images/wfpc . The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.

    Most galaxies form new stars at a fairly slow rate, but starburst galaxies blaze with extremely active star formation. Measuring the clusters' colors yields information about stellar temperatures. Since young stars are blue and older stars redder, the colors relate to their ages.

    NGC 3310 is forming clusters of new stars at a prodigious rate. The new image shows several hundred star clusters, visible as the bright blue, diffuse objects that trace the galaxy's spiral arms. Each of these star clusters represents the formation of up to about a million stars, a process that takes less than 100,000 years. In addition, hundreds of individual young, luminous stars can be seen throughout the galaxy.

    The star clusters become redder with age as the most massive and bluest stars exhaust their fuel and burn out. Measurements in this image of the wide range of cluster colors show their ages range between about one million and more than one hundred million years. This suggests that the starburst 'turned on' more than 100 million years ago. It may have been triggered when NGC 3310 collided with a companion galaxy.

    These observations may change astronomers' view of starbursts. Starbursts were once

  1. A UNIVERSAL, LOCAL STAR FORMATION LAW IN GALACTIC CLOUDS, NEARBY GALAXIES, HIGH-REDSHIFT DISKS, AND STARBURSTS

    SciTech Connect

    Krumholz, Mark R.; Dekel, Avishai; McKee, Christopher F. E-mail: dekel@phys.huji.ac.il

    2012-01-20

    Star formation laws are rules that relate the rate of star formation in a particular region, either an entire galaxy or some portion of it, to the properties of the gas, or other galactic properties, in that region. While observations of Local Group galaxies show a very simple, local star formation law in which the star formation rate per unit area in each patch of a galaxy scales linearly with the molecular gas surface density in that patch, recent observations of both Milky Way molecular clouds and high-redshift galaxies apparently show a more complicated relationship in which regions of equal molecular gas surface density can form stars at quite different rates. These data have been interpreted as implying either that different star formation laws may apply in different circumstances, that the star formation law is sensitive to large-scale galaxy properties rather than local properties, or that there are high-density thresholds for star formation. Here we collate observations of the relationship between gas and star formation rate from resolved observations of Milky Way molecular clouds, from kpc-scale observations of Local Group galaxies, and from unresolved observations of both disk and starburst galaxies in the local universe and at high redshift. We show that all of these data are in fact consistent with a simple, local, volumetric star formation law. The apparent variations stem from the fact that the observed objects have a wide variety of three-dimensional size scales and degrees of internal clumping, so even at fixed gas column density the regions being observed can have wildly varying volume densities. We provide a simple theoretical framework to remove this projection effect, and we use it to show that all the data, from small solar neighborhood clouds with masses {approx}10{sup 3} M{sub Sun} to submillimeter galaxies with masses {approx}10{sup 11} M{sub Sun }, fall on a single star formation law in which the star formation rate is simply {approx}1% of

  2. Probing a Starburst Galaxy's Superwind

    NASA Astrophysics Data System (ADS)

    Stocke, John

    The Cosmic Origins Spectrograph Science Team for IGM studies proposes to observe the bright QSO/starburst galaxy pair, SBS1108+560/M108 for the following purposes: 1. To measure the FUV brightness of the QSO to determine whether an HST/COS observation is viable and to set its exposure times. 2. To determine the locations of the brighter star forming regions in the disk of M108 to compare wth high resolution HI 21cm, H alpha and soft X-ray continuum maps which show supershells, line-emitting loops and extra-planar clumps of hot gas. 3. To use the relative extinctions of near-side and far-side star forming regions to determine the orientation of M108 in space. This determination is required in order to correctly interpret the kinematics of any QSO absorption line system(s) found in our COS spectrum of SBS1108+560. M108 (NGC3556) is a moderate starburst from the IRAS-selected sample of Lehnert & Heckman, moderately inclined on the sky (75 deg.) and very nearby (14 Mpc). The proximity of SBS1108+560 to M108 (25 kpc) and its location quite close to the minor-axis of M108 make this pairing quite unusual (one of only 3 to be observed by COS) and an important opportunity for understanding the nature and dynamics of starburst superwinds. An important question we hope to answer with this set of GALEX and HST data is whether starburst winds from massive spiral galaxies actually escape the gaalxy's gravitational potential and so enrich the IGM with metals."

  3. Evolutionary paths in starbursting transition dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Dellenbusch, Kate Erika

    2008-10-01

    In this thesis we present an observational optical study of a subgroup of dwarf galaxies which have characteristics of a possible evolutionary transition between actively star-forming systems and inactive dwarf galaxies. The goal of this thesis is to assess the transition nature of these systems and gain insight into their evolutionary histories. Data for the investigation consist primarily of broad-band and narrow-band Ha images taken with the WIYN 0.9m telescope. We find that these galaxies contain central starbursts embedded in older, smooth, elliptical outer stellar envelopes. They also have small HI contents and apparently lack sufficient amounts of ISM to sustain high star formation rates over a significant cosmic timescale; gas exhaustion timescales are < 1 Gyr. We also find these objects have surprisingly high HII region oxygen abundances with values near solar. This suggests the starburst came from internal gas that was previously enriched and that a significant fraction of the synthesized metals are retained. Additionally, these systems are located in loose groups and are not currently interacting with any nearby galaxies. Thus their origins are not immediately clear. We explore possible evolutionary histories for such starburst "transition" dwarf galaxies based on this puzzling set of characteristics and results from moderately deep optical imaging. We consider mechanisms where the starbursts are tied either to interactions with other galaxies or to the state of the interstellar medium.

  4. THE ACS NEARBY GALAXY SURVEY TREASURY. VII. THE NGC 4214 STARBURST AND THE EFFECTS OF STAR FORMATION HISTORY ON DWARF MORPHOLOGY

    SciTech Connect

    Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Weisz, Daniel R.; Seth, Anil C.; Skillman, Evan D.; Dolphin, Andrew E. E-mail: jd@astro.washington.edu E-mail: dweisz@astro.washington.edu E-mail: skillman@astro.umn.edu

    2011-07-01

    We present deep Hubble Space Telescope WFPC2 optical observations obtained as part of the ACS Nearby Galaxy Survey Treasury as well as early release Wide Field Camera 3 ultraviolet and infrared observations of the nearby dwarf starbursting galaxy NGC 4214. Our data provide a detailed example of how covering such a broad range in wavelength provides a powerful tool for constraining the physical properties of stellar populations. The deepest data reach the ancient red clump at M{sub F814W} {approx} - 0.2. All of the optical data reach the main-sequence turnoff for stars younger than {approx}300 Myr and the blue He-burning sequence for stars younger than 500 Myr. The full color-magnitude diagram (CMD) fitting analysis shows that all three fields in our data set are consistent with {approx}75% of the stellar mass being older than 8 Gyr, in spite of showing a wide range in star formation rates at present. Thus, our results suggest that the scale length of NGC 4214 has remained relatively constant for many gigayears. As previously noted by others, we also find the galaxy has recently ramped up production consistent with its bright UV luminosity and its population of UV-bright massive stars. In the central field we find UV point sources with F336W magnitudes as bright as -9.9. These are as bright as stars with masses of at least 52-56 M{sub sun} and ages near 4 Myr in stellar evolution models. Assuming a standard initial mass function, our CMD is well fitted by an increase in star formation rate beginning 100 Myr ago. The stellar populations of this late-type dwarf are compared with those of NGC 404, an early-type dwarf that is also the most massive galaxy in its local environment. The late-type dwarf appears to have a similar high fraction of ancient stars, suggesting that these dominant galaxies may form at early epochs even if they have low total mass and very different present-day morphologies.

  5. The Wolf-Rayet Population and ISM Interaction in Nearby Starbursts

    NASA Astrophysics Data System (ADS)

    Walsh, J. R.; Monreal-Ibero, A.; Vílchez, J. M.; Pérez-Montero, E.; Iglesias-Páramo, J.; Sandin, C.; Relano, M.; Amorín, R.

    The interaction between massive star formation and gas is a key ingredient in galaxy evolution. Given the level of observational detail currently achievable in nearby starbursts, they constitute ideal laboratories to study interaction process that contribute to global evolution in all types of galaxies. Wolf-Rayet (WR) stars, as an observational marker of high mass star formation, play a pivotal role and their winds can strongly influence the surrounding gas. Imaging spectroscopy of two nearby (<4 Mpc) starbursts, both of which show multiple regions with WR stars, are discussed. The relation between the WR content and the physical and chemical properties of the surrounding ionized gas is explored.

  6. ROSAT observations of nearby galaxies

    NASA Astrophysics Data System (ADS)

    Pietsch, W.; Truemper, J.

    1993-12-01

    First results of pointed and All Sky Survey observations of galaxies with the X-ray observatory satellite ROSAT are reported. During observations of the Magellanic Clouds and the Andromeda galaxy new super-soft X-ray sources have been detected. This new class of luminous X-ray sources may help to solve the millisecond pulsar progenitor problem. Due to the improved sensitivity and longer observation times of ROSAT new X-ray point sources have been resolved in several nearby galaxies. The diffuse emission of the Large Magellanic Cloud that was already reported by HEAO 2 (EINSTEIN) has been mapped in detail. It shows a lot of fine structure and temperatures around 5 x 106 K. The improved low energy response of ROSAT led to the discovery of 106 K gas from the spiral galaxy M101 and the halo of the starburst galaxy NGC 253. No diffuse emission was detected from the halo of the edge-on spiral galaxy NGC 5907.

  7. Do Tidal Interactions Trigger Starbursts in Dwarf Galaxies?

    NASA Astrophysics Data System (ADS)

    Martinkus, Charlotte; Cannon, John M.; McQuinn, Kristen B.; Johnson, Megan C.; Skillman, Evan D.; Bailin, Jeremy; Ford, Alyson; Koribalski, Baerbel

    2015-01-01

    Starburst dwarf galaxies are extensively studied systems, though the mechanism that triggers starbursts is poorly understood. Tidal interactions and gas accretion are thought to be potential starburst trigger mechanisms, although internal, secular drivers have not been ruled out. If starbursts are a result of external perturbations, then one would expect to see signatures of interaction in the gaseous disk of the galaxy. To examine this hypothesis, we analyze both archival and newly-obtained deep, wide-field HI maps from the Green Bank Telescope (GBT) of a sample of nineteen well-studied nearby starburst dwarf galaxies to search for such signs of interactions. Our sample is unique in that we have previously derived the star formation histories from Hubble Space Telescope imaging of the resolved stellar populations for all galaxies. In this work we focus on NGC 784 and NGC 672, which both may lie on a filament of dark matter isolated in space. We evaluate methods to determine the presence and properties of low surface-brightness neutral gas in the outer disk regions. This work serves as a prototype for forthcoming analysis of the full sample. With our results we hope to not only establish an effective data analysis procedure, but to also confirm or rule-out tidal interactions as a triggering mechanism of starbursts in this sample of dwarf galaxies.

  8. THE NATURE OF STARBURSTS. II. THE DURATION OF STARBURSTS IN DWARF GALAXIES

    SciTech Connect

    McQuinn, Kristen B. W.; Skillman, Evan D.; Stark, David; Weisz, Daniel; Cannon, John M.; Dalcanton, Julianne; Williams, Benjamin; Dolphin, Andrew; Hidalgo-RodrIguez, Sebastian

    2010-11-20

    The starburst phenomenon can shape the evolution of the host galaxy and the surrounding intergalactic medium. The extent of the evolutionary impact is partly determined by the duration of the starburst, which has a direct correlation with both the amount of stellar feedback and the development of galactic winds, particularly for smaller mass dwarf systems. We measure the duration of starbursts in twenty nearby, ongoing, and 'fossil' starbursts in dwarf galaxies based on the recent star formation histories derived from resolved stellar population data obtained with the Hubble Space Telescope. Contrary to the shorter times of 3-10 Myr often cited, the starburst durations we measure range from 450to650 Myr in fifteen of the dwarf galaxies and up to 1.3 Gyr in four galaxies; these longer durations are comparable to or longer than the dynamical timescales for each system. The same feedback from massive stars that may quench the flickering star formation does not disrupt the overall burst event in our sample of galaxies. While five galaxies present fossil bursts, fifteen galaxies show ongoing bursts and thus the final durations may be longer than we report here for these systems. One galaxy shows a burst that has been ongoing for only 20 Myr; we are likely seeing the beginning of a burst event in this system. Using the duration of the starbursts, we calculate that the bursts deposited 10{sup 53.9}-10{sup 57.2} erg of energy into the interstellar medium through stellar winds and supernovae, and produced 3%-26% of the host galaxy's mass.

  9. Stellar Evolution in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Conti, Peter

    2001-01-01

    The main thrust of the program was to obtain UV spectroscopy of a number of massive and hot luminous (OB type) stars in the nearby galaxy called the Small Magellanic Cloud (SMC). The objective was to analyze their atmospheres and winds so as to determine the effect of the lower abundance of the SIVIC on these parameters. Furthermore, the differences in evolution could be investigated. Additionally, the UV spectra themselves would be suitably weighted and systematically combined to provide a template for comparison to very distant galaxies formed in the early history of the Universe which also have a low abundance of elements. The spectra have been obtained and the analysis is proceeding, primarily by the groups in Munich and at STScl who are the leads for this project. Given the important role of the nearby SMC galaxy as a template of low metal abundance, I have begun to investigate the YOUNGEST phases of massive star birth, before the most massive and hottest stars become optically visible. Typically these stars form in clusters, in some cases having tens to hundreds of OB type stars. In this phase, each star is still buried in its natal cloud and visible only in the infrared (IR) from its self-heated dust and/or from radio free-free emission of the surrounding hydrogen (HII) region. Efforts to find and identify these buried clusters were conducted using a large radio telescope. A number of these were found and further analysis of the data is underway. These clusters are not visible optically, but ought to be seen in the IR, and are a likely topic for HST photometry on NICMOS. A proposal to do this will be made next semester. These objects are the precursors of the optically visible clusters that contain massive and hot luminous stars.

  10. AN IONIZATION CONE IN THE DWARF STARBURST GALAXY NGC 5253

    SciTech Connect

    Zastrow, Jordan; Oey, M. S.; Veilleux, Sylvain; McDonald, Michael; Martin, Crystal L.

    2011-11-01

    There are few observational constraints on how the escape of ionizing photons from starburst galaxies depends on galactic parameters. Here we report on the first major detection of an ionization cone in NGC 5253, a nearby starburst galaxy. This high-excitation feature is identified by mapping the emission-line ratios in the galaxy using [S III] {lambda}9069, [S II] {lambda}6716, and H{alpha} narrowband images from the Maryland-Magellan Tunable Filter at Las Campanas Observatory. The ionization cone appears optically thin, which suggests the escape of ionizing photons. The cone morphology is narrow with an estimated solid angle covering just 3% of 4{pi} steradians, and the young, massive clusters of the nuclear starburst can easily generate the radiation required to ionize the cone. Although less likely, we cannot rule out the possibility of an obscured active galactic nucleus source. An echelle spectrum along the minor axis shows complex kinematics that are consistent with outflow activity. The narrow morphology of the ionization cone supports the scenario that an orientation bias contributes to the difficulty in detecting Lyman continuum emission from starbursts and Lyman break galaxies.

  11. Stellar Rotation Curves of Starbursting Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    van Zee, Liese; Skillman, Evan D.; Salzer, John J.

    2001-02-01

    A year ago, we successfully completed a pilot project to obtain stellar rotation curves of starbursting dwarf galaxies. These observations provided the first spatially resolved stellar rotation curves of gas-rich dwarf galaxies. We now propose to expand our sample (by a factor of 2) by observing 4 additional dwarf galaxies with the CTIO 4m. The fundamental question to be addressed is whether the gas and stars are kinematically coupled in these small galaxies. These observations will place the first kinematic constraints on evolutionary models for dwarf galaxies.

  12. Starbursts and Galaxy Evolution: results from COSMOS survey.

    NASA Astrophysics Data System (ADS)

    Muñoz-Tuñón, C.; Hinojosa Goñi, R.; Jairo Méndez Abreu, J.; Sánchez Alméida, J.

    2016-06-01

    The search for starbursts galaxies in COSMOS database by a tailored procedure that uses the photometry from SUBARU, results in 220 targets at z<0.5. The typical mass of the starburst is 10^8 and its distribution is similar to that of the quiescent galaxies in the survey at the same redshift range. From the detailed analysis of the galaxies images using the HST, the star forming clumps are characterized. The galaxies are of three different kinds, Snot, Snot and diffuse light and multiple knots. The mass of the knots are typically one order of magnitude below that of the host galaxy and the clumps in multiple knot galaxies are bigger the closer they are to the center. The sSFR however does not change with the particular position of the burst in their host galaxy, which suggests a similar process independently of their location. This result applies also to the galaxies at the largest z range (0.9). Our interpretation is that the star formation is happening at all possible locations on the galaxy discs, possibly from gas accreted from the halo or the IGM, with clumps which grow as they spiral and get to the centermost regions. Our previous work on nearby SF -tadpole galaxies of similar mass reported metallicity drops coinciding with the location of the burst what we have interpreted as SF driven by cold flows. Our results in COSMOS would be consistent with a similar interpretation and a scenario in which medium mass disks are growing by gas accretion that show up as scattered starbursts knots.

  13. Dense circumnuclear molecular gas in starburst galaxies

    NASA Astrophysics Data System (ADS)

    Green, C.-E.; Cunningham, M. R.; Green, J. A.; Dawson, J. R.; Jones, P. A.; López-Sánchez, Á. R.; Verdes-Montenegro, L.; Henkel, C.; Baan, W. A.; Martín, S.

    2016-04-01

    We present results from a study of the dense circumnuclear molecular gas of starburst galaxies. The study aims to investigate the interplay between starbursts, active galactic nuclei and molecular gas. We characterize the dense gas traced by HCN, HCO+ and HNC and examine its kinematics in the circumnuclear regions of nine starburst galaxies observed with the Australia Telescope Compact Array. We detect HCN (1-0) and HCO+ (1-0) in seven of the nine galaxies and HNC (1-0) in four. Approximately 7 arcsec resolution maps of the circumnuclear molecular gas are presented. The velocity-integrated intensity ratios, HCO+ (1-0)/HCN (1-0) and HNC (1-0)/HCN (1-0), are calculated. Using these integrated intensity ratios and spatial intensity ratio maps, we identify photon-dominated regions (PDRs) in NGC 1097, NGC 1365 and NGC 1808. We find no galaxy which shows the PDR signature in only one part of the observed nuclear region. We also observe unusually strong HNC emission in NGC 5236, but it is not strong enough to be consistent with X-ray-dominated region chemistry. Rotation curves are derived for five of the galaxies and dynamical mass estimates of the inner regions of three of the galaxies are made.

  14. The Star Formation Relation in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Schruba, Andreas

    2013-03-01

    I review observational studies of the large-scale star formation process in nearby galaxies. A wealth of new multi-wavelength data provide an unprecedented view on the interplay of the interstellar medium and (young) stellar populations on a few hundred parsec scale in 100+ galaxies of all types. These observations enable us to relate detailed studies of star formation in the Milky Way to the zoo of galaxies in the distant universe. Within the disks of spiral galaxies, recent star formation strongly scales with the local amount of molecular gas (as traced by CO) with a molecular gas depletion time of ˜2 Gyr. This is consistent with the picture that stars form in giant molecular clouds that have about universal properties. Galaxy centers and star-bursting galaxies deviate from this normal trend as they show enhanced star formation per unit gas mass suggesting systematic changes in the molecular gas properties and especially the dense gas fraction. In the outer disks of spirals and in dwarf galaxies, the decreasing availability of atomic gas inevitably limits the amount of star formation, though with large local variations. The critical step for the gas-stars cycle seems therefore to be the formation of a molecular gas phase, a process that shows complex dependencies on various environmental properties and is being investigated by intensive simulational work.

  15. Starburst in the Interacting HII Galaxy II Zw 40 and in Non-Interacting HII Galaxies

    NASA Astrophysics Data System (ADS)

    Telles, E.

    2010-06-01

    In this poster, I summarize the results of our integral field spectroscopic observations of the nearby prototype of HII galaxies, II Zw 40. Observations with GMOS-IFU on GEMINI-North in the optical allowed us to make a detailed kinematic picture of the central starburst, while SINFONI with adaptive optics on the ESO-VLT gave us a near-IR view of the interplay between the ISM phases. Here, I also address the question that not all starbursts require an external trigger such as a galaxy-galaxy encounter, as it seems to be the case for a fraction of low luminosity HII galaxies. We speculate that these may form stars spontaneously like "popcorn in a pan".

  16. Ionized gas pressure correlates with star formation intensity in nearby starbursts

    NASA Astrophysics Data System (ADS)

    Jiang, Tianxing; Malhotra, Sangeeta; Yang, Huan

    2016-06-01

    We estimate the electron density of the ionized gas and thus the thermal pressure in HII regions; and compare that to the SFR (star formation rate) surface density for a combined sample of about 40 green peas and Lyman Break Analogs at z < 0.30. The electron density of the ionized gas is measured from sulfur line ratio ([SII] 6716 / 6731). We find that the SFR surface density is correlated with the electron density and the thermal pressure in HII regions for the star-forming galaxies with SFR surface density above a certain threshold. This work shows quantitatively the correlation between SFR surface density and electron density and that between SFR surface density and the thermal pressure in HII regions for the nearby starburst galaxies. This is consistent with theoretical models of disks (e.g. Kim et al. (2011) if we assume that the thermal pressure in HII regions is comparable to the total diffuse gas pressure at the midplane of the diffuse neutral gas. It is also in agreement with the results from star-forming galaxies at z ~ 2.5. We might infer that the starburst galaxies at low-redshift (z < 0.3) share similar physical properties to the galaxies at high redshift (z ~ 2.5).

  17. Green Pea Galaxies: Extreme, Optically-Thin Starbursts?

    NASA Astrophysics Data System (ADS)

    Jaskot, Anne

    2013-10-01

    The high UV luminosities, compact sizes, and enormous ionization parameters of the Green Pea galaxies make them some of the most extreme starburst galaxies known. Most importantly, due to their unusual emission line ratios and high specific star formation rates, the Green Peas are the best candidates for escaping ionizing radiation in the nearby Universe. We propose to study four Green Peas with COS FUV spectra and ACS emission line imaging to constrain the Lyman continuum {LyC} escape fraction and determine the origin of high ionization emission in these galaxies. COS spectra will set strong limits on the LyC optical depth via the residual intensity in the CII 1335 line, while the NV 1240 line will constrain the stellar population's age and ionizing flux. We will also observe the starbursts with ACS ramp filters in [OII], [OIII], HeII, and H-beta to determine whether the nebular emission is consistent with a low LyC optical depth. The [OIII]/[OII] ratio map will reveal the ionization structure of the emitting gas. If the [OIII] emission is found to be more spatially extended than the [OII] in any regions, it will imply that the regions are most likely optically thin. If HeII is found to be spatially offset from the dominant nebular emission, then we infer the presence of shocks. Correcting for this shock contribution to the observed emission is critical to accurately evaluate the LyC optical depth. These observations will either reveal the Green Peas as a class of galaxies having substantial LyC escape fractions or demonstrate that even some of the most extreme galaxies in the nearby Universe are optically thick.

  18. Supernova blast bonanza in nearby galaxy

    NASA Astrophysics Data System (ADS)

    2004-02-01

    involving one or more galaxy collisions and/or episodes of strongly enhanced star formation activity (so-called 'starbursts'). While most galaxies that are actually forming are too far away for detailed studies of their stellar populations even with Hubble, their local counterparts, nearby starburst and colliding galaxies, are far easier targets. NGC 1569 is a particularly suitable example, being one of the closest starburst galaxies. It harbours two very prominent young, massive clusters plus a large number of smaller star clusters. The two young massive clusters match the globular star clusters we find in our own Milky Way galaxy, while the smaller ones are comparable with the less massive open clusters around us. NGC 1569 was recently investigated in great detail by a group of European astronomers who published their results in the January 2004 issue of the British journal, Monthly Notices of the Royal Astronomical Society. The group used several of Hubble's high-resolution instruments, with deep observations spanning a wide wavelength range to determine the parameters of the clusters more precisely than is currently possible from the ground. The team found that the majority of clusters in NGC 1569 seem to have been produced in an energetic starburst that started around 25 million years ago and lasted for about 20 million years. First author Peter Anders from the Göttingen University Galaxy Evolution Group, Germany, says: "We are looking straight into the very creation processes of the stars and star clusters in this galaxy. The clusters themselves present us with a fossil record of NGC 1569’s intense star formation history.” The bubble-like structures seen in this image are made of hydrogen gas that glows when hit by the fierce winds and radiation from hot young stars and is racked by supernovae shocks. The first supernovae blew up when the most massive stars reached the end of their lifetimes roughly 20-25 million years ago. The environment in NGC 1569 is still

  19. Far-infrared activity and starburst galaxies

    NASA Technical Reports Server (NTRS)

    Belfort, P.; Mochkovitch, R.; Dennefeld, M.

    1987-01-01

    After the IRAS discovery of galaxies with large far-infrared to blue luminosity ratio, it has been proposed that an enhanced star formation could be the origin of the far-infrared emission through dust heating. Whether a simple photometric model is able to account for the FIR and optical properties of IRAS galaxies was investigated. The L sub IR/L sub B ratio, (B-V) color and H sub alpha equivalent width of normal spirals are well reproduced with smooth star formation histories. In the case of starburst galaxies, several theoretical diagrams allow us to estimate the burst strength and extinction. L sub IR/L sub B ratio up to 100 can be rather easily reached, whereas extreme values probably require IMF truncated at the low end.

  20. NuSTAR Observations of Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Ptak, Andrew; Hornschemeier, Ann E.; Wik, Daniel R.; Yukita, Mihoko; Lehmer, Bret; Zezas, Andreas; Maccarone, Tom; Venters, Tonia M.; Antoniou, Vallia; Harrison, Fiona; Stern, Daniel; NuSTAR Starburst Team

    2016-01-01

    NuSTAR, the first satellite with hard X-ray focusing optics, opens up the possibility to not only detect starburstn galaxies above 10 keV for the first time but also characterize their hard X-ray properties. Here we present an overview of a NuSTAR program to survey seven normal/starburst galaxies: NGC 253, M82, M83, NGC 3256, NGC 3310, Arp 299, and M31. We also discuss data analysis strategies. All galaxies have been observed coordinated with either Chandra or XMM-Newton or both. The main results of these observations were: we characterized the typical starburst spectrum above 10 keV and showed that the spectrum is soft (photon index ~ 3) above 7 keV and determined that individually detected sources are generally black holes in a "transition" accretion state or neutron star systems accreting near the Eddington rate, and variability on time scales of weeks to months is typically detected. In the case of NGC 253 we decomposed the unresolved hard X-ray emission between background, unresolved binaries and truly diffuse flux and found that the diffuse flux upper limit is marginally above model predictions for inverse-Compton scattering of IR photons by cosmic rays.

  1. Investigating Starburst Galaxy Emission Line Equivalent Widths

    NASA Astrophysics Data System (ADS)

    Meskhidze, Helen; Richardson, Chris T.

    2016-01-01

    Modeling star forming galaxies with spectral synthesis codes allows us to study the gas conditions and excitation mechanisms that are necessary to reproduce high ionization emission lines in both local and high-z galaxies. Our study uses the locally optimally-emitting clouds model to develop an atlas of starburst galaxy emission line equivalent widths. Specifically, we address the following question: What physical conditions are necessary to produce strong high ionization emission lines assuming photoionization via starlight? Here we present the results of our photoionization simulations: an atlas spanning 15 orders of magnitude in ionizing flux and 10 orders of magnitude in hydrogen density that tracks over 150 emission lines ranging from the UV to the near IR. Each simulation grid contains ~1.5x104 photoionization models calculated by supplying a spectral energy distribution, grain content, and chemical abundances. Specifically, we will be discussing the effects on the emission line equivalent widths of varying the metallicity of the cloud, Z = 0.2 Z⊙ to Z = 5.0 Z⊙, and varying the star-formation history, using the instantaneous and continuous evolution tracks and the newly released Starburst99 Geneva rotation tracks.

  2. Properties of Dust Extinction in Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Calzetti, D.; Kinney, A. L.; Storchi-Bergmann, T.; Panagia, N.

    1993-05-01

    We have studied the extinction properties of 38 starburst and Blue Compact galaxies covering the metallicity range 8.3<=log (O/H)<=9.2, by analyzing their UV+optical spectra. The UV spectra come from the compilation of IUE spectra by Kinney et al. (Kinney, Bohlin, Calzetti, Panagia, & Wyse, 1993, ApJS, to appear on the May issue). The optical spectra, spanning the wavelength range 3200-7500 Angstroms, have been observed in a IUE-matched aperture. Following standard techniques, we have derived the selective extinction E(B-V) from the Balmer decrement and the metallicity from the [OII] and [OIII] lines. In order to clarify the properties of dust extinction in the UV for starburst galaxies, we have fitted the observed UV fluxes of our galaxies in the wavelength range 1250-2600 Angstroms according to the power law F(lambda )~lambda (beta ) and studied the behaviour of beta as function of the selective extinction E(B-V). We find that these two quantities are correlated and that there is no difference between the loci occupied by the low and high metallicity galaxies in the plane beta -vs-E(B-V). The correlation indicates that a higher metallicity does not change the characteristics of individual grains, but merely increases their number. On this ground, our conclusion is that the shape of the extinction law in the UV does not depend on metallicity, for extinctions E(B-V)>0.2. Although the low metallicity galaxies in our sample follow neither the Large Magellanic Cloud nor the Small Magellanic Cloud extinction laws, the absence in our spectra of prominent 2200 Angstroms dust features illustrates that a simple application of a galactic extinction law may be inadequate to properly correct the UV spectra. Models of clumpy dust layers and of dust mixed with the ionized gas are currently under analysis.

  3. From Starburst to Quiescence: Testing Active Galactic Nucleus feedback in Rapidly Quenching Post-starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Yesuf, Hassen M.; Faber, S. M.; Trump, Jonathan R.; Koo, David C.; Fang, Jerome J.; Liu, F. S.; Wild, Vivienne; Hayward, Christopher C.

    2014-09-01

    Post-starbursts are galaxies in transition from the blue cloud to the red sequence. Although they are rare today, integrated over time they may be an important pathway to the red sequence. This work uses Sloan Digital Sky Survey, the Galaxy Evolution Explorer, and Wide-field Infrared Survey Explorer observations to identify the evolutionary sequence from starbursts to fully quenched post-starbursts (QPSBs) in the narrow mass range log M(M ⊙) = 10.3-10.7, and identifies "transiting" post-starbursts (TPSBs) which are intermediate between these two populations. In this mass range, ~0.3% of galaxies are starbursts, ~0.1% are QPSBs, and ~0.5% are the transiting types in between. The TPSBs have stellar properties that are predicted for fast-quenching starbursts and morphological characteristics that are already typical of early-type galaxies. The active galactic nucleus (AGN) fraction, as estimated from optical line ratios, of these post-starbursts is about three times higher (gsim 36% ± 8%) than that of normal star forming galaxies of the same mass, but there is a significant delay between the starburst phase and the peak of nuclear optical AGN activity (median age difference of >~ 200 ± 100 Myr), in agreement with previous studies. The time delay is inferred by comparing the broadband near-NUV-to-optical photometry with stellar population synthesis models. We also find that starbursts and post-starbursts are significantly more dust obscured than normal star forming galaxies in the same mass range. About 20% of the starbursts and 15% of the TPSBs can be classified as "dust-obscured galaxies" (DOGs), with a near-UV-to-mid-IR flux ratio of >~ 900, while only 0.8% of normal galaxies are DOGs. The time delay between the starburst phase and AGN activity suggests that AGNs do not play a primary role in the original quenching of starbursts but may be responsible for quenching later low-level star formation by removing gas and dust during the post-starburst phase.

  4. From starburst to quiescence: testing active galactic nucleus feedback in rapidly quenching post-starburst galaxies

    SciTech Connect

    Yesuf, Hassen M.; Faber, S. M.; Trump, Jonathan R.; Koo, David C.; Fang, Jerome J.; Liu, F. S.; Wild, Vivienne; Hayward, Christopher C.

    2014-09-10

    Post-starbursts are galaxies in transition from the blue cloud to the red sequence. Although they are rare today, integrated over time they may be an important pathway to the red sequence. This work uses Sloan Digital Sky Survey, the Galaxy Evolution Explorer, and Wide-field Infrared Survey Explorer observations to identify the evolutionary sequence from starbursts to fully quenched post-starbursts (QPSBs) in the narrow mass range log M(M {sub ☉}) = 10.3-10.7, and identifies 'transiting' post-starbursts (TPSBs) which are intermediate between these two populations. In this mass range, ∼0.3% of galaxies are starbursts, ∼0.1% are QPSBs, and ∼0.5% are the transiting types in between. The TPSBs have stellar properties that are predicted for fast-quenching starbursts and morphological characteristics that are already typical of early-type galaxies. The active galactic nucleus (AGN) fraction, as estimated from optical line ratios, of these post-starbursts is about three times higher (≳ 36% ± 8%) than that of normal star forming galaxies of the same mass, but there is a significant delay between the starburst phase and the peak of nuclear optical AGN activity (median age difference of ≳ 200 ± 100 Myr), in agreement with previous studies. The time delay is inferred by comparing the broadband near-NUV-to-optical photometry with stellar population synthesis models. We also find that starbursts and post-starbursts are significantly more dust obscured than normal star forming galaxies in the same mass range. About 20% of the starbursts and 15% of the TPSBs can be classified as 'dust-obscured galaxies' (DOGs), with a near-UV-to-mid-IR flux ratio of ≳ 900, while only 0.8% of normal galaxies are DOGs. The time delay between the starburst phase and AGN activity suggests that AGNs do not play a primary role in the original quenching of starbursts but may be responsible for quenching later low-level star formation by removing gas and dust during the post-starburst

  5. X-ray emission from starburst galaxies

    NASA Technical Reports Server (NTRS)

    Rephaeli, Yoel; Gruber, Duane; Macdonald, Dan; Persic, Massimo

    1991-01-01

    The results are reported of an investigation of X-ray emission from a sample of 53 IRAS-selected candidate starburst galaxies. Superposed soft and hard X-ray emission from these galaxies in the Einstein-IPC and HEAO-1 A-2 and A-4 energy bands, which span 0.5 to 160 keV, is detected at the 99.6 percent confidence level, after allowing for confusion noise in the HEAO-1 data. Above 15 keV the confidence level is 97 percent. The combined spectrum is flat, with a (photon) power-law index of 1.0 +/- 0.3. The contribution of the population of sources represented by this sample to the 3-50 keV residual cosmic X-ray background is estimated to be at least about 4 percent assuming no evolution. Moderate evolution, for which there is some observational evidence, increases this fractional contribution to about 26 percent.

  6. ROSAT PSPC observations of two starburst galaxies

    NASA Astrophysics Data System (ADS)

    Junkes, N.; Pietsch, W.; Hensler, G.

    1993-12-01

    We present results from ROSAT observations of NGC 1808 and NGC 2903. Exposures of 10 ksec each with the Position-Sensitive Proportional Counter (PSPC) detector show X-ray sources at the central positions of both galaxies which are classified as nuclear starburst galaxies. Both targets, NGC 1808 and NGC 2903 appear slightly extended in X-ray maps in the energy band 0.1-2.4 keV. The X-ray spectrum of NGC 1808 shows almost complete absorption below 0.5 keV, indicating an extremely high hydrogen column density towards that source (NH approx. = 8 x 1021/sq cm resulting from model fits on the PSPC spectrum). In the case of NGC 2903, the number of counts in the ROSAT band is significantly lower than expected from a previous EINSTEIN (HEAO 2) investigation of the source.

  7. Bright Submillimeter Galaxies: Evidence for Maximal Starbursts

    NASA Astrophysics Data System (ADS)

    Aretxaga, I.

    2014-09-01

    AzTEC is a sensitive bolometer camera that, coupled with 10 - 15m-class sub-mm telescopes, has mapped more than 3 sq. deg of the extragalactic sky to depths between 0.7 and 1.1 mJy at 1.1mm, prior to its current installation and operation on the 32m Large Millimeter Telescope (LMT). These extragalactic surveys targeted towards blank-fields and biased high-z environments alike have allowed us to identify a few thousands of submillimeter galaxies, powerful obscured starbursts at high-redshifts (z > 1), some of which have intrinsic Star Formation Rates SFR > 1000 Msun/yr and furthermore are extremely compact (~ 1 kpc). Our results imply that these extraordinary systems are forming stars in a gravitationally bound regime in which gravity prohibits the formation of superwinds, leading to matter accumulation within the galaxy and further generations of star formation.

  8. STAR CLUSTER DISRUPTION IN THE STARBURST GALAXY MESSIER 82

    SciTech Connect

    Li, Shuo; Li, Chengyuan; De Grijs, Richard; Anders, Peter

    2015-01-01

    Using high-resolution, multiple-passband Hubble Space Telescope images spanning the entire optical/near-infrared wavelength range, we obtained a statistically complete U-band-selected sample of 846 extended star clusters across the disk of the nearby starburst galaxy M82. Based on a careful analysis of the clusters' spectral energy distributions, we determined their galaxy-wide age and mass distributions. The M82 clusters exhibit three clear peaks in their age distribution, thus defining relatively young, log (t yr{sup –1}) ≤ 7.5, intermediate-age, log (t yr{sup –1}) in [7.5, 8.5], and old samples, log (t yr{sup –1}) ≥ 8.5. Comparison of the completeness-corrected mass distributions offers a firm handle on the galaxy's star cluster disruption history. The most massive star clusters in the young and old samples are (almost) all concentrated in the most densely populated central region, while the intermediate-age sample's most massive clusters are more spatially dispersed, which may reflect the distribution of the highest-density gas throughout the galaxy's evolutionary history, combined with the solid-body nature of the galaxy's central region.

  9. Densitometry and Thermometry of Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Mangum, J. G.; Darling, J.; Menten, K. M.; Henkel, C.; Aalto, S.; Spaans, M.; van der Werf, P.; Ginsburg, A.; Fomalont, E.; Cotton, B.; Kent, B.

    2016-05-01

    With a goal toward deriving the physical conditions in external galaxies, we have conducted a survey and subsequent high spatial resolution imaging of formaldehyde (H2CO) and ammonia (NH3) emission and absorption in a sample of starburst galaxies. In this article we present the results from a subset of this survey which focuses on high spatial resolution measurements of volume density- and kinetic temperature-sensitive transitions of the H2CO molecule. The volume density structure toward the nuclear region of NGC 253 has been derived from θ ≃ 4 arcsec NRAO Very Large Array (VLA) measurements of the 110 - 111 and 211 - 212 K-doublet transitions of H2CO. The kinetic temperature structure toward NGC 253 and NGC 4945 has been derived from θ ≃ 0.5 - 1.0 arcsec measurements of the H2CO 3K-1K+1 - 2K-1K+1 (near 218 GHz) and 5K-1K+1 - 4K-1K+1 (near 365 GHz) transitions acquired using the Atacama Large Millimeter/submillimeter Array (ALMA). These measurements have allowed us to characterize the dense gas and kinetic temperature structure within these star forming galaxies, which is a first step toward associating dense star-forming gas and the heating processes at work within galaxies.

  10. Mapping the HI Neighborhood Around Starburst Dwarf Galaxies NGC 1569, NGC 4214 and NGC 4163

    NASA Astrophysics Data System (ADS)

    Johnson, Megan C.; LITTLE THINGS Team

    2013-01-01

    Dwarf galaxies are believed to be the building blocks of larger galaxies. However, there are some studies that indicate the dwarf galaxies observed in the nearby universe may have formed later, after the most massive galaxies coalesced. Dwarf galaxy formation and evolution is important for our understanding of cosmology. If dwarf galaxies mimic their more massive counterparts, then starburst dwarfs may be present day merger remnants and provide information on the building block hypothesis. The origins of starburst dwarf irregular galaxies of the Magellanic type (dIm) are not well known. The role of interactions and mergers as mechanisms to create these systems has been hypothesized, but not well studied. We present deep HI maps around three starburst dwarf galaxies NGC 1569, NGC 4214 and NGC 4163. The purpose of these maps is to determine if there are tenuous HI structures around these objects that would indicate a recent interaction or merger. We detect HI filamentary structures that may be connected with NGC 1569 thereby indicating a recent interaction with nearby dwarf irregular UGCA 92. However, our map of NGC 4163 and NGC 4214 does not show any tenuous HI at our 5σ sensitivity limit of 1 x 10^18 for a 25 km/s line width.

  11. Panchromatic observations of dwarf starburst galaxies: Infant super star clusters and a low-luminosity AGN

    NASA Astrophysics Data System (ADS)

    Reines, Amy Ellen

    2011-01-01

    Globular star clusters and supermassive black holes are fundamental components of today's massive galaxies, with origins dating back to the very early universe. Both globular clusters and the seeds of supermassive black holes are believed to have formed in the progenitors of modern massive galaxies, although the details are poorly understood. Direct observations of these low-mass, distant, and hence faint systems are unobtainable with current capabilities. However, gas-rich dwarf starburst galaxies in the local universe, analogous in many ways to protogalaxies at high-redshift, can provide critical insight into the early stages of galaxy evolution including the formation of globular clusters and massive black holes. This thesis presents a panchromatic study of nearby dwarf starburst galaxies harboring nascent globular clusters still embedded in their birth material. Infant clusters are identified via their production of thermal radio emission at centimeter wavelengths, which comes from dense gas ionized by young massive stars. By combining radio observations with complementary data at ultraviolet, optical and infrared wavelengths, we obtain a comprehensive view of massive clusters emerging from their gaseous and dusty birth cocoons. This thesis also presents the first example of a nearby dwarf starburst galaxy hosting an actively accreting massive central black hole. The black hole in this dwarf galaxy is unusual in that it is not associated with a bulge, a nuclear star cluster, or any other well-defined nucleus, likely reflecting an early phase of black hole and galaxy evolution that has not been previously observed.

  12. The Ubiquity of Coeval Starbursts in Massive Galaxy Cluster Progenitors

    NASA Astrophysics Data System (ADS)

    Casey, Caitlin M.

    2016-06-01

    The universe’s largest galaxy clusters likely built the majority of their massive >1011 M {}ȯ galaxies in simultaneous, short-lived bursts of activity well before virialization. This conclusion is reached based on emerging data sets for z\\gt 2 proto-clusters and the characteristics of their member galaxies, in particular, rare starbursts and ultraluminous active galactic nuclei (AGN). The most challenging observational hurdle in identifying such structures is their very large volumes, ∼104 comoving Mpc3 at z\\gt 2, subtending areas of approximately half a degree on the sky. Thus, the contrast afforded by an overabundance of very rare galaxies in comparison to the background can more easily distinguish overdense structures from the surrounding, normal density field. Five 2≲ z≲ 3 proto-clusters from the literature are discussed in detail and are found to contain up to 12 dusty starbursts or luminous AGN galaxies each, a phenomenon that is unlikely to occur by chance even in overdense environments. These are contrasted with three higher-redshift (4≲ z≲ 5.5) dusty star-forming galaxy (DSFG) groups, whose evolutionary fate is less clear. Measurements of DSFGs’ gas depletion times suggest that they are indeed short-lived on ∼100 Myr timescales, and accordingly the probability of finding a structure containing more than 8 such systems is ∼0.2%, unless their “triggering” is correlated on very large spatial scales, ∼10 Mpc across. The volume density of DSFG-rich proto-clusters is found to be comparable to all of the >1015 M {}ȯ galaxy clusters in the nearby universe, which is a factor of five larger than expected in some simulations. Some tension still exists between measurements of the volume density of DSFG-rich proto-clusters and the expectation that they are generated via short-lived episodes, as the latter suggests that only a fraction (\\lt \\tfrac{1}{2}) of all proto-clusters should be rich with DSFGs. However, improved observations of

  13. FISICA observations of the starburst galaxy, NGC 1569

    NASA Astrophysics Data System (ADS)

    Clark, D. M.; Eikenberry, S. S.; Raines, S. N.; Gruel, N.; Elston, R.; Guzman, R.; Julian, J.; Boreman, G.; Glenn, P. E.; Hull-Allen, C. G.; Hoffman, J.; Rodgers, M.; Thompson, K.; Flint, S.; Comstock, L.; Myrick, B.

    2006-06-01

    Using the Florida Image Slicer for Infrared Cosmology and Astrophysics (FISICA) we obtained observations of the dwarf starburst galaxy NGC 1569. We present our JH band spectra, particularly noting the existence of extended emission in Paschen β and He I.

  14. An Integrated Spectrophotometric Survey of Nearby Star-forming Galaxies

    NASA Astrophysics Data System (ADS)

    Moustakas, John; Kennicutt, Robert C., Jr.

    2006-05-01

    We present integrated optical spectrophotometry for a sample of 417 nearby galaxies. Our observations consist of spatially integrated, S/N=10-100 spectroscopy between 3600 and 6900 Å at ~8 Å FWHM resolution. In addition, we present nuclear (2.5"×2.5") spectroscopy for 153 of these objects. Our sample targets a diverse range of galaxy types, including starbursts, peculiar galaxies, interacting/merging systems, dusty, infrared-luminous galaxies, and a significant number of normal galaxies. We use population synthesis to model and subtract the stellar continuum underlying the nebular emission lines. This technique results in emission-line measurements reliably corrected for stellar absorption. Here we present the integrated and nuclear spectra, the nebular emission-line fluxes and equivalent widths, and a comprehensive compilation of ancillary data available in the literature for our sample. In a series of subsequent papers we use these data to study optical star formation rate indicators, nebular abundance diagnostics, the luminosity-metallicity relation, the dust properties of normal and starburst galaxies, and the star formation histories of infrared-luminous galaxies.

  15. SYNCHRONIZED FORMATION OF STARBURST AND POST-STARBURST GALAXIES IN MERGING CLUSTERS OF GALAXIES

    SciTech Connect

    Bekki, Kenji; Owers, Matt S.; Couch, Warrick J.

    2010-07-20

    We propose that synchronized triggering of star formation in gas-rich galaxies is possible during major mergers of cluster of galaxies, based on new numerical simulations of the time evolution of the physical properties of the intracluster medium (ICM) during such a merger event. Our numerical simulations show that the external pressure of the ICM, in which cluster member galaxies are embedded, can increase significantly during cluster merging. As such, efficient star formation can be triggered in gas-rich members as a result of the strong compression of their cold gas by the increased pressure. We also suggest that these star-forming galaxies can subsequently be transformed into post-starburst galaxies, with their spatial distribution within the cluster being different than that of the rest of the population. We discuss whether this possible merger-induced enhancement in the number of star-forming and post-star-forming cluster galaxies is consistent with the observed evolution of galaxies in merging clusters.

  16. HIGH-DENSITY MOLECULAR GAS PROPERTIES OF THE STARBURST GALAXY NGC 1614 REVEALED WITH ALMA

    SciTech Connect

    Imanishi, Masatoshi; Nakanishi, Kouichiro

    2013-09-15

    We present the results of HCN/HCO{sup +}/HNC J = 4-3 transition line observations of the nearby starburst galaxy NGC 1614, obtained with ALMA Cycle 0. We find that high density molecular gas traced with these lines shows a velocity structure such that the northern (southern) side of the nucleus is redshifted (blueshifted) with respect to the nuclear velocity of this galaxy. The redshifted and blueshifted emission peaks are offset by {approx}0.''6 at the northern and southern sides of the nucleus, respectively. At these offset positions, observations at infrared >3 {mu}m indicate the presence of active dusty starbursts, supporting the picture that high-density molecular gas is the site of active starbursts. The enclosed dynamical mass within the central {approx}2'' in radius, derived from the dynamics of the high-density molecular gas, is {approx}10{sup 9} M{sub Sun }, which is similar to previous estimates. Finally, the HCN emission is weaker than HCO{sup +} but stronger than HNC for J = 4-3 for all starburst regions of NGC 1614, as seen for J = 1-0 transition lines in starburst-dominated galaxies.

  17. Infrared spectroscopy of starburst and Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Moorwood, A. F. M.; Oliva, E.

    1994-03-01

    We present and discuss some recent results ofgroundbased IR spectroscopie studies ofstarburst and Seyfert galaxies through the 1-5 μm atmospheric windows. Of particular interest in this spectral range are H and He recombination lines, stellar CO and other absorption bands which can provide information on the stellar populations; [SiVI, VII, IX], [CaVIII] and [SIX] coronal lines in Seyferts and [FeII] and ro-vibrational H2 lines from circumnuclear gas excited by high energy photons and winds associated with recently formed hot stars, SN/SNR and AGN. Recent progress in the latter case has largely been achieved through the first use of 2D arrays to obtain maps and images of the extended line emission in several relatively nearby galaxies.

  18. The Butcher-Oemler effect in a nearby cluster of galaxies

    SciTech Connect

    Vigroux, L.; Boulade, O.; Rose, J.A. North Carolina Univ., Chapel Hill )

    1989-12-01

    The integrated spectra of early-type galaxies in the nearby Abell 262, Pegasus I, and Virgo clusters are compared with those of several field galaxies. The spectra of five galaxies in Pegasus I and one galaxy in the Virgo Cluster show evidence of recent star formation. The average blue magnitude for the star-forming galaxies is M(B) = -20. The star-formation activity in Pegasus I is found to be similar to that of starburst and poststarburst galaxies in Butcher-Oemler clusters at redshifts greater than 2. 38 refs.

  19. Chandra Observations of the Evening Core of the Starburst Galaxy NGC 253

    NASA Technical Reports Server (NTRS)

    Weaver, K. A.; Heckman, T. M.; Dahlem, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Chandra observations of the core of the nearby starburst galaxy NGC 253 reveal a heavily absorbed source of hard X-rays embedded within the nuclear starburst region. The source has an unabsorbed, 2 to 10 keV luminosity of greater than or equal to 10(exp 39) erg per s and photoionizes the surrounding gas. We observe this source through a dusty torus with a neutral absorbing column density of N(sub eta) approximately 2 x 10(exp 23)cm (exp -2). The torus is hundreds of pc across and collimates the starburst-driven nuclear outflow. We suggest that the ionizing source is an intermediate-mass black hole or a weakly accreting supermassive black hole, which may signal the beginnings or endings of AGN (active galactic nuclei) activity.

  20. HIERARCHICAL STAR FORMATION IN NEARBY LEGUS GALAXIES

    SciTech Connect

    Elmegreen, Debra Meloy; Elmegreen, Bruce G.; Adamo, Angela; Gouliermis, Dimitrios A.; Aloisi, Alessandra; Bright, Stacey N.; Cignoni, Michele; Lee, Janice; Sabbi, Elena; Andrews, Jennifer; Calzetti, Daniela; Annibali, Francesca; Evans, Aaron S.; Johnson, Kelsey; Gallagher III, John S.; Grebel, Eva K.; Hunter, Deidre A.; Kim, Hwihyun; Smith, Linda J.; Thilker, David; and others

    2014-05-20

    Hierarchical structure in ultraviolet images of 12 late-type LEGUS galaxies is studied by determining the numbers and fluxes of nested regions as a function of size from ∼1 to ∼200 pc, and the number as a function of flux. Two starburst dwarfs, NGC 1705 and NGC 5253, have steeper number-size and flux-size distributions than the others, indicating high fractions of the projected areas filled with star formation. Nine subregions in seven galaxies have similarly steep number-size slopes, even when the whole galaxies have shallower slopes. The results suggest that hierarchically structured star-forming regions several hundred parsecs or larger represent common unit structures. Small galaxies dominated by only a few of these units tend to be starbursts. The self-similarity of young stellar structures down to parsec scales suggests that star clusters form in the densest parts of a turbulent medium that also forms loose stellar groupings on larger scales. The presence of super star clusters in two of our starburst dwarfs would follow from the observed structure if cloud and stellar subregions more readily coalesce when self-gravity in the unit cell contributes more to the total gravitational potential.

  1. Hierarchical Star Formation in Nearby LEGUS Galaxies

    NASA Astrophysics Data System (ADS)

    Elmegreen, Debra Meloy; Elmegreen, Bruce G.; Adamo, Angela; Aloisi, Alessandra; Andrews, Jennifer; Annibali, Francesca; Bright, Stacey N.; Calzetti, Daniela; Cignoni, Michele; Evans, Aaron S.; Gallagher, John S., III; Gouliermis, Dimitrios A.; Grebel, Eva K.; Hunter, Deidre A.; Johnson, Kelsey; Kim, Hwihyun; Lee, Janice; Sabbi, Elena; Smith, Linda J.; Thilker, David; Tosi, Monica; Ubeda, Leonardo

    2014-05-01

    Hierarchical structure in ultraviolet images of 12 late-type LEGUS galaxies is studied by determining the numbers and fluxes of nested regions as a function of size from ~1 to ~200 pc, and the number as a function of flux. Two starburst dwarfs, NGC 1705 and NGC 5253, have steeper number-size and flux-size distributions than the others, indicating high fractions of the projected areas filled with star formation. Nine subregions in seven galaxies have similarly steep number-size slopes, even when the whole galaxies have shallower slopes. The results suggest that hierarchically structured star-forming regions several hundred parsecs or larger represent common unit structures. Small galaxies dominated by only a few of these units tend to be starbursts. The self-similarity of young stellar structures down to parsec scales suggests that star clusters form in the densest parts of a turbulent medium that also forms loose stellar groupings on larger scales. The presence of super star clusters in two of our starburst dwarfs would follow from the observed structure if cloud and stellar subregions more readily coalesce when self-gravity in the unit cell contributes more to the total gravitational potential.

  2. Detection of gamma rays from a starburst galaxy.

    PubMed

    Acero, F; Aharonian, F; Akhperjanian, A G; Anton, G; Barres de Almeida, U; Bazer-Bachi, A R; Becherini, Y; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Borrel, V; Brucker, J; Brun, F; Brun, P; Bühler, R; Bulik, T; Büsching, I; Boutelier, T; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L-M; Clapson, A C; Coignet, G; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Füssling, M; Gabici, S; Gallant, Y A; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Hauser, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Hoppe, S; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jung, I; Katarzyński, K; Katz, U; Kaufmann, S; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Keogh, D; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Lamanna, G; Lenain, J-P; Lohse, T; Marandon, V; Martineau-Huynh, O; Marcowith, A; Masbou, J; Maurin, D; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; de Oña Wilhelmi, E; Orford, K J; Ostrowski, M; Panter, M; Paz Arribas, M; Pedaletti, G; Pelletier, G; Petrucci, P-O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raubenheimer, B C; Raue, M; Rayner, S M; Reimer, O; Renaud, M; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Superina, G; Szostek, A; Tam, P H; Tavernet, J-P; Terrier, R; Tibolla, O; Tluczykont, M; van Eldik, C; Vasileiadis, G; Venter, C; Venter, L; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A

    2009-11-20

    Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of approximately 10(15) electron volts. We report the detection of gamma rays--tracers of such cosmic rays--from the starburst galaxy NGC 253 using the High Energy Stereoscopic System (H.E.S.S.) array of imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 billion electron volts is F = (5.5 +/- 1.0(stat) +/- 2.8(sys)) x 10(-13) cm(-2) s(-1), implying a cosmic-ray density about three orders of magnitude larger than that in the center of the Milky Way. The fraction of cosmic-ray energy channeled into gamma rays in this starburst environment is five times as large as that in our Galaxy. PMID:19779150

  3. Starburst galaxies as seen by gamma-ray telescopes

    NASA Astrophysics Data System (ADS)

    Ohm, Stefan

    2016-06-01

    Starburst galaxies have a highly increased star-formation rate compared to regular galaxies and inject huge amounts of kinetic power into the interstellar medium via supersonic stellar winds, and supernova explosions. Supernova remnants, which are considered to be the main source of cosmic rays (CRs), form an additional, significant energy and pressure component and might influence the star-formation process in a major way. Observations of starburst galaxies at γ-ray energies give us the unique opportunity to study non-thermal phenomena associated with hadronic CRs and their relation to the star-formation process. In this work, recent observations of starburst galaxies with space and ground-based γ-ray telescopes are being reviewed, and the current state of theoretical work on the γ-ray emission is discussed. A special emphasis is put on the prospects of the next-generation Cherenkov Telescope Array for the study of starburst galaxies in particular and star-forming galaxies in general. xml:lang="fr"

  4. High resolution sub-millimetre mapping of starburst galaxies: Comparison with CO emission

    NASA Technical Reports Server (NTRS)

    Smith, P. A.; Brand, P. W. J. L.; Puxley, Phil J.; Mountain, C. M.; Nakai, Naomasa

    1990-01-01

    Researchers present first results from a program of submillimeter continuum mapping of starburst galaxies, and comparison of their dust and CO emission. This project was prompted by surprising results from the first target, the nearby starburst M82, which shows in the dust continuum a morphology quite unlike that of its CO emission, in contrast to what might be expected if both CO and dust are accurately tracing the molecular hydrogen. Possible explanations for this striking difference are discussed. In the light of these results, the program has been extended to include sub-mm mapping of the nearby, vigorously star forming spirals, M83 and Maffei 2. The latter were also observed extensively in CO, in order to study excitation conditions in its central regions. The James Clerk Maxwell Telescope was used in these studies.

  5. Comparing Local Starbursts to High-Redshift Galaxies: A Search for Lyman-Break Analogs

    NASA Technical Reports Server (NTRS)

    Petty, Sara M.; de Mello, Duila F.; Gallagher III, John S.; Gardner, Jonathan; Lotz, Jennifer M.; Mountain, C. Matt; Smith, Linda J.

    2008-01-01

    We compare the restframe far-ultraviolet (FUV) morphologies of 8 nearby interacting and starburst galaxies (Arp 269, M 82, Mrk 08, NGC 0520, NGC 1068, NGC 3079, NGC 3310, NGC 7673) with 54 galaxies at z approx.1.5 and 46 galaxies at z approx.4 in the Great Observatories Origins Deep Survey (GOODS) images taken with the Advanced Camera for Surveys onboard the Hubble Space Telescope. We calculate the Gini coefficient (G), the second order moment of 20% of the brightest pixels (M20), and the S ersic index (n). We find that 20% (11/54) of z approx.1.5 and 37% (17/46) of z approx.4 galaxies are bulge-like, using G and M20. We also find approx.70% of the z approx.1.5 and z approx.4 galaxies have exponential disks with n > 0.8. The 2D profile combined with the nonparametric methods provides more detail, concerning the nature of disturbed systems, such as merger and post-merger types. We also provide qualitative descriptions of each galaxy system and at each redshift. We conclude that Mrk 08, NGC 3079, and NGC 7673 have similar morphologies as the starburst FUV restframe galaxies and Lyman-break galaxies at z approx.1.5 and 4, and determine that they are Lyman-break analogs.

  6. An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10.

    PubMed

    Reines, Amy E; Sivakoff, Gregory R; Johnson, Kelsey E; Brogan, Crystal L

    2011-02-01

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first 'seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize 2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize 2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize 2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids. PMID:21217688

  7. An actively accreting massive black hole in the dwarf starburst galaxy Henize2-10

    NASA Astrophysics Data System (ADS)

    Reines, Amy E.; Sivakoff, Gregory R.; Johnson, Kelsey E.; Brogan, Crystal L.

    2011-02-01

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first `seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids.

  8. Important Nearby Galaxies without Accurate Distances

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen

    2014-10-01

    The Spitzer Infrared Nearby Galaxies Survey (SINGS) and its offspring programs (e.g., THINGS, HERACLES, KINGFISH) have resulted in a fundamental change in our view of star formation and the ISM in galaxies, and together they represent the most complete multi-wavelength data set yet assembled for a large sample of nearby galaxies. These great investments of observing time have been dedicated to the goal of understanding the interstellar medium, the star formation process, and, more generally, galactic evolution at the present epoch. Nearby galaxies provide the basis for which we interpret the distant universe, and the SINGS sample represents the best studied nearby galaxies.Accurate distances are fundamental to interpreting observations of galaxies. Surprisingly, many of the SINGS spiral galaxies have numerous distance estimates resulting in confusion. We can rectify this situation for 8 of the SINGS spiral galaxies within 10 Mpc at a very low cost through measurements of the tip of the red giant branch. The proposed observations will provide an accuracy of better than 0.1 in distance modulus. Our sample includes such well known galaxies as M51 (the Whirlpool), M63 (the Sunflower), M104 (the Sombrero), and M74 (the archetypal grand design spiral).We are also proposing coordinated parallel WFC3 UV observations of the central regions of the galaxies, rich with high-mass UV-bright stars. As a secondary science goal we will compare the resolved UV stellar populations with integrated UV emission measurements used in calibrating star formation rates. Our observations will complement the growing HST UV atlas of high resolution images of nearby galaxies.

  9. Searching for Tidal Disruption Events in Post-Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Guevel, David; Arcavi, Iair

    2016-06-01

    Tidal Disruption Events (TDEs) are a class of transient phenomena that occur when a star passes sufficiently close to a supermassive black hole (SMBH) to be destroyed by tidal forces. Increasing the number of known TDEs will facilitate the study of SMBHs and black hole accretion physics. Recently it has been shown that TDEs occur most often in quiescent post-starburst galaxies (identified by strong Balmer absorption), some of which are know as "E+A" galaxies. These galaxies may have undergone a merger possibly contributing to the likelihood of TDEs. Using Las Cumbres Observatory Global Telescope (LCOGT) we are conducting a transient survey, called SEATiDE (Searching E+A Galaxies for Tidal Disruption Events), of 100 E+A galaxies. We experiment with different image subtraction techniques to improve our ability of detecting TDE flares in the centers of these galaxies. A future survey will cover an order of magnitude more post-starburst galaxies to measure their TDE rates in more detail with the aim of understanding why TDEs so strongly prefer post-starburst environments.

  10. ACA [CI] observations of the starburst galaxy NGC 253

    NASA Astrophysics Data System (ADS)

    Krips, M.; Martín, S.; Sakamoto, K.; Aalto, S.; Bisbas, T. G.; Bolatto, A. D.; Downes, D.; Eckart, A.; Feruglio, Ch.; García-Burillo, S.; Geach, J.; Greve, T. R.; König, S.; Matsushita, S.; Neri, R.; Offner, S.; Peck, A. B.; Viti, S.; Wagg, J.

    2016-07-01

    Context. Carbon monoxide (CO) is widely used as a tracer of the molecular gas in almost all types of environments. However, several shortcomings of CO complicate usaging it as H2 tracer, such as its optical depth effects, the dependence of its abundance on metallicity, or its susceptibility to dissociation in highly irradiated regions. Neutral carbon emission has been proposed to overcome some of these shortcomings and hence to help revealing the limits of CO as a measure of the molecular gas. Aims: We aim to study the general characteristics of the spatially and spectrally resolved carbon line emission in a variety of extragalactic sources and evaluate its potential as complementary H2 tracer to CO. Methods: We used the Atacama Compact Array to map the [CI](3P1-3P0) line emission in the nearby starburst galaxy NGC 253 at unprecedented angular resolution (~3''). This is the first well-resolved interferometric [CI] map of an extragalactic source. Results: We have detected the [CI] line emission at high significance levels along the central disk of NGC 253 and its edges where expanding shells have previously been found in CO. Globally, the distribution of the [CI] line emission strongly resembles that of CO, confirming the results of previous Galactic surveys that [CI] traces the same molecular gas as CO. However, we also identify a significant increase of [CI] line emission with respect to CO in (some of) the outflow or shocked regions of NGC 253, namely the bipolar outflow emerging from the nucleus. A first-order estimate of the [CI] column densities indicates abundances of [CI] that are very similar to the abundance of CO in NGC 253. Interestingly, we find that the [CI] line is marginally optically thick within the disk. Conclusions: The enhancement of the [CI]/CO line ratios (~0.4-0.6) with respect to Galactic values (≤0.1), especially in the shocked regions of NGC 253, clearly indicates that mechanical perturbation such as shocks and the strong radiation

  11. Spectroscopic Observations of the Star Formation Regions in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Kong, X.; Lin, L.; Li, J. R.; Zhou, X.; Zou, H.; Li, H. Y.; Chen, F. Z.; Du, W.; Fan, Z.; Mao, Y. W.; Wang, J.; Zhu, Y. N.; Zhou, Z. M.

    2014-01-01

    During the late 1990s and the first decade of the 21st century, the 8˜10 m scale ground-based telescopes are helping astronomers learn much more about how galaxies develop. The existing 2˜4 m scale telescopes become less important for astrophysical researches. To use the existing 2˜4 m scale telescopes to address important issues in cosmology and extragalactic and galactic astronomy, we have to consider very carefully which kind of things we can do, and which we can not. For this reason, the Time Allocation Committee (TAC) of the National Astronomical Observatories of China (NAOC) 2.16 m telescope decides to support some key projects since 2013. Nearby galaxies supply us with the opportunity to study galaxy dynamics and star formation on large scales, yet are close enough to reveal the details. Star formation regions in nearby galaxies provide an excellent laboratory to study the star formation processes, the evolution of massive stars, and the properties of the surrounding interstellar medium. A wealth of information can be obtained from the spectral analysis of the bright emission lines and the stellar continuum. Considering these, we proposed a long-term project ``Spectroscopic Observations of the Star Formation Regions in Nearby Galaxies'', and it becomes the key project of the NAOC 2.16 m telescope since 2013, supported with 30 dark/grey nights per year. The primary goal of this project is to observe the spectroscopy of star formation regions in 20 nearby galaxies, with the NAOC 2.16 m telescope and the Hectospec/MMT (Multiple Mirror Telescope) multifiber spectrograph by Telescope Access Program (TAP). With the spectra of a large sample of star formation regions, combining multi-wavelength data from UV to IR, we can investigate, understand, and quantify the nature of the deviation from the starbursts' IRX-β (the IR/UV ratio ``IRX'' versus the UV color ``β'') correlation. It will be important for a better understanding of the interaction of dust and

  12. New constraints on the escape of ionizing photons from starburst galaxies using ionization-parameter mapping

    SciTech Connect

    Zastrow, Jordan; Oey, M. S.; Veilleux, Sylvain; McDonald, Michael

    2013-12-10

    The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S III]/[S II] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrowband images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40° ± 5° (0.4 sr), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble activity, which should be conducive to escaping radiation, yet they are optically thick. These results support the scenario that an orientation bias limits our ability to directly detect escaping Lyman continuum in many starburst galaxies. A comparison of the star formation properties and histories of the optically thin and thick galaxies is consistent with the model that high escape fractions are limited to galaxies that are old enough (≳3 Myr) for mechanical feedback to have cleared optically thin passageways in the interstellar medium, but young enough (≲5 Myr) that the ionizing stars are still present.

  13. New Constraints on the Escape of Ionizing Photons from Starburst Galaxies Using Ionization-parameter Mapping

    NASA Astrophysics Data System (ADS)

    Zastrow, Jordan; Oey, M. S.; Veilleux, Sylvain; McDonald, Michael

    2013-12-01

    The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S III]/[S II] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrowband images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40° ± 5° (0.4 sr), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble activity, which should be conducive to escaping radiation, yet they are optically thick. These results support the scenario that an orientation bias limits our ability to directly detect escaping Lyman continuum in many starburst galaxies. A comparison of the star formation properties and histories of the optically thin and thick galaxies is consistent with the model that high escape fractions are limited to galaxies that are old enough (gsim3 Myr) for mechanical feedback to have cleared optically thin passageways in the interstellar medium, but young enough (lsim5 Myr) that the ionizing stars are still present.

  14. Reconstruction of SDSS Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Kushner, Laura K.; Obric, M.; West, A. A.; Dalcanton, J.

    2006-12-01

    We present The SDSS Multiple Offspring Recombination Engine (SMORE), a newly developed code that automatically and interactively recombines galaxies fragmented by the Sloan Digital Sky Survey (SDSS) Photo pipeline. The SDSS software was optimized for the faint-end of the brightness limit and tends to over-deblend galaxies with angular sizes over 2 arcmin, sometimes separating spiral arms and HII regions from their parent galaxies. This process can remove a large percentage of the flux from the galaxy and bias datasets due to incorrect photometry. SMORE automatically builds galaxies from the fragments ("children"). Decisions on which child to include are made on the basis of its g-r and r-i color (relative to the mean colors of the largest galaxy children), size, distance to the center of the galaxy, type (as assigned by SDSS Photo) and the position angle. If there are pieces for which a decision cannot be made and their relative flux is more than 5% of the total flux of the galaxy, the interactive SMORE gives a user option to manually choose which of those children should be included. Recombined galaxies are built on a clean background without foreground and background objects and new photometry is performed.

  15. Understanding the SEDS of Massive Stars and Radiative Feedback from Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Zastrow, Jordan A.; Oey, M. S.; Pellegrini, E. W.; Veilleux, S.; McDonald, M.; Martin, C. L.

    2013-01-01

    Massive stars strongly influence the properties of their interstellar and intergalactic environments through radiative feedback. The resulting HII regions are used as diagnostics for many galaxy properties, and the radiation from massive stars is thought to be a source for reionization in the early universe. Yet, there are still unanswered questions about the shape of the massive star spectral energy distribution and how far the radiation propagates in a galaxy. We use the emission-line spectra of a sample of single-star HII regions, in conjunction with photoionization simulations, to evaluate the predictions of widely used stellar atmosphere models. The model atmospheres generate simulated HII region spectra that agree well with the observations, except at the highest energy transitions, provided that the nebular density distributions are inhomogeneous. WM-basic atmospheres are better at reproducing the observed nebular spectrum, while TLUSTY atmospheres more closely match the observed rate of ionizing photons. Based on the results of our detailed CLOUDY simulations, we create a new spectral type to stellar effective temperature calibration. We also investigate the galactic parameters that control the propagation of ionizing radiation out of a galaxy by searching for extended, photoionized emission in a sample of nearby, dwarf starburst galaxies. Using narrowband emission-line images taken with the Maryland-Magellan Tunable Filter, we create ionization parameter maps of the starbursts. In NGC 5253, we detect an optically thin ionization cone extending from the central starburst, which is suggestive of the escape of ionizing radiation. The narrow morphology of the cone supports the scenario that an orientation bias contributes to the challenge of detecting Lyman continuum in starbursts and Lyman Break Galaxies.

  16. The ultraviolet spectra of nearby radio galaxies

    NASA Technical Reports Server (NTRS)

    Keel, William C.; Windhorst, Rogier A.

    1991-01-01

    New and archival IUE SWP spectra are reported for nine nearby radio galaxies (V is less than 15 mag), together with optical emissionlike data for these galaxies as well as a number of candidates with weaker line emission. Both their UV line and continuum properties, as well as their UV and UV-optical line ratios, are examined. Ly-alpha emission is found to be common among local radio galaxies, at modest luminosities (typically 10 exp 41-42 erg/s). No apparent relation is found between L(Ly-alpha) and radio power for the nearby radio galaxies alone. The Ly-alpha/H-alpha ratio in low power nearby radio galaxies is 2-5 times lower than the prediction for case B recombination. The destruction of Ly-alpha photons by grains during resonant scattering can explain the observed deficiency for reasonable metallicities. The nearby radio galaxies have in general a small C IV/Ly-alpha ratio (less than 0.1). Comparison of the C IV and Ly-alpha strengths with those in luminous AGN suggests that most of the UV continuum comes from the stellar population, and not from the AGN.

  17. Discrete X-Ray Source Populations and Star Formation History in Nearby Galaxies

    NASA Technical Reports Server (NTRS)

    Zezas, Andreas; Hasan, Hashima (Technical Monitor)

    2005-01-01

    This program aims in understanding the connection between the discrete X-ray source populations observed in nearby galaxies and the history of star-formation in these galaxies. The ultimate goal is to use this knowledge in order to constrain X-ray binary evolution channels. For this reason although the program is primarily observational it has a significant modeling component. During the second year of this study we focused on detailed studies of the Antennae galaxies and the Small Magellanic Cloud (SMC). We also performed the initial analysis of the 5 galaxies forming a starburst-age sequence.

  18. The stellar populations in the earliest dusty starburst galaxies

    NASA Astrophysics Data System (ADS)

    Wardlow, Julie; Conley, Alexander; Perez-Fournon, Ismael; Cooray, Asantha; Riechers, Dominik; Dannerbauer, Helmut; Farrah, Duncan; Omont, Alain

    2014-12-01

    We propose Spitzer IRAC imaging of the two brightest spectroscopically confirmed dusty starburst galaxies at z>4 that do not yet have mid-IR observations. The targeted galaxies are members of a rare class of Herschel sources that provide some of the most stringent constraints on galaxy formation theories. The two targets already have complementary optical and far-IR observations, and the proposed short IRAC data are all that is missing to ~double the number of confirmed z>4 dusty starbursts with well-sampled stellar SEDs. The IRAC data are critical for deriving accurate measurements of physical conditions such as dust extinction and stellar mass to ~30% accuracy (~10x better than otherwise). The proposed data complete the IRAC coverage of the four most luminous confirmed z>4 dusty starburst galaxies, which will be observed with HST in cycle 22. The targets already have CO observations and their [CII] 158 micron emission is being mapped with ALMA in cycle 2; with the addition of the proposed IRAC data we will be able to probe the dust-to-gas and stellar-to-gas mass ratios at the highest redshifts and in the most active galaxies. The IRAC data are also key to determining whether these highest redshift dusty starbursts are markers of overdensities in the early Universe via photometric dropout searches. By probing the details of star-formation in the most extreme sources in the first 1.5 Gyr of the Universe the proposed observations will critically test theories of galaxy formation and evolution.

  19. Are bars essential for starbursts in non-interacting galaxies

    NASA Technical Reports Server (NTRS)

    Pompea, Stephen M.; Rieke, G. H.

    1990-01-01

    Analyzed here are the 1.6 and 2.2 micron images of a sample of galaxies that are classified as unbarred by the Revised Shapley-Ames Catalog. These galaxies have characteristic properties of nuclear starbursts and are examined through near infrared imaging in a search for hidden bars. Researchers selected a sample of 36 galaxies from the Revised Shapley-Ames Catalog that have far infrared luminosities greater than 10(exp 10) solar luminosity and hot Infrared Astronomy Satellite (IRAS) colors between 60 and 100 microns, indicative of nuclear starbursts, but are not classified as Seyfert 1 or 2. Their determination of the presence of a bar relies primarily on an analysis of the 2 micron image using the Galaxy Surface Photometry (GASP) package (Cawson, 1983). The GASP analysis programs determine the galaxy surface brightness and ellipticity profiles as well as the position angle and the center coordinates of the ellipses. To test the way that GASP will characterize the surface brightness of barred galaxies, two galaxies with known bars, NGC 1068 and NGC 2523, were imaged with the 2 micron camera and analyzed with GASP. Fifteen of the sample that are not clearly barred from optical data and are isolated were imaged at 1.6 and 2.2 microns; 9 of these do not appear to have bars. Strong bars therefore do not appear to be an absolute requirement for high infrared luminosity in isolated galaxies.

  20. Diffuse Gamma-Ray Emission from the Starburst Galaxy NGC 253

    NASA Technical Reports Server (NTRS)

    Bertsch, David L.; Paglione, Timothy A. D.; Marscher, Alan P.; Jackson, James M.

    1995-01-01

    The starburst galaxy NGC 253 was observed with the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory (CGRO) satellite. We obtain a 2 sigma upper limit to the gamma-ray emission above 100 MeV of 8 x 10(exp -8) photons/sq cm/s. Because of their large gas column densities and supernova rates, nearby starburst galaxies were predicted to have gamma-ray fluxes detectable by EGRET. Our nondetection of gamma-rays from NGC 253 motivates us to reexamine in detail the premise of supernova acceleration of cosmic rays and the effect of enhanced cloud densities, photon densities, and magnetic fields on the high-energy spectra of galaxies. By modeling the expected gamma-ray and synchrotron spectra from NGC 253, we find that up to 20% of the energy from supernovae is transferred to cosmic rays in the starburst, which is consistent with supernova acceleration models. Our calculations match the EGRET and radio data well with a supernova rate of 0.08/yr, a magnetic field B greater than or approximately equal to 5 x 10(exp -5) G, a density n approximately 300/cu cm, a photon density U(sub ph) approximately 200 eV/cu cm, and an escape timescale tau(sub o) less than or approximately equal to 10 Myr.

  1. Gamma-rays from pulsar wind nebulae in starburst galaxies

    NASA Astrophysics Data System (ADS)

    Mannheim, Karl; Elsässer, Dominik; Tibolla, Omar

    2012-07-01

    Recently, gamma-ray emission at TeV energies has been detected from the starburst galaxies NGC253 (Acero et al., 2009) [1] and M82 (Acciari et al., 2009) [2]. It has been claimed that pion production due to cosmic rays accelerated in supernova remnants interacting with the interstellar gas is responsible for the observed gamma rays. Here, we show that the gamma-ray pulsar wind nebulae left behind by the supernovae contribute to the TeV luminosity in a major way. A single pulsar wind nebula produces about ten times the total luminosity of the Sun at energies above 1 TeV during a lifetime of 105 years. A large number of 3 × 104 pulsar wind nebulae expected in a typical starburst galaxy at a distance of 4 Mpc can readily produce the observed TeV gamma rays.

  2. Morphology and Structures of Nearby Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Seo, Mira; Ann, HongBae

    2015-08-01

    We performed an analysis of the structure of nearby dwarf galaxies based on a 2-dimensional decomposition of galaxy images using GALFIT. The present sample consists of ~1,100 dwarf galaxies with redshift less than z = 0.01, which is is derived from the morphology catalog of the Visually classified galaxies in the local universe (Ann, Seo, and Ha 2015). In this catalog, dwarf galaxies are divided into 5 subtypes: dS0, dE, dSph, dEbc, dEblue with distinction of the presence of nucleation in dE, dSph, and dS0. We found that dSph and dEblue galaxies are fainter than other subtypes of dwarf galaxies. In most cases, single component, represented by the Sersic profile with n=1~1.5, well describes the luminosity distribution of dwarf galaxies in the present sample. However, a significant fraction of dS0, dEbc, and dEbue galaxies show sub-structures such as spiral arms and rings. We will discuss the morphology dependent evolutionary history of the local dwarf galaxies.

  3. From nearby low-mass protostars to high redshift starbursts: protostellar outflows tracing the IMF

    NASA Astrophysics Data System (ADS)

    Kristensen, Lars E.; Bergin, Edwin

    2015-08-01

    Embedded low-mass protostars are notoriously difficult to observe even in the nearest Galactic high-mass clusters where they outnumber the high-mass protostars by orders of magnitude. Thus, without a good tracer of the low-mass population, we do not have a good handle on the shape of the initial (core) mass function, leaving little hope for extrapolating to extragalactic regions where we will never have neither the sensitivity nor the resolution to directly observe this population. A good tracer of the low-mass population is needed.One such physical tracer is outflows. Outflow emission is directly proportional to envelope mass, and outflows are predominantly active during the deeply embedded phases of star formation. What is required for this method to work is species and transitions tracing outflows uniquely such that any signal is not diluted by the surrounding cloud, such as certain methanol transitions, water, high-J CO (J > 10).I will present a statistical model of a forming high-mass cluster. The model includes what we currently know about Galactic high-mass clusters and incorporates outflow emission from low-mass protostars. The latter component is obtained from observations of tens of nearby embedded low-mass protostellar outflows in the above-mentioned tracers. The model is benchmarked against ALMA and Herschel-HIFI observations of Galactic clusters proving the concept, and preliminary extrapolations to the extragalactic regime are presented. With this new probe, and traditional probes of the distant star formation which predominantly trace high mass stars, we will be able to explore the IMF in starburst galaxies from low to high redshift.

  4. Orbital masses of nearby luminous galaxies

    SciTech Connect

    Karachentsev, Igor D.; Kudrya, Yuri N. E-mail: yukudrya@gmail.com

    2014-09-01

    We use observational properties of galaxies accumulated in the Updated Nearby Galaxy Catalog to derive a dark matter mass of luminous galaxies via motions of their companions. The data on orbital-to-stellar mass ratio are presented for 15 luminous galaxies situated within 11 Mpc from us: the Milky Way, M31, M81, NGC 5128, IC342, NGC 253, NGC 4736, NGC 5236, NGC 6946, M101, NGC 4258, NGC 4594, NGC 3115, NGC 3627, and NGC 3368, as well as for a composite suite around other nearby galaxies of moderate and low luminosity. The typical ratio for these galaxies is M {sub orb}/M {sub *} = 31, corresponding to the mean local density of matter Ω {sub m} = 0.09, i.e., one-third of the global cosmic density. This quantity seems to be rather an upper limit of dark matter density, since the peripheric population of the suites may suffer from the presence of fictitious unbound members. We note that the Milky Way and M31 halos have lower dimensions and lower stellar masses than those of the other 13 nearby luminous galaxies. However, the dark-to-stellar mass ratio for both the Milky Way and M31 is typical for other neighboring luminous galaxies. The distortion in the Hubble flow, observed around the Local Group and five other neighboring groups, yields their total masses within the radius of a zero velocity surface, R {sub 0}; these masses are slightly lower than the orbital and virial values. This difference may be due to the effect of dark energy producing a kind of 'mass defect' within R {sub 0}.

  5. Infrared Spectral Energy Distributions of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Dale, D. A.; Bendo, G. J.; Engelbracht, C. W.; Gordon, K. D.; Regan, M. W.; Armus, L.; Cannon, J. M.; Calzetti, D.; Draine, B. T.; Helou, G.; Joseph, R. D.; Kennicutt, R. C.; Li, A.; Murphy, E. J.; Roussel, H.; Walter, F.; Hanson, H. M.; Hollenbach, D. J.; Jarrett, T. H.; Kewley, L. J.; Lamanna, C. A.; Leitherer, C.; Meyer, M.; Rieke, G. H.; Rieke, M. J.; Sheth, K.; Smith, J. D. T.; Thornley, M. D.

    2005-05-01

    The Spitzer Infrared Nearby Galaxies Survey (SINGS) is carrying out a comprehensive multi-wavelength survey on a sample of 75 nearby galaxies. The 1-850 \\micron\\ spectral energy distributions are presented for the first portion of the SINGS sample using broadband imaging data from Spitzer, 2MASS, ISO, IRAS, and SCUBA. The infrared colors derived from the globally-integrated Spitzer data are generally consistent with the previous generation of models that were developed based on global data for normal star-forming galaxies, though significant deviations are observed. Spitzer's excellent sensitivity and resolution also allow a detailed investigation of the infrared spectral energy distributions for various locations within the three large, nearby galaxies NGC 3031 (M 81), NGC 5194 (M 51), and NGC 7331. A wide variety of spectral shapes are found within each galaxy, especially for NGC 3031, the closest of the three targets and thus the galaxy for which the smallest spatial scales can be explored. The local star formation rate, as gauged by Hα emission, is shown to strongly correlate with local infrared fluxes and colors. If the galaxy-to-galaxy variations in spectral energy distributions seen in our sample are representative of the range present at high redshift then extrapolations of total infrared luminosities and star formation rates from the observed 24 \\micron\\ flux will be uncertain at the factor-of-five level. The corresponding uncertainties in the redshifted 8.0 \\micron\\ flux (e.g. observed 24 \\micron\\ flux for a z = 2 source) are factors of 5--10. Considerable caution should be used when interpreting such extrapolated infrared luminosities. Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through Contract Number 1224769 issued by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407.

  6. Suites of Dwarfs around nearby Giant Galaxies

    NASA Astrophysics Data System (ADS)

    Karachentsev, Igor D.; Kaisina, Elena I.; Makarov, Dmitry I.

    2014-01-01

    The Updated Nearby Galaxy Catalog (UNGC) contains the most comprehensive summary of distances, radial velocities, and luminosities for 800 galaxies located within 11 Mpc from us. The high density of observables in the UNGC makes this sample indispensable for checking results of N-body simulations of cosmic structures on a ~1 Mpc scale. The environment of each galaxy in the UNGC was characterized by a tidal index Θ1, depending on the separation and mass of the galaxy's main disturber (MD). We grouped UNGC galaxies with a common MD in suites, and ranked suite members according to their Θ1. All suite members with positive Θ1 are assumed to be physical companions of the MD. About 58% of the sample are members of physical groups. The distribution of suites by the number of members, n, follows a relation N(n) ~ n -2. The 20 most populated suites contain 468 galaxies, i.e., 59% of the UNGC sample. The fraction of MDs among the brightest galaxies is almost 100% and drops to 50% at MB = -18m. We discuss various properties of MDs, as well as galaxies belonging to their suites. The suite abundance practically does not depend on the morphological type, linear diameter, or hydrogen mass of the MD, the tightest correlation being with the MD dynamical mass. Dwarf galaxies around MDs exhibit well-known segregation effects: the population of the outskirts has later morphological types, richer H I contents, and higher rates of star formation activity. Nevertheless, there are some intriguing cases where dwarf spheroidal galaxies occur at the far periphery of the suites, as well as some late-type dwarfs residing close to MDs. Comparing simulation results with galaxy groups, most studies assume the Local Group is fairly typical. However, we recognize that the nearby groups significantly differ from each other and there is considerable variation in their properties. The suites of companions around the Milky Way and M31, consisting of the Local Group, do not quite seem to be a typical

  7. Suites of dwarfs around Nearby giant galaxies

    SciTech Connect

    Karachentsev, Igor D.; Kaisina, Elena I.; Makarov, Dmitry I. E-mail: kei@sao.ru

    2014-01-01

    The Updated Nearby Galaxy Catalog (UNGC) contains the most comprehensive summary of distances, radial velocities, and luminosities for 800 galaxies located within 11 Mpc from us. The high density of observables in the UNGC makes this sample indispensable for checking results of N-body simulations of cosmic structures on a ∼1 Mpc scale. The environment of each galaxy in the UNGC was characterized by a tidal index Θ{sub 1}, depending on the separation and mass of the galaxy's main disturber (MD). We grouped UNGC galaxies with a common MD in suites, and ranked suite members according to their Θ{sub 1}. All suite members with positive Θ{sub 1} are assumed to be physical companions of the MD. About 58% of the sample are members of physical groups. The distribution of suites by the number of members, n, follows a relation N(n) ∼ n {sup –2}. The 20 most populated suites contain 468 galaxies, i.e., 59% of the UNGC sample. The fraction of MDs among the brightest galaxies is almost 100% and drops to 50% at M{sub B} = –18{sup m}. We discuss various properties of MDs, as well as galaxies belonging to their suites. The suite abundance practically does not depend on the morphological type, linear diameter, or hydrogen mass of the MD, the tightest correlation being with the MD dynamical mass. Dwarf galaxies around MDs exhibit well-known segregation effects: the population of the outskirts has later morphological types, richer H I contents, and higher rates of star formation activity. Nevertheless, there are some intriguing cases where dwarf spheroidal galaxies occur at the far periphery of the suites, as well as some late-type dwarfs residing close to MDs. Comparing simulation results with galaxy groups, most studies assume the Local Group is fairly typical. However, we recognize that the nearby groups significantly differ from each other and there is considerable variation in their properties. The suites of companions around the Milky Way and M31, consisting of the

  8. Giant Molecular Cloud Populations in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Hughes, Annie; Meidt, Sharon; Leroy, Adam; Dobbs, Clare; Schinnerer, Eva; Colombo, Dario; Wong, Tony; Pety, Jerome

    2015-08-01

    The structure of the molecular interstellar medium on the scale of individual giant molecular clouds (GMCs) is an important quantity for models of star formation, and one that is often invoked to explain the correlations between tracers of gas and star formation obtained by kiloparsec-scale observations of nearby galaxies. In this talk, I will highlight new results from recent wide-field, cloud-scale imaging surveys of CO emission in nearby galaxies that have provided important new insights into the timescales of GMC evolution, the dominant processes of GMC formation and destruction, and the emergence of a kiloparsec-scale star formation law from the physical properties of individual clouds. These results underscore the importance of galactic environment on the evolution of GMCs, and on a galaxy's global pattern of star formation.

  9. Chandra Images the Seething Cauldron of Starburst Galaxy

    NASA Astrophysics Data System (ADS)

    2000-01-01

    NASA's Chandra X-ray Observatory has imaged the core of the nearest starburst galaxy, Messier 82 (M82). The observatory has revealed a seething cauldron of exploding stars, neutron stars, black holes, 100 million degree gas, and a powerful galactic wind. The discovery will be presented by a team of scientists from Carnegie Mellon University, Pittsburgh, Penn., Pennsylvania State University, University Park, and the University of Michigan, Ann Arbor, on January 14 at the 195th national meeting of the American Astronomical Society. "In the disk of our Milky Way Galaxy, stars form and die in a relatively calm fashion like burning embers in a campfire," said Richard Griffiths, Professor of Astrophysics at Carnegie Mellon University. "But in a starburst galaxy, star birth and death are more like explosions in a fireworks factory." Short-lived massive stars in a starburst galaxy produce supernova explosions, which heat the interstellar gas to millions of degrees, and leave behind neutron stars and black holes. These explosions emit light in the X rays rather than in visible light. Because the superhot components inside starburst galaxies are complex and sometimes confusing, astronomers need an X-ray-detecting telescope with the highest focusing power (spatial resolution) to clearly discriminate the various structures. "NASA's Chandra X-ray Observatory is the perfect tool for studying starburst galaxies since it has the critical combination of high-resolution optics and good sensitivity to penetrating X rays," said Gordon Garmire, the Evan Pugh Professor of Astronomy and Astrophysics at Pennsylvania State University, and head of the team that conceived and built Chandra's Advanced CCD Imaging Spectrograph (ACIS) X-ray camera, which acquired the data. Many intricate structures missed by earlier satellite observatories are now visible in the ACIS image, including more than twenty powerful X-ray binary systems that contain a normal star in a close orbit around a neutron star

  10. PHOTODISSOCIATION CHEMISTRY FOOTPRINTS IN THE STARBURST GALAXY NGC 253

    SciTech Connect

    MartIn, Sergio; MartIn-Pintado, J.; Viti, S.

    2009-12-01

    UV radiation from massive stars is thought to be the dominant heating mechanism of the nuclear interstellar medium (ISM) in the late stages of evolution of starburst galaxies, creating large photodissociation regions (PDRs) and driving a very specific chemistry. We report the first detection of PDR molecular tracers, namely HOC{sup +} and CO{sup +}, and also confirm the detection of the PDR tracer HCO toward the starburst galaxy NGC 253, claimed to be mainly dominated by shock heating and in an earlier stage of evolution than M 82, the prototypical extragalactic PDR. Our CO{sup +} detection suffers from significant blending to a group of transitions of {sup 13}CH{sub 3}OH, tentatively detected for the first time in the extragalactic ISM. These species are efficiently formed in the highly UV-irradiated outer layers of molecular clouds, as observed in the late stage nuclear starburst in M 82. The molecular abundance ratios we derive for these molecules are very similar to those found in M 82. This strongly supports the idea that these molecules are tracing the PDR component associated with the starburst in the nuclear region of NGC 253. The presence of large abundances of PDR molecules in the ISM of NGC 253, which is dominated by shock chemistry, clearly illustrates the potential of chemical complexity studies to establish the evolutionary state of starbursts in galaxies. A comparison with the predictions of chemical models for PDRs shows that the observed molecular ratios are tracing the outer layers of UV-illuminated clouds up to two magnitudes of visual extinction. We combine the column densities of PDR tracers reported in this paper with those of easily photodissociated species, such as HNCO, to derive the fraction of material in the well-shielded core relative to the UV-pervaded envelopes. Chemical models, which include grain formation and photodissociation of HNCO, support the scenario of a photo-dominated chemistry as an explanation to the abundances of the

  11. A statistical study of properties of Seyfert and starburst galaxies

    NASA Technical Reports Server (NTRS)

    Dahari, Oved; De Robertis, Michael M.

    1988-01-01

    Spectral and morphological data for 282 Seyfert and emission-line galaxies spanning radio to X-ray wavelengths are compiled. The data include a large number of optical emission-line measurements which have not been reported previously. These data are intended to provide a convenient summary of the relevant properties of these galaxies, as well as a data base to search for correlations among the various parameters in order to obtain a better understanding of the active galaxy phenomenon. The paper presents the data and analyzes the distributions of various properties of Seyfert 1 and Seyfert 2 galaxies and starburst galaxies. It is found that Seyferts 2s have a higher 60 micron/forbidden O III 5007 A flux ratio than Seyfert 1s. This result, combined with the fact that Seyfert 2s are more heavily reddened, indicate that they have a higher dust content. It is also found that starburst nuclei are comparable to Seyfert 2s in far-infrared and 20 cm luminosities, although their optical spectra are markedly different.

  12. Gas distribution and starbursts in shell galaxies

    NASA Technical Reports Server (NTRS)

    Weil, Melinda L.; Hernquist, Lars

    1993-01-01

    Detailed maps of most elliptical galaxies reveal that, whereas the greatest part of their luminous mass originates from a smooth distribution with a surface brightness approximated by a de Vaucouleurs law, a small percentage of their light is contributed by low surface brightness distortions termed 'fine structures'. The sharp-edged features called 'shells' are successfully reproduced by merger and infall models involving accretion from less massive companions. In this context, dwarf spheroidal and compact disk galaxies are likely progenitors of these stellar phenomena. However, it is probable that the sources of shell-forming material also contain significant amounts of gas. This component may play an important role in constraining the formation and evolution of shell galaxies. To investigate the effects of the gaseous component, numerical simulations were performed to study the tidal disruption of dwarf galaxies containing both gas and stars by more massive primaries, and the evolution of the ensuing debris. The calculations were performed with a hybrid N-body/hydrodynamics code. Collisionless matter is evolved using a conventional N-body technique and gas is treated using smoothed particle hydrodynamics in which self-gravitating fluid elements are represented as particles evolving according to Lagrangian hydrodynamic equations. An isothermal equation of state is employed so the gas remains at a temperature 104 K. Owing to the large mass ratio between the primary and companion, the primary is modeled as a rigid potential and the self-gravity of both galaxies is neglected.

  13. SN Heating Efficiency of the ISM of Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Melioli, C.; de Gouveia dal Pino, E. M.; D'Ercole, A.; Raga, A.

    2004-06-01

    The interstellar medium heated by supernova explosions (SN) may acquire an expansion velocity larger than the escape velocity and leave the galaxy through a supersonic wind. Galactic winds are effectively observed in many local starburst galaxies (Lehnert & Heckman 1996). The SN ejecta are transported out of the galaxies by such winds which must affect the chemical evolution of the galaxies. The effectiveness of the processes mentioned above depends on the heating efficiency (HE) of the SNs, i.e., the ratio between the kinetic plus internal energy density of the ambient gas and the SN energy density. In a starburst region, several SN explosions occur at a large rate inside a relatively small volume. If the successive generations of SN remnants (SNRs) interact with each other very fast, then a superbubble of high temperature and low density will rapidly develop, before a significant increase of the ambient gas density that could lead to substantial losses of energy by radiation. In this case, it is common to assume a value for HE of the order of unity, since most of the available energy of the SNs will be transferred to the ambient gas in the form of kinetic and internal energy, instead of being radiated away. However this assumption fails to reproduce both the chemical and dynamical characteristics of most starburst (SB) galaxies. In order to solve this paradigm, we have constructed a simple semi-analytical model, considering the essential ingredients of a SB environment, i.e., a three-phase medium composed by hot diffuse gas, SNRs and clouds, which is able to qualitatively trace the thermalisation history of the ISM in a SB region and determine the HE evolution (Melioli, de Gouveia Dal Pino, & D'Ercole, A&A, 2003, submitted). Our study has also been accompanied by fully 3-D radiative cooling, hydrodynamical simulations of SNR-SNR and SNR-clouds interactions (see Melioli, de Gouveia Dal Pino, & Raga 2003, in preparation).

  14. Chemical Pollution and Evolution of Massive Starbursts: Cleaning up the Environment in Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Kobulnicky, C.

    1996-12-01

    I present the results of a research program seeking to characterize the impact of massive star-clusters on the chemical and dynamical evolution of metal-poor, irregular and blue compact galaxies. The evolution of high mass stars is thought to contribute the bulk of heavy element enrichment in the interstellar medium, especially alpha -process elements like O, Si, etc. Yet, in actively star-forming galaxies, localized chemical inhomogeneities are seldom observed. Spatially-resolved optical and ultraviolet spectroscopy from the Hubble Space Telescope and ground-based observatories is used to search for chemical enrichment in the vicinity of young star clusters in nearby galaxies. VLA aperture synthesis maps are used to examine the neutral hydrogen content, dynamics, and local environment of the sample galaxies. Despite the spread in evolutionary state of the starbursts determined by the EW of Balmer emission lines and the radio continuum spectral index, few instances of localized enrichment are found. In light of these data, the ``instantaneous enrichment'' scenario for extragalactic HII regions appears less probable than one which operates on long timescales and global spatial scales. The results are consistent with the idea that starburst driven winds expel freshly synthesized metals in a hot 10(6) K phase into the halos of galaxies where they cool, condense into globules, and mix homogeneously with the rest of the galaxy on long (dynamical) timescales. The C/O and N/O ratios of the galaxies are used as new tools for measuring the recent star formation history. Implications for chemical evolution of galaxies both locally and cosmologically are developed.

  15. Starburst Galaxies: Hard X-ray spectra and contribution to the diffuse background

    NASA Technical Reports Server (NTRS)

    Gruber, Duane E.

    1993-01-01

    During the period of this grant two main tasks were performed: a determination of a selection criterion for starburst galaxies most likely to emit X-rays, and performance of a pilot study of the X-ray emission from nine such systems. Starburst galaxies may be expected to emit flat-spectrum X-ray at energies above 10 keV resulting from the various remnants of the short-lived massive stars which characterize the starburst. The investigation to determine the optimum sample resulted in a change from an X-ray selected (HEAO-2) sample to infrared selection based on the IRAS catalogue. A much broader sample thereby available for study, and selection could be limited to only the nearest objects and still obtain a reasonably large sample. A sample of 99 of the brightest infrared starburst galaxies was settled on for the X-ray survey. For a set of practical size, this was then reduced to a subset of 53, based on luminosity and nearness. X-ray emission from these objects was individually measured from the UCSD HEAO-1 all-sky survey in four energy bands between 13 keV to 160 keV. This data base consists of about 20 optical disk volumes. Net significance for the result was roughly two sigma, and a very hard spectral shape is indicated for the net spectrum of the surveyed galaxies. With the possibility of detection of the class, it was then felt worthwhile to examine fluxes from these sources in other archival data. This was performed with the HEAO-1 A2 data and the HEAO-2 (EINSTEIN) main archive and slew survey. Positive results were also obtained for the sample, but again at weak significance. With three independent measures of weak X-ray fluxes from nearby starburst galaxies, we wrote a letter to the Astrophysical Journal (enclosed) discussing these results and their likely significance, in particular, for the contribution to the cosmic diffuse x-ray background, perhaps as much as 25 percent.

  16. Spatially resolved star-formation in nearby analogues of Lyman break galaxies

    NASA Astrophysics Data System (ADS)

    Appel, Sabrina; Baker, Andrew J.; Hall, Kirsten

    2016-01-01

    At redshifts of z > 1.5, UV-selected galaxy populations (such as z ~ 3 Lyman break galaxies = LBGs) have the largest number of spectroscopic redshifts. As a result, LBGs have an important role in our understanding of the history of galaxy formation. However, LBGs are rather poorly understood at longer wavelengths, and thus our understanding of the total star formation rates and (especially) gas masses in such galaxies is incomplete. A common strategy is to assume that the Kennicutt-Schmidt relation between star formation rate (SFR) surface density and gas mass surface density holds, even in these high redshift galaxies where testing the relation directly is not feasible. To help assess the validity of this assumption, we examine the Kennicutt-Schmidt relation in selected nearby (z ~ 0.2) starburst galaxies in the hope of better understanding key questions regarding star formation processes in UV-selected galaxies. Several nearby galaxies with high UV luminosities and surface brightnesses, reminiscent of those found in LBGs, were identified and used for this project. We have obtained new, spatially resolved observations of these nearby analogues in Paschen alpha emission and carbon monoxide emission, from the ESO Very Large Telescope and the IRAM Plateau de Bure Interferometer, respectively. We examine whether the galaxies follow the expected Kennicutt-Schmidt relation, and investigate any implied variation in gas depletion times between and within galaxies. This research has been supported by National Science Foundation grant AST-0955810.

  17. WINGS: WFIRST Infrared Nearby Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Williams, Benjamin

    WFIRST's combination of wide field and high resolution will revolutionize the study of nearby galaxies. We propose to produce and analyze simulated WFIRST data of nearby galaxies and their halos to maximize the scientific yield in the limited observing time available, ensuring the legacy value of WFIRST's eventual archive. We will model both halo structure and resolved stellar populations to optimize WFIRST's constraints on both dark matter and galaxy formation models in the local universe. WFIRST can map galaxy structure down to ~35 mag/square arcsecond using individual stars. The resulting maps of stellar halos and accreting dwarf companions will provide stringent tests of galaxy formation and dark matter models on galactic (and even sub-galactic) scales, which is where the most theoretical tension exists with the Lambda-CDM model. With a careful, coordinated plan, WFIRST can be expected to improve current sample sizes by 2 orders of magnitude, down to surface brightness limits comparable to those currently reached only in the Local Group, and that are >4 magnitudes fainter than achievable from the ground due to limitations in star-galaxy separation. WFIRST's maps of galaxy halos will simultaneously produce photometry for billions of stars in the main bodies of galaxies within 10 Mpc. These data will transform studies of star formation histories that track stellar mass growth as a function of time and position within a galaxy. They also will constrain critical stellar evolution models of the near-infrared bright, rapidly evolving stars that can contribute significantly to the integrated light of galaxies in the near-infrared. Thus, with WFIRST we can derive the detailed evolution of individual galaxies, reconstruct the complete history of star formation in the nearby universe, and put crucial constraints on the theoretical models used to interpret near-infrared extragalactic observations. We propose a three-component work plan that will ensure these gains by

  18. Suppression of star formation in the galaxy NGC 253 by a starburst-driven molecular wind.

    PubMed

    Bolatto, Alberto D; Warren, Steven R; Leroy, Adam K; Walter, Fabian; Veilleux, Sylvain; Ostriker, Eve C; Ott, Jürgen; Zwaan, Martin; Fisher, David B; Weiss, Axel; Rosolowsky, Erik; Hodge, Jacqueline

    2013-07-25

    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 (that is, the total mass flowing out from the nuclear region) is likely to be in atomic and molecular phases that are cooler than the ionized phases. Expanding molecular shells observed in starburst systems such as NGC 253 (ref. 12) and M 82 (refs 13, 14) may facilitate the entrainment of molecular gas in the wind. Although 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 better than 100 parsecs coupled with sensitivity to a wide range of spatial scales, a combination hitherto not available. Here we report observations of NGC 253, a nearby starburst galaxy (distance ∼ 3.4 megaparsecs) known to possess a wind, that trace the cool molecular wind at 50-parsec resolution. At this resolution, the extraplanar molecular gas closely tracks the Hα filaments, and it appears to be connected to expanding molecular shells located in the starburst region. These observations allow us to determine that the molecular outflow rate is greater than 3 solar masses per year and probably about 9 solar masses per year. This implies a ratio of mass-outflow rate to star-formation rate of at least 1, and probably ∼3, indicating that the starburst-driven wind limits the star-formation activity and the final stellar content. PMID:23887428

  19. Infrared Spectral Energy Distributions of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Dale, D. A.; Bendo, G. J.; Engelbracht, C. W.; Gordon, K. D.; Regan, M. W.; Armus, L.; Cannon, J. M.; Calzetti, D.; Draine, B. T.; Helou, G.; Joseph, R. D.; Kennicutt, R. C.; Li, A.; Murphy, E. J.; Roussel, H.; Walter, F.; Hanson, H. M.; Hollenbach, D. J.; Jarrett, T. H.; Kewley, L. J.; Lamanna, C. A.; Leitherer, C.; Meyer, M. J.; Rieke, G. H.; Rieke, M. J.; Sheth, K.; Smith, J. D. T.; Thornley, M. D.

    2005-11-01

    The Spitzer Infrared Nearby Galaxies Survey (SINGS) is carrying out a comprehensive multiwavelength survey on a sample of 75 nearby galaxies. The 1-850 μm spectral energy distributions (SEDs) are presented using broadband imaging data from Spitzer, 2MASS, ISO, IRAS, and SCUBA. The infrared colors derived from the globally integrated Spitzer data are generally consistent with the previous generation of models that were developed using global data for normal star-forming galaxies, although significant deviations are observed. Spitzer's excellent sensitivity and resolution also allow a detailed investigation of the infrared SEDs for various locations within the three large, nearby galaxies NGC 3031 (M81), NGC 5194 (M51), and NGC 7331. A wide variety of spectral shapes is found within each galaxy, especially for NGC 3031, the closest of the three targets and thus the galaxy for which the smallest spatial scales can be explored. Strong correlations exist between the local star formation rate and the infrared colors fν(70 μm)/fν(160 μm) and fν(24 μm)/fν(160 μm), suggesting that the 24 and 70 μm emission are useful tracers of the local star formation activity level. Preliminary evidence indicates that variations in the 24 μm emission, and not variations in the emission from polycyclic aromatic hydrocarbons at 8 μm, drive the variations in the fν(8.0 μm)/fν(24 μm) colors within NGC 3031, NGC 5194, and NGC 7331. If the galaxy-to-galaxy variations in SEDs seen in our sample are representative of the range present at high redshift, then extrapolations of total infrared luminosities and star formation rates from the observed 24 μm flux will be uncertain at the factor of 5 level (total range). The corresponding uncertainties using the redshifted 8.0 μm flux (e.g., observed 24 μm flux for a z=2 source) are factors of 10-20. Considerable caution should be used when interpreting such extrapolated infrared luminosities.

  20. THINGS: THE H I NEARBY GALAXY SURVEY

    SciTech Connect

    Walter, Fabian; Bigiel, Frank; Leroy, Adam; Brinks, Elias; De Blok, W. J. G.; Kennicutt, Robert C. Jr; Thornley, Michele D.

    2008-12-15

    We present 'The H I Nearby Galaxy Survey (THINGS)', a high spectral ({<=}5.2 km s{sup -1}) and spatial ({approx}6'') resolution survey of H I emission in 34 nearby galaxies obtained using the NRAO Very Large Array (VLA). The overarching scientific goal of THINGS is to investigate fundamental characteristics of the interstellar medium (ISM) related to galaxy morphology, star formation, and mass distribution across the Hubble sequence. Unique characteristics of the THINGS database are the homogeneous sensitivity as well as spatial and velocity resolution of the H I data, which is at the limit of what can be achieved with the VLA for a significant number of galaxies. A sample of 34 objects at distances 2 {approx}< D {approx}< 15 Mpc (resulting in linear resolutions of {approx}100 to 500 pc) are targeted in THINGS, covering a wide range of star formation rates ({approx}10{sup -3} to 6 M{sub sun} yr{sup -1}), total H I masses M{sub HI} (0.01 to 14 x 10{sup 9} M{sub sun}), absolute luminosities M{sub B} (-11.5 to -21.7 mag), and metallicities (7.5 to 9.2 in units of 12+log[O/H]). We describe the setup of the VLA observations, the data reduction procedures, and the creation of the final THINGS data products. We present an atlas of the integrated H I maps, the velocity fields, the second moment (velocity dispersion) maps and individual channel maps of each THINGS galaxy. The THINGS data products are made publicly available through a dedicated webpage. Accompanying THINGS papers (in this issue of the Astronomical Journal) address issues such as the small-scale structure of the ISM, the (dark) matter distribution in THINGS galaxies, and the processes leading to star formation.

  1. THINGS: The H I Nearby Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Walter, Fabian; Brinks, Elias; de Blok, W. J. G.; Bigiel, Frank; Kennicutt, Robert C., Jr.; Thornley, Michele D.; Leroy, Adam

    2008-12-01

    We present "The H I Nearby Galaxy Survey (THINGS)," a high spectral (<=5.2 km s-1) and spatial (~6'') resolution survey of H I emission in 34 nearby galaxies obtained using the NRAO Very Large Array (VLA). The overarching scientific goal of THINGS is to investigate fundamental characteristics of the interstellar medium (ISM) related to galaxy morphology, star formation, and mass distribution across the Hubble sequence. Unique characteristics of the THINGS database are the homogeneous sensitivity as well as spatial and velocity resolution of the H I data, which is at the limit of what can be achieved with the VLA for a significant number of galaxies. A sample of 34 objects at distances 2 <~ D <~ 15 Mpc (resulting in linear resolutions of ~100 to 500 pc) are targeted in THINGS, covering a wide range of star formation rates (~10-3 to 6 M sun yr-1), total H I masses M HI (0.01 to 14 × 109 M sun), absolute luminosities M B (-11.5 to -21.7 mag), and metallicities (7.5 to 9.2 in units of 12+log[O/H]). We describe the setup of the VLA observations, the data reduction procedures, and the creation of the final THINGS data products. We present an atlas of the integrated H I maps, the velocity fields, the second moment (velocity dispersion) maps and individual channel maps of each THINGS galaxy. The THINGS data products are made publicly available through a dedicated webpage. Accompanying THINGS papers (in this issue of the Astronomical Journal) address issues such as the small-scale structure of the ISM, the (dark) matter distribution in THINGS galaxies, and the processes leading to star formation.

  2. THE ACS NEARBY GALAXY SURVEY TREASURY

    SciTech Connect

    Dalcanton, Julianne J.; Williams, Benjamin F.; Rosema, Keith; Gogarten, Stephanie M.; Christensen, Charlotte; Gilbert, Karoline; Hodge, Paul; Seth, Anil C.; Dolphin, Andrew; Holtzman, Jon; Skillman, Evan D.; Weisz, Daniel; Cole, Andrew; Girardi, Leo; Karachentsev, Igor D.; Olsen, Knut; Freeman, Ken; Gallart, Carme; De Jong, Roelof S. E-mail: ben@astro.washington.edu E-mail: stephanie@astro.washington.edu E-mail: fabio@astro.washington.edu E-mail: aseth@cfa.harvard.edu

    2009-07-15

    The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D < 4 Mpc). The survey volume encompasses 69 galaxies in diverse environments, including close pairs, small and large groups, filaments, and truly isolated regions. The galaxies include a nearly complete range of morphological types spanning a factor of {approx}10{sup 4} in luminosity and star formation rate. The survey data consist of images taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST), supplemented with archival data and new Wide Field Planetary Camera 2 (WFPC2) imaging taken after the failure of ACS. Survey images include wide field tilings covering the full radial extent of each galaxy, and single deep pointings in uncrowded regions of the most massive galaxies in the volume. The new wide field imaging in ANGST reaches median 50% completenesses of m {sub F475W} = 28.0 mag, m {sub F606W} = 27.3 mag, and m {sub F814W} = 27.3 mag, several magnitudes below the tip of the red giant branch (TRGB). The deep fields reach magnitudes sufficient to fully resolve the structure in the red clump. The resulting photometric catalogs are publicly accessible and contain over 34 million photometric measurements of >14 million stars. In this paper we present the details of the sample selection, imaging, data reduction, and the resulting photometric catalogs, along with an analysis of the photometric uncertainties (systematic and random), for both ACS and WFPC2 imaging. We also present uniformly derived relative distances measured from the apparent magnitude of the TRGB.

  3. The rest-frame optical morphology of starburst galaxies at 1 < z < 3.5

    NASA Astrophysics Data System (ADS)

    Lee, Bomee; Giavalisco, Mauro; Candels, Goods-Hershcel

    2015-01-01

    Using CANDELS combined with GOODS-Herschel in the GOODS-North and South field, we investigate the rest-frame optical morphologies of starburst galaxies at 1 We compare morphologies of MS and SB galaxies using non-parametric (Sersic Index) and parametric measures as well as the visual identification. FIR luminous starburst galaxies are usually interpreted as major wet mergers. We find that the average morphologies of SB galaxies are disky and generally have much more diffuse optical light profile than massive compact early-type galaxies (ETGs), challenging gas-rich merging as the primary dissipative mechanism to assemble very compact, massive galaxies. We find that the sizes of the SB galaxies are clearly larger than those of the MS galaxies on average. NIR to MIR colors of starburst galaxies show no evidence of highly dust-obscured compact component, which could eventually emerge as the massive compact core. Very compact SB galaxies are rather rare, and hence even from a statistical standpoint, our morphological analysis of starburst galaxies does not support the popular mechanism that powerful starburst in a highly dissipative wet merger of gas-rich disks, and subsequent quenching, is the key driver behind the formation of the massive, compact early-type galaxies observed at z~2. The light distribution of the bulk of stars in starburst galaxies is simply not compact enough to eventually evolve into the massive ultra compact ETGs at high redshift universe.

  4. Excess Submillimeter Emission in the Starburst Galaxy NGC 3310?

    NASA Astrophysics Data System (ADS)

    Zhu, M.; Papadopoulos, P. P.; Xilouris, M.; Kuno, N.; Lisenfeld, U.

    2011-10-01

    We present a new observational study of the gas and dust properties in the starburst galaxy NGC 3310, whose bulk interstellar medium (ISM) resides in environments that mark (and bracket) the excitation extremes of the ISM conditions found in infrared luminous galaxies (Zhu et al. 2009). One of our major findings is that the dust emission spectrum in NGC 3310 shows a pronounced submillimeter “excess”. We tried to fit this excess by a cold dust component but very low temperatures were required (Tc ˜ 5-11 K) with a correspondingly low gas-to-dust mass ratio of 5-43. We furthermore show that it is not possible to maintain the large quantities of dust required at these low temperatures in this starburst galaxy. Instead, we conclude that the dust properties need to be different from Galactic dust in order to fit the submillimeter “excess”. We show that the dust spectral energy distribution can be fitted by an enhanced abundance of very small grains and discuss different alternatives.

  5. A Multiwavelength Study of the Starburst Galaxy NGC 7771

    NASA Technical Reports Server (NTRS)

    Davies, Richard I.; Alonso-Herrero, Almudena; Ward, Martin J.

    1997-01-01

    We present a multiwavelength study of the interacting starburst galaxy NGC 7771, including new optical and ultra-violet spectra and a previously unpublished soft X-ray ROSAT image and spectrum. The far-infrared, radio, and X-ray fluxes suggest that a massive burst of star-formation is currently in progress but the small equivalent width of the Balmer emission lines (equivalent width H(alpha approximately equals 100 A), the weak UV flux, the low abundance of ionised oxygen, and the shape of the optical spectrum lead us to conclude that there are few 0 stars. This might normally suggest that star-formation has ceased but the galaxy's barred gravitational potential and large gas reserves imply that this should not be so, and we therefore consider other explanations. We argue that the observations cannot be due to effects of geometry, density bounded nebulae, or dust within the nebulae, and conclude that a truncated IMF is required. The dwarf galaxy NGC 7770 appears to be in the initial stages of a merger with NGC 7771, and the resulting tidal perturbations may have induced the apparent two-armed spiral pattern, and driven a substantial fraction of the disk gas inwards. The presence of a bulge in NGC 7771 may be moderating the starburst so that, while still occuring on a large scale with a supernova rate of 0.8-1/yr, it is less violent and the IMF has a relatively low upper mass limit. We find that there is a cluster of stars obscuring part of the starburst region, and we offer an explanation of its origin.

  6. The multifrequency spectrum of the starburst galaxy NGC 2782

    NASA Technical Reports Server (NTRS)

    Kinney, A. L.; Bregman, J. N.; Huggins, P. J.; Glassgold, A. E.; Cohen, R. D.

    1984-01-01

    The nuclear region of NGC 2782 has been observed at radio, millimeter, infrared, optical, ultraviolet, and X-ray frequencies to understand the ionization source that gives rise to the narrow emission lines. The continuum is probably caused by a normal galactic population plus considerable numbers of young stars and warm dust. In the ultraviolet and optical spectra, which are powerful diagnostics, no strong lines are detected in the 1200 A-3200 A region aside from L-alpha, and the optical emission lines cover only a narrow ionization range. The line and continuum properties suggest that NGC 2782 is a starburst galaxy, in which young stars photoionize the surrounding gas.

  7. THE IMACS CLUSTER BUILDING SURVEY. V. FURTHER EVIDENCE FOR STARBURST RECYCLING FROM QUANTITATIVE GALAXY MORPHOLOGIES

    SciTech Connect

    Abramson, Louis E.; Gladders, Michael D.; Dressler, Alan; Oemler, Augustus Jr.; Monson, Andrew; Persson, Eric; Poggianti, Bianca M.; Vulcani, Benedetta

    2013-11-10

    Using J- and K{sub s}-band imaging obtained as part of the IMACS Cluster Building Survey (ICBS), we measure Sérsic indices for 2160 field and cluster galaxies at 0.31 < z < 0.54. Using both mass- and magnitude-limited samples, we compare the distributions for spectroscopically determined passive, continuously star-forming, starburst, and post-starburst systems and show that previously established spatial and statistical connections between these types extend to their gross morphologies. Outside of cluster cores, we find close structural ties between starburst and continuously star-forming, as well as post-starburst and passive types, but not between starbursts and post-starbursts. These results independently support two conclusions presented in Paper II of this series: (1) most starbursts are the product of a non-disruptive triggering mechanism that is insensitive to global environment, such as minor mergers; (2) starbursts and post-starbursts generally represent transient phases in the lives of 'normal' star-forming and quiescent galaxies, respectively, originating from and returning to these systems in closed 'recycling' loops. In this picture, spectroscopically identified post-starbursts constitute a minority of all recently terminated starbursts, largely ruling out the typical starburst as a quenching event in all but the densest environments.

  8. Alma observations of nearby luminous infrared galaxies with various agn energetic contributions using dense gas tracers

    SciTech Connect

    Imanishi, Masatoshi; Nakanishi, Kouichiro

    2014-07-01

    We present the results of our ALMA Cycle 0 observations, using HCN/HCO{sup +}/HNC J = 4-3 lines, of six nearby luminous infrared galaxies with various energetic contributions from active galactic nuclei (AGNs) estimated from previous infrared spectroscopy. These lines are very effective for probing the physical properties of high-density molecular gas around the hidden energy sources in the nuclear regions of these galaxies. We find that HCN to HCO{sup +} J = 4-3 flux ratios tend to be higher in AGN-important galaxies than in starburst-dominated regions, as was seen at the J = 1-0 transition, while there is no clear difference in the HCN-to-HNC J = 4-3 flux ratios among observed sources. A galaxy with a starburst-type infrared spectral shape and very large molecular line widths shows a high HCN-to-HCO{sup +} J = 4-3 flux ratio, which could be due to turbulence-induced heating. We propose that enhanced HCN J = 4-3 emission relative to HCO{sup +} J = 4-3 could be used to detect more energetic activity than normal starbursts, including deeply buried AGNs, in dusty galaxy populations.

  9. The evolution of the cold interstellar medium in galaxies following a starburst

    NASA Astrophysics Data System (ADS)

    Rowlands, K.; Wild, V.; Nesvadba, N.; Sibthorpe, B.; Mortier, A.; Lehnert, M.; da Cunha, E.

    2015-03-01

    We present the evolution of dust and molecular gas properties in a sample of 11 z ˜ 0.03 starburst to post-starburst (PSB) galaxies selected to span an age sequence from ongoing starburst to 1 Gyr after the starburst ended. All PSBs harbour significant molecular gas and dust reservoirs and residual star formation, indicating that complete quenching of the starburst due to exhaustion or expulsion of gas has not occurred during this timespan. As the starburst ages, we observe a clear decrease in the star formation efficiency, molecular gas and star formation rate (SFR) surface density, and effective dust temperature, from levels coincident with starburst galaxies to those of normal star-forming galaxies. These trends are consistent with a natural decrease in the SFR following consumption of molecular gas by the starburst, and corresponding decrease in the interstellar radiation field strength as the starburst ages. The gas and dust contents of the PSBs are coincident with those of star-forming galaxies and molecular gas-rich early-type galaxies, and are not consistent with galaxies on the red sequence. We find no evidence that the global gas reservoir is expelled by stellar winds or active galactic nuclei feedback. Our results show that although a strong starburst in a low-redshift galaxy may cause the galaxy to ultimately have a lower specific SFR and be of an earlier morphological type, the galaxy will remain in the `green valley' for an extended time. Multiple such episodes may be needed to complete migration of the galaxy from the blue- to red sequence.

  10. Hα Imaging of Nearby Seyfert Host Galaxies

    NASA Astrophysics Data System (ADS)

    Theios, Rachel L.; Malkan, Matthew A.; Ross, Nathaniel R.

    2016-05-01

    We used narrowband (Δλ = 70 Å) interference filters with the CCD imaging camera on the Nickel 1.0 m telescope at Lick Observatory to observe 31 nearby (z < 0.03) Seyfert galaxies in the 12 μm active galaxy sample. We obtained pure emission-line images of each galaxy, which reach down to a flux limit of 7.3 × 10‑15 erg cm‑2 s‑1 arcsec‑2, and corrected these images for [N ii] emission and extinction. We separated the Hα emission line of the “nucleus” (central 100–1000 pc) from that of the host galaxy. The extended Hα emission is expected to be powered by newly formed hot stars, and indeed correlates well with other indicators of current star formation rates (SFRs) in these galaxies: extended 7.7 μm polycyclic aromatic hydrocarbon, total far-infrared, and radio luminosity. Relative to what would be expected from recent star formation, there is a 0.8 dex excess of radio emission in our Seyfert galaxies. The Hα luminosity we measured in the centers of our galaxies is dominated by the active galactic nucleus (AGN), and is linearly correlated with the hard X-ray luminosity. There is, however, an upward offset of 1 dex in this correlation for the Seyfert 1s, because their nuclear Hα emission includes a strong additional contribution from the broad-line region. We found a correlation between SFR and AGN luminosity. In spite of selection effects, we concluded that the absence of bright Seyfert nuclei in galaxies with low SFRs is real, albeit only weakly significant. Finally, we used our measured spatial distributions of Hα emission to determine what these Seyfert galaxies would look like when observed through fixed apertures (e.g., a spectroscopic fiber) at high redshifts. We found that although all of these Seyfert galaxies would be detectable emission-line galaxies at any redshift, most of them would appear to be dominated by (>67%) their H ii region emission. Only the most luminous AGNs (log(L Hα /erg s‑1) > 41.5) would still be identified as

  11. Hα Imaging of Nearby Seyfert Host Galaxies

    NASA Astrophysics Data System (ADS)

    Theios, Rachel L.; Malkan, Matthew A.; Ross, Nathaniel R.

    2016-05-01

    We used narrowband (Δλ = 70 Å) interference filters with the CCD imaging camera on the Nickel 1.0 m telescope at Lick Observatory to observe 31 nearby (z < 0.03) Seyfert galaxies in the 12 μm active galaxy sample. We obtained pure emission-line images of each galaxy, which reach down to a flux limit of 7.3 × 10‑15 erg cm‑2 s‑1 arcsec‑2, and corrected these images for [N ii] emission and extinction. We separated the Hα emission line of the “nucleus” (central 100–1000 pc) from that of the host galaxy. The extended Hα emission is expected to be powered by newly formed hot stars, and indeed correlates well with other indicators of current star formation rates (SFRs) in these galaxies: extended 7.7 μm polycyclic aromatic hydrocarbon, total far-infrared, and radio luminosity. Relative to what would be expected from recent star formation, there is a 0.8 dex excess of radio emission in our Seyfert galaxies. The Hα luminosity we measured in the centers of our galaxies is dominated by the active galactic nucleus (AGN), and is linearly correlated with the hard X-ray luminosity. There is, however, an upward offset of 1 dex in this correlation for the Seyfert 1s, because their nuclear Hα emission includes a strong additional contribution from the broad-line region. We found a correlation between SFR and AGN luminosity. In spite of selection effects, we concluded that the absence of bright Seyfert nuclei in galaxies with low SFRs is real, albeit only weakly significant. Finally, we used our measured spatial distributions of Hα emission to determine what these Seyfert galaxies would look like when observed through fixed apertures (e.g., a spectroscopic fiber) at high redshifts. We found that although all of these Seyfert galaxies would be detectable emission-line galaxies at any redshift, most of them would appear to be dominated by (>67%) their H ii region emission. Only the most luminous AGNs (log(L Hα /erg s‑1) > 41.5) would still be identified as

  12. The Radio–Gamma Correlation in Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Eichmann, B.; Becker Tjus, J.

    2016-04-01

    We present a systematic study of non-thermal electron–proton plasma and its emission processes in starburst galaxies in order to explain the correlation between the luminosity in the radio band and the recently observed gamma luminosity. In doing so, a steady state description of the cosmic-ray (CR) electrons and protons within the spatially homogeneous starburst is considered where continuous momentum losses are included as well as catastrophic losses due to diffusion and advection. The primary source of the relativistic CRs, e.g., supernova remnants, provides a quasi-neutral plasma with a power-law spectrum in momentum where we account for rigidity-dependent differences between the electron and proton spectrum. We examine the resulting leptonic and hadronic radiation processes by synchrotron radiation, inverse Compton scattering, Bremsstrahlung, and hadronic pion production. Finally, the observations of NGC 253, M82, NGC 4945, and NGC 1068 in the radio and gamma-ray bands as well as the observed supernova rate are used to constrain a best-fit model. In the case of NGC 253, M82, and NGC 4945 our model is able to accurately describe the data, showing that: (i) supernovae are the dominant particle accelerators for NGC 253, M82, and NGC 4945, but not for NGC 1068; (ii) all considered starburst galaxies are poor proton calorimeters in which for NGC 253 the escape is predominantly driven by the galactic wind, whereas the diffusive escape dominates in NGC 4945 and M82 (at energies >1 TeV); and (iii) secondary electrons from hadronic pion production are important to model the radio flux, but the associated neutrino flux is below the current observation limit.

  13. The Radio-Gamma Correlation in Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Eichmann, B.; Becker Tjus, J.

    2016-04-01

    We present a systematic study of non-thermal electron-proton plasma and its emission processes in starburst galaxies in order to explain the correlation between the luminosity in the radio band and the recently observed gamma luminosity. In doing so, a steady state description of the cosmic-ray (CR) electrons and protons within the spatially homogeneous starburst is considered where continuous momentum losses are included as well as catastrophic losses due to diffusion and advection. The primary source of the relativistic CRs, e.g., supernova remnants, provides a quasi-neutral plasma with a power-law spectrum in momentum where we account for rigidity-dependent differences between the electron and proton spectrum. We examine the resulting leptonic and hadronic radiation processes by synchrotron radiation, inverse Compton scattering, Bremsstrahlung, and hadronic pion production. Finally, the observations of NGC 253, M82, NGC 4945, and NGC 1068 in the radio and gamma-ray bands as well as the observed supernova rate are used to constrain a best-fit model. In the case of NGC 253, M82, and NGC 4945 our model is able to accurately describe the data, showing that: (i) supernovae are the dominant particle accelerators for NGC 253, M82, and NGC 4945, but not for NGC 1068; (ii) all considered starburst galaxies are poor proton calorimeters in which for NGC 253 the escape is predominantly driven by the galactic wind, whereas the diffusive escape dominates in NGC 4945 and M82 (at energies >1 TeV); and (iii) secondary electrons from hadronic pion production are important to model the radio flux, but the associated neutrino flux is below the current observation limit.

  14. Brackett alpha and gamma Observations of Starburst and Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Kawara, Kimiaki; Nishida, Minoru; Phillips, M. M.

    1989-02-01

    Br (Brackett) α and γ line fluxes of starburst and Seyfert galaxies are presented. The Bra line has been detected in seven of 12 galaxies. These data are combined with published Brackett line fluxes of M82 and NGC 253 to examine the relation between the extinction, A_v_, derived from the Brα/Brγ ratio and the optical depth, τ(10), of the silicate absorption at 10 microns. Generally speaking, a line of slope A_v_/τ(10) = 14 fits the data well, which is the same relation as found in the Milky Way. In the type 2 Seyferts NGC 1068 and NGC 5506, the observed Brα/Brγ ratios may not be simply explained by case B recombination with heavy extinction. The extinction values derived from Brα/Brγ are compared with those determined from optical and X-ray observations, and the implications are discussed.

  15. THE DRIVING MECHANISM OF STARBURSTS IN GALAXY MERGERS

    SciTech Connect

    Teyssier, Romain; Chapon, Damien; Bournaud, Frederic

    2010-09-10

    We present hydrodynamic simulations of a major merger of disk galaxies, and study the interstellar medium (ISM) dynamics and star formation (SF) properties. High spatial and mass resolutions of 12 pc and 4 x 10{sup 4} M {sub sun} allow us to resolve cold and turbulent gas clouds embedded in a warmer diffuse phase. We compare lower-resolution models, where the multiphase ISM is not resolved and is modeled as a relatively homogeneous and stable medium. While merger-driven bursts of SF are generally attributed to large-scale gas inflows toward the nuclear regions, we show that once a realistic ISM is resolved, the dominant process is actually gas fragmentation into massive and dense clouds and rapid SF therein. As a consequence, SF is more efficient by a factor of up to {approx}10 and is also somewhat more extended, while the gas density probability distribution function rapidly evolves toward very high densities. We thus propose that the actual mechanism of starburst triggering in galaxy collisions can only be captured at high spatial resolution and when the cooling of gas is modeled down to less than 10{sup 3} K. Not only does our model reproduce the properties of the Antennae system, but it also explains the 'starburst mode' recently revealed in high-redshift mergers compared to quiescent disks.

  16. The Driving Mechanism of Starbursts in Galaxy Mergers

    NASA Astrophysics Data System (ADS)

    Teyssier, Romain; Chapon, Damien; Bournaud, Frédéric

    2010-09-01

    We present hydrodynamic simulations of a major merger of disk galaxies, and study the interstellar medium (ISM) dynamics and star formation (SF) properties. High spatial and mass resolutions of 12 pc and 4 × 104 M sun allow us to resolve cold and turbulent gas clouds embedded in a warmer diffuse phase. We compare lower-resolution models, where the multiphase ISM is not resolved and is modeled as a relatively homogeneous and stable medium. While merger-driven bursts of SF are generally attributed to large-scale gas inflows toward the nuclear regions, we show that once a realistic ISM is resolved, the dominant process is actually gas fragmentation into massive and dense clouds and rapid SF therein. As a consequence, SF is more efficient by a factor of up to ~10 and is also somewhat more extended, while the gas density probability distribution function rapidly evolves toward very high densities. We thus propose that the actual mechanism of starburst triggering in galaxy collisions can only be captured at high spatial resolution and when the cooling of gas is modeled down to less than 103 K. Not only does our model reproduce the properties of the Antennae system, but it also explains the "starburst mode" recently revealed in high-redshift mergers compared to quiescent disks.

  17. Starbursts and dusty tori in distant 3CR radio galaxies

    NASA Astrophysics Data System (ADS)

    Podigachoski, Pece; Rocca-Volmerange, Brigitte; Barthel, Peter; Drouart, Guillaume; Fioc, Michel

    2016-08-01

    We present a study of the complete ultraviolet to submillimetre spectral energy distributions (SEDs) of twelve 3CR radio galaxy hosts in the redshift range 1.0 < z < 2.5, which were all detected in the far-infrared by the Herschel Space Observatory. The study employs the new spectro-chemical evolutionary code PÉGASE.3, in combination with recently published clumpy AGN torus models. We uncover the properties of the massive host galaxy stellar populations, the AGN torus luminosities, and the properties of the recent starbursts, which had earlier been inferred in these objects from their infrared SEDs. The PÉGASE.3 fitting yields very luminous (up to 1013 L⊙) young stellar populations with ages of several hundred million years in hosts with masses exceeding 1011 M⊙. Dust masses are seen to increase with redshift, and a surprising correlation - or better upper envelope behaviour - is found between the AGN torus luminosity and the starburst luminosity, as revealed by their associated dust components. The latter consistently exceeds the former by a constant factor, over a range of one order of magnitude in both quantities.

  18. Extremely Isolated Galaxies in the Nearby Universe

    NASA Astrophysics Data System (ADS)

    Fanelli, Michael N.; Marcum, P. M.; Fuse, C.; Aars, C.

    2007-12-01

    Highly isolated systems provide a framwork for exploring the role of interactions within galaxy evolution. We use the spectroscopic component of the Sloan Sky Survey to select extremely isolated galaxies in the nearby universe. Redshifts derived from the Sloan spectra permit a three-dimensional assessment of the local environment surrounding candidate isolated systems. The lack of redshifts has strongly limited prior searches for isolated systems. We have constructed a searchable database for the 600K objects contained in the Sloan Survey.. Isolated systems are chosen utilizing a range of criteria, including projected physical separations, differential velocities, and luminosity limits for potential dwarf companions. We describe the morphological, photometric and star formation properties of the most isolated systems found within the SDSS footprint. Highly isolated systems are extremely rare, most are blue, and exhibit ongoing star formation. One object appears to be a merging compact group. We acknowledge support from NASA's Astrophysical Data Program, grant #NNG05C53G.

  19. A massive, cooling-flow-induced starburst in the core of a luminous cluster of galaxies.

    PubMed

    McDonald, M; Bayliss, M; Benson, B A; Foley, R J; Ruel, J; Sullivan, P; Veilleux, S; Aird, K A; Ashby, M L N; Bautz, M; Bazin, G; Bleem, L E; Brodwin, M; Carlstrom, J E; Chang, C L; Cho, H M; Clocchiatti, A; Crawford, T M; Crites, A T; de Haan, T; Desai, S; Dobbs, M A; Dudley, J P; Egami, E; Forman, W R; Garmire, G P; George, E M; Gladders, M D; Gonzalez, A H; Halverson, N W; Harrington, N L; High, F W; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Jones, C; Joy, M; Keisler, R; Knox, L; Lee, A T; Leitch, E M; Liu, J; Lueker, M; Luong-Van, D; Mantz, A; Marrone, D P; McMahon, J J; Mehl, J; Meyer, S S; Miller, E D; Mocanu, L; Mohr, J J; Montroy, T E; Murray, S S; Natoli, T; Padin, S; Plagge, T; Pryke, C; Rawle, T D; Reichardt, C L; Rest, A; Rex, M; Ruhl, J E; Saliwanchik, B R; Saro, A; Sayre, J T; Schaffer, K K; Shaw, L; Shirokoff, E; Simcoe, R; Song, J; Spieler, H G; Stalder, B; Staniszewski, Z; Stark, A A; Story, K; Stubbs, C W; Suhada, R; van Engelen, A; Vanderlinde, K; Vieira, J D; Vikhlinin, A; Williamson, R; Zahn, O; Zenteno, A

    2012-08-16

    In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10(45) erg s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers. PMID:22895340

  20. A massive, cooling-flow-induced starburst in the core of a luminous cluster of galaxies

    NASA Astrophysics Data System (ADS)

    McDonald, M.; Bayliss, M.; Benson, B. A.; Foley, R. J.; Ruel, J.; Sullivan, P.; Veilleux, S.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.; Bazin, G.; Bleem, L. E.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Egami, E.; Forman, W. R.; Garmire, G. P.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-van, D.; Mantz, A.; Marrone, D. P.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Miller, E. D.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Rawle, T. D.; Reichardt, C. L.; Rest, A.; Rex, M.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Simcoe, R.; Song, J.; Spieler, H. G.; Stalder, B.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Šuhada, R.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.

    2012-08-01

    In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous `cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these `cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 1045 erg s-1) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.

  1. Suppression of star formation in the galaxy NGC 253 by a starburst-driven molecular wind

    NASA Astrophysics Data System (ADS)

    Warren, Steven R.; Bolatto, A. D.; Leroy, A. K.; Walter, F.; Veilleux, S.; Ostriker, E. C.; Ott, J.; Zwaan, M.; Fisher, D. B.; Weiss, A.; Rosolowsky, E.; Hodge, J.

    2014-01-01

    We present Atacama Large (Sub)Millimeter Array (ALMA) CO (J=1-0) observations of the nearby, nuclear starburst galaxy NGC 253. NGC 253 is host to a "superwind" emanating from the central ~200 pc. Galaxy superwinds are thought to help shape the galactic mass function, play a critical role in galaxy evolution, and pollute the intergalactic medium with heavy metals. Detailed studies of nearby systems frequently focus on the warm or hot phases of the wind, visible in X-ray or Halpha emission. However, most of the mass in the outflowing material is thought to be in the form of neutral atomic and molecular gas. We use the observed CO luminosities and velocities to estimate the mass, mass loss rate, and energetics of the molecular wind. We compute an outflow mass of M_mo 6.6x10^6 Msun. The observed projected velocities of the CO filaments range from ~30-60 km s^-1 resulting in a mass loss rate of ~9 Msun yr^-1. The nuclear region of NGC 253 has a star formation rate of ~3 Msun yr^-1 resulting in a mass loading parameter 1-3. It is not immediately clear if the outflowing gas will escape the halo or eventually rain back onto the disk. What is clear is that NGC 253 will exhaust its nuclear star forming gas in ~60-120 Myr at its current mass loss rate, cementing the superwind as an important contributor in the evolution of NGC 253.

  2. Detection of the 158 Micrometers[CII] Transition at z=1.3: Evidence for a Galaxy-Wide Starburst

    NASA Technical Reports Server (NTRS)

    Hailey-Dunsheath, S.; Nikola, T.; Oberst, T. E.; Parshley, S. C.; Benford, D. J.; Staguhn, J. G.; Tucker, C. E.

    2010-01-01

    We report the detection of 158 micron [C II] fine-structure line emission from MIPS J142824.0+352619, a hyperluminous ( L(sub IR) approximates 10(exp 13) L (sub solar)) starburst galaxy at z = 1.3. The line is bright, corresponding to a fraction L(sub [Cu II] L(sub Fir) approximates 2 x 10(exp -3) of the far-IR (FIR) continuum. The [C II], CO, and FIR continuum emission may be modeled as arising from photodissociation regions (PDRs) that have a characteristic gas density of n approximates 10(exp 4.2) /cm(exp 3) , and that are illuminated by a far-UV radiation field approximately 10(exp 3.2) times more intense than the local interstellar radiation field. The mass in these PDRs accounts for approximately half of the molecular gas mass in this galaxy. The L(sub [CII])/L(sub FIR) ratio is higher than observed in local ultralummous infrared galaxies or in the few high-redshift QSOs detected in [C II], but the L(sub [CII])/L(sub FIR) and L(sub CO)/L(sub FIR) ratios are similar to the values seen in nearby starburst galaxies. This suggests that MIPS J142824.0+352619 is a scaled-up version of a starburst nucleus, with the burst extended over several kiloparsecs.

  3. Direct Measurement of the Supernova Rate in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse D.; Temi, Pasquale; Rank, David; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short times. Many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extintion is especially severe. Thus, determining the supernova rate in the active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micron emission line was the strongest line in the infrared spectrum for a period of a year and a half after the explosion. Since dust extintion is much less at 6.63 pm than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the NiII line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micron using ISOCAM to search for the NiII emission line characteristic of recent supernovae. We did not detect any NiII line emission brighter than a 5sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled to the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a NiII with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a NiII line luminosity greater than the line in SN1987A.

  4. Extinction Mapping of Nearby Galaxies with LEGUS

    NASA Astrophysics Data System (ADS)

    Kahre, Lauren; Walterbos, Rene A. M.; Sabbi, Elena; Thilker, David A.; Ubeda, Leonardo; LEGUS Science Team

    2016-01-01

    Using 5-band (NUV (2750 A), U, B, V, I) photometry from the Legacy ExtraGalactic Ultraviolet Survey (LEGUS), we generate extinction maps for nearby (within 10 Mpc) galaxies at resolutions of a few arcseconds. Dust is commonly used as a tracer for cold dense gas, either through IR and NIR emission maps or through extinction mapping. Extinction mapping has been used to trace dust column densities in the Milky Way, the Magellanic Clouds, and M31. The maps for M31 use IR and NIR photometry of red giant branch stars, which is more difficult to obtain for more distant galaxies. Our method uses the extinctions derived for individual massive stars using the isochrone-matching method described by Kim et al. (2012). With our 5-band photometry, which extends into the UV, we are able to trace even small amounts of extinction. These maps are then compared to HI and CO maps of the same galaxies with the goal of constraining the dust-to-gas mass ratio, which we can then correlate with the gas phase metallicity from other observations. This poster will demonstrate the technique on a few galaxies, but the project will subsequently be expanded to cover the full LEGUS sample of nearly 50 galaxies. These maps can then be used to correct massive star and cluster photometry and HII region Halpha observations for the effects of extinction in order to better characterize star formation rates and massive stellar populations for other projects, such as initial mass function studies and ionization balance studies for HII regions and the diffuse ionized gas.

  5. ORIENTATION OF BRIGHTER GALAXIES IN NEARBY GALAXY CLUSTERS

    SciTech Connect

    Panko, E.; Juszczyk, T.; Flin, P. E-mail: sfflin@cyf-kr.edu.pl

    2009-12-15

    A sample of 6188 nearby galaxy structures, complete to r{sub F} = 18fm3 and containing at least 10 members each, was the observational basis for an investigation of the alignment of bright galaxies with the major axes for the parent clusters. The distribution of position angles for galaxies within the clusters, specifically the brightest, the second brightest, the third, and the tenth brightest galaxies was tested for isotropy. Galaxy position angles appear to be distributed isotropically, as are the distributions of underlying cluster structure position angles. The characterization of galaxy structures according to richness class also appears to be isotropic. Characterization according to BM types, which are known for 1056 clusters, is more interesting. Only in the case of clusters of BM type I is there an alignment of the brightest cluster member with the major axis of the parent cluster. The effect is observed at the 2 significance level. In other investigated cases the distributions are isotropic. The results confirm the special role of cD galaxies in the origin/evolution of large-scale structures.

  6. Characteristics of HI Supershells in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Thilker, D. A.; Braun, R.; Walterbos, R. A. M.

    1998-05-01

    Analysis of expanding HI supershells in a large sample of galaxies has benefited greatly from a recently developed automated method for finding and accurately characterizing bubble-like structures. Thilker, Braun, and Walterbos (1998) described a 3D pattern recognition method for use with spectral-line datacubes. Mashchenko, Thilker, and Braun (1998) refined the procedure, incorporating realistic projected supershell models as template patterns. We have applied the automated method to a sample of 11 nearby spiral galaxies. Here we present characteristics of all HI supershells observed in these systems. Our analysis suggests a possible correlation between the global rate of star formation (SFR) and the total kinetic energy of supershells in a galaxy. We also discuss the observed supershell size distribution, making comparison with the theoretical predictions of Oey & Clarke (1997). Finally, in selected regions, we examine properties of the 21-cm line profile attributable to shell expansion. It appears that superbubble structures may be largely responsible for the presence of low-level, high velocity wings in the CNM, as traced by the high-brightness network (HBN) of Braun (1997).

  7. CONNECTIONS BETWEEN GALAXY MERGERS AND STARBURST: EVIDENCE FROM THE LOCAL UNIVERSE

    SciTech Connect

    Luo, Wentao; Yang, Xiaohu; Zhang, Youcai E-mail: xyang@sjtu.edu.cn

    2014-07-01

    Major mergers and interactions between gas-rich galaxies with comparable masses are thought to be the main triggers of starburst. In this work, we study, for a large stellar mass range, the interaction rate of the starburst galaxies in the local universe. We focus independently on central and satellite star forming galaxies extracted from the Sloan Digital Sky Survey. Here the starburst galaxies are selected in the star formation rate (SFR) stellar mass plane with SFRs five times larger than the median value found for ''star forming'' galaxies of the same stellar mass. Through visual inspection of their images together with close companions determined using spectroscopic redshifts, we find that ∼50% of the ''starburst'' populations show evident merger features, i.e., tidal tails, bridges between galaxies, double cores, and close companions. In contrast, in the control sample we selected from the normal star forming galaxies, only ∼19% of galaxies are associated with evident mergers. The interaction rates may increase by ∼5% for the starburst sample and 2% for the control sample if close companions determined using photometric redshifts are considered. The contrast of the merger rate between the two samples strengthens the hypothesis that mergers and interactions are indeed the main causes of starburst.

  8. High mass stars: starbursts

    NASA Astrophysics Data System (ADS)

    González Delgado, R. M.

    2006-08-01

    Starbursts are the preferred place where massive stars form; the main source of thermal and mechanical heating in the interstellar medium, and the factory where the heavy elements form. Thus, starbursts play an important role in the origin and evolution of galaxies. Starbursts are bright at ultraviolet (UV) wavelengths, and after the pioneering IUE program, high spatial and spectral resolution UV observations of local starburst galaxies, mainly taken with HST and FUSE, have made relevant contributions to the following issues: a) The determination of the initial mass function in violent star forming systems in low and high metallicity environments, and in dense (e.g. in stellar clusters) and diffuse environments. b) The modes of star formation: Starburst clusters are an important mode of star formation. c) The role of starbursts in AGN. d) The interaction between massive stars and the interstellar and intergalactic media. e) The contribution of starbursts to the reionization of the universe. Despite the very significant progress obtained over the past two decades of UV observations of starbursts, there are important problems that still need to be solved. High-spatial resolution UV observations of nearby starbursts are crucial to further progress in understanding the violent star formation processes in galaxies, the interaction between the stellar clusters and the interstellar medium, and the variation of the IMF. Thus, a new UV mission furnished with an intermediate spectral resolution long-slit spectrograph with high spatial resolution and high UV sensitivity is required to further progress in the study of starburst galaxies and their impact on the evolution of galaxies.

  9. The evolution of post-starburst galaxies from z = 2 to z = 0.5

    NASA Astrophysics Data System (ADS)

    Wild, Vivienne; Almaini, Omar; Dunlop, Jim; Simpson, Chris; Rowlands, Kate; Bowler, Rebecca; Maltby, David; McLure, Ross

    2016-08-01

    We present the evolution in the number density and stellar mass functions of photometrically selected post-starburst galaxies in the UKIDSS Deep Survey (UDS), with redshifts of 0.5 < z < 2 and stellar masses log (M/M⊙)>10. We find that this transitionary species of galaxy is rare at all redshifts, contributing ˜5% of the total population at z ˜ 2, to <1% by z ˜ 0.5. By comparing the mass functions of quiescent galaxies to post-starburst galaxies at three cosmic epochs, we show that rapid quenching of star formation can account for 100% of quiescent galaxy formation, if the post-starburst spectral features are visible for ˜250 Myr. The flattening of the low mass end of the quiescent galaxy stellar mass function seen at z ˜ 1 can be entirely explained by the addition of rapidly quenched galaxies. Only if a significant fraction of post-starburst galaxies have features that are visible for longer than 250 Myr, or they acquire new gas and return to the star-forming sequence, can there be significant growth of the red sequence from a slower quenching route. The shape of the mass function of these transitory post-starburst galaxies resembles that of quiescent galaxies at z ˜ 2, with a preferred stellar mass of log (M/M⊙)˜10.6, but evolves steadily to resemble that of star-forming galaxies at z < 1. This leads us to propose a dual origin for post-starburst galaxies: (1) at z ≳ 2 they are exclusively massive galaxies that have formed the bulk of their stars during a rapid assembly period, followed by complete quenching of further star formation; (2) at z ≲ 1 they are caused by the rapid quenching of gas-rich star-forming galaxies, independent of stellar mass, possibly due to environment and/or gas-rich major mergers.

  10. Near-IR spectral evolution of dusty starburst galaxies

    NASA Astrophysics Data System (ADS)

    Lançon, Ariane; Rocca-Volmerange, Brigitte

    1996-11-01

    We propose a multicomponent analysis of starburst galaxies, based on a model that takes into account the young and evolved stellar components and the gas emission, with their respective extinction, in the frame of a coherent dust distribution pattern. Near-IR signatures are preferentially investigated, in order to penetrate as deep as possible into the dusty starburst cores. We computed the 1.4-2.5 μm spectra of synthetic stellar populations evolving through strong, short timescale bursts of star formation (continuum and lines, R ≃ 500). The evolution model is specifically sensitive to cool stellar populations (AGB and red supergiant stars). It takes advantage of the stellar library of Lançon & Rocca-Volmerange (1992) [A&ASS, 96, 593], observed with the same instrument (FTS/CFHT) as the analysed galaxy sample, so that the instrumental effects are minimised. The main near-IR observable constraints are the molecular signatures of CO and H2O and the slope of the continuum, observed over a range exceptionally broad for spectroscopic data. The H - K colour determined from the spectra measures the intrinsic stellar energy distribution but also differential extinction, which is further constrained by optical emission line ratios. Other observational constraints are the near-IR emission lines (Brγ, He I 2.06 μm, [Fe II] 1.64 μm, H2 2.12 μm) and the far-IR luminosity. The coherence of the results relies on the interpretation in terms of stellar populations from which all observable properties are derived, so that the link between the various wavelength ranges is secured. The luminosity LK is used for the absolute calibration. We apply this approach to the typical spectrum of the core of NGC 1614. Consistent solutions for the starburst characteristics (star-formation rate, IMF, burst age, morphology) are found and the role of each observational constraint in deriving satisfactory models is extensively discussed. The acceptable contamination of the K band light by the

  11. Nearby Galaxies as Damped Lyman alpha Absorbers

    NASA Astrophysics Data System (ADS)

    Rao, Sandhya

    1993-12-01

    The evolution of the neutral hydrogen content of galaxies as a function of time is an important constraint on processes in galactic evolution. We present a comprehensive, statistical description of the HI content and distribution within galaxies at the present epoch and compare these statistics with the properties of HI associated with ``damped Lyman alpha '' absorption systems at high redshift that are observed in the spectra of QSOs. Omega_ {HI}(z=0), the HI mass density at the present epoch relative to the present critical mass density, is found to be (2.3 +/- 0.6) times 10(-4) h75(-1) , consistent with the decreasing trend of the HI content with time deduced from QSO absorption line statistics for redshifts from about 4 to 0.5 (Lanzetta 1993). Spiral galaxies contain an overwhelming 94% of this neutral hydrogen mass. The rest is contained in irregulars (3%), and S0s plus ellipticals (3%). Spirals also offer the largest cross-section to line-of-sight absorption of light from QSOs. By considering nearby spirals as potential absorbers, the interception probability as a function of the HI column density, N(HI), is derived for comparison with the cross-sections inferred from observations of damped Lyman alpha systems. Consistent with previous studies, the comparison shows that the damped Ly alpha lines are created by absorbers that subtend larger cross-sections than present-day spirals by a factor of 5 implying that galaxies were either larger or more numerous at z ~ 2.5. We are also investigating the statistics of damped Lyman alpha absorbers in the redshift range 0.2 1.5.

  12. Lambda = 3 mm line survey of nearby active galaxies

    NASA Astrophysics Data System (ADS)

    Aladro, R.; Martín, S.; Riquelme, D.; Henkel, C.; Mauersberger, R.; Martín-Pintado, J.; Weiß, A.; Lefevre, C.; Kramer, C.; Requena-Torres, M. A.; Armijos-Abendaño, R. J.

    2015-07-01

    Aims: We aim to better understand the imprints that the nuclear activity in galaxies leaves in the molecular gas. Methods: We used the IRAM 30 m telescope to observe the frequency range ~[86-116] GHz towards the central regions of the starburst galaxies M 83, M 82, and NGC 253, the galaxies hosting an active galactic nucleus (AGN) M 51, NGC 1068, and NGC 7469, and the ultra-luminous infrared galaxies (ULIRGs) Arp 220 and Mrk 231. Assuming local thermodynamic equilibrium (LTE), we calculated the column densities of 27 molecules and 10 isotopologues (or their upper limits in case of non-detections). Results: Among others, we report the first tentative detections of CH3CHO, HNCO, and NS in M 82 and, for the first time in the extragalactic medium, HC5N in NGC 253. Hα recombination lines were only found in M 82 and NGC 253. Vibrationally excited lines of HC3N were only detected in Arp 220. CH3CCH emission is only seen in the starburst-dominated galaxies. By comparison of the fractional abundances among the galaxies, we looked for the molecules that are best suited to characterise the chemistry of each group of galaxies (starbursts, AGNs and ULIRGs), as well as the differences among galaxies within the same group. Conclusions: Suitable species for characterising and comparing starburst galaxies are CH3OH and HNCO as tracers of large-scale shocks, which dominate early to intermediate starburst stages, and CH3CCH, c-C3H2, and HCO as tracers of UV fields, which control the intermediate-to-old or post starburst phases. M 83 shows signs of a shock-dominated environment. NGC 253 is characterised by both strong shocks and some UV fields. M 82 stands out for its bright photo-dissociated region tracers, which indicate an UV field-dominated environment. Regarding AGNs, the abundances of HCN and CN (previously claimed as enhanced in AGNs) in M 51 are similar to those in starburst galaxies, while the HCN/HCO+ ratio is high in M 51 and NGC 1068, but not in NGC 7469. We did not find

  13. THE STAR FORMATION HISTORY AND CHEMICAL EVOLUTION OF STAR-FORMING GALAXIES IN THE NEARBY UNIVERSE

    SciTech Connect

    Torres-Papaqui, J. P.; Coziol, R.; Ortega-Minakata, R. A.; Neri-Larios, D. M. E-mail: rcoziol@astro.ugto.mx E-mail: daniel@astro.ugto.mx

    2012-08-01

    We have determined the metallicity (O/H) and nitrogen abundance (N/O) of a sample of 122,751 star-forming galaxies (SFGs) from the Data Release 7 of the Sloan Digital Sky Survey. For all these galaxies we have also determined their morphology and obtained a comprehensive picture of their star formation history (SFH) using the spectral synthesis code STARLIGHT. The comparison of the chemical abundance with the SFH allows us to describe the chemical evolution of the SFGs in the nearby universe (z {<=} 0.25) in a manner consistent with the formation of their stellar populations and morphologies. A high fraction (45%) of the SFGs in our sample show an excess abundance of nitrogen relative to their metallicity. We also find this excess to be accompanied by a deficiency of oxygen, which suggests that this could be the result of effective starburst winds. However, we find no difference in the mode of star formation of the nitrogen-rich and nitrogen-poor SFGs. Our analysis suggests that they all form their stars through a succession of bursts of star formation extended over a period of few Gyr. What produces the chemical differences between these galaxies seems therefore to be the intensity of the bursts: the galaxies with an excess of nitrogen are those that are presently experiencing more intense bursts or have experienced more intense bursts in their past. We also find evidence relating the chemical evolution process to the formation of the galaxies: the galaxies with an excess of nitrogen are more massive, and have more massive bulges and earlier morphologies than those showing no excess. Contrary to expectation, we find no evidence that the starburst wind efficiency decreases with the mass of the galaxies. As a possible explanation we propose that the loss of metals consistent with starburst winds took place during the formation of the galaxies, when their potential wells were still building up, and consequently were weaker than today, making starburst winds more

  14. ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. III. AN EXTREMELY METAL DEFICIENT GALAXY

    SciTech Connect

    Skillman, Evan D.; Berg, Danielle A.; Olive, Keith A.; McQuinn, Kristen B. W. E-mail: berg@astro.umn.edu E-mail: kmcquinn@astro.umn.edu; and others

    2013-07-01

    We present KPNO 4 m and LBT/MODS spectroscopic observations of an H II region in the nearby dwarf irregular galaxy Leo P discovered recently in the Arecibo ALFALFA survey. In both observations, we are able to accurately measure the temperature sensitive [O III] {lambda}4363 line and determine a ''direct'' oxygen abundance of 12 + log(O/H) = 7.17 {+-} 0.04. Thus, Leo P is an extremely metal deficient (XMD) galaxy, and, indeed, one of the most metal deficient star-forming galaxies ever observed. For its estimated luminosity, Leo P is consistent with the relationship between luminosity and oxygen abundance seen in nearby dwarf galaxies. Leo P shows normal {alpha} element abundance ratios (Ne/O, S/O, and Ar/O) when compared to other XMD galaxies, but elevated N/O, consistent with the ''delayed release'' hypothesis for N/O abundances. We derive a helium mass fraction of 0.2509{sup +0.0184}{sub -0.0123}, which compares well with the WMAP + BBN prediction of 0.2483 {+-} 0.0002 for the primordial helium abundance. We suggest that surveys of very low mass galaxies compete well with emission line galaxy surveys for finding XMD galaxies. It is possible that XMD galaxies may be divided into two classes: the relatively rare XMD emission line galaxies which are associated with starbursts triggered by infall of low-metallicity gas and the more common, relatively quiescent XMD galaxies like Leo P, with very low chemical abundances due to their intrinsically small masses.

  15. Powerful Molecular Outflows in Nearby Active Galaxies

    NASA Astrophysics Data System (ADS)

    Veilleux, Sylvain; Meléndez, Marcio

    2014-07-01

    We report the results from a systematic search for molecular (OH 119 μm) outflows with Herschel-PACS† in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7-μm silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than -50 km s-1, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (~ 145°) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km s-1, is seen in only 4 objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ~ -1000 km s-1 are measured in several objects, but median outflow velocities are typically ~ -200 km s-1. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large AGN fractions and luminosities [log (L AGN/L ⊙) >= 11.8 +/- 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. In contrast, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  16. Aspects of the interstellar medium in starburst galaxies

    NASA Astrophysics Data System (ADS)

    Fanelli, Michael N.

    1990-07-01

    Researchers are engaged in a multifaceted program to investigate the stellar content and star formation history of actively star-forming galaxies. A large body of stellar spectra have been examined to identify spectral features characteristic of specific stellar types. These spectral diagnostics are then calibrated in terms of temperature (spectral type), gravity (luminosity class) and metallicity. The spectral data is compiled into a stellar library whose members represent specific locations in the HR diagram. Through the use of population synthesis techniques, both optimizing and evolutionary approaches, the stellar luminosity function in composite populations can be determined by analysis of their integrated light. Researchers have concentrated on the ultraviolet wavelength region (lambda lambda 1200 to 3200), utilizing the International Ultraviolet Explorer (IUE) archives supplemented by additional observations. In the optical, virtually all stars will contribute to the integrated light. In the ultraviolet however, cool stars will produce negligible flux due to their steep ultraviolet-to-visual continua, greatly simplifying the investigation of the hot component in a composite population. The researchers' initial stellar library has been applied to several blue compact galaxies, (BCGs), a class of starburst galaxy which is UV luminous. BCGs possess a complex interstellar medium which affects the emergent stellar continuum in several ways. This presents a challenge to the stellar analysis but affords insight into the properties of the gas and dust from which the massive OB stars have formed. The optimizing synthesis method solves for the stellar luminosity function and extinction simultaneously. This therefore provides an independent measure of the extinction affecting the hot population component. Despite the rise of the reddening law towards the ultraviolet, BCGs are found to be brighter in the ultraviolet than expected.

  17. Aspects of the interstellar medium in starburst galaxies

    NASA Technical Reports Server (NTRS)

    Fanelli, Michael N.

    1990-01-01

    Researchers are engaged in a multifaceted program to investigate the stellar content and star formation history of actively star-forming galaxies. A large body of stellar spectra have been examined to identify spectral features characteristic of specific stellar types. These spectral diagnostics are then calibrated in terms of temperature (spectral type), gravity (luminosity class) and metallicity. The spectral data is compiled into a stellar library whose members represent specific locations in the HR diagram. Through the use of population synthesis techniques, both optimizing and evolutionary approaches, the stellar luminosity function in composite populations can be determined by analysis of their integrated light. Researchers have concentrated on the ultraviolet wavelength region (lambda lambda 1200 to 3200), utilizing the International Ultraviolet Explorer (IUE) archives supplemented by additional observations. In the optical, virtually all stars will contribute to the integrated light. In the ultraviolet however, cool stars will produce negligible flux due to their steep ultraviolet-to-visual continua, greatly simplifying the investigation of the hot component in a composite population. The researchers' initial stellar library has been applied to several blue compact galaxies, (BCGs), a class of starburst galaxy which is UV luminous. BCGs possess a complex interstellar medium which affects the emergent stellar continuum in several ways. This presents a challenge to the stellar analysis but affords insight into the properties of the gas and dust from which the massive OB stars have formed. The optimizing synthesis method solves for the stellar luminosity function and extinction simultaneously. This therefore provides an independent measure of the extinction affecting the hot population component. Despite the rise of the reddening law towards the ultraviolet, BCGs are found to be brighter in the ultraviolet than expected.

  18. A High-Resolution Map of 12CO J = 6-5 Emission in the Starburst Galaxy M82

    NASA Astrophysics Data System (ADS)

    Seaquist, E. R.; Lee, S. W.; Moriarty-Schieven, G. H.

    2006-02-01

    We present a map of 12CO J=6-5 emission of the nuclear region of the nearby starburst galaxy M82 at resolution 7" taken with the James Clerk Maxwell Telescope (JCMT). This is the highest resolution map yet available at this transition. A detailed quantitative comparison is made with emission at 12CO J=1-0 at the same resolution, yielding new insights into the excitation of molecular gas in this galaxy. The excitation is found to be highest in the central area of the starburst region where the ratio r61=12CO J=6-5/12CO J=1-0 is as high as 0.5, compared to the mean value over the starburst region of 0.24. The excitation ratio peaks along the inner edge of the molecular ring outlined by atomic and molecular gas at lower excitation, and also in two spurs extending northward from the disk toward the outflow associated with the superwind. Emission with higher than average excitation is also found to be associated with the supershell surrounding the luminous SNR candidate 41.9+58, and possibly on a larger scale in gas whose orbits are strongly influenced by the stellar bar. The higher excitation in M82 is likely to be caused predominantly by local increases in kinetic temperature and/or in the geometric filling factor of a preexisting higher excitation component and less likely to be caused by local increases in gas density.

  19. Detection of the 158 Micrometers[CII] Transition at z=1.3: Evidence for a Galaxy-Wide Starburst

    NASA Technical Reports Server (NTRS)

    Hailey-Dunsheath, S.; Nikola, T.; Stacey, G. J.; Oberst, T. E.; Parshley, S. C.; Benford, D. J.; Staguhn, J. G.; Tucker, C. E.

    2010-01-01

    We report the detection of 158 micrometer [C II] fine-structure line emission from MIPS J 142824.0+3526l9, a hyperluminous (L(sub IR) approx. 10(exp 13) Solar Luminosity starburst galaxy at z = 1.3. The line is bright, corresponding to a fraction L[C II]/L(sub FIR) approx. equals 2 x l0(exp -3) of the far-IR(FIR) continuum. The [C II], CO, and FIR continuum emission may be modeled as arising from photodissociation regions (PDRs) that have a characteristic gas density of n approx. 10(exp 4.2)/cu cm., and that are illuminated by a far-UV radiation field approx. 10(exp 3.2) times more intense than the local interstellar radiation field. The mass in these PDRs accounts for approximately half of the molecular gas mass in this galaxy. The L[C II]/L(sub F1R) ratio is higher than observed in local ultraluminous infrared galaxies or in the few high-redshift QSOs detected in [C II], but the L[CII]/L(sub FIR) and L(sub CO)/L(sub FIR) ratios are similar to the values seen in nearby starburst galaxies

  20. The role of magnetic fields in starburst galaxies as revealed by OH megamasers

    SciTech Connect

    McBride, James; Quataert, Eliot; Heiles, Carl; Bauermeister, Amber E-mail: eliot@astro.berkeley.edu

    2014-01-10

    We present estimates of magnetic field strengths in the interstellar media of starburst galaxies derived from measurements of Zeeman splitting associated with OH megamasers. The results for eight galaxies with Zeeman detections suggest that the magnetic energy density in the interstellar medium of starburst galaxies is comparable to their hydrostatic gas pressure, as in the Milky Way. We discuss the significant uncertainties in this conclusion, and possible measurements that could reduce these uncertainties. We also compare the Zeeman splitting derived magnetic field estimates to magnetic field strengths estimated using synchrotron fluxes and assuming that the magnetic field and cosmic rays have comparable energy densities, known as the 'minimum energy' argument. We find that the minimum energy argument systematically underestimates magnetic fields in starburst galaxies, and that the conditions that would be required to produce agreement between the minimum energy estimate and the Zeeman derived estimate of interstellar medium magnetic fields are implausible. The conclusion that magnetic fields in starburst galaxies exceed the minimum energy magnetic fields is consistent with starburst galaxies adhering to the linearity of the far-infrared-radio correlation.

  1. Local starburst galaxies and their descendants. Statistics from the Sloan Digital Sky Survey

    NASA Technical Reports Server (NTRS)

    Bergvall, Nils; Marquart, Thomas; Way, Michael J.; Blomqvist, Anna; Holst, Emma; Ostlin, Goran; Zackrisson, Erik

    2016-01-01

    Despite strong interest in the starburst phenomenon in extragalactic astronomy, the concept remains ill-defined. Here we use a strict definition of starburst to examine the statistical properties of starburst galaxies in the local universe. We also seek to establish links between starburst galaxies, post-starburst (hereafter postburst) galaxies, and active galaxies. Data were selected from the Sloan Digital Sky Survey DR7. We applied a novel method of treating dust attenuation and derive star formation rates, ages, and stellar masses assuming a two-component stellar population model. Dynamical masses are calculated from the width of the H-alpha line. These masses agree excellently with the photometric masses. The mass (gas+stars) range is approximately 10( exp 9) - 10(exp 11.5) solar mass. As a selection criterion for starburst galaxies, we use, the birthrate parameter, b = SFR/SFR, requiring that b is greater than 3. For postburst galaxies, we use, the equivalent width of Hdelta in absorption with the criterion EW (sub Hdelta_abs) is greater than 6 A. Results. We find that only 1% of star-forming galaxies are starburst galaxies. They contribute 3-6% to the stellar production and are therefore unimportant for the local star formation activity. The median starburst age is 70 Myr roughly independent of mass, indicating that star formation is mainly regulated by local feedback processes. The b-parameter strongly depends on burst age. Values close to b = 60 are found at ages approximately 10 Myr, while almost no starbursts are found at ages greater than 1 Gyr. The median baryonic burst mass fraction of sub-L galaxies is 5% and decreases slowly towards high masses. The median mass fraction of the recent burst in the postburst sample is 5-10%. A smaller fraction of the postburst galaxies, however, originates in non-bursting galaxies. The age-mass distribution of the postburst progenitors (with mass fractions is greater than 3%) is bimodal with a break at logM(solar mass

  2. The Role AGN Play in the Evolution of Quasars Host Galaxies with Spectral Signatures of Post-Starburst Stellar Polulations

    NASA Astrophysics Data System (ADS)

    Cales, Sabrina; Brotherton, M. S.; Shang, Z.; Bennert, V.; Canalizo, G.; Diamond-Stanic, A. M.

    2014-01-01

    Motivation: Our understanding of the link between galaxies and the active galactic nuclei (AGN) they host is crucial for our understanding of galaxy evolution, a major question for astronomy today. As such, galaxies that harbor both luminous, broad-lined AGN phenomenon and massive, post-starburst stellar populations (post- starburst quasars, PSQs) provide a natural laboratory for those studying AGN, galaxies and galaxy evolution alike. PSQs are predicted to be transitioning galaxies whereby both the AGN and post-starburst phenomenon exist simultaneously. Thus studying these objects can prove invaluable for understanding connections between nuclear activity and host galaxy evolution. Project: We present the latest work on the study of PSQs and their role in mutual black hole and galaxy evolution. In particular we utilize AGN/host galaxy light decomposition analysis of high quality imaging and spectroscopic data (including IFU) to look at PSQ morphology and AGN and post-starburst fundamental physical properties.

  3. The effect of central starbursts on the interstellar medium of dwarf galaxies

    NASA Technical Reports Server (NTRS)

    De Young, David S.; Heckman, Timothy M.

    1994-01-01

    Major starburst events can last tens of millions of years, and in the process they can deposit significant amounts of energy into the surrounding interstellar medium. This energy from supernova and stellar winds imparts enough momentum to the interstellar medium (ISM) that portions of the ISM can become unbound and leave the parent galaxy, taking the metal-enriched stellar debris along. In dwarf galaxies, starbursts can produce enough total energy to unbind most or all of the ambient ISM. Whether this actually occurs is a strong function of the ellipticity of the ISM distribution, with flat disks and spheres being the limiting cases. We calculate whether 'blow out' along the symmetry axis of 'blow away' of the entire ISM occurs during a central starburst in dwarf galaxies as a function of galactic mass, starburst energy, ISM density, and ISM ellipticity. The calculations cover a range of 10(exp 7) to 10(exp 9) solar mass for dwarf galaxies and include 'normal' galaxies of 10(exp 11) solar mass as well. No massive dark matter halos are assumed to be present. We find that for physically reasonable values of total ISM mass and starburst energy a blow out along the symmetry axis occurs in the majority of cases, though a significant fraction of small dwarf galaxies can lose most of their ISM. As no dark matter halos or clumpy ISM distributions are included, it is apparent that the ISM in most dwarf galaxies may be generally resistant to significant disruption by a central starburst event. The effects of this range of behavi or on the metallicities that would be observed in these galaxies is discussed.

  4. Massive stars: Starbursts

    NASA Astrophysics Data System (ADS)

    González Delgado, Rosa María

    2007-07-01

    Starbursts are the preferred place where massive stars form; the main source of thermal and mechanical heating in the interstellar medium, and the factory where the heavy elements form. Thus, starbursts play an important role in the origin and evolution of galaxies. Starbursts are bright at ultraviolet (UV) wavelengths, and after the pioneering IUE program, high spatial and spectral resolution UV observations of local starburst galaxies, mainly taken with HST and FUSE, have made relevant contributions to the following issues: a) The determination of the initial mass function (IMF) in violent star forming systems in low and high metallicity environments, and in dense (e.g. in stellar clusters) and diffuse environments: A Salpeter IMF with high-mass stars constrains well the UV properties. b) Stellar clusters are an important mode of star formation in starbursts. c) The role of starbursts in AGN: Nuclear starbursts can dominate the UV light in Seyfert 2 galaxies, having bolometric luminosities similar to the estimated bolometric luminosities of the obscured AGN. d) The interaction between massive stars and the interstellar medium: Outflows in cold, warm and coronal phases leave their imprints on the UV interstellar lines. Outflows of a few hundred km s%u22121 are ubiquitous phenomena in starbursts. Despite the very significant progress obtained over the past two decades of UV observations of starbursts, there are important problems that still need to be solved. High-spatial resolution UV observations of nearby starbursts are crucial to further progress in understanding the violent star formation processes in galaxies, the interaction between the stellar clusters and the interstellar medium, and the variation of the IMF. High-spatial resolution spectra are also needed to isolate the light from the center to the disk in UV luminous galaxies found by GALEX. Thus, a new UV mission furnished with an intermediate spectral resolution spectrograph with high spatial

  5. HUBBLE SURVEYS DYING STARS IN NEARBY GALAXY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    From ground-based telescopes, the glowing gaseous debris surrounding dying, sun-like stars in a nearby galaxy, called the Large Magellanic Cloud, appear as small, shapeless dots of light. But through the 'eyes' of NASA's Hubble Space Telescope, these bright dots take on a variety of shapes, from round- to pinwheel-shaped clouds of gas. Using Hubble's Space Telescope Imaging Spectrograph, scientists probed the glowing gas surrounding 27 dying stars, called planetary nebulae, in the Large Magellanic Cloud. The observations represent the most detailed study of planetary nebulae outside the Milky Way. The six objects in the picture illustrate the assortment of planetary nebulae identified in the galaxy. SMP 16, 30, and 93 are examples of a bipolar nebula, twin lobes of gas projecting away from a dying star. SMP 10 has a pinwheel shape and is known as a 'point-symmetric' nebula. SMP 4 has an elliptical appearance, and SMP 27, consisting of four lobes of gas, is called a 'quadrupolar' nebula. The lines point to the objects' locations in the Large Magellanic Cloud. A ground-based observatory snapped the picture of this galaxy. In the pictures of the planetary nebulae, color corresponds to temperature. Blue represents hotter regions of the nebulae and red, cooler. Scientists are probing these illuminated stellar relics in our neighboring galaxy because they are at relatively the same distance - about 168,000 light-years -- from Earth. Knowing the distance to these objects allows scientists to compare their shapes and sizes, and precisely determine the brightness of their central stars. For this reason, even though these glowing remains of dying stars are about 50 times farther away than the stunning planetary nebulae photographed in the Milky Way, they are of invaluable importance. By sampling this population, scientists noticed that the bipolar nebulae are richer in some heavier elements, such as neon, than those with a more spherical shape. At the dawn of the universe

  6. HUBBLE SURVEYS DYING STARS IN NEARBY GALAXY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    From ground-based telescopes, the glowing gaseous debris surrounding dying, sun-like stars in a nearby galaxy, called the Large Magellanic Cloud, appear as small, shapeless dots of light. But through the 'eyes' of NASA's Hubble Space Telescope, these bright dots take on a variety of shapes, from round- to pinwheel-shaped clouds of gas. Using Hubble's Space Telescope Imaging Spectrograph, scientists probed the glowing gas surrounding 27 dying stars, called planetary nebulae, in the Large Magellanic Cloud. The observations represent the most detailed study of planetary nebulae outside the Milky Way. The six objects in the picture illustrate the assortment of planetary nebulae identified in the galaxy. SMP 16, 30, and 93 are examples of a bipolar nebula, twin lobes of gas projecting away from a dying star. SMP 10 has a pinwheel shape and is known as a 'point-symmetric' nebula. SMP 4 has an elliptical appearance, and SMP 27, consisting of four lobes of gas, is called a 'quadrupolar' nebula. The lines point to the objects' locations in the Large Magellanic Cloud. A ground-based observatory snapped the picture of this galaxy. In the pictures of the planetary nebulae, color corresponds to temperature. Blue represents hotter regions of the nebulae and red, cooler. Scientists are probing these illuminated stellar relics in our neighboring galaxy because they are at relatively the same distance - about 168,000 light-years -- from Earth. Knowing the distance to these objects allows scientists to compare their shapes and sizes, and precisely determine the brightness of their central stars. For this reason, even though these glowing remains of dying stars are about 50 times farther away than the stunning planetary nebulae photographed in the Milky Way, they are of invaluable importance. By sampling this population, scientists noticed that the bipolar nebulae are richer in some heavier elements, such as neon, than those with a more spherical shape. At the dawn of the universe

  7. A dust-obscured massive maximum-starburst galaxy at a redshift of 6.34.

    PubMed

    Riechers, Dominik A; Bradford, C M; Clements, D L; Dowell, C D; Pérez-Fournon, I; Ivison, R J; Bridge, C; Conley, A; Fu, Hai; Vieira, J D; Wardlow, J; Calanog, J; Cooray, A; Hurley, P; Neri, R; Kamenetzky, J; Aguirre, J E; Altieri, B; Arumugam, V; Benford, D J; Béthermin, M; Bock, J; Burgarella, D; Cabrera-Lavers, A; Chapman, S C; Cox, P; Dunlop, J S; Earle, L; Farrah, D; Ferrero, P; Franceschini, A; Gavazzi, R; Glenn, J; Solares, E A Gonzalez; Gurwell, M A; Halpern, M; Hatziminaoglou, E; Hyde, A; Ibar, E; Kovács, A; Krips, M; Lupu, R E; Maloney, P R; Martinez-Navajas, P; Matsuhara, H; Murphy, E J; Naylor, B J; Nguyen, H T; Oliver, S J; Omont, A; Page, M J; Petitpas, G; Rangwala, N; Roseboom, I G; Scott, D; Smith, A J; Staguhn, J G; Streblyanska, A; Thomson, A P; Valtchanov, I; Viero, M; Wang, L; Zemcov, M; Zmuidzinas, J

    2013-04-18

    Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts--that is, increased rates of star formation--in the most massive dark-matter haloes at early epochs. However, it remains unknown how soon after the Big Bang massive starburst progenitors exist. The measured redshift (z) distribution of dusty, massive starbursts has long been suspected to be biased low in z owing to selection effects, as confirmed by recent findings of systems with redshifts as high as ~5 (refs 2-4). Here we report the identification of a massive starburst galaxy at z = 6.34 through a submillimetre colour-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine-structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40 per cent of the baryonic mass. A 'maximum starburst' converts the gas into stars at a rate more than 2,000 times that of the Milky Way, a rate among the highest observed at any epoch. Despite the overall downturn in cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang. PMID:23598341

  8. THE ROLE OF MERGER STAGE ON GALAXY RADIO SPECTRA IN LOCAL INFRARED-BRIGHT STARBURST GALAXIES

    SciTech Connect

    Murphy, Eric J.

    2013-11-01

    An investigation of the steep, high-frequency (i.e., ν ∼ 12 GHz) radio spectra among a sample of 31 local infrared-bright starburst galaxies is carried out in light of their Hubble-Space-Telescope-based merger classifications. Radio data covering as many as 10 individual bands allow for spectral indices to be measured over three frequency bins between 0.15 and 32.5 GHz. Sources having the flattest spectral indices measured at ∼2 and 4 GHz, arising from large free-free optical depths among the densest starbursts, appear to be in ongoing through post-stage mergers. The spectral indices measured at higher frequencies (i.e., ∼12 GHz) are steepest for sources associated with ongoing mergers in which their nuclei are distinct, but share a common stellar envelope and/or exhibit tidal tails. These results hold after excluding potential active galactic nuclei based on their low 6.2 μm polycyclic aromatic hydrocarbon equivalent widths. Consequently, the low-, mid-, and high-frequency spectral indices each appear to be sensitive to the exact merger stage. It is additionally shown that ongoing mergers, whose progenitors are still separated and share a common envelope and/or exhibit tidal tails, also exhibit excess radio emission relative to what is expected given the far-infrared/radio correlation, suggesting that there may be a significant amount of radio emission that is not associated with ongoing star formation. The combination of these observations, along with high-resolution radio morphologies, leads to a picture in which the steep high-frequency radio spectral indices and excess radio emission arise from radio continuum bridges and tidal tails that are not associated with star formation, similar to what is observed for so-called 'taffy' galaxies. This scenario may also explain the seemingly low far-infrared/radio ratios measured for many high-z submillimeter galaxies, a number of which are merger-driven starbursts.

  9. Cosmic-ray induced gamma-ray emission from the starburst galaxy NGC 253

    SciTech Connect

    Wang, Xilu; Fields, Brian D.

    2014-05-09

    Cosmic rays in galaxies interact with the interstellar medium and give us a direct view of nuclear and particle interactions in the cosmos. For example, cosmic-ray proton interactions with interstellar hydrogen produce gamma rays via PcrPism→π{sup 0}→γγ. For a 'normal' star-forming galaxy like the Milky Way, most cosmic rays escape the Galaxy before such collisions, but in starburst galaxies with dense gas and huge star formation rate, most cosmic rays do suffer these interactions [1,2]. We construct a 'thick-target' model for starburst galaxies, in which cosmic rays are accelerated by supernovae, and escape is neglected. This model gives an upper limit to the gamma-ray emission. Only two free parameters are involved in the model: cosmic-ray proton acceleration energy rate from supernova and the proton injection spectral index. The pionic gamma-radiation is calculated from 10 MeV to 10 TeV for the starburst galaxy NGC 253, and compared to Fermi and HESS data. Our model fits NGC 253 well, suggesting that cosmic rays in this starburst are in the thick target limit, and that this galaxy is a gamma-ray calorimeter.

  10. Galaxy Clustering Around Nearby Luminous Quasars

    NASA Technical Reports Server (NTRS)

    Fisher, Karl B.; Bahcall, John N.; Kirhakos, Sofia; Schneider, Donald P.

    1996-01-01

    We examine the clustering of galaxies around a sample of 20 luminous low redshift (z approx. less than 0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope (HST). The HST resolution makes possible galaxy identification brighter than V = 24.5 and as close as 1 min or 2 min to the quasar. We find a significant enhancement of galaxies within a projected separation of approx. less than 100 1/h kpc of the quasars. If we model the QSO/galaxy correlation function as a power law with a slope given by the galaxy/galaxy correlation function, we find that the ratio of the QSO/galaxy to galaxy/galaxy correlation functions is 3.8 +/- 0.8. The galaxy counts within r less than 15 1/h kpc of the quasars are too high for the density profile to have an appreciable core radius (approx. greater than 100 1/h kpc). Our results reinforce the idea that low redshift quasars are located preferentially in groups of 10-20 galaxies rather than in rich clusters. We see no significant difference in the clustering amplitudes derived from radio-loud and radio-quiet subsamples.

  11. HUBBLE'S ULTRAVIOLET VIEWS OF NEARBY GALAXIES YIELD CLUES TO EARLY UNIVERSE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Astronomers are using these three NASA Hubble Space Telescope images to help tackle the question of why distant galaxies have such odd shapes, appearing markedly different from the typical elliptical and spiral galaxies seen in the nearby universe. Do faraway galaxies look weird because they are truly weird? Or, are they actually normal galaxies that look like oddballs, because astronomers are getting an incomplete picture of them, seeing only the brightest pieces? Light from these galaxies travels great distances (billions of light-years) to reach Earth. During its journey, the light is 'stretched' due to the expansion of space. As a result, the light is no longer visible, but has been shifted to the infrared where present instruments are less sensitive. About the only light astronomers can see comes from regions where hot, young stars reside. These stars emit mostly ultraviolet light. But this light is stretched, appearing as visible light by the time it reaches Earth. Studying these distant galaxies is like trying to put together a puzzle with some of the pieces missing. What, then, do distant galaxies really look like? Astronomers studied 37 nearby galaxies to find out. By viewing these galaxies in ultraviolet light, astronomers can compare their shapes with those of their distant relatives. These three Hubble telescope pictures, taken with the Wide Field and Planetary Camera 2, represent a sampling from that survey. Astronomers observed the galaxies in ultraviolet and visible light to study all the stars that make up these 'cities of stars.' The results of their survey support the idea that astronomers are detecting the 'tip of the iceberg' of very distant galaxies. Based on these Hubble ultraviolet images, not all the faraway galaxies necessarily possess intrinsically odd shapes. The results are being presented today at the 197th meeting of the American Astronomical Society in San Diego, CA. The central region of the 'star-burst' spiral galaxy at far left

  12. MOLECULAR GAS AND STAR FORMATION IN NEARBY DISK GALAXIES

    SciTech Connect

    Leroy, Adam K.; Munoz-Mateos, Juan-Carlos; Walter, Fabian; Sandstrom, Karin; Meidt, Sharon; Rix, Hans-Walter; Schinnerer, Eva; Schruba, Andreas; Bigiel, Frank; Bolatto, Alberto; Brinks, Elias; De Blok, W. J. G.; Rosolowsky, Erik; Schuster, Karl-Friedrich; Usero, Antonio

    2013-08-01

    We compare molecular gas traced by {sup 12}CO (2-1) maps from the HERACLES survey, with tracers of the recent star formation rate (SFR) across 30 nearby disk galaxies. We demonstrate a first-order linear correspondence between {Sigma}{sub mol} and {Sigma}{sub SFR} but also find important second-order systematic variations in the apparent molecular gas depletion time, {tau}{sub dep}{sup mol}={Sigma}{sub mol}/{Sigma}{sub SFR}. At the 1 kpc common resolution of HERACLES, CO emission correlates closely with many tracers of the recent SFR. Weighting each line of sight equally, using a fixed {alpha}{sub CO} equivalent to the Milky Way value, our data yield a molecular gas depletion time, {tau}{sub dep}{sup mol}={Sigma}{sub mol}/{Sigma}{sub SFR}{approx}2.2 Gyr with 0.3 dex 1{sigma} scatter, in very good agreement with recent literature data. We apply a forward-modeling approach to constrain the power-law index, N, that relates the SFR surface density and the molecular gas surface density, {Sigma}{sub SFR}{proportional_to}{Sigma}{sub mol}{sup N}. We find N = 1 {+-} 0.15 for our full data set with some scatter from galaxy to galaxy. This also agrees with recent work, but we caution that a power-law treatment oversimplifies the topic given that we observe correlations between {tau}{sub dep}{sup mol} and other local and global quantities. The strongest of these are a decreased {tau}{sub dep}{sup mol} in low-mass, low-metallicity galaxies and a correlation of the kpc-scale {tau}{sub dep}{sup mol} with dust-to-gas ratio, D/G. These correlations can be explained by a CO-to-H{sub 2} conversion factor ({alpha}{sub CO}) that depends on dust shielding, and thus D/G, in the theoretically expected way. This is not a unique interpretation, but external evidence of conversion factor variations makes this the most conservative explanation of the strongest observed {tau}{sub dep}{sup mol} trends. After applying a D/G-dependent {alpha}{sub CO}, some weak correlations between {tau}{sub dep

  13. Search for AN Intermediate Mass Black Hole in the Starburst Galaxy NGC2146

    NASA Astrophysics Data System (ADS)

    Matsumoto, Hironori

    2001-09-01

    We discovered an Intermediate Mass Black Hole (IMBH) of 10(3) - 10(6) M_⊙ in the starburst galaxy M82 with Chandra HRC. Our follow-up ground-based observations found a near-infrared star cluster in the vicinity of the IMBH as well as an Expanding Molecular Super Bubble (EMSB) which surrounds the IMBH and has a kinematic energy of 10(55) erg. Based on these results, we propose a scenario that an IMBH is produced by starburst activity and it grows to become a Super Massive Black Hole (SMBH). We believe this scenario can explain the formation of SMBHs in other galaxies universally. We propose a CXO monitoring observation of another starburst galaxy NGC2146 to examine our scenario.

  14. A Survey of nearby, nearly face-on spiral galaxies

    NASA Astrophysics Data System (ADS)

    Garmire, Gordon

    2014-09-01

    This is a continuation of a survey of nearby, nearly face-on spiral galaxies. The main purpose is to search for evidence of collisions with small galaxies that show up in X-rays by the generation of hot shocked gas from the collision. Secondary objectives include study of the spatial distribution point sources in the galaxy and to detect evidence for a central massive blackhole. These are alternate targets.

  15. A Survey of nearby, nearly face-on spiral galaxies

    NASA Astrophysics Data System (ADS)

    Garmire, Gordon

    2014-09-01

    This is a continuation of a survey of nearby, nearly face-on spiral galaxies. The main purpose is to search for evidence of collisions with small galaxies that show up in X-rays by the generation of hot shocked gas from the collision. Secondary objectives include study of the spatial distribution point sources in the galaxy and to detect evidence for a central massive blackhole.

  16. Morphology of High Redshifted Galaxies using GALEX Ultraviolet Observations of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Yeom, Bum-Suk; Kim, Y.; Rey, S.; Kim, S.; Joe, Y.; Gil de Paz, A.

    2009-01-01

    Galaxy morphology provides clues about the processes in the understanding of the formation and evolution of galaxies. In this respect, the prediction of optical-band morphologies at high redshifts requires ultraviolet (UV) images of local galaxies with various morphologies. We simulated optical images at high redshifts using more diverse and high-quality nearby galaxies obtained through the Galaxy Evolution Explorer (GALEX) UV observations. We present a quantitative analysis of the morphology of galaxies at near-ultraviolet (NUV) and simulated optical images. We also present a correlation between the isophotal-shape parameter and UV colors for nearby early-type galaxies.

  17. X-ray emission of post-starburst galaxies: looking into the feedback mechanism

    NASA Astrophysics Data System (ADS)

    Ballo, Lucia

    2011-11-01

    The tight relation between galaxy bulges and black holes shows that star formation and accretion must have co-evolved throughout the history of the Universe. The leading hypothesis is that intense periods of star formation and black hole growth concurrently occur in the history of massive galaxies, possibly triggered by mergers. The feedback from the AGN could terminate the star formation and, eventually, extinguish the AGN itself. The complex physics involved in such a scenario is, however, poorly understood. The best class of objects to investigate the relative time-scales of this feedback are the post-starburst galaxies, i.e. galaxies observed shortly after the star-formation has ended (about 0.1-1 Gyr). ~0.3% of the SDSS galaxies in the local Universe show evidence in the optical band of the presence of both a nucleus still accreting in their centre and a post-starburst signature. This suggests that the switching off for a starburst event occurs before the extinguishing of the nuclear activity. However, it is not clear whether this result is a common law in the feedback mechanisms. Here we present a project devoted to study the X-ray emission of the apparently quiescent post-starburst galaxies detected in the SDSS, to deeply investigate the real lack of nuclear activity (possibly obscured in the optical band), and to study the energetics of these systems.

  18. THE JAMES CLERK MAXWELL TELESCOPE NEARBY GALAXIES LEGACY SURVEY. II. WARM MOLECULAR GAS AND STAR FORMATION IN THREE FIELD SPIRAL GALAXIES

    SciTech Connect

    Warren, B. E.; Wilson, C. D.; Sinukoff, E.; Israel, F. P.; Van der Werf, P. P.; Serjeant, S.; Bendo, G. J.; Clements, D. L.; Brinks, E.; Irwin, J. A.; Knapen, J. H.; Leech, J.; Tan, B. K.; Matthews, H. E.; Muehle, S.; Mortimer, A. M. J.; Petitpas, G.; Spekkens, K.; Tilanus, R. P. J.; Usero, A. E-mail: wilson@physics.mcmaster.c E-mail: israel@strw.leidenuniv.n

    2010-05-01

    We present the results of large-area {sup 12}CO J = 3-2 emission mapping of three nearby field galaxies, NGC 628, NGC 3521, and NGC 3627, completed at the James Clerk Maxwell Telescope as part of the Nearby Galaxies Legacy Survey. These galaxies all have moderate to strong {sup 12}CO J = 3-2 detections over large areas of the fields observed by the survey, showing resolved structure and dynamics in their warm/dense molecular gas disks. All three galaxies were part of the Spitzer Infrared Nearby Galaxies Survey sample, and as such have excellent published multiwavelength ancillary data. These data sets allow us to examine the star formation properties, gas content, and dynamics of these galaxies on sub-kiloparsec scales. We find that the global gas depletion time for dense/warm molecular gas in these galaxies is consistent with other results for nearby spiral galaxies, indicating this may be independent of galaxy properties such as structures, gas compositions, and environments. Similar to the results from The H I Nearby Galaxy Survey, we do not see a correlation of the star formation efficiency with the gas surface density consistent with the Schmidt-Kennicutt law. Finally, we find that the star formation efficiency of the dense molecular gas traced by {sup 12}CO J = 3-2 is potentially flat or slightly declining as a function of molecular gas density, the {sup 12}CO J = 3-2/J = 1-0 ratio (in contrast to the correlation found in a previous study into the starburst galaxy M83), and the fraction of total gas in molecular form.

  19. An Updated Ultraviolet Catalog of GALEX Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Bai, Yu; Zou, Hu; Liu, JiFeng; Wang, Song

    2015-09-01

    The ultraviolet (UV) catalog of nearby galaxies compiled by Gil de Paz et al. presents the integrated photometry and surface brightness profiles for 1034 nearby galaxies observed by GALEX. We provide an updated catalog of 4138 nearby galaxies based on the latest Genral Release (GR6/GR7) of GALEX. These galaxies are selected from HyperLeda with apparent diameters larger than 1‧. From the surface brightness profiles accurately measured using the deep NUV and FUV images, we have calculated the asymptotic magnitudes, aperture (D25) magnitudes, colors, structural parameters (effective radii and concentration indices), luminosities, and effective surface brightness for these galaxies. Archival optical and infrared photometry from HyperLeda, 2MASS, and IRAS are also integrated into the catalog. Our parameter measurements and some analyses are consistent with those of Paz et al. The (FUV - K) color provides a good criterion to distinguish between early- and late-type galaxies, which can be improved further using the concentration indices. The IRX-β relation is reformulated with our UV-selected nearby galaxies.

  20. Superdense Massive Galaxies in the Nearby Universe

    NASA Astrophysics Data System (ADS)

    Trujillo, Ignacio; Cenarro, A. Javier; de Lorenzo-Cáceres, Adriana; Vazdekis, Alexandre; de la Rosa, Ignacio G.; Cava, Antonio

    2009-02-01

    Superdense massive galaxies (re ~ 1 kpc; M ~ 1011 M sun) were common in the early universe (z gsim 1.5). Within some hierarchical merging scenarios, a non-negligible fraction (1%-10%) of these galaxies is expected to survive since that epoch, retaining their compactness and presenting old stellar populations in the present universe. Using the NYU Value-Added Galaxy Catalog from the Sloan Digital Sky Survey Data Release 6, we find only a tiny fraction of galaxies (~0.03%) with re lsim 1.5 kpc and M sstarf gsim 8 × 1010 M sun in the local universe (z < 0.2). Surprisingly, they are relatively young (~2 Gyr) and metal-rich ([Z/H] ~0.2). The consequences of these findings within the current two competing size evolution scenarios for the most massive galaxies ("dry" mergers vs. "puffing up" due to quasar activity) are discussed.

  1. The Morphology of Nearby Ultraviolet Galaxy Halos

    NASA Astrophysics Data System (ADS)

    Hodges-Kluck, Edmund J.; Bregman, Joel N.; Cafmeyer, Julian

    2016-04-01

    We have detected diffuse ultraviolet light around highly inclined galaxies within 100 Mpc, and around galaxies within 25 Mpc we can characterize its structure. The morphology of the diffuse light often corresponds to diffuse H-alpha and X-ray emission and is found above the central regions of galaxies as well as above regions with strong star formation. In some cases, brighter regions of diffuse ultraviolet light correspond to cold dust seen with Herschel. The most plausible explanation is that we are seeing extragalactic reflection nebulae, in which case the UV light traces the dust distribution and underlying star formation. The dust masses implied by the extragalactic flux are comparable to the dust in galaxy disks; if the dust-to-gas ratio is constant, then these galaxies expel about as much gas as they contain.

  2. The CLU Nearby Galaxy Catalog: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Kasliwal, Mansi M.; iPTF

    2016-01-01

    The intermediate Palomar Transient Factory (iPTF) has been undertaking the Census of the Local Universe (CLU) project to complete our survey of galaxies out to 200 Mpc. CLU deploys four contiguous narrow-band filters to search for extended, emission line (Hα) sources across 3π of the sky. The estimated 5σ limiting flux for a point source is 2×10-17 erg s-1 cm-2 (Rau et al., 2009), which corresponds to a star formation rate (SFR) of 10-3 M⊙ yr-1 at a distance of 200 Mpc. Thus, the CLU galaxy catalog will capture 85% of the B-band light and 92% of the Hα luminosity out to 200 Mpc resulting in tens-of-thousands of newly discovered galaxies. We present the narrowband imaging characteristics, the criteria used for selecting galaxy candidates, and a sub-set of newly discovered galaxies that have been spectroscopically confirmed.

  3. Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph

    NASA Astrophysics Data System (ADS)

    Leitherer, Claus; Hernandez, Svea; Lee, Janice C.; Oey, M. S.

    2016-05-01

    We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232, and Mrk 54 were observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The three galaxies have radial velocities of ˜13,000 km s‑1, permitting a ˜35 Å window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 Å. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2000 Å. We developed a dedicated background subtraction method to account for the temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 Å. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. We determined the current star formation properties from the far-ultraviolet continuum and spectral lines and used synthesis models to predict the Lyman continuum radiation emitted by the current population of hot stars. We discuss various model uncertainties such as, among others, atmospheres and evolution models. Lyman continuum escape fractions were derived from a comparison between the observed and predicted Lyman continuum fluxes. Tol 1247-232, Mrk 54, and Tol 0440-381 have absolute escape fractions of (4.5 ± 1.2)%, (2.5 ± 0.72)%, and <(7.1 ± 1.1)%, respectively.

  4. Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph

    NASA Astrophysics Data System (ADS)

    Leitherer, Claus; Hernandez, Svea; Lee, Janice C.; Oey, M. S.

    2016-05-01

    We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232, and Mrk 54 were observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The three galaxies have radial velocities of ∼13,000 km s‑1, permitting a ∼35 Å window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 Å. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2000 Å. We developed a dedicated background subtraction method to account for the temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 Å. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. We determined the current star formation properties from the far-ultraviolet continuum and spectral lines and used synthesis models to predict the Lyman continuum radiation emitted by the current population of hot stars. We discuss various model uncertainties such as, among others, atmospheres and evolution models. Lyman continuum escape fractions were derived from a comparison between the observed and predicted Lyman continuum fluxes. Tol 1247-232, Mrk 54, and Tol 0440-381 have absolute escape fractions of (4.5 ± 1.2)%, (2.5 ± 0.72)%, and <(7.1 ± 1.1)%, respectively.

  5. Confirming the First Supermassive Black Hole in a Dwarf Starburst Galaxy

    NASA Astrophysics Data System (ADS)

    Reines, Amy

    2011-10-01

    In the modern universe, supermassive black holes lie at the heart of most, if not all, galaxies with bulges. However, the birth and growth of the first "seed" black holes, back in the earlier universe, is observationally unconstrained. Reines et al. {2011} have recently discovered a candidate million-solar mass black hole in the bulgeless dwarf starburst galaxy Henize 2-10, offering the first opportunity to study a growing black hole in a nearby galaxy much like those in the infant universe. The case for an accreting black hole in Henize 2-10 is strong {e.g. co-spatial non-thermal radio and hard X-ray point sources}, but not watertight. Our proposal aims to confirm {or refute} the presence of this candidate black hole using STIS optical spectroscopy to trace the kinematics and ionization conditions in its immediate vicinity. Existing HST observations show a marginally resolved H-alpha knot coincident with the radio and X-ray point source, so our primary aim is to detect a compact rotating disk of ionized gas, directly yielding a black hole mass. Our secondary aim is to find evidence for AGN-related emission line signatures at the location of the H-alpha knot, and possibly along a narrow jet-like filament. Confirming the presence of a supermassive black hole in Henize 2-10 with these HST observations has immediate implications for our understanding of the birth and early evolution of the first black holes in the high-redshift universe.

  6. EXTREME EMISSION-LINE GALAXIES IN CANDELS: BROADBAND-SELECTED, STARBURSTING DWARF GALAXIES AT z > 1

    SciTech Connect

    Van der Wel, A.; Rix, H.-W.; Jahnke, K.; Straughn, A. N.; Finkelstein, S. L.; Salmon, B. W.; Koekemoer, A. M.; Ferguson, H. C.; Weiner, B. J.; Wuyts, S.; Bell, E. F.; Faber, S. M.; Trump, J. R.; Koo, D. C.; Hathi, N. P.; Dunlop, J. S.; Newman, J. A.; Dickinson, M.; De Mello, D. F.; and others

    2011-12-01

    We identify an abundant population of extreme emission-line galaxies (EELGs) at redshift z {approx} 1.7 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). Sixty-nine EELG candidates are selected by the large contribution of exceptionally bright emission lines to their near-infrared broadband magnitudes. Supported by spectroscopic confirmation of strong [O III] emission lines-with rest-frame equivalent widths {approx}1000 A-in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are galaxies with {approx}10{sup 8} M{sub Sun} in stellar mass, undergoing an enormous starburst phase with M{sub *}/ M-dot{sub *} of only {approx}15 Myr. These bursts may cause outflows that are strong enough to produce cored dark matter profiles in low-mass galaxies. The individual star formation rates and the comoving number density (3.7 Multiplication-Sign 10{sup -4} Mpc{sup -3}) can produce in {approx}4 Gyr much of the stellar mass density that is presently contained in 10{sup 8}-10{sup 9} M{sub Sun} dwarf galaxies. Therefore, our observations provide a strong indication that many or even most of the stars in present-day dwarf galaxies formed in strong, short-lived bursts, mostly at z > 1.

  7. Chandra survey of nearby highly inclined disc galaxies - III. Comparison with hydrodynamical simulations of circumgalactic coronae

    NASA Astrophysics Data System (ADS)

    Li, Jiang-Tao; Crain, Robert A.; Wang, Q. Daniel

    2014-05-01

    X-ray observations of circumgalactic coronae provide a valuable means by which to test galaxy formation theories. Two primary mechanisms are thought to be responsible for the establishment of such coronae: accretion of intergalactic gas and/or galactic feedback. In this paper, we first compare our Chandra sample of galactic coronae of 53 nearby highly inclined disc galaxies to an analytical model considering only the accretion of intergalactic gas. We confirm the existing conclusion that this pure accretion model substantially overpredicts the coronal emission. We then select 30 field galaxies from our original sample, and correct their coronal luminosities to uniformly compare them to deep X-ray measurements of several massive disc galaxies from the literature, as well as to a comparable sample of simulated galaxies drawn from the Galaxies-Intergalactic Medium Interaction Calculation (GIMIC). These simulations explicitly model both accretion and supernovae feedback and yield galaxies that exhibit X-ray properties in broad agreement with our observational sample. However, notable and potentially instructive discrepancies exist between the slope and scatter of the LX-M200 and LX-SFR relations, highlighting some known shortcomings of GIMIC, for example, the absence of active galactic nuclei feedback, and possibly the adoption of constant stellar feedback parameters. The simulated galaxies exhibit a tight correlation (with little scatter) between coronal luminosity and halo mass. Having inferred M200 for our observational sample via the Tully-Fisher relation, we find a weaker and more scattered correlation. In the simulated and observed samples alike, massive non-starburst galaxies above a typical transition mass of M* ˜ 2 × 1011 M⊙ or M200 ˜ 1013 M⊙ tend to have higher LX/M* and LX/M200 than low-mass counterparts, indicating that the accretion of intergalactic gas plays an increasingly important role in establishing the observable hot circumgalactic medium

  8. Outflows in infrared-luminous galaxies: Absorption-line spectroscopy of starbursts and AGN

    NASA Astrophysics Data System (ADS)

    Rupke, David S.

    Large-scale galactic outflows, better known as superwinds, are driven by the powerful energy reservoirs in star forming and active galaxies. They play a significant role in galaxy formation, galaxy evolution, and the evolution of the intergalactic medium. We have performed a survey of over 100 infrared-luminous galaxies in order to address the exact frequency with which they occur in different galaxy types, the dependence of their properties on those of their host galaxies, and their properties in the most luminous starburst and active galaxies. Most of our sample consists of ultraluminous infrared galaxies (ULIRGs), and we use moderate- resolution spectroscopy of the Na I D interstellar absorption feature (which directly probes the neutral gas phase). We find superwinds in the majority of these galaxies at typical maximum, deprojected velocities of 500 700 km s-1. The detection rate increases with star formation rate (SFR) in starbursts, while the mass outflow rate appears constant with SFR, contrary to theoretical expectations. The resulting mass entrainment efficiencies in ULIRGs are quite low, of order a few percent of the star formation rate. There is some dependence of outflow velocity on host galaxy properties; the outflow velocities in LINERs are higher than those in H II galaxies, and the highest column density gas in each galaxy may have an upper envelope in velocity that increases with SFR. Outflows in most galaxies hosting a dominant AGN have very similar properties to those in starbursts, so discerning their power source is difficult. The velocities in Seyfert 2 outflows may be slightly higher than those in starbursts, and the fraction of neutral gas escaping Seyfert 2s is higher than that in starbursts (˜50% vs. ≲ 20%). The outflows in our Seyfert 1 galaxies have extreme velocities of up to ˜104 km s-1, and two of three Seyfert is with outflows possess broad absorption lines. Finally, we find that spectroscopy of a few galaxies at very high

  9. The Missing Baryons Around Nearby Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Bregman, Joel

    2013-10-01

    Dwarf galaxies are missing nearly all of their baryons, which have presumably flowed away as a wind. This mass loss accounts for a significant fraction of all baryons lost from galaxies, so there is great interest in determining the size and scope of the gas lost. This gas is not visible in emission but is detectable through absorption features toward background AGNs. Here we propose to observe the absorbing material around three isolated dwarfs on the periphery of the Local Group: Sextans A, Sextans B, and NGC 3109. Unlike more distant dwarfs, the star formation history and cold gaseous content of these galaxies are well-studied. The isolation of these dwarfs, far from large galaxies, means that they have not yet interacted with other systems so their mass loss history is well-preserved, making them ideal targets for study.

  10. The Effects of Dust on the Ultraviolet Spectral Energy Distribution of Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Gordon, K. D.; Witt, A. N.

    1994-05-01

    The effects of dust on the spectral energy distribution (SED) of starburst regions of galaxies was investigated using Monte Carlo techniques to model the transport of radiation in systems where the dust and stars are mixed. In a recent paper, Calzetti, Kinney, & Storchi-Bergmann (ApJ, 10 July 1994) derive an extinction curve from observations of starburst galaxies assuming the dust is in a screen geometry. This gives an extinction curve where the geometrical effects of mixing of the dust and stars are convolved with the extinguishing effects of the dust. The resulting extinction curve is greyer than the Galactic extinction curve and featureless in the ultraviolet, i.e. lacking both the 2200 Angstroms bump and far-UV rise. In an attempt to explain this ``effective'' starburst extinction curve we have modeled the effects of dust on the SED of starbursts. A simple starburst model was used to determine the different populations of stars as a function of the starburst age. The flux at 23 wavelengths, ranging between 1000 Angstroms to 5500 Angstroms, was computed using Monte Carlo techniques assuming the dust and stars were spherically distributed. The dust was assumed to have similar properties as dust in our Galaxy. The distribution of different star types ranged from mostly centrally located for O stars to constant density for A and later stars. In addition, the fraction of stars lying outside the dust ranged from very few for O stars to a majority for A and later stars. Combining the two models, it was found that the SED was strongly dependent on the distribution of the different types of stars relative to the dust, the age of the starburst, and the amount of dust. The ``effective'' UV extinction curve became greyer and featureless as the amount of dust was increased. For example, the 2200 Angstroms bump was almost non-existent for large amounts of dust. This work was supported by NASA LTSA Grant NAGW-3168.

  11. Just-After THE FALL: Post-Starburst Galaxies and the E+B Phase

    NASA Astrophysics Data System (ADS)

    Smercina, Adam; Tremonti, Christina A.; Chisholm, John P.

    2015-01-01

    A key question in galaxy evolution is how star formation is quenched. Post-starburst galaxies, which can be identified by their distinctive optical spectra, are excellent laboratories for studying various quenching processes. However, canonical post-starbursts, called E+A's or K+A's, are several 100 Myr past the epoch of active quenching, making it challenging to measure quenching timescales and make inferences about the processes at work. To address this problem, we have identified a sample of 23 young, B-star dominated post-starbursts (E+B's) at z = 0.45 - 0.82 in SDSS-III's Baryon Oscillation Spectroscopic Survey (BOSS). In this new class of objects, we determine how abruptly star formation is truncated and probe the role of various possible feedback mechanisms.This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881.

  12. Chandra Survey of Distant Galaxies Provides Evidence for Vigorous Starbursts

    NASA Astrophysics Data System (ADS)

    2000-05-01

    Using NASA's Chandra X-ray Observatory, astronomers have made the first long-duration X-ray survey of the Hubble Deep Field North. They detected X rays from six of the galaxies in the field, and were surprised by the lack of X rays from some of the most energetic galaxies in the field. The X-ray emitting objects discovered by the research team are a distant galaxy thought to contain a central giant black hole, three elliptically shaped galaxies, an extremely red distant galaxy, and a nearby spiral galaxy. "We were expecting about five X-ray sources in this field,"said Professor Niel Brandt of Penn State University, University Park, and one of the leaders of the research team that conducted the survey. "However, it was very surprising to find that none of the X-ray sources lined up with any of the submillimeter sources." The submillimeter sources are extremely luminous, dusty galaxies that produce large amounts of infrared radiation. Because they are over ten billion light years from Earth, their infrared radiation is shifted to longer, submillimeter wavelengths as it traverses the expanding universe. The primary source of the large power of the submillimeter sources is thought to be an unusually high rate of star formation, or the infall, or accretion of matter into a giant black hole in the center of the galaxy. X-ray observations provide the most direct measure of black hole accretion power. X rays, because of their high-energy, would be expected to pass through the gas and dust in these galaxies, unlike visible light. "With Chandra we have been able to place the best X-ray constraints ever on submillimeter sources," said Ann Hornschemeier, also of Penn State, and the lead author of an upcoming Astrophysical Journal paper describing the discovery. "Our results indicate that less than 15 percent of the submillimeter sources can be luminous X-ray sources." "That means," Brandt explains, "Either there is an enormous amount of star formation in those galaxies, or

  13. NEARBY GALAXIES IN MORE DISTANT CONTEXTS

    SciTech Connect

    Eskew, Michael; Zaritsky, Dennis E-mail: dzaritsky@as.arizona.edu

    2011-02-15

    We use published reconstructions of the star formation history (SFH) of the Large Magellanic Cloud (LMC), Small Magellanic Cloud, and NGC 300 from the analysis of resolved stellar populations to investigate where such galaxies might land on well-known extragalactic diagnostic plots over the galaxies' lifetime (assuming that nothing other than their stellar populations change). For example, we find that the evolution of these galaxies implies a complex evolution in the Tully-Fisher relation with look-back time and that the observed scatter is consistent with excursions these galaxies take as their stellar populations evolve. We find that the growth of stellar mass is weighted to early times, despite the strongly star-forming current nature of the three systems. Lastly, we find that these galaxies can take circuitous paths across the color-magnitude diagram. For example, it is possible, within the constraints provided by the current determination of its SFH, that the LMC reached the red sequence at intermediate age prior to ending back up on the blue cloud at the current time. Unfortunately, this behavior happens at sufficiently early times that our resolved SFH is crude and insufficiently constraining to convincingly demonstrate that this was the actual evolutionary path. The limited sample size precludes any general conclusions, but we present these as examples how we can bridge the study of resolved populations and the more distant universe.

  14. Distribution of Molecules in the Circumnuclear Disk and Surrounding Starburst Ring in the Seyfert Galaxy NGC 1068 Observed with ALMA

    NASA Astrophysics Data System (ADS)

    Takano, S.; Nakajima, T.; Kohno, K.; Harada, N.; Herbst, E.; Tamura, Y.; Izumi, T.; Taniguchi, A.; Tosaki, T.

    2015-12-01

    We report distributions of several molecular transitions including shock and dust related species (13CO and C18O J = 1-0, 13CN N = 1-0, CS J = 2-1, SO JN = 32-21, HNCO JKa,Kc = 50,5-40,4, HC3N J = 11-10, 12-11, CH3OH JK = 2K-1K, and CH3CN JK = 6K-5K) in the nearby Seyfert 2 galaxy NGC 1068 observed with ALMA. The central ˜1' (˜4.3 kpc) of this galaxy was observed in the 100 GHz region with an angular resolution of ˜4" x 2" (290 pc x 140 pc) to study the effects of an active galactic nucleus and its surrounding starburst ring on molecular abundances. We report a classification of molecular distributions into three main categories. Organic molecules such as CH3CN are found to be concentrated in the circumnuclear disk. In the starburst ring, the intensity of methanol at each clumpy region is not consistent with that of 13CO.

  15. Hydrogen fluoride toward luminous nearby galaxies: NGC 253 and NGC 4945

    SciTech Connect

    Monje, R. R.; Lis, D. C.; Phillips, T. G.; Lord, S.; Falgarone, E.; Güsten, R.

    2014-04-10

    We present the detection of hydrogen fluoride (HF) in two luminous nearby galaxies, NGC 253 and NGC 4945 using the Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory. The HF line toward NGC 253 has a P-Cygni profile, while an asymmetric absorption profile is seen toward NGC 4945. The P-Cygni profile in NGC 253 suggests an outflow of molecular gas with a mass of M(H{sub 2}){sub out} ∼ 1 × 10{sup 7} M {sub ☉} and an outflow rate as large as M-dot ∼6.4 M {sub ☉} yr{sup –1}. In the case of NGC 4945, the axisymmetric velocity components in the HF line profile are compatible with the interpretation of a fast-rotating nuclear ring surrounding the nucleus and the presence of inflowing gas. The gas falls into the nucleus with an inflow rate of ≤1.2 M {sub ☉} yr{sup –1}, inside an inner radius of ≤200 pc. The gas accretion rate to the central active galactic nucleus is much smaller, suggesting that the inflow may be triggering a nuclear starburst. From these results, the HF J = 1-0 line is seen to provide an important probe of the kinematics of absorbing material along the sight-line to nearby galaxies with bright dust continuum and a promising new tracer of molecular gas in high-redshift galaxies.

  16. Hydrogen Fluoride toward Luminous Nearby Galaxies: NGC 253 and NGC 4945

    NASA Astrophysics Data System (ADS)

    Monje, R. R.; Lord, S.; Falgarone, E.; Lis, D. C.; Neufeld, D. A.; Phillips, T. G.; Güsten, R.

    2014-04-01

    We present the detection of hydrogen fluoride (HF) in two luminous nearby galaxies, NGC 253 and NGC 4945 using the Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory. The HF line toward NGC 253 has a P-Cygni profile, while an asymmetric absorption profile is seen toward NGC 4945. The P-Cygni profile in NGC 253 suggests an outflow of molecular gas with a mass of M(H2)out ~ 1 × 107 M ⊙ and an outflow rate as large as dot M ~6.4 M ⊙ yr-1. In the case of NGC 4945, the axisymmetric velocity components in the HF line profile are compatible with the interpretation of a fast-rotating nuclear ring surrounding the nucleus and the presence of inflowing gas. The gas falls into the nucleus with an inflow rate of <=1.2 M ⊙ yr-1, inside an inner radius of <=200 pc. The gas accretion rate to the central active galactic nucleus is much smaller, suggesting that the inflow may be triggering a nuclear starburst. From these results, the HF J = 1-0 line is seen to provide an important probe of the kinematics of absorbing material along the sight-line to nearby galaxies with bright dust continuum and a promising new tracer of molecular gas in high-redshift galaxies.

  17. SHAKEN, NOT STIRRED: THE DISRUPTED DISK OF THE STARBURST GALAXY NGC 253

    SciTech Connect

    Davidge, T. J.

    2010-12-10

    Near-infrared images obtained with WIRCam on the Canada-France-Hawaii Telescope are used to investigate the recent history of the nearby Sculptor Group spiral NGC 253, which is one of the nearest starburst galaxies. Bright asymptotic giant branch (AGB) stars are traced out to projected distances of {approx}22-26 kpc ({approx}13-15 disk scale lengths) along the major axis. The distribution of stars in the disk is lopsided, in the sense that the projected density of AGB stars in the northeast portion of the disk between 10 and 20 kpc from the galaxy center is {approx}0.5 dex higher than on the opposite side of the galaxy. A large population of red supergiants is also found in the northeast portion of the disk and, with the exception of the central 2 kpc, this area appears to have been the site of the highest levels of star-forming activity in the galaxy during the past {approx}0.1 Gyr. It is argued that such high levels of localized star formation may have produced a fountain that ejected material from the disk, and the extraplanar H I detected by Boomsma et al. may be one manifestation of such activity. Diffuse stellar structures are found in the periphery of the disk, and the most prominent of these is to the south and east of the galaxy. Bright AGB stars, including cool C stars that are identified based on their J - K colors, are detected out to 15 kpc above the disk plane, and these are part of a diffusely distributed, flattened extraplanar component. Comparisons between observed and model luminosity functions suggest that the extraplanar regions contain stars that formed throughout much of the age of the universe. Additional evidence of a diffuse, extraplanar stellar component that contains moderately young stars comes from archival Galaxy Evolution Explorer images. It is suggested that the disk of NGC 253 was disrupted by a tidal encounter with a now defunct companion. This encounter introduced asymmetries that remain to this day, and the projected distribution

  18. Shaken, Not Stirred: The Disrupted Disk of the Starburst Galaxy NGC 253

    NASA Astrophysics Data System (ADS)

    Davidge, T. J.

    2010-12-01

    Near-infrared images obtained with WIRCam on the Canada-France-Hawaii Telescope are used to investigate the recent history of the nearby Sculptor Group spiral NGC 253, which is one of the nearest starburst galaxies. Bright asymptotic giant branch (AGB) stars are traced out to projected distances of ~22-26 kpc (~13-15 disk scale lengths) along the major axis. The distribution of stars in the disk is lopsided, in the sense that the projected density of AGB stars in the northeast portion of the disk between 10 and 20 kpc from the galaxy center is ~0.5 dex higher than on the opposite side of the galaxy. A large population of red supergiants is also found in the northeast portion of the disk and, with the exception of the central 2 kpc, this area appears to have been the site of the highest levels of star-forming activity in the galaxy during the past ~0.1 Gyr. It is argued that such high levels of localized star formation may have produced a fountain that ejected material from the disk, and the extraplanar H I detected by Boomsma et al. may be one manifestation of such activity. Diffuse stellar structures are found in the periphery of the disk, and the most prominent of these is to the south and east of the galaxy. Bright AGB stars, including cool C stars that are identified based on their J - K colors, are detected out to 15 kpc above the disk plane, and these are part of a diffusely distributed, flattened extraplanar component. Comparisons between observed and model luminosity functions suggest that the extraplanar regions contain stars that formed throughout much of the age of the universe. Additional evidence of a diffuse, extraplanar stellar component that contains moderately young stars comes from archival Galaxy Evolution Explorer images. It is suggested that the disk of NGC 253 was disrupted by a tidal encounter with a now defunct companion. This encounter introduced asymmetries that remain to this day, and the projected distribution of stars in and around NGC

  19. DETECTION OF THE 158 {mu}m [C II] TRANSITION AT z = 1.3: EVIDENCE FOR A GALAXY-WIDE STARBURST

    SciTech Connect

    Hailey-Dunsheath, S.; Nikola, T.; Stacey, G. J.; Oberst, T. E.; Parshley, S. C.; Benford, D. J.; Staguhn, J. G.; Tucker, C. E.

    2010-05-01

    We report the detection of 158 {mu}m [C II] fine-structure line emission from MIPS J142824.0+352619, a hyperluminous (L {sub IR} {approx} 10{sup 13} L {sub sun}) starburst galaxy at z = 1.3. The line is bright, corresponding to a fraction L {sub [CII]}/L {sub FIR} {approx} 2 x 10{sup -3} of the far-IR (FIR) continuum. The [C II], CO, and FIR continuum emission may be modeled as arising from photodissociation regions (PDRs) that have a characteristic gas density of n {approx} 10{sup 4.2} cm{sup -3}, and that are illuminated by a far-UV radiation field {approx}10{sup 3.2} times more intense than the local interstellar radiation field. The mass in these PDRs accounts for approximately half of the molecular gas mass in this galaxy. The L {sub [CII]}/L {sub FIR} ratio is higher than observed in local ultraluminous infrared galaxies or in the few high-redshift QSOs detected in [C II], but the L {sub [CII]}/L {sub FIR} and L {sub CO}/L {sub FIR} ratios are similar to the values seen in nearby starburst galaxies. This suggests that MIPS J142824.0+352619 is a scaled-up version of a starburst nucleus, with the burst extended over several kiloparsecs.

  20. Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA

    NASA Astrophysics Data System (ADS)

    Salak, Dragan; Nakai, Naomasa; Hatakeyama, Takuya; Miyamoto, Yusuke

    2016-05-01

    NGC 1808 is a nearby barred starburst galaxy with an outflow from the nuclear region. To study the inflow and outflow processes related to star formation and dynamical evolution of the galaxy, we have carried out 12CO (J=1-0) mapping observations of the central r ∼ 4 kpc of NGC 1808 using the Atacama Large Millimeter/submillimeter Array. Four distinct components of molecular gas are revealed at high spatial resolution of 2″ (∼100 pc): (1) a compact (r < 200 pc) circumnuclear disk (CND), (2) r ∼ 500 pc ring, (3) gas-rich galactic bar, and (4) spiral arms. Basic geometric and kinematic parameters are derived for the central 1 kpc region using tilted-ring modeling. The derived rotation curve reveals multiple mass components that include (1) a stellar bulge, (2) a nuclear bar and molecular CND, and (3) an unresolved massive (∼107 M ⊙) core. Two systemic velocities, 998 km s‑1 for the CND and 964 km s‑1 for the 500 pc ring, are revealed, indicating a kinematic offset. The pattern speed of the primary bar, derived by using a cloud-orbit model, is 56 ± 11 km s‑1 kpc‑1. Noncircular motions are detected associated with a nuclear spiral pattern and outflow in the central 1 kpc region. The ratio of the mass outflow rate to the star formation rate is {\\dot{M}}{out}/{SFR}∼ 0.2 in the case of optically thin CO (1–0) emission in the outflow, suggesting low efficiency of star formation quenching.

  1. PrISM: Mapping Nearby Galaxies with Slit Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sterling Rich, Jeffrey Austin

    2015-08-01

    The information gained from spatially resolved optical spectroscopy has proven crucial to understanding the complete picture of galaxies and their contents. In order to fully understand the interplay between the processes that govern and regulate star formation and galaxy evolution we are building building a sample of the largest, highest spatial resolution, and widest spectral coverage data cubes ever taken for nearby galaxies: the Las Campanas PrISM Survey.I will present recent results and ongoing work using our data cubes to map the ionized ISM and its properties at spatial scales of order 10 pc in nearby galaxies such as M83. The high spatial resolution of our data affords us the opportunity to study the characteristics and total contribution of diffuse ionized gas, a less well-understood component of nearby galaxies, as well as metallicties, star formation rates gas kinematics and more. I will also discuss how resolved spectroscopy can help detect, quantify and distinguish between star formation, shocks, diffuse ionized gas and AGN to help better inform larger, less resolved studies of galaxy properties.

  2. High velocity clouds in nearby disk galaxies

    NASA Technical Reports Server (NTRS)

    Schulman, Eric; Bregman, Joel N.; Roberts, Morton S.; Brinks, Elias

    1993-01-01

    Clouds of neutral hydrogen in our galaxy with the absolute value of v greater than 100 km/s cover approximately 10 percent of the sky to a limiting column density of 1 x 10(exp 18) cm(exp -2). These high velocity clouds (HVCs) may dominate the kinetic energy of neutral hydrogen in non-circular motion, and are an important though poorly understood component of galactic gas. It has been suggested that the HVCs can be reproduced by a combination of three phenomena: a galactic fountain driven by disk supernovae which would account for most of the HVCs, material tidally torn from the Magellanic Clouds, and an outer arm complex which is associated with the large scale structure of the warped galactic disk. We sought to detect HVCs in external galaxies in order to test the galactic fountain model.

  3. A New Interpretation for the Variation in Starburst Galaxy Emission Line Spectra

    NASA Astrophysics Data System (ADS)

    Richardson, Chris T.; Allen, James T.; Baldwin, Jack A.; Hewett, Paul C.; Ferland, Gary J.; Meskhidze, Helen

    2015-01-01

    Starburst galaxies have been easily distinguished from AGN using diagnostic emission line ratio diagrams constraining their excitation mechanism. Previous modeling of the star forming (SF) galaxy sequence outlined on the BPT diagram has led to the interpretation that high metallicity SF galaxies and low ionization SF galaxies are synonymous. Here, we present a new interpretation. Using a large sample of low-z SDSS galaxies, we co-added similar spectra of pure star forming galaxies allowing many weaker emission lines to act as consistency checks on strong line diagnostics. For the first time, we applied a locally optimally-emitting cloud (LOC) model to understand the physical reason for the variation in starburst galaxy emission line spectra. We fit over twenty diagnostic diagrams constraining the excitation mechanism, SED, temperature, density, metallicity, and grain content, making this work far more constrained than previous studies. Our results indicate that low luminosity SF galaxies could simply have less concentrated regions of ionized gas compared to their high luminosity counterparts, but have similar metallicities, thus requiring reevaluation about underlying nature of star forming galaxies.

  4. Monitoring variable X-ray sources in nearby galaxies

    NASA Astrophysics Data System (ADS)

    Kong, A. K. H.

    2010-12-01

    In the last decade, it has been possible to monitor variable X-ray sources in nearby galaxies. In particular, since the launch of Chandra, M31 has been regularly observed. It is perhaps the only nearby galaxy which is observed by an X-ray telescope regularly throughout operation. With 10 years of observations, the center of M31 has been observed with Chandra for nearly 1 Msec and the X-ray skies of M31 consist of many transients and variables. Furthermore, the X-ray Telescope of Swift has been monitoring several ultraluminous X-ray sources in nearby galaxies regularly. Not only can we detect long-term X-ray variability, we can also find spectral variation as well as possible orbital period. In this talk, I will review some of the important Chandra and Swift monitoring observations of nearby galaxies in the past 10 years. I will also present a "high-definition" movie of M31 and discuss the possibility of detecting luminous transients in M31 with MAXI.

  5. A connection between star formation activity and cosmic rays in the starburst galaxy M82

    NASA Astrophysics Data System (ADS)

    VERITAS Collaboration; Acciari, V. A.; Aliu, E.; Arlen, T.; Aune, T.; Bautista, M.; Beilicke, M.; Benbow, W.; Boltuch, D.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cannon, A.; Celik, O.; Cesarini, A.; Chow, Y. C.; Ciupik, L.; Cogan, P.; Colin, P.; Cui, W.; Dickherber, R.; Duke, C.; Fegan, S. J.; Finley, J. P.; Finnegan, G.; Fortin, P.; Fortson, L.; Furniss, A.; Galante, N.; Gall, D.; Gibbs, K.; Gillanders, G. H.; Godambe, S.; Grube, J.; Guenette, R.; Gyuk, G.; Hanna, D.; Holder, J.; Horan, D.; Hui, C. M.; Humensky, T. B.; Imran, A.; Kaaret, P.; Karlsson, N.; Kertzman, M.; Kieda, D.; Kildea, J.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; Lebohec, S.; Maier, G.; McArthur, S.; McCann, A.; McCutcheon, M.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nagai, T.; Ong, R. A.; Otte, A. N.; Pandel, D.; Perkins, J. S.; Pizlo, F.; Pohl, M.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Roache, E.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Smith, A. W.; Steele, D.; Swordy, S. P.; Theiling, M.; Thibadeau, S.; Varlotta, A.; Vassiliev, V. V.; Vincent, S.; Wagner, R. G.; Wakely, S. P.; Ward, J. E.; Weekes, T. C.; Weinstein, A.; Weisgarber, T.; Williams, D. A.; Wissel, S.; Wood, M.; Zitzer, B.

    2009-12-01

    Although Galactic cosmic rays (protons and nuclei) are widely believed to be mainly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery. The active regions of starburst galaxies have exceptionally high rates of star formation, and their large size-more than 50 times the diameter of similar Galactic regions-uniquely enables reliable calorimetric measurements of their potentially high cosmic-ray density. The cosmic rays produced in the formation, life and death of massive stars in these regions are expected to produce diffuse γ-ray emission through interactions with interstellar gas and radiation. M82, the prototype small starburst galaxy, is predicted to be the brightest starburst galaxy in terms of γ-ray emission. Here we report the detection of >700-GeV γ-rays from M82. From these data we determine a cosmic-ray density of 250eVcm-3 in the starburst core, which is about 500 times the average Galactic density. This links cosmic-ray acceleration to star formation activity, and suggests that supernovae and massive-star winds are the dominant accelerators.

  6. High Redshift Simulations Using the GALEX Ultraviolet Images of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Yeom, Bum-Suk; Kim, Young Kwang; Rey, Soo-Chang; Joe, Young Hoon; Gil de Paz, Armando

    2009-03-01

    We present simulated optical images of galaxies at high redshift using diverse and high-quality ultraviolet (UV) images of nearby galaxies obtained through the GALEX (Galaxy Evolution Explorer). Galaxy morphology plays an important role in the study of the evolution of galaxies. In this respect, the appearance of galaxies at high redshift requires images of nearby galaxies with various morphologies in the UV bandpass. Our simulation will be important in providing the basic information needed to study the evolution of galaxies.

  7. Star Formation and Gas Accretion in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Yim, Kijeong; van der Hulst, J. M.

    2016-08-01

    In order to quantify the relationship between gas accretion and star formation, we analyse a sample of 29 nearby galaxies from the WHISP survey which contains galaxies with and without evidence for recent gas accretion. We compare combined radial profiles of FUV (GALEX) and IR 24 μm (Spitzer) characterizing distributions of recent star formation with radial profiles of CO (IRAM, BIMA, or CARMA) and H I (WSRT) tracing molecular and atomic gas contents to examine star formation efficiencies in symmetric (quiescent), asymmetric (accreting), and interacting (tidally disturbed) galaxies. In addition, we investigate the relationship between star formation rate and H I in the outer discs for the three groups of galaxies. We confirm the general relationship between gas surface density and star formation surface density, but do not find a significant difference between the three groups of galaxies.

  8. Star Formation in The HI Nearby Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Leroy, A.; Bigiel, F.; Walter, F.; Brinks, E.; de Blok, W. J. G.; Madore, B.

    2008-05-01

    We combine The HI Nearby Galaxy Survey (THINGS) with our new survey of CO at the IRAM~30m, the Spitzer Infrared Nearby Galaxies Survey, and the GALEX Nearby Galaxies Survey to assemble an atlas of "star formation in context" for 24 nearby galaxies. This includes kinematics and estimates of the surface densities of atomic gas, molecular gas, stellar mass, and star formation rate. We use these data to test theories and recipes of star formation on galactic scales. Here we present two basic results for spiral galaxies. First, molecular gas and star formation rate surface density (SFRSD) are well related by a linear relation across most of our sample while atomic gas and SFRSD are essentially uncorrelated. We interpret this as evidence that star formation is proceeding in a more or less universal population of giant molecular clouds (GMCs) across most of the area we survey. Second, while the star formation efficiency (SFE), i.e., the star formation per unit neutral gas, is nearly constant where the ISM is mostly molecular, it drops steadily with increasing galactocentric radius where the ISM is mostly atomic. This drop is well-defined and common to most galaxies. We interpret this as a decreasing efficiency of GMC formation with changing local conditions. At intermediate galactocentric radii, the observed SFE is roughly consistent with several expectations for GMC formation: either formation occuring over the free fall time in the disk or the equilibrium molecular fraction being set by the gas pressure. If GMC formation occurs over a dynamical timescale, a star formation threshold must come into play in the outer disk to match the observed SFE.

  9. MaNGA: Mapping Nearby Galaxies at Apache Point Observatory

    NASA Astrophysics Data System (ADS)

    Bundy, Kevin

    2015-01-01

    I present the design and execution of a new survey to obtain resolved spectroscopy for 10,000 nearby galaxies called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory). One of three core programs in the 6-year SDSS-IV project that began on July 1st, 2014, MaNGA will deploy 17 fiber-bundle IFUs across the Sloan 2.5m Telescope's 3 degree field-of-view, targeting a mass-selected sample with a median redshift of 0.03, typical spatial resolution of 1-2 kpc, and a per-fiber signal-to-noise ratio of 4-8 in the outskirts of target galaxies. For each galaxy in the sample, MaNGA will provide maps and measured gradients of the composition and dynamics of both stars and gas. Early results highlight MaNGA's potential to shed light on the ionization and chemical enrichment of gas in galaxies, spatial patterns in their star formation histories, and the internal makeup of stellar populations. MaNGA's unprecedented data set will not only provide powerful new insight on galaxy formation and evolution but will serve as a valuable benchmark for future high-z observations from large telescopes as well as space-based facilities.

  10. Starbursts at space ultraviolet wavelengths

    NASA Astrophysics Data System (ADS)

    González Delgado, Rosa M.

    2006-06-01

    Starbursts are systems with very high star formation rate per unit area. They are the preferred place where massive stars form; the main source of thermal and mechanical heating in the interstellar medium, and the factory where the heavy elements form. Thus, starbursts play an important role in the origin and evolution of galaxies. The similarities between the physical properties of local starbursts and high-z star-forming galaxies, highlight the cosmological relevance of starbursts. On the other hand, nearby starbursts are laboratories where to study violent star formation processes and their interaction with the interstellar and intergalactic media, in detail and deeply. Starbursts are bright at ultraviolet (UV) wavelengths, as they are in the far-infrared, due to the ‘picket-fence’ interstellar dust distribution. After the pioneering IUE program, high spatial and spectral resolution UV observations of local starburst galaxies, mainly taken with HST and FUSE, have made relevant contributions to the following issues: The determination of the initial mass function (IMF) in violent star forming systems in low and high metallicity environments, and in dense (e.g. in stellar clusters) and diffuse environments: A Salpeter IMF with high-mass stars constrains well the UV properties. The modes of star formation: Starburst clusters are an important mode of star formation. Super-stellar clusters have properties similar to globular clusters. The role of starbursts in AGN: Nuclear starbursts can dominate the UV light in Seyfert 2 galaxies, having bolometric luminosities similar to the estimated bolometric luminosities of the obscured AGN. The interaction between massive stars and the interstellar and intergalactic media: Outflows in cold, warm and coronal phases leave their imprints on the UV

  11. The dwarf galaxy population of nearby galaxy clusters

    NASA Astrophysics Data System (ADS)

    Lisker, Thorsten; Wittmann, Carolin; Pak, Mina; Janz, Joachim; Bialas, Daniel; Peletier, Reynier; Grebel, Eva; Falcon Barroso, Jesus; Toloba, Elisa; Smakced Collaboration, Focus Collaboration

    2015-01-01

    The Fornax, Virgo, Ursa Major and Perseus galaxy clusters all have very different characteristics, in terms of their density, mass, and large-scale environment. We can regard these clusters as laboratories for studying environmental influence on galaxy evolution, using the sensitive low-mass galaxies as probes for external mechanisms. Here we report on recent and ongoing observational studies of the said clusters with imaging and spectroscopy, as well as on the interpretation of present-day cluster galaxy populations with the aid of cosmological simulations.Multicolor imaging data allow us to identify residual star formation in otherwise red early-type dwarf galaxies, which hold clues to the strength of gas stripping processes. Major-axis spectra and 2D kinematical maps provide insight regarding the amount of rotational support and how much dynamical heating a dwarf galaxy may have experienced. To this end, dedicated N-body simulations that follow the evolution of galaxies since early epochs reveal their path through parameter space, and can be compared to observations in order to understand the time-integrated effect of environmental influence.

  12. Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy.

    PubMed

    Geach, J E; Hickox, R C; Diamond-Stanic, A M; Krips, M; Rudnick, G H; Tremonti, C A; Sell, P H; Coil, A L; Moustakas, J

    2014-12-01

    Recent observations have revealed that starburst galaxies can drive molecular gas outflows through stellar radiation pressure. Molecular gas is the phase of the interstellar medium from which stars form, so these outflows curtail stellar mass growth in galaxies. Previously known outflows, however, involve small fractions of the total molecular gas content and have typical scales of less than a kiloparsec. In at least some cases, input from active galactic nuclei is dynamically important, so pure stellar feedback (the momentum return into the interstellar medium) has been considered incapable of rapidly terminating star formation on galactic scales. Molecular gas has been detected outside the galactic plane of the archetypal starburst galaxy M82 (refs 4 and 5), but so far there has been no evidence that starbursts can propel substantial quantities of cold molecular gas to the same galactocentric radius (about 10 kiloparsecs) as the warmer gas that has been traced by metal ion absorbers in the circumgalactic medium. Here we report observations of molecular gas in a compact (effective radius 100 parsecs) massive starburst galaxy at redshift 0.7, which is known to drive a fast outflow of ionized gas. We find that 35 per cent of the total molecular gas extends approximately 10 kiloparsecs, and one-third of this extended gas has a velocity of up to 1,000 kilometres per second. The kinetic energy associated with this high-velocity component is consistent with the momentum flux available from stellar radiation pressure. This demonstrates that nuclear bursts of star formation are capable of ejecting large amounts of cold gas from the central regions of galaxies, thereby strongly affecting their evolution by truncating star formation and redistributing matter. PMID:25471881

  13. Extended LY alpha -absorbing Halos around Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Bowen, David V.; Blades, J. Chris; Pettini, Max

    1996-06-01

    In order to establish the Lyα absorption cross section of present-day galaxies, we have identified 38 galaxies with z = 0-0.08 that lie within 40-500 h^-1^ kpc of the line of sight to a QSO observed with the Faint Object Spectrograph aboard the Hubble Space Telescope (HST). Including three galaxies in the field of 3C 273 investigated by previous authors, we find that nine of 41 galaxies have associated Lyα absorption. If the identified Lyα absorption systems are genuinely associated with the galaxies, then the covering factor of gas around galaxies remains roughly constant at ~40% between 100 and 300 h^-1^ kpc. Beyond 300 h^-1^ kpc, the incidence of absorption drops sharply. We conclude that (1) nearby galaxies do not possess Lyα-absorbing halos beyond 300 h^-1^ kpc in radius and (2) the covering factor of present-day galaxies between 50 and 300 h^-1^ kpc is 44% at an equivalent width limit of W >= 0.3 A. For the nine galaxies with associated Lyα absorption lines, differences in the galaxies systemic velocities and the velocity of the absorption line, {DELTA}v, range over +/- 300 km s^-1^, consistent with the distribution found at redshifts > 0.1 by Lanzetta et al. and Le Brun, Bergeron, & Boisse. Values of {DELTA}v spanning several hundred km s^-1^ are probably real for some of the QSO-galaxy pairs, however, and do not simply arise from errors in measuring cz_gal_ or cz_abs_. This suggests that the absorbing clouds are kinematically tied to the galaxy disks and that the distribution of {DELTA}v may arise because of the effects of galaxy inclination. We find no evidence for a correlation between Lyα equivalent width and galaxy line-of-sight separation, which weakens the argument that the identified galaxies are directly associated with the Lyα lines. Also, we find that absorption does not arise only from bright galaxies, since there are several examples in which low-luminosity galaxies apparently cause absorption. Yet we show that the absorbing halos around

  14. ROSAT PSPC and HRI observations of the composite starburst/Seyfert 2 galaxy NGC 1672

    NASA Technical Reports Server (NTRS)

    Brandt, W. N.; Halpern, Jules P.; Iwasawa, K.

    1995-01-01

    The nearby barred spiral galaxy NGC 1672 has been observed with the Position Sensitive Proportional Counter (PSPC) and High Resolution Imager (HRI) instruments on board the ROSAT X-ray satellite. NGC 1672 is thought to have an obscured Seyfert nucleus, and it has strong starburst activity as well. Three bright X-ray sources with luminosities 1-2 x 10(exp 40) erg/s are clearly identified with NGC 1672. The strongest lies at the nucleus, and the other two lie at the ends of NGC 1672's prominent bar, locations that are also bright in H alpha and near-infrared images. The nuclear source is resolved by the HRI on about the scale of the recently identified nuclear ring, and one of the sources at the ends of the bar is also probably resolved. The X-ray spectrum of the nuclear source is quite soft, having a Raymond-Smith plasma temperature of approximately equals 0.7 keV and little evidence for intrinsic absorption. The ROSAT band X-ray flux of the nuclear source appears to be dominated not by X-ray binary emission but rather by diffuse gas emission. The absorption and emission properties of the sources, as well as their spatial extents, lead us to models of superbubbles driven by supernovae. However, the large density and emission measure of the nuclear X-ray source stretch the limits that can be comfortably accommodated by these models. We do not detect direct emission from the putative Seyfert nucleus, although an alternative model for the nuclear source is thermal emission from gas that is photoionized by a hidden Seyfert nucleus. The spectra of the other two X-ray sources are harder than that of the nuclear source, and have similar difficulties with regard to superbubble models.

  15. UVES Abundances of Stars in Nearby Dwarf Spheroidal Galaxies

    NASA Astrophysics Data System (ADS)

    Tolstoy, Eline; Venn, Kim; Shetrone, Matt; Primas, Francesca; Hill, Vanessa; Kaufer, Andreas; Szeifert, Thomas

    2002-07-01

    It is a truth universally acknowledged, that a galaxy in possession of a good quantity of gas must want to form stars. It is the details of how and why that baffle us all. The simplest theories either would have this process a carefully self-regulated affair, or one that goes completely out of control and is capable of wrecking the galaxy which hosts it. Of course the majority of galaxies seem to amble along somewhere between these two extremes, and the mean properties tend to favour a quiescent self-regulated evolutionary scenario. But there area variety of observations which require us to invoke transitory ‘bursts’ of star-formation at one time or another in most galaxy types. Several nearby dwarf spheroidal galaxies have clearly determined star-formation histories with apparent periods of zero star formation followed by periods of fairly active star formation. If we are able to understand what separated these bursts we would understand several important phenomena in galaxy evolution. Were these galaxies able to clear out their gas reservoir in a burst of star formation? How did this gas return? or did it? Have these galaxies receieved gas from the IGM instead? Could stars from these types of galaxy contribute significantly to the halo population in our Galaxy? To answer these questions we need to combine accurate stellar photometry and Colour-Magnitude Diagram interpretation with detailed metal abundances to combine a star-formation rate versus time with a range of element abundances with time. Different elements trace different evolutionary process (e.g., relative contributions of type I and II supernovae). We often aren't even sure of the abundance spread in these galaxies. We have collected detailed high resolution UVES spectra of four nearby dwarf spheroidal galaxies (Sculptor, Fornax, Leo I & Carina) to begin to answer these questions. This is a precursor study to a more complete study with FLAMES. We presented at this meeting the initial results for

  16. High-J CO Sleds in Nearby Infrared Bright Galaxies Observed By Herschel/PACS

    NASA Astrophysics Data System (ADS)

    Mashian, N.; Sturm, E.; Sternberg, A.; Janssen, A.; Hailey-Dunsheath, S.; Fischer, J.; Contursi, A.; González-Alfonso, E.; Graciá-Carpio, J.; Poglitsch, A.; Veilleux, S.; Davies, R.; Genzel, R.; Lutz, D.; Tacconi, L.; Verma, A.; Weiß, A.; Polisensky, E.; Nikola, T.

    2015-04-01

    We report the detection of far-infrared (FIR) CO rotational emission from nearby active galactic nuclei (AGNs) and starburst galaxies, as well as several merging systems and Ultra-Luminous Infrared Galaxies (ULIRGs). Using the Herschel Photodetector Array Camera and Spectrometer (PACS), we have detected transitions in the Jupp = 14-30 range. The PACS CO data obtained here provide the first reference of well-sampled FIR extragalactic CO spectral line energy distributions (SLEDs) for this range. We find a large range in the overall SLED shape, even among galaxies of similar type, demonstrating the uncertainties in relying solely on high-J CO diagnostics to characterize the excitation source of a galaxy. Combining our data with low-J line intensities taken from the literature, we present a CO ratio-ratio diagram and discuss its value in distinguishing excitation sources and physical properties of the molecular gas. The position of a galaxy on such a diagram is less a signature of its excitation mechanism, than an indicator of the presence of warm, dense molecular gas. We then quantitatively analyze the CO emission from a subset of the detected sources with single-component and two-component large velocity gradient (LVG) radiative transfer models to fit the CO SLEDs. From these fits we derive the molecular gas mass and the corresponding CO-to-H2 conversion factor, {{α }CO}, for each respective source. For the ULIRGs we find α values in the canonical range 0.4- 5M⊙ (K km s-1 pc2)-1, while for the other objects, α varies between 0.2 and 14. Finally, we compare our best-fit LVG model results with previous studies of the same galaxies and comment on any differences. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  17. STAR FORMATION RATES FOR STARBURST GALAXIES FROM ULTRAVIOLET, INFRARED, AND RADIO LUMINOSITIES

    SciTech Connect

    Sargsyan, Lusine A.; Weedman, Daniel W. E-mail: dweedman@isc.astro.cornell.edu

    2009-08-20

    We present a comparison of star formation rates (SFR) determined from mid-infrared 7.7 {mu}m polycyclic aromatic hydrocarbon (PAH) luminosity [SFR(PAH)], from 1.4 GHz radio luminosity [SFR(radio)], and from far-ultraviolet luminosity [SFR(UV)] for a sample of 287 starburst galaxies with z < 0.5 having Spitzer IRS observations. The previously adopted relation log [SFR(PAH)] = log [{nu}L {sub {nu}}(7.7 {mu}m)] - 42.57 {+-} 0.2, for SFR in M{sub sun} yr{sup -1} and {nu}L {sub {nu}}(7.7 {mu}m) the luminosity at the peak of the 7.7 {mu}m PAH feature in erg s{sup -1}, is found to agree with SFR(radio). Comparing with SFR(UV) determined independently from ultraviolet observations of the same sources with the Galaxy Evolution Explorer mission (not corrected for dust extinction), the median log [SFR(PAH)/SFR(UV)] = 1.67, indicating that only 2% of the ultraviolet continuum typically escapes extinction by dust within a starburst. This ratio SFR(PAH)/SFR(UV) depends on infrared luminosity, with the form log [SFR(PAH)/SFR(UV)] = (0.53 {+-} 0.05)log [{nu}L{sub {nu}}(7.7 {mu}m)] - 21.5 {+-} 0.18, indicating that more luminous starbursts are also dustier. Using our adopted relation between {nu}L{sub {nu}}(7.7 {mu}m) and L {sub ir}, this becomes log [SFR(PAH)/SFR(UV)]= (0.53 {+-} 0.05)log L{sub ir} - 4.11 {+-} 0.18, for L{sub ir} in L{sub sun}. Only blue compact dwarf galaxies show comparable or greater SFR(UV) compared to SFR(PAH). We also find that the ratio SFR(PAH)/SFR(UV) is similar to that in infrared-selected starbursts for a sample of Markarian starburst galaxies originally selected using optical classification, which implies that there is no significant selection effect in SFR(PAH)/SFR(UV) using starburst galaxies discovered by Spitzer. These results indicate that SFRs determined with ultraviolet luminosities require dust corrections by a factor of {approx}10 for typical local starbursts but this factor increases to >700 for the most luminous starbursts at z {approx} 2

  18. A UNIVERSAL NEUTRAL GAS PROFILE FOR NEARBY DISK GALAXIES

    SciTech Connect

    Bigiel, F.; Blitz, L.

    2012-09-10

    Based on sensitive CO measurements from HERACLES and H I data from THINGS, we show that the azimuthally averaged radial distribution of the neutral gas surface density ({Sigma}{sub HI}+ {Sigma}{sub H2}) in 33 nearby spiral galaxies exhibits a well-constrained universal exponential distribution beyond 0.2 Multiplication-Sign r{sub 25} (inside of which the scatter is large) with less than a factor of two scatter out to two optical radii r{sub 25}. Scaling the radius to r{sub 25} and the total gas surface density to the surface density at the transition radius, i.e., where {Sigma}{sub HI} and {Sigma}{sub H2} are equal, as well as removing galaxies that are interacting with their environment, yields a tightly constrained exponential fit with average scale length 0.61 {+-} 0.06 r{sub 25}. In this case, the scatter reduces to less than 40% across the optical disks (and remains below a factor of two at larger radii). We show that the tight exponential distribution of neutral gas implies that the total neutral gas mass of nearby disk galaxies depends primarily on the size of the stellar disk (influenced to some degree by the great variability of {Sigma}{sub H2} inside 0.2 Multiplication-Sign r{sub 25}). The derived prescription predicts the total gas mass in our sub-sample of 17 non-interacting disk galaxies to within a factor of two. Given the short timescale over which star formation depletes the H{sub 2} content of these galaxies and the large range of r{sub 25} in our sample, there appears to be some mechanism leading to these largely self-similar radial gas distributions in nearby disk galaxies.

  19. Starbursts and their dynamics

    NASA Technical Reports Server (NTRS)

    Norman, Colin

    1987-01-01

    Detailed mechanisms associated with dynamical process occurring in starburst galaxies are considered including the role of bars, waves, mergers, sinking satellites, self gravitating gas and bulge heating. The current understanding of starburst galaxies both observational and theoretical is placed in the context of theories of galaxy formations, Hubble sequence evolution, starbursts and activity, and the nature of quasar absorption lines.

  20. Nearby stars to distant galaxies: TMT-ALMA synergies

    NASA Astrophysics Data System (ADS)

    Sheth, Kartik; Wilson, Christine

    2014-07-01

    Although they will probe very different wavelength regimes, significant synergies will exist for TMT and ALMA due to their capabilities for high angular resolution photometric and spectroscopic imaging. We illustrate this complementarity by examining a few specific science examples ranging from exoplanets, star forming disks in our Milky Way to black hole mass measurements in nearby galaxies to high redshift galaxy assemly. Since ALMA will be a relatively mature instrument by the end of TMT construction, we focus on synergies with the TMT first-light instruments as much as possible. We will also describe the current status and capabilities of ALMA and showcase some recent science results.

  1. A very deep IRAS survey - Constraints on the evolution of starburst galaxies

    NASA Astrophysics Data System (ADS)

    Hacking, Perry; Condon, J. J.; Houck, J. R.

    1987-05-01

    Counts of sources (primarily starburst galaxies) from a deep 60 microns IRAS survey published by Hacking and Houck (1987) are compared with four evolutionary models. The counts below 100 mJy are higher than expected if no evolution has taken place out to a redshift of approximately 0.2. Redshift measurements of the survey sources should be able to distinguish between luminosity-evolution and density-evolution models and detect as little as a 20 percent brightening or increase in density of infrared sources per billion years ago (H/0/ = 100 km/s per Mpc). Starburst galaxies cannot account for the reported 100 microns background without extreme evolution at high redshifts.

  2. HDI in Action: Comparison Imaging of the Interacting Starburst Galaxy NGC 3310

    NASA Astrophysics Data System (ADS)

    Wehner, Elizabeth

    2015-01-01

    NGC 3310 is an interacting starburst galaxy located approximately 18 Mpc away. Previous studies reveal a circumnuclear starburst, substantial star formation in its spiral arms, and an extensive system of tidal debris likely induced from the collision with and subsequent merger of a now-destroyed companion galaxy. A study by Wehner et al. in 2006 revealed the presence of a previously undetected tidal loop in the Northeast quadrant of the system. We have obtained follow up observations of this system using the newly-built Half Degree Imager (HDI) recently mounted on the WIYN 0.9m telescope in Kitt Peak, Arizaon. We present a comparison of deep imaging of NGC 3310 from HDI and from S2KB, the former primary CCD camera on the 0.9m. We present our results for comparison of image depth and image quality in order to assess the new HDI camera for future low surface brightness observations.

  3. A systematic investigation of edge-on starburst galaxies: Evidence for supernova-driven superwinds

    NASA Technical Reports Server (NTRS)

    Lehnert, Matthew D.

    1993-01-01

    We are completing a project designed to realistically assess the global/cosmological significance of superwinds by attempting to systematize our understanding of them (determine their incidence rate and the dependence of their properties on the star-formation that drives them). Specifically, we are analyzing data from an optical spectroscopic and narrow-band imaging survey of an infrared flux-limited sample of about 50 starburst galaxies whose stellar disks are viewed nearly edge-on. This edge-on orientation is crucial because the relevant properties of the superwind can be far more easily measured when the flow is seen in isolation against the sky rather than projected onto the much brighter gas associated with the starburst galaxy itself.

  4. Very deep IRAS survey - constraints on the evolution of starburst galaxies

    SciTech Connect

    Hacking, P.; Houck, J.R.; Condon, J.J.

    1987-05-01

    Counts of sources (primarily starburst galaxies) from a deep 60 microns IRAS survey published by Hacking and Houck (1987) are compared with four evolutionary models. The counts below 100 mJy are higher than expected if no evolution has taken place out to a redshift of approximately 0.2. Redshift measurements of the survey sources should be able to distinguish between luminosity-evolution and density-evolution models and detect as little as a 20 percent brightening or increase in density of infrared sources per billion years ago (H/0/ = 100 km/s per Mpc). Starburst galaxies cannot account for the reported 100 microns background without extreme evolution at high redshifts. 21 references.

  5. DIFFUSE HARD X-RAY EMISSION IN STARBURST GALAXIES AS SYNCHROTRON FROM VERY HIGH ENERGY ELECTRONS

    SciTech Connect

    Lacki, Brian C.; Thompson, Todd A.

    2013-01-01

    The origin of the diffuse hard X-ray (2-10 keV) emission from starburst galaxies is a long-standing problem. We suggest that synchrotron emission of 10-100 TeV electrons and positrons (e {sup {+-}}) can contribute to this emission, because starbursts have strong magnetic fields. We consider three sources of e {sup {+-}} at these energies: (1) primary electrons directly accelerated by supernova remnants, (2) pionic secondary e {sup {+-}} created by inelastic collisions between cosmic ray (CR) protons and gas nuclei in the dense interstellar medium of starbursts, and (3) pair e {sup {+-}} produced between the interactions between 10 and 100 TeV {gamma}-rays and the intense far-infrared (FIR) radiation fields of starbursts. We create one-zone steady-state models of the CR population in the Galactic center (R {<=} 112 pc), NGC 253, M82, and Arp 220's nuclei, assuming a power-law injection spectrum for electrons and protons. We consider different injection spectral slopes, magnetic field strengths, CR acceleration efficiencies, and diffusive escape times, and include advective escape, radiative cooling processes, and secondary and pair e {sup {+-}}. We compare these models to extant radio and GeV and TeV {gamma}-ray data for these starbursts, and calculate the diffuse synchrotron X-ray and inverse Compton (IC) luminosities of these starbursts in the models which satisfy multiwavelength constraints. If the primary electron spectrum extends to {approx}PeV energies and has a proton/electron injection ratio similar to the Galactic value, we find that synchrotron emission contributes 2%-20% of their unresolved, diffuse hard X-ray emission. However, there is great uncertainty in this conclusion because of the limited information on the CR electron spectrum at these high energies. IC emission is likewise a minority of the unresolved X-ray emission in these starbursts, from 0.1% in the Galactic center to 10% in Arp 220's nuclei, with the main uncertainty being the starbursts

  6. Diffuse Hard X-Ray Emission in Starburst Galaxies as Synchrotron from Very High Energy Electrons

    NASA Astrophysics Data System (ADS)

    Lacki, Brian C.; Thompson, Todd A.

    2013-01-01

    The origin of the diffuse hard X-ray (2-10 keV) emission from starburst galaxies is a long-standing problem. We suggest that synchrotron emission of 10-100 TeV electrons and positrons (e ±) can contribute to this emission, because starbursts have strong magnetic fields. We consider three sources of e ± at these energies: (1) primary electrons directly accelerated by supernova remnants, (2) pionic secondary e ± created by inelastic collisions between cosmic ray (CR) protons and gas nuclei in the dense interstellar medium of starbursts, and (3) pair e ± produced between the interactions between 10 and 100 TeV γ-rays and the intense far-infrared (FIR) radiation fields of starbursts. We create one-zone steady-state models of the CR population in the Galactic center (R <= 112 pc), NGC 253, M82, and Arp 220's nuclei, assuming a power-law injection spectrum for electrons and protons. We consider different injection spectral slopes, magnetic field strengths, CR acceleration efficiencies, and diffusive escape times, and include advective escape, radiative cooling processes, and secondary and pair e ±. We compare these models to extant radio and GeV and TeV γ-ray data for these starbursts, and calculate the diffuse synchrotron X-ray and inverse Compton (IC) luminosities of these starbursts in the models which satisfy multiwavelength constraints. If the primary electron spectrum extends to ~PeV energies and has a proton/electron injection ratio similar to the Galactic value, we find that synchrotron emission contributes 2%-20% of their unresolved, diffuse hard X-ray emission. However, there is great uncertainty in this conclusion because of the limited information on the CR electron spectrum at these high energies. IC emission is likewise a minority of the unresolved X-ray emission in these starbursts, from 0.1% in the Galactic center to 10% in Arp 220's nuclei, with the main uncertainty being the starbursts' magnetic field. We also model generic starbursts, including

  7. Observations of the CO J=6-5 transition in starburst galaxies

    NASA Technical Reports Server (NTRS)

    Harris, A. I.; Hills, R. E.; Stutzki, J.; Graf, U. U.; Russell, A. P. G.; Tacconi, L. J.; Genzel, R.

    1993-01-01

    Over the past several years, short-submillimeter observations of carbon monoxide's (CO) mid-J rotational levels have revealed the presence of a large amount of excited molecular gas in luminous giant molecular clouds in our Galaxy. Submillimeter lines are specific probes of excited material: collisional excitation of the level energy of 116 K above ground, and 6-5 transition's critical density is approximately 10(exp 6) cm(exp -3) in optically thin gas. Radiative trapping effects reduce the excitation requirements to some extent, but detection of the CO J=6-5 line is nearly indisputable proof of the existence of gas that is both warm and dense. The excitation conditions also imply that cool (T less than 20 K) molecular clouds within the beam neither emit nor absorb in the short-submillimeter lines; in our Galaxy, clouds with active massive star formation emit the strongest short-submillimeter CO rotational lines. We used these properties to explore the distribution of excited molecular material and physical conditions within the star formation regions of several classical starburst nuclei: NGC253, M82, and IC342. We have used the 6-5 transition as a thermometer of warm molecular gas in starburst nuclei, unambiguously finding that the nuclear molecular gas in starburst galaxies is substantially warmer than in typical disk clouds.

  8. Class I methanol megamasers: a potential probe of starburst activity and feedback in active galaxies

    NASA Astrophysics Data System (ADS)

    Chen, X.; Ellingsen, S. P.; Zhang, J.-S.; Wang, J.-Z.; Shen, Z.-Q.; Wu, Q.-W.; Wu, Z.-Z.

    2016-06-01

    Previous observations have shown that the distribution of 36.2-GHz class I methanol megamaser (MM) emission in Arp 220 is highly correlated with the diffuse X-rays. On this basis it was suggested that methanol MM may be produced either by the effects of galactic-outflow-driven shocks and/or cosmic rays. Here we report the results of a single-dish survey undertaken with the Greenbank Telescope (GBT) to improve our understanding of the pumping conditions of extragalactic class I methanol masers and their relationship to starburst and feedback processes within the host galaxies, towards a sample which includes 16 galaxies which show both extended soft X-ray emission, and either OH or H2O MM emission. Large baseline ripples in the GBT spectra limited our results to tentative detections towards 11 of the target galaxies. Analysis of these tentative detections shows that there are significant correlations between the methanol intensity and the host-galaxy infrared, radio and OH MM emission, but no correlation with the X-ray and H2O MM emission. Some sources show methanol emission significantly offset from the systemic velocity of the galaxy (by up to 1000 km s-1) and we propose that these are associated with galactic-scale outflows from active galactic nuclei (AGNs) feedback. The combined observational properties suggest that class I methanol MMs are related to significant starburst and molecular outflow activity and hence may provide a potential probe of AGN feedback and starburst processes in the host galaxies.

  9. The identification of post-starburst galaxies at z ˜ 1 using multiwavelength photometry: a spectroscopic verification

    NASA Astrophysics Data System (ADS)

    Maltby, David T.; Almaini, Omar; Wild, Vivienne; Hatch, Nina A.; Hartley, William G.; Simpson, Chris; McLure, Ross J.; Dunlop, James; Rowlands, Kate; Cirasuolo, Michele

    2016-06-01

    Despite decades of study, we still do not fully understand why some massive galaxies abruptly switch off their star formation in the early Universe, and what causes their rapid transition to the red sequence. Post-starburst galaxies provide a rare opportunity to study this transition phase, but few have currently been spectroscopically identified at high redshift (z > 1). In this paper, we present the spectroscopic verification of a new photometric technique to identify post-starbursts in high-redshift surveys. The method classifies the broad-band optical-near-infrared spectral energy distributions (SEDs) of galaxies using three spectral shape parameters (supercolours), derived from a principal component analysis of model SEDs. When applied to the multiwavelength photometric data in the UKIDSS Ultra Deep Survey, this technique identified over 900 candidate post-starbursts at redshifts 0.5 < z < 2.0. In this study, we present deep optical spectroscopy for a subset of these galaxies, in order to confirm their post-starburst nature. Where a spectroscopic assessment was possible, we find the majority (19/24 galaxies; ˜80 per cent) exhibit the strong Balmer absorption (H δ equivalent width Wλ > 5 Å) and Balmer break, characteristic of post-starburst galaxies. We conclude that photometric methods can be used to select large samples of recently-quenched galaxies in the distant Universe.

  10. The SDSS Discovery of a Strongly Lensed Post-Starburst Galaxy at z=0.766

    SciTech Connect

    Shin, Min-Su; Strauss, Michael A.; Oguri, Masamune; Inada, Naohisa; Falco, Emilio E.; Broadhurst, Tom; Gunn, James E.

    2008-09-30

    We present the first result of a survey for strong galaxy-galaxy lenses in Sloan Digital Sky Survey (SDSS) images. SDSS J082728.70+223256.4 was selected as a lensing candidate using selection criteria based on the color and positions of objects in the SDSS photometric catalog. Follow-up imaging and spectroscopy showed this object to be a lensing system. The lensing galaxy is an elliptical at z = 0.349 in a galaxy cluster. The lensed galaxy has the spectrum of a post-starburst galaxy at z = 0.766. The lensing galaxy has an estimated mass of {approx} 1.2 x 10{sup 12} M{sub {circle_dot}} and the corresponding mass to light ratio in the B-band is {approx} 26 M{sub {circle_dot}}/L{sub {circle_dot}} inside 1.1 effective radii of the lensing galaxy. Our study shows how catalogs drawn from multi-band surveys can be used to find strong galaxy-galaxy lenses having multiple lens images. Our strong lensing candidate selection based on photometry-only catalogs will be useful in future multi-band imaging surveys such as SNAP and LSST.

  11. The IRAM 30m Nearby Galaxy Dense Gas Survey

    NASA Astrophysics Data System (ADS)

    Bigiel, Frank

    2015-08-01

    I will present work in progress from EMPIRE, a large program (~440 hr) with the EMIR receiver at the IRAM 30m telescope to map dense gas tracers (HCN, HCO+, HNC, N2H+, C2H etc.) as well as the optically thin 1-0 lines of 13CO and C18O for the first time systematically across the disks of 9 nearby spiral galaxies. Building on a large suite of available ancillary data from the radio to the UV, we will be able to study, among other things, dense gas fractions and star formation efficiencies and how they vary with environment within and among nearby disk galaxies. While the survey has only recently started, we have similar data from a pilot program in M51 as well as from an ancillary study with CARMA in the Antennae Galaxies. I will present results from these two studies, provide an outlook and show first data from EMPIRE, and place our work in context with other work, including existing studies of dense gas tracers in other galaxies as well as our HERACLES CO and THINGS HI surveys.

  12. Resolved Star Formation Law In Nearby Infrared-bright Galaxies

    NASA Astrophysics Data System (ADS)

    Rahman, Nurur; Bolatto, A.; Wong, T.; Leroy, A.; Ott, J.; Calzetti, D.; Blitz, L.; Walter, F.; Rosolowsky, E.; West, A.; Vogel, S.; Bigiel, F.; Xue, R.

    2009-05-01

    An accurate knowledge of star formation law is crucial to make progress in understanding galaxy formation and evolution. We are studying this topic using CARMA STING (Survey Toward Infrared-bright Nearby Galaxies), an interferometric CO survey of a sample of 27 star-forming nearby galaxies with a wealth of multi-wavelength data designed to study star formation in environments throughout the blue sequence at sub-kpc scales. We present results for NGC 4254 (M99), one of our sample galaxies. We construct star formation rate surface density (SFRSD) and gas (atomic and molecular) surface density indicators using a combination of high resolution data from CARMA, KPNO, Spitzer, IRAM and VLA. We find a tight correlation between SFRSD and molecular gas surface density (MGSD), whereas the relation between atomic gas surface density and SFRSD shows very large scatter. Within the central 6 kpc (radius) where CARMA is the most sensitive the MGSD derived from CO(1-0) and CO(2-1) shows similar trend, however, in the extended disk the slope, derived from CO(2-1) data alone, gets steeper.

  13. X-Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 with Chandra

    NASA Technical Reports Server (NTRS)

    Gallagher, S. C.; Brandt, W. N.; Chartas, G.; Garmire, G. P.; Sambruna, R. M.

    2002-01-01

    With 40 ks of Clzandra ACIS-S3 exposure, new information on both the starburst and QSO components of the X-ray emission of Markarian 231, an ultraluminous infrared galaxy and broad absorption line QSO, has been obtained. The bulk of the X-ray luminosity is emitted from an unresolved nuclear point source, and the spectrum is remarkably hard, with the majority of the flux emitted above 2 keV. Most notably, significant nuclear variability (a decrease of -45% in approximately 6 hr) at energies above 2 keV indicates that Chuizdra has probed within light-hours of the central black hole. Although we concur with Maloney & Reynolds that the direct continuum is not observed, this variability coupled with the 188 eV upper limit on the equivalent width of the Fe K o emission line argues against the reflection-dominated model put forth by these authors based on their ASCA data. Instead, we favor a model in which a small, Compton-thick absorber blocks the direct X-rays, and only indirect, scattered X-rays from multiple lines of sight can reach the observer. Extended soft, thermal emission encompasses the optical extent of the galaxy and exhibits resolved structure. An off-nuclear X-ray source with a 0.35-8.0 keV luminosity of Lx = 7 x 10 sup39 ergs s sup -1 , consistent with the ultraluminous X-ray sources in other nearby starbursts, is detected. We also present an unpublished Faint Object Spectrograph spectrum from the Hirhhle Spuce Telescope archive showing the broad C IV absorption.

  14. Completing the AGN Census for Nearby Galaxies (Archival Component)

    NASA Astrophysics Data System (ADS)

    Ho, Luis

    2010-09-01

    The census of AGNs in the local Universe provides an efficient and effective estimate of the occupation fraction of central black holes in galaxies. While the demographics of AGNs in bulge-dominated systems is fairly well known, the situation in later-type galaxies is still murky because of potential optical selection biases. Searching for X-ray cores using Chandra can bypass these complications. We propose to complete the local AGN census by surveying all 188 star-forming (H II) nuclei in the well-studied Palomar sample of nearby galaxies. We request funding to analyze the 85 objects already in the archive; new observations have been proposed for the rest. We will establish with unprecedented reliability the AGN fraction across a wide range in Hubble type and Eddington ratios.

  15. Sizes of Young Massive Clusters in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Ryon, Jenna E.; Gallagher, John S.; LEGUS Team

    2016-01-01

    Out to distances of a few tens of Mpc, the surface brightness profiles of star clusters can be resolved with HST imaging. At these distances, a typical spiral galaxy will span a few HST imaging fields, so hundreds of star clusters can be readily observed in one pointing. The apparent uniformity in star cluster size across a huge range of mass, age, environment, and metallicity has been noted by many studies and remains unexplained. We measure the half-light radii of YMC populations in nearby galaxies using the galfit software package in an attempt to address this issue. Our analysis reliably shows most YMCs are similar in size with half-light radii of 2-5 pc. In this talk, I will present our results on the shape of the cluster size distribution and its dependence on cluster age, mass, and galaxy environment for YMCs in M83 and NGC 628.

  16. A spectroscopic analysis of the starburst galaxies NGC 3395 and NGC 3396

    NASA Astrophysics Data System (ADS)

    Plaks, Kenneth

    2003-11-01

    We have obtained ultraviolet and visible wavelength spectra of 31 bright star forming knots in the interacting galaxies NGC 3395 and NGC 3396 using the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope. The knots are possible super star clusters on the order of ˜100 pc diameter with measured metallicities on the order of 0.5 0.6 Z⊙ . The spectra are consistent with a massive production of hot young stars in a starburst. Ages of the starburst knots were calculated using several diagnostics from the Leitherer et al. Starburst 99 code (SB99) using an Initial Mass Function (IMF) with a power law coefficient α = 2.35 and an upper mass limit of 100 M⊙ . We modeled our star forming knots as instantaneous starbursts with the measured metallicity and we obtained consistent and reasonable estimates of the starburst age. The UV-brightest knots are ˜5 Myr old in both galaxies. We found no age gradient in the galaxies implying the starburst does not propagate across the galaxy but rather occurs simultaneously everywhere. The data are also consistent with the interpretation that the starburst is not only happening more or less simultaneously within each galaxy, it is also occurring simultaneously in both galaxies. If true, the fact that it is occurring simultaneously in both galaxies gives credence to the interaction being the source of the star formation in line with current theory. While our starforming knots were spatially resolved, at high redshift one cannot resolve individual knots and instead has to rely on spatially unresolved spectra. To assess the representativeness of these spectra of the underlying structure, we simulated the spectra one would observe by defining the entire portion of each galaxy observed as an unresolved knot. We found the metallicities for the unresolved knots were very representative of the resolved knots that made them up. We also found that the ages we derived for the unresolved knots were representative of the

  17. Completing the ACS Nearby Galaxy Survey with WFPC2

    NASA Astrophysics Data System (ADS)

    Dalcanton, Julianne

    2006-07-01

    We are requesting 25 orbits of Director's Discretionary Time to complete the primary science goals of our highly-ranked ACS Nearby Galaxy Survey Treasury program {ANGST}. Our program lost 2/3 of its orbits due to the ACS failure. Roughly half of these were restored as a result of an appeal to the Telescope Time Review Board which re-scoped the program. The Board's response to our appeal was explicit in terms of which targets were to be observed and how. We were directed to request Director's discretionary time for the components of the appeal which were not granted by the Review Board, but which were vital to the success of the program.The observing strategy for ANGST is two-fold: to obtain one deep field per galaxy which enables derivation of an accurate ancient star formation history, and to obtain radial tilings sufficient for recovering the full star formation history. The Review Board granted WFPC2 observations for deep fields in 7 galaxies, but no time for radial tilings. However, recovering the full star formation history of a galaxy is not possible without additional radial coverage. We have searched the archives for observations which may be used in place of the tilings {conceding some of the Treasury goals, but providing significant constraints on the full star formation history}, and have identified suitable observations for all but two of the galaxies. Here we request DD time for radial tilings for those last two galaxies.

  18. A survey of the molecular ISM properties of nearby galaxies using the Herschel FTS

    SciTech Connect

    Kamenetzky, J.; Rangwala, N.; Glenn, J.; Maloney, P. R.; Conley, A.

    2014-11-10

    The {sup 12}CO J = 4 → 3 to J = 13 → 12 lines of the interstellar medium from nearby galaxies, newly observable with the Herschel SPIRE Fourier transform spectrometer, offer an opportunity to study warmer, more luminous molecular gas than that traced by {sup 12}CO J = 1 → 0. Here we present a survey of 17 nearby infrared-luminous galaxy systems (21 pointings). In addition to photometric modeling of dust, we modeled full {sup 12}CO spectral line energy distributions from J = 1 → 0 to J = 13 → 12 with two components of warm and cool CO gas, and included LTE analysis of [C I], [C II], [N II], and H{sub 2} lines. CO is emitted from a low-pressure/high-mass component traced by the low-J lines and a high-pressure/low-mass component that dominates the luminosity. We found that, on average, the ratios of the warm/cool pressure, mass, and {sup 12}CO luminosity are 60 ± 30, 0.11 ± 0.02, and 15.6 ± 2.7. The gas-to-dust-mass ratios are <120 throughout the sample. The {sup 12}CO luminosity is dominated by the high-J lines and is 4 × 10{sup –4} L {sub FIR} on average. We discuss systematic effects of single-component and multi-component CO modeling (e.g., single-component J ≤ 3 models overestimate gas pressure by ∼0.5 dex), as well as compare to Galactic star-forming regions. With this comparison, we show the molecular interstellar medium of starburst galaxies is not simply an ensemble of Galactic-type giant molecular clouds. The warm gas emission is likely dominated by regions resembling the warm extended cloud of Sgr B2.

  19. Nuclear activity and the environments of nearby radio galaxies

    NASA Technical Reports Server (NTRS)

    Dey, Arjun; Vanbreugel, Wil

    1993-01-01

    Much of our present understanding of galaxy evolution over a large redshift range is based on the study of samples selected on the basis of non-thermal radio emission. It is therefore necessary to understand the relationship between radio source activity and the host galaxy. Recent observations suggest that there is a connection between radio galaxy (RG) activity and radio galaxy evolution. For example, high-redshift RGs (z approx. greater than 0.7) show evidence for significant populations of young stars, and have optical continuum morphologies nearly always aligned with the radio axis (McCarthy et al. 1987; Chambers et al. 1987). This phenomenon is generally attributed to radio jet induced star formation (DeYoung 1989), but the lack of high S/N spectra of the galaxy continua, and recent detections of polarized light in a few objects make it hard to rule out other processes such as scattering or synchrotron radiation. A detailed study of the continuum light in the distant RGs is difficult as they are optically very faint. However, nearby RGs (z approx. less than 0.1) have bluer B-V colors than radio-quiet ellipticals, presumably due to the presence of young stellar populations (Smith and Heckman 1989) and several have extended UV continuum emitting regions along their radio axes (van Bruegel et al. 1985a, b, di Serego Alighieri et al. 1989), reminiscent of the alignment effect seen in the high redshift RGs. We have almost completed a continuum imaging survey of nearby (and therefore optically brighter), powerful RGs to study any possible relationships between the optical continuum light and radio source activity. In particular we are interested in (1) whether these lower redshift RGs shown any evidence of the alignment effect (in their rest-frame UV light) that is seen in the distant RGs, and (2) the effects that the radio source has on the environment of the host galaxy.

  20. Characterizing the radio continuum emission from intense starburst galaxies

    NASA Astrophysics Data System (ADS)

    Galvin, T. J.; Seymour, N.; Filipović, M. D.; Tothill, N. F. H.; Marvil, J.; Drouart, G.; Symeonidis, M.; Huynh, M. T.

    2016-09-01

    The intrinsic thermal (free-free) and non-thermal (synchrotron) emission components that comprise the radio continuum of galaxies represent unique, dust-free measures of star formation rates (SFR). Such high SFR galaxies will dominate the deepest current and future radio surveys. We disentangle the thermal and non-thermal emission components of the radio continuum of six ultraluminous infrared galaxies (LFIR > 1012.5 L⊙) at redshifts of 0.2 ≤ z ≤ 0.5 and 22 IR selected galaxies. Radio data over a wide frequency range (0.8 < ν < 10 GHz) are fitted with a star-forming galaxy model comprising of thermal and non-thermal components. The luminosities of both radio continuum components are strongly correlated to the 60 μm luminosity across many orders of magnitude (consistent with the far-IR to radio correlation). We demonstrate that the spectral index of the radio continuum spectral energy distribution is a useful proxy for the thermal fraction. We also find that there is an increase in mean and scatter of the thermal fraction with FIR to radio luminosity ratio which could be influenced by different time-scales of the thermal and non-thermal emission mechanisms.

  1. Fueling nuclear activity in disk galaxies: Starbursts and monsters

    NASA Astrophysics Data System (ADS)

    Heller, Clayton H.; Shlosman, Isaac

    1994-03-01

    We study the evolution of the gas distribution in a globally unstable galactic disk with a particular emphasis on the gasdynamics in the central kiloparsec and the fueling activity there. The two-component self-gravitating disk is embedded in a responsive halo of comparable mass. The gas and stars are evolved using a three-dimensional hybrid smoothed particle hydrodynamics/N-body code and the gravitational interactions are calculated using a hierarchical TREE algorithm. A massive 'star formation' is introduced when the gas becomes Jeans unstable and locally exceeds the critical density of approximately 100 solar mass pc-3. The newly formed OB stars deposit energy in the gas by means of radiation-driven winds and supernovae. This energy is partially thermalized (efficiency of a few percent); the rest is radiated away. Models without star formation are evolved for a comparison. The effect of a massive object at the disk center is studied by placing a 'seed' black hole (BH) of 5 x 107 solar mass with an accretion radius of 20 pc. The tendency of the system to form a massive object 'spontaneously' is tested in models without the BH. We find that for models without star formation the bar- or dynamical friction-driven inflows lead to (1) domination of the central kpc by a few massive clouds that evolve into a single object probably via a cloud binary system, with and without a 'seed' BH, (2) accretion onto the BH which has a sporadic character, and (3) formation of remnant disks around the BH with a radius of 60-80 pc which result from the capture and digestion of clouds. For models with star formation, we find that (1) the enrgy input into the gas induces angular momentum loss and inflow rates by a factor less than 3, (2) the star formation is concentrated mainly at the apocenters of the gaseous circulation in the stellar bar and in the nuclear region, (3) the nuclear starburst phase appears to be very luminous approximately 1045-1046 erg/s and episodic with a typical

  2. Searching for X-ray sources in nearby late-type galaxies with low-star formation rates

    NASA Astrophysics Data System (ADS)

    Chatterjee, K.; Kaaret, P.; Brorby, M.; Kajava, J. J. E.; Grisé, F.; Farrell, S.; Poutanen, J.

    2016-03-01

    Late-type non-starburst galaxies have been shown to contain X-ray emitting objects, some being ultraluminous X-ray sources. We report on XMM-Newton observations of 11 nearby, late-type galaxies previously observed with the Hubble Space Telescope (HST) in order to find such objects. We found 18 X-ray sources in or near the optical extent of the galaxies, most being point-like. If associated with the corresponding galaxies, the source luminosities range from 2 × 1037 erg s-1 to 6 × 1039 erg s-1. We found one ultraluminous X-ray source, which is in the galaxy IC 5052, and one source coincident with the galaxy IC 4662 with a blackbody temperature of 0.166 ± 0.015 keV that could be a quasi-soft source or a quiescent neutron star X-ray binary in the Milky Way. One X-ray source, XMMU J205206.0-691316, is extended and coincident with a galaxy cluster visible on an HST image. The X-ray spectrum of the cluster reveals a redshift of z = 0.25 ± 0.02 and a temperature of 3.6±0.4 keV. The redshift was mainly determined by a cluster of Fe XXIV lines between the observed energy range 0.8 - 1.0 keV.

  3. Starbursts triggered by central overpressure in interacting galaxies

    NASA Technical Reports Server (NTRS)

    Jog, Chanda J.; Das, Mousumi

    1993-01-01

    A triggering mechanism for the origin of enhanced, massive-star formation in the central regions of interacting spiral galaxy pairs is proposed. Our mechanism is based on the detailed evolution of a realistic interstellar medium in a galaxy following an encounter. As a disk giant molecular cloud (GMC) tumbles into the central region following a galaxy encounter, it undergoes a radiative shock compression via the pre-existing high pressure of the central intercloud medium. The shocked outer shell of a GMC becomes gravitationally unstable and begins to fragment thus resulting in a burst of star formation, when the growth time for the gravitational instabilities in the shell becomes smaller than the crossing time of the shock. The resulting values of typical infrared luminosity agree with observations.

  4. Ultraviolet Radiative Transfer Modeling of Nearby Galaxies with Extraplanar Dusts

    NASA Astrophysics Data System (ADS)

    Shinn, Jong-Ho; Seon, Kwang-Il

    2015-12-01

    In order to examine their relation to the host galaxy, the extraplanar dusts of six nearby galaxies are modeled, employing a three-dimensional Monte Carlo radiative transfer code. The targets are from the highly inclined galaxies that show dust-scattered ultraviolet halos, and the archival Galaxy Evolution Explorer FUV band images were fitted with the model. The observed images are generally well-reproduced by two dust layers and one light source layer, whose vertical and radial distributions have exponential profiles. We obtained several important physical parameters, such as star formation rate (SFRUV), face-on optical depth, and scale-heights. Three galaxies (NGC 891, NGC 3628, and UGC 11794) show clear evidence for the existence of an extraplanar dust layer. However, it is found that the remaining three targets (IC 5249, NGC 24, and NGC 4173) do not necessarily need a thick dust disk to model the ultraviolet (UV) halo, because its contribution is too small and the UV halo may be caused by the wing part of the GALEX point spread function. This indicates that the galaxy samples reported to have UV halos may be contaminated by galaxies with negligible extraplanar (halo) dust. The galaxies showing evidence of an extraplanar dust layer fall within a narrow range on the scatter plots between physical parameters such as SFRUV and extraplanar dust mass. Several mechanisms that could possibly produce the extraplanar dust are discussed. We also found a hint that the extraplanar dust scale-height might not be much different from the polycyclic aromatic hydrocarbon emission characteristic height.

  5. THE ACS NEARBY GALAXY SURVEY TREASURY. X. QUANTIFYING THE STAR CLUSTER FORMATION EFFICIENCY OF NEARBY DWARF GALAXIES

    SciTech Connect

    Cook, David O.; Dale, Daniel A.; Seth, Anil C.; Johnson, L. Clifton; Weisz, Daniel R.; Fouesneau, Morgan; Dalcanton, Julianne J.; Olsen, Knut A. G.; Engelbracht, Charles W.

    2012-06-01

    We study the relationship between the field star formation and cluster formation properties in a large sample of nearby dwarf galaxies. We use optical data from the Hubble Space Telescope and from ground-based telescopes to derive the ages and masses of the young (t{sub age} {approx}< 100 Myr) cluster sample. Our data provide the first constraints on two proposed relationships between the star formation rate (SFR) of galaxies and the properties of their cluster systems in the low SFR regime. The data show broad agreement with these relationships, but significant galaxy-to-galaxy scatter exists. In part, this scatter can be accounted for by simulating the small number of clusters detected from stochastically sampling the cluster mass function. However, this stochasticity does not fully account for the observed scatter in our data, suggesting that there may be true variations in the fraction of stars formed in clusters in dwarf galaxies. Comparison of the cluster formation and the brightest cluster in our sample galaxies also provide constraints on cluster destruction models.

  6. Dust and Molecular Gas in the Winds of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    McCormick, Alexander N.

    Galactic winds provide a fundamental mechanism for galaxy evolution. The outflow of material in winds remains the most likely culprit responsible for a host of galaxy observations, plus mounting evidence for galactic winds at times in the past points to their importance in understanding the history of the universe. Therefore, detailed observations of galactic winds are critical to fleshing out the narrative of galaxy evolution. In particular, the dust and molecular gas of a galaxy's interstellar medium (ISM) play crucial roles in the absorption, scattering, and reemission of starlight, the heating of the ISM, and provide critical materials for star formation. We present results from archival Spitzer Space Telescope ata and exceptionally deep Herschel Space Observatory data of the dust and molecular gas found in and around 20 nearby galaxies known to host galactic-scale winds. Selecting nearby galaxies has allowed us the resolution and sensitivity to differentiate dust and molecular gas outside the galaxies and observe their typically faint emission. These are the most detailed surveys currently available of the faint dust and molecular gas components in galactic winds, and we have utilized them to address the following questions: i) What are the location and morphology of dust and molecular gas, and how do these components compare with better known neutral and ionized gas features? ii) How much do dust and molecular gas contribute to the mass and energy of galactic winds? iii) Do the properties of the dust and molecular gas correlate with the properties of the wind-hosting galaxy? Spitzer archival data has revealed kiloparsec-scale polycyclic aromatic hydrocarbon (PAH) structures in the extraplanar regions of nearly all the wind-hosting galaxies we investigated. We found a nearly linear correlation between the extraplanar PAH emission and the total infrared flux, a proxy for star formation. Our results also suggest a correlation between the height of extraplanar

  7. MaNGA: Mapping Nearby Galaxies at Apache Point Observatory

    NASA Astrophysics Data System (ADS)

    Bundy, Kevin

    2015-04-01

    I describe a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory). One of three core programs in the 6-year SDSS-IV project† that began on July 1st, 2014, MaNGA will deploy 17 fiber-bundle IFUs across the Sloan 2.5m Telescope's 3 degree field-of-view, targeting a mass-selected sample with a median redshift of 0.03, typical spatial resolution of 1-2 kpc, and a per-fiber signal-to-noise ratio of 4-8 in the outskirts of target galaxies. For each galaxy in the sample, MaNGA will provide maps and measured gradients of the composition and dynamics of both stars and gas. I discuss early results that highlight MaNGA's potential to shed light on the ionization and chemical enrichment of gas in galaxies, spatial patterns in their star formation histories, and the internal makeup of stellar populations. MaNGA's unprecedented data set will not only provide powerful new insight on galaxy formation and evolution but will serve as a valuable benchmark for future high-z observations from large telescopes and space-based facilities.

  8. The Violent Interstellar Medium of Nearby Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Walter, Fabian

    1999-04-01

    High resolution HI observations of nearby dwarf galaxies (most of which are situated in the M81 group at a distance of about 3.2 Mpc) reveal that their neutral interstellar medium (ISM) is dominated by hole-like features most of which are expanding. A comparison of the physical properties of these holes with the ones found in more massive spiral galaxies (such as M31 and M33) shows that they tend to reach much larger sizes in dwarf galaxies. This can be understood in terms of the galaxy's gravitational potential. The origin of these features is still a matter of debate. In general, young star forming regions (OB-associations) are held responsible for their formation. This picture, however, is not without its critics and other mechanisms such as the infall of high velocity clouds, turbulent motions or even gamma ray bursters have been recently proposed. Here I will present one example of a supergiant shell in IC 2574 which corroborates the picture that OB associations are indeed creating these structures. This particular supergiant shell is currently the most promising case to study the effects of the combined effects of stellar winds and supernova explosions which shape the neutral interstellar medium of (dwarf) galaxies.

  9. Wide Integral Field Infrared Spectroscopic Survey of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Sivanandam, Suresh; Moon, Dae-Sik; Zaritsky, Dennis F.; Chou, Richard; Meyer, Elliot; Ma, Ke; Jarvis, Miranda; Eisner, Joshua A.

    2015-01-01

    We are constructing a novel infrared integral field spectrograph with a large field of view (~50'x20') that will be available on the Kitt Peak 90' Bok telescope this spring. This wide integral field infrared spectrograph (WIFIS) operates over two wavelength ranges, zJ-band (0.9-1.35 microns) and H-band (1.5-1.8 microns), and has moderate spectral resolving power, 3,000 in zJ-band and 2,200 in H-band, respectively. WIFIS' field-of-view is comparable to current optical integral field spectrographs that are carrying out large galaxy surveys, e.g. SAMI, CALIFA, and MaNGA. We are designing a large nearby galaxy survey to complement the data already been taken by these optical integral field spectroscopic surveys. The near-infrared window provides a sensitive probe of the initial mass functions of stellar populations, the OB stellar fractions in massive star forming regions, and the kinematics of and obscured star formation within merging systems. This will be the first large scale infrared integral field spectroscopic survey of nearby galaxies.

  10. Observations of CO J=3-2 in the Outflow of the Starburst Galaxy M82

    NASA Astrophysics Data System (ADS)

    Seaquist, E. R.; Clark, Jason

    2001-05-01

    Observations are presented of the distribution of 12CO J=3-2 emission in the starburst galaxy M82 covering a region 3''×3'' (2.8×2.8 kpc). This area includes the halo region involved in the superwind outflow. More limited coverage is presented for 13CO J=3-2 and C18O J=3-2. The mass of molecular gas in the halo is about 5×108 Msolar, with a dynamical timescale of the order of 107 yr. The results show the region of the outflow at higher CO excitation than previous published observations. Comparison with recently made observations of 12CO J=2-1 shows that the CO gas becomes progressively de-excited at larger distances from the starburst disk, and the isotopic ratio 13CO/12CO J=3-2 also becomes smaller outside the starburst disk. These effects are interpreted as differences in excitation and optical depth between the starburst region and the outflow and outer disk. A comparison between the 12CO J=3-2 emission with a published 850 μm continuum map shows that CO makes a significant contribution to the continuum in this band and that the fractional contribution is greatest near +/-30" from the nucleus approximately along the major axis. The progressively slower rotation of the halo gas with distance above and below the disk, coupled with consideration of the conservation of angular momentum, is analyzed to reveal the pattern of the outflow. The flow appears to diverge more strongly below the disk, with a cone angle of about 90°, which compares to about 40° above the disk. The mass and energetics of the halo molecular gas suggest the possibility that the molecular material and dust in the halo will not escape from M82 but are instead being recycled through the halo after injection as supershells by one or more transient starburst events.

  11. Extended HCN and HCO+ Emission in the Starburst Galaxy M82

    NASA Astrophysics Data System (ADS)

    Salas, P.; Galaz, G.; Salter, D.; Herrera-Camus, R.; Bolatto, A. D.; Kepley, A.

    2014-12-01

    We mapped 3 mm continuum and line emission from the starburst galaxy M82 using the Combined Array for Research in Millimeter-wave Astronomy. We targeted the HCN, HCO+, HNC, CS, and HC3N lines, but here we focus on the HCN and HCO+ emission. The map covers a field of 1.'2 with an ≈5'' resolution. The HCN and HCO+ observations are short spacings corrected. The molecular gas in M82 had been previously found to be distributed in a molecular disk, coincident with the central starburst, and a galactic scale outflow which originates in the central starburst. With the new short spacings-corrected maps we derive some of the properties of the dense molecular gas in the base of the outflow. From the HCN and HCO+ J = (1-0) line emission, and under the assumptions of the gas being optically thin and in local thermodynamic equilibrium, we place lower limits on the amount of dense molecular gas in the base of the outflow. The lower limits are 7 × 106 M ⊙ and 21 × 106 M ⊙, or >~ 2% of the total molecular mass in the outflow. The kinematics and spatial distribution of the dense gas outside the central starburst suggests that it is being expelled through chimneys. Assuming a constant outflow velocity, the derived outflow rate of dense molecular gas is >=0.3 M ⊙ yr-1, which would lower the starburst lifetime by >=5%. The energy required to expel this mass of dense gas is (1-10) × 1052 erg.

  12. EXTENDED HCN AND HCO{sup +} EMISSION IN THE STARBURST GALAXY M82

    SciTech Connect

    Salas, P.; Galaz, G.; Salter, D.; Herrera-Camus, R.; Bolatto, A. D.; Kepley, A.

    2014-12-20

    We mapped 3 mm continuum and line emission from the starburst galaxy M82 using the Combined Array for Research in Millimeter-wave Astronomy. We targeted the HCN, HCO{sup +}, HNC, CS, and HC{sub 3}N lines, but here we focus on the HCN and HCO{sup +} emission. The map covers a field of 1.'2 with an ≈5'' resolution. The HCN and HCO{sup +} observations are short spacings corrected. The molecular gas in M82 had been previously found to be distributed in a molecular disk, coincident with the central starburst, and a galactic scale outflow which originates in the central starburst. With the new short spacings-corrected maps we derive some of the properties of the dense molecular gas in the base of the outflow. From the HCN and HCO{sup +} J = (1-0) line emission, and under the assumptions of the gas being optically thin and in local thermodynamic equilibrium, we place lower limits on the amount of dense molecular gas in the base of the outflow. The lower limits are 7 × 10{sup 6} M {sub ☉} and 21 × 10{sup 6} M {sub ☉}, or ≳ 2% of the total molecular mass in the outflow. The kinematics and spatial distribution of the dense gas outside the central starburst suggests that it is being expelled through chimneys. Assuming a constant outflow velocity, the derived outflow rate of dense molecular gas is ≥0.3 M {sub ☉} yr{sup –1}, which would lower the starburst lifetime by ≥5%. The energy required to expel this mass of dense gas is (1-10) × 10{sup 52} erg.

  13. Comparing [C II] , HI, and CO Dynamics of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    de Blok, W. J. G.; Walter, F.; Smith, J.-D. T.; Herrera-Camus, R.; Bolatto, A. D.; Requena-Torres, M. A.; Crocker, A. F.; Croxall, K. V.; Kennicutt, R. C.; Koda, J.; Armus, L.; Boquien, M.; Dale, D.; Kreckel, K.; Meidt, S.

    2016-08-01

    The H i and CO components of the interstellar medium (ISM) are usually used to derive the dynamical mass {M}{{dyn}} of nearby galaxies. Both components become too faint to be used as a tracer in observations of high-redshift galaxies. In those cases, the 158 μm line of atomic carbon ([C ii]) may be the only way to derive {M}{{dyn}}. As the distribution and kinematics of the ISM tracer affects the determination of {M}{{dyn}}, it is important to quantify the relative distributions of H i, CO, and [C ii]. H i and CO are well-characterized observationally, however, for [C ii] only very few measurements exist. Here we compare observations of CO, H i, and [C ii] emission of a sample of nearby galaxies, drawn from the HERACLES, THINGS, and KINGFISH surveys. We find that within R 25, the average [C ii] exponential radial profile is slightly shallower than that of the CO, but much steeper than the H i distribution. This is also reflected in the integrated spectrum (“global profile”), where the [C ii] spectrum looks more like that of the CO than that of the H i. For one galaxy, a spectrally resolved comparison of integrated spectra was possible; other comparisons were limited by the intrinsic line-widths of the galaxies and the coarse velocity resolution of the [C ii] data. Using high-spectral-resolution SOFIA [C ii] data of a number of star forming regions in two nearby galaxies, we find that their [C ii] linewidths agree better with those of the CO than the H i. As the radial extent of a given ISM tracer is a key input in deriving {M}{{dyn}} from spatially unresolved data, we conclude that the relevant length-scale to use in determining {M}{{dyn}} based on [C ii] data, is that of the well-characterized CO distribution. This length scale is similar to that of the optical disk.

  14. Understanding the Structure and Evolution of Nearby Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Zheng, Zheng

    2014-01-01

    In order to understand the structure and evolution of disk galaxies, we studied the stellar and gaseous components as well as the star formation rate in nearby disk galaxies. We used PS1 medium deep survey images to derive five-band (grizy) surface brightness profiles down to 30 ABmag/arcsec^2 for about 700 galaxies. From these stellar mass and mass-to-light ratio radial profiles are derived. The stellar mass radial profiles tend to bend-up at large radii, this often traces an extended old stellar population. The mass-to-light ratio profiles tend to rise outside the r25 radii. We also find a larger fraction of up-bending surface brightness profiles than Polen & Trujillo (2006). This may be because their sample is biased towards low surface brightness galaxies. We used HIPASS data as well as VLA HI 21cm data to study the gas component and dynamics of disk galaxies. We used the GALEX UV images to study the star formation of a HI-selected star-forming sample of about 400 galaxies, compiling a database of FUV and NUV radial profiles and related parameters. We used this to study the star forming efficiency (SFE, star formation rate per unit area divided by gas surface mass density) of the sample galaxies. We found that the UV based SFE has a tighter relationship with HI mass than an H_alpha based SFE as typically used in previous studies and the UV SFE is flat across wide range of stellar mass. We constructed a simple model to predict the distribution of interstellar medium and star formation rate in an equilibrium disk with constant two-fluid Toomre Q. This model can reproduces the SFE relations we derived.

  15. Resolving the Milky Way and Nearby Galaxies with WFIRST

    NASA Astrophysics Data System (ADS)

    Kalirai, Jasonjot

    High-resolution studies of nearby stellar populations have served as a foundation for our quest to understand the nature of galaxies. Today, studies of resolved stellar populations constrain fundamental relations -- such as the initial mass function of stars, the time scales of stellar evolution, the timing of mass loss and amount of energetic feedback, the color-magnitude relation and its dependency on age and metallicity, the stellar-dark matter connection in galaxy halos, and the build up of stellar populations over cosmic time -- that represent key ingredients in our prescription to interpret light from the Universe and to measure the physical state of galaxies. More than in any other area of astrophysics, WFIRST will yield a transformative impact in measuring and characterizing resolved stellar populations in the Milky Way and nearby galaxies. The proximity and level of detail that such populations need to be studied at directly map to all three pillars of WFIRST capabilities - sensitivity from a 2.4 meter space based telescope, resolution from 0.1" pixels, and large 0.3 degree field of view from multiple detectors. Our WFIRST GO Science Investigation Team (F) will develop three WFIRST (notional) GO programs related to resolved stellar populations to fully stress WFIRST's Wide Field Instrument. The programs will include a Survey of the Milky Way, a Survey of Nearby Galaxy Halos, and a Survey of Star-Forming Galaxies. Specific science goals for each program will be validated through a wide range of observational data sets, simulations, and new algorithms. As an output of this study, our team will deliver optimized strategies and tools to maximize stellar population science with WFIRST. This will include: new grids of IR-optimized stellar evolution and synthetic spectroscopic models; pipelines and algorithms for optimal data reduction at the WFIRST sensitivity and pixel scale; wide field simulations of MW environments and galaxy halos; cosmological simulations

  16. Detailed Analysis of Starburst and AGN Activity in Blue E/S0 Galaxies in RESOLVE

    NASA Astrophysics Data System (ADS)

    Bittner, Ashley; Snyder, Elaine M.; Kannappan, Sheila; Norman, Dara J.; Norris, Mark A.; Moffett, Amanda J.; Hoversten, Erik A.; Stark, David; RESOLVE Team

    2016-01-01

    We identify a population of ~120 blue E/S0 galaxies among the ~1350 galaxies that are targeted for spectroscopy and have measured morphologies in the highly complete REsolved Spectroscopy Of a Local Volume (RESOLVE) survey. Blue E/S0s are identified as being early type objects morphologically classified between E and S0/a that fall on the blue sequence. Most (~85%) of our blue E/S0s have stellar masses <10^10 M_sun. Using pPXF, we have measured the stellar velocity dispersions (sigma values) from high resolution 485 - 550 nm spectroscopy for ~15% of the blue E/S0 sample. Using three variations of the M_BH -- sigma relation, this kinematic subsample is estimated to typically host central black holes within the range log M_BH = 4-6 M_sun. Following up on previous suggestions of nuclear activity in the blue E/S0 population, we investigate nuclear starburst and/or AGN activity occurring within the full sample. Preliminary results from cross-checking known AGN catalogs with the blue E/S0 sample have revealed nuclear activity in ~20 of these galaxies based on heterogeneous criteria (BPT line ratio analysis, spectral line broadening, etc.), some of which may not entirely distinguish starburst from AGN activity. In an attempt to break the degeneracy between AGN and starburst activity, we perform detailed spectral analysis for a few of the galaxies with kinematic data. We also consider the viability of alternate AGN detection methods based on L_Edd estimates calculated from the M_BH estimates. This research has been supported by the National Science Foundation through the CAP REU Program (ACI-1156614) and the RESOLVE Survey (AST-0955368) as well as the National Space Grant College and Fellowship Program and the NC Space Grant Consortium.

  17. Formaldehyde Densitometry of Starburst Galaxies: Density-independent Global Star Formation

    NASA Astrophysics Data System (ADS)

    Mangum, Jeffrey G.; Darling, Jeremy; Henkel, Christian; Menten, Karl M.

    2013-04-01

    Accurate techniques that allow for the derivation of the spatial density in star formation regions are rare. A technique that has found application for the derivation of spatial densities in Galactic star formation regions utilizes the density-sensitive properties of the K-doublet transitions of formaldehyde (H2CO). In this paper, we present an extension of our survey of the formaldehyde 110-111 (λ = 6.2 cm) and 211-212 (λ = 2.1 cm) K-doublet transitions of H2CO in a sample of 56 starburst systems. We have extended the number of galaxies in which both transitions have been detected from 5 to 13. We have improved our spatial density measurements by incorporating kinetic temperatures based upon NH3 measurements of 11 of the galaxies with a total of 14 velocity components in our sample. Our spatial density measurements lie in a relatively narrow range from 104.5 to 105.5 cm-3. This implies that the Schmidt-Kennicutt relation between L IR and M dense (1) is an indication of the dense gas mass reservoir available to form stars and (2) is not directly dependent upon a higher average density driving the star formation process in the most luminous starburst galaxies. We have also used our H2CO measurements to derive two separate measures of the dense gas mass which are generally smaller, in many cases by a factor of 102-103, than those derived using HCN. This disparity suggests that H2CO traces a denser, more compact component of the giant molecular clouds in our starburst galaxy sample. We also report measurements of the rotationally excited λ = 6.3 cm 2Π1/2 J = 1/2 state of OH and the H111α radio recombination line taken concurrently with our H2CO 110-111 measurements.

  18. Interpreting the low-frequency radio spectra of starburst galaxies: a pudding of Strömgren spheres

    NASA Astrophysics Data System (ADS)

    Lacki, Brian C.

    2013-06-01

    The low-frequency radio emission of starburst galaxies is informative, but it can be absorbed in several ways. Most importantly, starburst galaxies are home to many H II regions, whose free-free absorption blocks low-frequency radio waves. These H II regions are discrete objects, but most multiwavelength models of starbursts assume a uniform medium of ionized gas, if they include the absorption at all. I calculate the effective absorption coefficient of H II regions in starbursts, which is ultimately a cross-section times the density of H II regions. The cross-sections are calculated by assuming that H II regions are Strömgren spheres. The coefficient asymptotes to a constant value at low frequencies, because H II regions partially cover the starburst and are buried part way into the starburst's synchrotron-emitting material. Considering Strömgren spheres around either OB stars or Super Star Clusters, I demonstrate the method by fitting to the low-frequency radio spectrum of M82. I discuss implications of the results for synchrotron spectrum shape, H II region pressure and free-free emission as a star formation rate indicator. However, these results are preliminary and could be affected by systematics. I argue that there is no volume-filling warm ionized medium in starbursts and that H II regions may be the most important absorption process down to ˜10 MHz. Future data at low and high radio frequency will improve our knowledge of the ionized gas.

  19. Observations of the impact of starbursts on the interstellar medium in dwarf galaxies

    NASA Technical Reports Server (NTRS)

    Marlowe, Amanda T.; Heckman, Timothy M.; Wyse, Rosemary F. G.; Schommer, Robert

    1995-01-01

    Dwarf galaxies play a crucial role in our understanding of the formation and evolution of galaxies, and the concept of supernova-driven mass outflows is a vital ingredient in theories of the structure and evolution of dwarf galaxies. Despite the theoretical importance of these outflows, there is a very limited amount of direct observational evidence for their existence. We have therefore begun a detailed multi-wave-band search for outflows in dwarf (M(sub B) greater than or = -18) galaxies with extensive recent or ongoing centrally concentrated star formation. We report the first results of this search in the present paper. Observations of the ionized gas in dwarf amorphous galaxies with centrally concentrated populations of massive stars provide evidence for the large-scale expansion of their expansion of their ionized interstellar media. Fabry-Perot H alpha images reveal the presence of kiloparsec-scale 'superbubbles' and filaments which tend to be oriented along the galaxy minor axis. These structures are comparable in size to the chracteristic optical sizes of the galaxies, and dominate the morphology of the galaxies at low surface brightness in H alpha. Since expanding structure of this size and velocity are not observed in all low-mass galaxies with recent or ongoing star formation, we suggest that we are witnessing transient events that likely have a relatively low 'duty cycle' in such galaxies. That is, we argue that the particular galaxies in the present paper have had significantly elevated star formation rates over the past 10(exp 7)-10(exp 8) yr (i.e., these are starburst or young poststarburst systems). This interpretation is consistent with the optical colors and emission-line properties of these galaxies.

  20. Nearby Galaxy is a Hotbed of Star Birth Activity

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This new image taken with NASA's Hubble Space Telescope (HST) is of the nearby dwarf galaxy NGC 1569. This galaxy is a hotbed of vigorous star birth activity which blows huge bubbles that riddle its main body. The bubble structure is sculpted by the galactic super-winds and outflows caused by a colossal input of energy from collective supernova explosions that are linked with a massive episode of star birth. The bubbles seen in this image are made of hydrogen gas that glows when hit by the fierce wind and radiation from hot young stars and is racked by supernova shocks. Its 'star factories' are also manufacturing brilliant blue star clusters. NGC 1569 had a sudden onset of star birth about 25 million years ago, which subsided about the time the very earliest human ancestors appeared on Earth. The Marshall Space Flight Center had responsibility for the design, development, and construction of the HST.

  1. Mid-J CO Emission in Nearby Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Pereira-Santaella, Miguel; Spinoglio, Luigi; Busquet, Gemma; Glenn, Jason; Isaak, Kate; Kamenetzky, Julia; Rangwala, Naseem; Schirm, Maximilien R. P.; Baes, Maarten; Barlow, Michael J.; Boselli, Alessandro; Cooray, Asantha; Cormier, Diane

    2012-12-01

    We study for the first time the complete sub-millimeter spectra (450 GHz to 1550 GHz) of a sample of nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel. The CO ladder (from Jup = 4 to 12) is the most prominent spectral feature in this range. These CO lines probe warm molecular gas that can be heated by ultraviolet photons, shocks, or X-rays originated in the active galactic nucleus or in young star-forming regions. In these proceedings we investigate the physical origin of the CO emission using the averaged CO spectral line energy distribution (SLED) of six Seyfert galaxies. We use a radiative transfer model assuming an isothermal homogeneous medium to estimate the molecular gas conditions. We also compare this CO SLED with the predictions of photon and X-ray dominated region (PDR and XDR) models.

  2. Full stellar kinematical profiles of central parts of nearby galaxies

    NASA Astrophysics Data System (ADS)

    Vudragović, A.; Samurović, S.; Jovanović, M.

    2016-09-01

    Context. We present the largest catalog of detailed stellar kinematics of the central parts of nearby galaxies, which includes higher moments of the line-of-sight velocity distribution (LOSVD) function represented by the Gauss-Hermite series. The kinematics is measured on a sample of galaxies selected from the Arecibo Legacy Fast ALFA (Alfalfa) survey using spectroscopy from the Sloan Digital Sky Survey (SDSS DR7). Aims: The SDSS DR7 offers measurements of the LOSVD based on the assumption of a pure Gaussian shape of the broadening function caused by the combination of rotational and random motion of the stars in galaxies. We discuss the consequences of this oversimplification since the velocity dispersion, one of the measured quantities, often serves as the proxy to important modeling parameters such as the black-hole mass and the virial mass of galaxies. Methods: The publicly available pPXF code is used to calculate the full kinematical profile for the sample galaxies including higher moments of their LOSVD. Both observed and synthetic stellar libraries were used and the related template mismatch problem is discussed. Results: For the whole sample of 2180 nearby galaxies reflecting morphological distribution characteristic for the local Universe, we successfully recovered stellar kinematics of their central parts, including higher order moments of the LOSVD function, for signal-to-noise above 50. Conclusions: We show the consequences of the oversimplification of the LOSVD function with Gaussian function on the velocity dispersion for the empirical and the synthetic stellar library. For the empirical stellar library, this approximation leads to an increase in the virial mass of 13% on average, while for the synthetic library the effect is weaker, with an increase of 9% on average. Systematic erroneous estimates of the velocity dispersion comes from the use of the synthetic stellar library instead of the empirical one and is much larger than the value imposed by

  3. The Environment of X-Ray Binaries in the Dwarf Starburst Galaxy NGC 1569

    NASA Astrophysics Data System (ADS)

    Clark, David M.; Eikenberry, Stephen S.; Raines, Steven N.

    2008-05-01

    We use deep, J and Ks observations of NGC 1569 acquired with FLAMINGOS on the KPNO 4-m to search for star cluster counterparts to X-ray binaries identified in archived Chandra images of this dwarf starburst galaxy. Performing near-IR photometry on the star cluster counterparts, we determine their colors, luminosities and masses. Comparing these results to the properties for all clusters in this galaxy, we search for trends in clusters associated with X-ray sources. Combining this study with FISICA, near-IR spectral observations, we further characterize the surroundings to X-ray binaries in NGC 1569. Contrasting this work with findings from a similar study performed on the Antennae galaxies, a large, merging system, we investigate the differences in X-ray binary environments.

  4. Deep photometry and integral magnitudes of 8 nearby galaxies

    NASA Astrophysics Data System (ADS)

    Georgiev, Ts. B.

    2016-02-01

    We estimated integral magnitudes of galaxies trying to include the contribution of the brightest part of their halos. We performed surface photometry based on (i) concentric elliptical rims, corresponding to the peripheral ellipticity of the image, (ii) median estimation of the mean value of the rim pixels, (iii) apparent radial brightness profiles, corresponding to the rim medians, and (iv) magnitude curves of growth, derived by numerical integrations of the apparent rim profiles, without preliminary background estimation and removal. Furthermore, we used the magnitude curves of growth to determine the integral magnitudes (limited by size and deepness of our frames) and compared them with the total magnitudes in the data base HyperLeda. Also, we used the rim-profiles to estimate the background level far enough from the galaxy center and we build (here—only for trial) the intrinsic radial profiles (with background removal). We apply this photometry on 8 nearby galaxies, observed with CCD in the system BVRC IC by the 50 cm Schmidt telescope of the Rozhen NAO in 2003-2004. We build radial profiles which occur to be as average 1.8 times (1.2-2.5 times) larger than in data base NED and of integral brightness that occurs to be about 1.4 times (1.2-1.7 times) higher than in data base HyperLeda. The relative brightness additions, found here, correlate with the color index and anti-correlate with the luminosity of the galaxy.

  5. The Red and Featureless Outer Disks of Nearby Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Watkins, Aaron E.; Mihos, J. Christopher; Harding, Paul

    2016-07-01

    We present results from deep, wide-field surface photometry of three nearby (D = 4–7 Mpc) spiral galaxies: M94 (NGC 4736), M64 (NGC 4826), and M106 (NGC 4258). Our imaging reaches a limiting surface brightness of {μ }B ∼ 28–30 mag arcsec‑2 and probes colors down to {μ }B ∼ 27.5 mag arcsec‑2. We compare our broadband optical data to available ultraviolet and high column density H i data to better constrain the star-forming history and stellar populations of the outermost parts of each galaxy’s disk. Each galaxy has a well-defined radius beyond which little star formation occurs and the disk light appears both azimuthally smooth and red in color, suggestive of old, well-mixed stellar populations. Given the lack of ongoing star formation or blue stellar populations in these galaxies’ outer disks, the most likely mechanisms for their formation are dynamical processes such as disk heating or radial migration, rather than inside-out growth of the disks. This is also implied by the similarity in outer disk properties despite each galaxy showing distinct levels of environmental influence, from a purely isolated galaxy (M94) to one experiencing weak tidal perturbations from its satellite galaxies (M106) to a galaxy recovering from a recent merger (M64), suggesting that a variety of evolutionary histories can yield similar outer disk structure. While this suggests a common secular mechanism for outer disk formation, the large extent of these smooth, red stellar populations—which reach several disk scale lengths beyond the galaxies’ spiral structure—may challenge models of radial migration given the lack of any nonaxisymmetric forcing at such large radii.

  6. Observations of supershells in the interstellar medium of nearby galaxies

    NASA Astrophysics Data System (ADS)

    Brinks, Elias; Bagetakos, Ioannis; Walter, Fabian; de Blok, Erwin

    The formation of massive stars in a gas-rich spiral or dwarf galaxy has a dramatic effect on the surrounding Interstellar Medium (ISM). Newly formed massive stars (M > 8 M[⊙]) will have a major impact, first of all through their ionizing flux and stellar winds and, when they eventually have exhausted their fuel supply, as supernovae (SNe). Because massive stars usually form in clusters or associations a large amount of energy is dumped into the ISM within a small volume and within a short time span, creating large scale structures known as supergiant shells and superbubbles. These structures are filled with metal-enriched, coronal gas from SNe which, through overpressure, powers their expansion. Material swept up by these expanding shells can go "critical" and form the sites of subsequent (secondary or propagating) star formation. Shells that grow larger than the thickness of the gas layer will blow out of the disk, spilling enriched material into the halo (or in the case of violent starbursts, the Intergalactic Medium). In this paper I will critically review the observational evidence which has been accumulating and which is underpinning the picture painted above, I will highlight the importance of imaging surveys of the neutral, atomic gas (via its 21-cm hydrogen line emission), and mention some of the exciting projects which are currently underway that link the large scale structure of the ISM with "Triggered Star Formation in a Turbulent ISM".

  7. Peculiar Chemical Abundances in the Starburst Galaxy M82 and Hypernova Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Umeda, Hideyuki; Nomoto, Ken'ichi; Tsuru, Takeshi Go; Matsumoto, Hironori

    2002-10-01

    X-ray observations have shown that the chemical abundance in the starburst galaxy M82 is quite rich in Si and S compared to oxygen. Such an abundance pattern cannot be explained with any combination of conventional Type I and II supernova yields. In addition, the energy-to-heavy-element mass ratio of the observed hot plasma is much higher than the value resulting from normal supernovae. We calculate abundances for explosive nucleosynthesis in core-collapse hypernovae and show that the abundance pattern and the large ratio between the energy and the heavy-element mass can be explained with hypernova nucleosynthesis. Such hypernova explosions are expected to occur for stars more massive than >~20-25 Msolar, and they likely dominate the starburst, because the time since the starburst in M82 is estimated to be as short as ~106-107 yr. We also investigate pair-instability supernovae (~150-300 Msolar) and conclude that the energy-to-heavy-element mass ratio in these supernovae is too small to explain the observation.

  8. A Spitzer High-resolution Mid-Infrared Spectral Atlas of Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Bernard-Salas, J.; Spoon, H. W. W.; Charmandaris, V.; Lebouteiller, V.; Farrah, D.; Devost, D.; Brandl, B. R.; Wu, Yanling; Armus, L.; Hao, L.; Sloan, G. C.; Weedman, D.; Houck, J. R.

    2009-10-01

    We present an atlas of Spitzer/IRS high-resolution (R ~ 600) 10-37 μm spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, and emission bands of polycyclic aromatic hydrocarbons (PAHs). Six out of the eight objects with a known active galactic nucleus (AGN) component show emission of the high excitation [Ne V] line. This line is also seen in one other object (NGC 4194) with, a priori, no known AGN component. In addition to strong PAH emission features in this wavelength range (11.3, 12.7, 16.4 μm), the spectra reveal other weak hydrocarbon features at 10.6, 13.5, 14.2 μm, and a previously unreported emission feature at 10.75 μm. An unidentified absorption feature at 13.7 μm is detected in many of the starbursts. We use the fine-structure lines to derive the abundance of neon and sulfur for 14 objects where the H I 7-6 line is detected. We further use the molecular hydrogen lines to sample the properties of the warm molecular gas. Several basic diagrams characterizing the properties of the sample are also shown. We have combined the spectra of all the pure starburst objects to create a high signal-to-noise ratio template, which is available to the community.

  9. A SPITZER HIGH-RESOLUTION MID-INFRARED SPECTRAL ATLAS OF STARBURST GALAXIES

    SciTech Connect

    Bernard-Salas, J.; Spoon, H. W. W.; Lebouteiller, V.; Farrah, D.; Wu, Yanling; Hao, L.; Sloan, G. C.; Weedman, D.; Houck, J. R.; Charmandaris, V.; Devost, D.; Brandl, B. R.; Armus, L.

    2009-10-01

    We present an atlas of Spitzer/IRS high-resolution (R {approx} 600) 10-37 {mu}m spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, and emission bands of polycyclic aromatic hydrocarbons (PAHs). Six out of the eight objects with a known active galactic nucleus (AGN) component show emission of the high excitation [Ne V] line. This line is also seen in one other object (NGC 4194) with, a priori, no known AGN component. In addition to strong PAH emission features in this wavelength range (11.3, 12.7, 16.4 {mu}m), the spectra reveal other weak hydrocarbon features at 10.6, 13.5, 14.2 {mu}m, and a previously unreported emission feature at 10.75 {mu}m. An unidentified absorption feature at 13.7 {mu}m is detected in many of the starbursts. We use the fine-structure lines to derive the abundance of neon and sulfur for 14 objects where the H I 7-6 line is detected. We further use the molecular hydrogen lines to sample the properties of the warm molecular gas. Several basic diagrams characterizing the properties of the sample are also shown. We have combined the spectra of all the pure starburst objects to create a high signal-to-noise ratio template, which is available to the community.

  10. Lyman Alpha Emitting Galaxies in the Nearby Universe

    NASA Astrophysics Data System (ADS)

    Hayes, Matthew

    2015-07-01

    The Lyman alpha emission line (Lyα) of neutral hydrogen (Hi) is intrinsically the brightest emission feature in the spectrum of astrophysical nebulae, making it a very attractive observational feature with which to survey galaxies. Moreover as an ultraviolet resonance line, Lyα possesses several unique characteristics that make it useful to study the properties of the interstellar medium and ionising stellar population at all cosmic epochs. In this review, I present a summary of Lyα observations of galaxies in the nearby universe. By ultraviolet continuum selection, at the magnitudes reachable with current facilities, only ≈ 5% of the local galaxy population shows a Lyα equivalent width (W Lyα) that exceeds 20 Å. This fraction increases dramatically at higher redshifts, but only in the local universe can we study galaxies in detail and assemble unprecedented multi-wavelength datasets. I discuss many local Lyα observations, showing that when galaxies show net Lyα emission, they ubiquitously also produce large-scale halos of scattered Lyα, that dominate the integrated luminosity. Concerning global measurements, we discuss how W Lyα and the Lyα escape fraction (f Lyα esc) are higher (W Lyα ≳ 20 Å and f Lyα esc ≳ 10%) in galaxies that represent the less massive and younger end of the distribution for local objects. This is connected with various properties, such that Lyα-emitting galaxies have lower metal abundances (median value of 12 + log(O/H) ~ 8.1) and dust reddening. However, the presence of galactic outflows/winds is also vital to Doppler shift the Lyα line out of resonance with the atomic gas, and high W Lyα is found only among galaxies with winds faster than ~ 50 km s-1. The empirical evidence is then assembled into a coherent picture, and the requirement for star-formation-driven feedback is discussed in the context of an evolutionary sequence where the interstellar medium is accelerated and/or subject to hydrodynamical instabilities