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84 results on '"Józsa, Gyula I. G."'

52. Discovery of a Damped Lyα Absorber Originating in a Spectacular Interacting Dwarf Galaxy Pair at z = 0.026

Author

Boettcher, Erin, primary, Gupta, Neeraj, additional, Chen, Hsiao-Wen, additional, Chen, Mandy C., additional, Józsa, Gyula I. G., additional, Rudie, Gwen C., additional, Cantalupo, Sebastiano, additional, Johnson, Sean D., additional, Balashev, S. A., additional, Combes, Françoise, additional, Cooksey, Kathy L., additional, Faucher-Giguère, Claude-André, additional, Krogager, Jens-Kristian, additional, Lopez, Sebastian, additional, Momjian, Emmanuel, additional, Noterdaeme, Pasquier, additional, Petitjean, Patrick, additional, Rafelski, Marc, additional, Srianand, Raghunathan, additional, Walth, Gregory L., additional, and Zahedy, Fakhri S., additional

Published
2022
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53. The ALFALFA Almost Dark Galaxy AGC 229101: A 2 Billion Solar Mass H i Cloud with a Very Low Surface Brightness Optical Counterpart

Author

Leisman, Lukas, primary, Rhode, Katherine L., additional, Ball, Catherine, additional, Pagel, Hannah J., additional, Cannon, John M., additional, Salzer, John J., additional, Janowiecki, Steven, additional, Janesh, William F., additional, Józsa, Gyula I. G., additional, Giovanelli, Riccardo, additional, Haynes, Martha P., additional, Adams, Elizabeth A. K., additional, Gray, Laurin, additional, and Smith, Nicholas J., additional

Published
2021
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54. Viewing Classical Radio Galaxies with the Upgraded GMRT and MeerKAT—A Progress Report

Author

Lal, Dharam V., primary, Legodi, Portia, additional, Fanaroff, Bernie, additional, Venturi, Tiziana, additional, Smirnov, Oleg M., additional, Bondi, Marco, additional, Thorat, Kshitij, additional, Bester, Landman H., additional, Józsa, Gyula I. G., additional, Kleiner, Dane, additional, Loi, Francesca, additional, Makhathini, Sphesihle, additional, and White, Sarah V., additional

Published
2021
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56. CARACal - The Containerized Automated Radio Astronomy Calibration Pipeline.

Author

Józsa, Gyula I. G., Andati, Lexy A. L., de Blok, W. J. G., Hugo, Benjamin V., Kamphuis, Peter, Kleiner, Dane, Maccagni, Filippo M., Makhathini, Sphesihle, Molnár, Dániel Cs., Perkins, Simon J., Ramaila, Athanaseus, Ramatsoku, Mpati, Serra, P., Smirnov, O. M., Thorat, Kshitij, and White, Sarah V.

Published
2022

57. Anomalous gas in ESO 149-G003: a MeerKAT-16 view

Author

Józsa, Gyula I G, primary, Thorat, Kshitij, additional, Kamphuis, Peter, additional, Sebokolodi, Lerato, additional, Maina, Eric K, additional, Wang, Jing, additional, Pieterse, Daniëlle L A, additional, Groot, Paul, additional, Ramaila, Athanaseus J T, additional, Serra, Paolo, additional, Andati, Lexy A L, additional, de Blok, W J G, additional, Hugo, Benjamin V, additional, Kleiner, Dane, additional, Maccagni, Filippo M, additional, Makhathini, Sphesihle, additional, Molnár, Dániel Cs, additional, Ramatsoku, Mpati, additional, Smirnov, Oleg M, additional, Bloemen, Steven, additional, Paterson, Kerry, additional, Vreeswijk, Paul, additional, McBride, Vanessa, additional, Klein-Wolt, Marc, additional, Woudt, Patrick, additional, Körding, Elmar, additional, Le Poole, Rudolf, additional, Goedhart, Sharmila, additional, Passmoor, Sean S, additional, Serylak, Maciej, additional, and Dettmar, Ralf-Jürgen, additional

Published
2020
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58. MeerKAT-16 H i observation of the dIrr galaxy WLM

Author

Ianjamasimanana, Roger, primary, Namumba, Brenda, additional, Ramaila, Athanaseus J T, additional, Saburova, Anna S, additional, Józsa, Gyula I G, additional, Myburgh, Talon, additional, Thorat, Kshitij, additional, Carignan, Claude, additional, Maina, Eric, additional, de Blok, W J G, additional, Andati, Lexy A L, additional, Hugo, Benjamin V, additional, Kleiner, Dane, additional, Kamphuis, Peter, additional, Serra, Paolo, additional, Smirnov, Oleg M, additional, Maccagni, Filippo M, additional, Makhathini, Sphesihle, additional, Molnár, Dániel Cs, additional, Perkins, Simon, additional, Ramatsoku, Mpati, additional, and White, Sarah V, additional

Published
2020
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59. Anomalous gas in ESO 149-G003: a MeerKAT-16 view.

Author

Józsa, Gyula I G, Thorat, Kshitij, Kamphuis, Peter, Sebokolodi, Lerato, Maina, Eric K, Wang, Jing, Pieterse, Daniëlle L A, Groot, Paul, Ramaila, Athanaseus J T, Serra, Paolo, Andati, Lexy A L, de Blok, W J G, Hugo, Benjamin V, Kleiner, Dane, Maccagni, Filippo M, Makhathini, Sphesihle, Molnár, Dániel Cs, Ramatsoku, Mpati, Smirnov, Oleg M, and Bloemen, Steven

Subjects
OPTICAL telescopes, RADIO telescopes, GASES, KINEMATICS, GALACTIC dynamics, DWARF galaxies
Abstract

ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous observations with the ATCA indicated the presence of anomalous neutral hydrogen (⁠|$\rm{H{\small I}}$|⁠) deviating from the kinematics of a regularly rotating disc. We conducted follow-up observations with the MeerKAT radio telescope during the 16-dish Early Science programme as well as with the MeerLICHT optical telescope. Our more sensitive radio observations confirm the presence of anomalous gas in ESO 149-G003, and further confirm the formerly tentative detection of an extraplanar |$\rm{H{\small I}}$| component in the galaxy. Employing a simple tilted-ring model, in which the kinematics is determined with only four parameters but including morphological asymmetries, we reproduce the galaxy's morphology, which shows a high degree of asymmetry. By comparing our model with the observed |$\rm{H{\small I}}$|⁠ , we find that in our model, we cannot account for a significant (but not dominant) fraction of the gas. From the differences between our model and the observed data cube, we estimate that at least 7–8 per cent of the |$\rm{H{\small I}}$| in the galaxy exhibits anomalous kinematics, while we estimate a minimum mass fraction of less than 1 per cent for the morphologically confirmed extraplanar component. We investigate a number of global scaling relations and find that, besides being gas-dominated with a neutral gas-to-stellar mass ratio of 1.7, the galaxy does not show any obvious global peculiarities. Given its isolation, as confirmed by optical observations, we conclude that the galaxy is likely currently acquiring neutral gas. It is either re-accreting gas expelled from the galaxy or accreting pristine intergalactic material. [ABSTRACT FROM AUTHOR]

Published
2021
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60. A Large Sky Survey with MeerKAT

Author

Santos, Mário G., Bull, Philip, Camera, Stefano, Chen, Song, Fonseca, José, Heywood, Ian, Hilton, Matt, Jarvis, Matt, Józsa, Gyula I. G., Knowles, Kenda, Leeuw, Lerothodi, Maartens, Roy, Malefahlo, Eliab, McAlpine, Kim, Moodley, Kavilan, Patel, Prina, Pourtsidou, Alkistis, Prescott, Matthew, Spekkens, Kristine, Taylor, Russ, Witzemann, Amadeus, Whittam, Imogen H., Santos, Mário G., Bull, Philip, Camera, Stefano, Chen, Song, Fonseca, José, Heywood, Ian, Hilton, Matt, Jarvis, Matt, Józsa, Gyula I. G., Knowles, Kenda, Leeuw, Lerothodi, Maartens, Roy, Malefahlo, Eliab, McAlpine, Kim, Moodley, Kavilan, Patel, Prina, Pourtsidou, Alkistis, Prescott, Matthew, Spekkens, Kristine, Taylor, Russ, Witzemann, Amadeus, and Whittam, Imogen H.

Abstract

We discuss the ground-breaking science that will be possible with a wide area survey, using the MeerKAT telescope, known as MeerKLASS (MeerKAT Large Area Synoptic Survey). The current specifications of MeerKAT make it a great fit for cosmological applications, which require large volumes. In particular, a large survey over ~4,000 deg^2 for ~4,000 hours will potentially provide the first ever measurements of the baryon acoustic oscillations using the 21cm intensity mapping technique, with enough accuracy to impose constraints on the nature of dark energy. The combination with multi-wavelength data will give unique additional information, such as the first constraints on primordial non-Gaussianity using the multi-tracer technique, as well as a better handle on foregrounds and systematics. The survey will also produce a large continuum galaxy sample down to a depth of 5 µJy in L-band, unmatched by any other concurrent telescope, which will allow to study the large-scale structure of the Universe out to high redshifts. Finally, the same survey will supply unique information for a range of other science applications, including a large statistical investigation of galaxy clusters, and the discovery of rare high-redshift AGN that can be used to probe the epoch of reionization as well as produce a rotation measure map across a huge swathe of the sky. The MeerKLASS survey will be a crucial step on the road to using SKA1-MID for cosmological applications, as described in the top priority SKA key science projects.

Published
2018

61. The Enigmatic (Almost) Dark Galaxy Coma P: The Atomic Interstellar Medium

Author

Ball, Catherine, primary, Cannon, John M., additional, Leisman, Lukas, additional, Adams, Elizabeth A. K., additional, Haynes, Martha P., additional, Józsa, Gyula I. G., additional, McQuinn, Kristen B. W., additional, Salzer, John J., additional, Brunker, Samantha, additional, Giovanelli, Riccardo, additional, Hallenbeck, Gregory, additional, Janesh, William, additional, Janowiecki, Steven, additional, Jones, Michael G., additional, and Rhode, Katherine L., additional

Published
2018
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63. SHIELD: NEUTRAL GAS KINEMATICS AND DYNAMICS

Author

McNichols, Andrew T., primary, Teich, Yaron G., additional, Nims, Elise, additional, Cannon, John M., additional, Adams, Elizabeth A. K., additional, Bernstein-Cooper, Elijah Z., additional, Giovanelli, Riccardo, additional, Haynes, Martha P., additional, Józsa, Gyula I. G., additional, McQuinn, Kristen B. W., additional, Salzer, John J., additional, Skillman, Evan D., additional, Warren, Steven R., additional, Dolphin, Andrew, additional, Elson, E. C., additional, Haurberg, Nathalie, additional, Ott, Jürgen, additional, Saintonge, Amelie, additional, Cave, Ian, additional, Hagen, Cedric, additional, Huang, Shan, additional, Janowiecki, Steven, additional, Marshall, Melissa V., additional, Thomann, Clara M., additional, and Sistine, Angela Van, additional

Published
2016
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64. SHIELD: COMPARING GAS AND STAR FORMATION IN LOW-MASS GALAXIES

Author

Teich, Yaron G., primary, McNichols, Andrew T., additional, Nims, Elise, additional, Cannon, John M., additional, Adams, Elizabeth A. K., additional, Giovanelli, Riccardo, additional, Haynes, Martha P., additional, McQuinn, Kristen B. W., additional, Salzer, John J., additional, Skillman, Evan D., additional, Bernstein-Cooper, Elijah Z., additional, Dolphin, Andrew, additional, Elson, E. C., additional, Haurberg, Nathalie, additional, Józsa, Gyula I. G., additional, Ott, Jürgen, additional, Saintonge, Amelie, additional, Warren, Steven R., additional, Cave, Ian, additional, Hagen, Cedric, additional, Huang, Shan, additional, Janowiecki, Steven, additional, Marshall, Melissa V., additional, Thomann, Clara M., additional, and Sistine, Angela Van, additional

Published
2016
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66. TiRiFiC: Tilted Ring Fitting Code

Author

Józsa, Gyula I. G., Kenn, Franz, Oosterloo, Thomas A., Klein, Ulrich, and Astronomy

Subjects
ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Astrophysics::Galaxy Astrophysics
Abstract

Tilted Ring Fitting Code (TiRiFiC) is a prototype computer program to construct simulated (high-resolution) astronomical spectroscopic 3d-observations (data cubes) of simple kinematical and morphological models of rotating (galactic) disks. It is possible to automatically optimize the parameterizations of constructed model disks to fit spectroscopic (3d-) observations via a χ2 minimization. TiRiFiC is currently implemented as an add-on to the Groningen Image Processing System (GIPSY) software package and attempts to provide a method to automatically fit an extended tilted-ring model directly to a data cube.

Published
2012

67. THE SUDDEN DEATH OF THE NEAREST QUASAR

Author

MIT Kavli Institute for Astrophysics and Space Research, Evans, Daniel A., Schawinski, Kevin, Virani, Shanil, Urry, C. Megan, Keel, William C., Natarajan, Priyamvada, Lintott, Chris J., Manning, Anna, Coppi, Paolo, Kaviraj, Sugata, Bamford, Steven P., Józsa, Gyula I. G., Garrett, Michael, van Arkel, Hanny, Gay, Pamela L., Fortson, Lucy, MIT Kavli Institute for Astrophysics and Space Research, Evans, Daniel A., Schawinski, Kevin, Virani, Shanil, Urry, C. Megan, Keel, William C., Natarajan, Priyamvada, Lintott, Chris J., Manning, Anna, Coppi, Paolo, Kaviraj, Sugata, Bamford, Steven P., Józsa, Gyula I. G., Garrett, Michael, van Arkel, Hanny, Gay, Pamela L., and Fortson, Lucy

Abstract

Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition into and out of such phases is, however, unknown. We present the first measurement of the shutdown timescale for an individual quasar using X-ray observations of the nearby galaxy IC 2497, which hosted a luminous quasar no more than 70,000 years ago that is still seen as a light echo in "Hanny's Voorwerp," but whose present-day radiative output is lower by at least two, and more likely by over four, orders of magnitude. This extremely rapid shutdown provides new insight into the physics of accretion in supermassive black holes and may signal a transition of the accretion disk to a radiatively inefficient state., United States. National Aeronautics and Space Administration (Grant NNX09AR22G), United States. National Aeronautics and Space Administration (Grant NXX09AV69G)

Published
2015

69. The H I Tully-Fisher relation of early-type galaxies

Author

den Heijer, Milan, primary, Oosterloo, Tom A., additional, Serra, Paolo, additional, Józsa, Gyula I. G., additional, Kerp, Jürgen, additional, Morganti, Raffaella, additional, Cappellari, Michele, additional, Davis, Timothy A., additional, Duc, Pierre-Alain, additional, Emsellem, Eric, additional, Krajnović, Davor, additional, McDermid, Richard M., additional, Naab, Torsten, additional, Weijmans, Anne-Marie, additional, and Tim de Zeeuw, P., additional

Published
2015
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72. THE ALFALFA “ALMOST DARKS” CAMPAIGN: PILOT VLA HI OBSERVATIONS OF FIVE HIGH MASS-TO-LIGHT RATIO SYSTEMS

Author

Cannon, John M., primary, Martinkus, Charlotte P., additional, Leisman, Lukas, additional, Haynes, Martha P., additional, Adams, Elizabeth A. K., additional, Giovanelli, Riccardo, additional, Hallenbeck, Gregory, additional, Janowiecki, Steven, additional, Jones, Michael, additional, Józsa, Gyula I. G., additional, Koopmann, Rebecca A., additional, Nichols, Nathan, additional, Papastergis, Emmanouil, additional, Rhode, Katherine L., additional, Salzer, John J., additional, and Troischt, Parker, additional

Published
2015
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73. STAR FORMATION IN TWO LUMINOUS SPIRAL GALAXIES

Author

Hunter, Deidre A., primary, Elmegreen, Bruce G., additional, Rubin, Vera C., additional, Ashburn, Allison, additional, Wright, Teresa, additional, Józsa, Gyula I. G., additional, and Struve, Christian, additional

Published
2013
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74. The Bluedisks project, a study of unusually H i-rich galaxies – I. H i sizes and morphology

Author

Wang, Jing, primary, Kauffmann, Guinevere, additional, Józsa, Gyula I. G., additional, Serra, Paolo, additional, van der Hulst, Thijs, additional, Bigiel, Frank, additional, Brinchmann, Jarle, additional, Verheijen, M. A. W., additional, Oosterloo, Tom, additional, Wang, Enci, additional, Li, Cheng, additional, den Heijer, Milan, additional, and Kerp, Jürgen, additional

Published
2013
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75. Probing quasar shutdown timescales with Hanny's Voorwerp

Author

Evans, Daniel A., primary, Schawinski, Kevin, additional, Virani, Shanil, additional, Urry, C. Megan, additional, Keel, William C., additional, Natarajan, Priyamvada, additional, Lintott, Chris J., additional, Manning, Anna, additional, Coppi, Paolo, additional, Kaviraj, Sugata, additional, Bamford, Steven P., additional, Józsa, Gyula I. G., additional, Garrett, Michael, additional, van Arkel, Hanny, additional, Gay, Pamela, additional, and Fortson, Lucy, additional

Published
2012
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77. THE SUDDEN DEATH OF THE NEAREST QUASAR

Author

Schawinski, Kevin, primary, Evans, Daniel A., additional, Virani, Shanil, additional, Megan Urry, C., additional, Keel, William C., additional, Natarajan, Priyamvada, additional, Lintott, Chris J., additional, Manning, Anna, additional, Coppi, Paolo, additional, Kaviraj, Sugata, additional, Bamford, Steven P., additional, Józsa, Gyula I. G., additional, Garrett, Michael, additional, van Arkel, Hanny, additional, Gay, Pamela, additional, and Fortson, Lucy, additional

Published
2010
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78. The WSRT HALOGAS Survey

Author

Heald, George, primary, Józsa, Gyula I. G., additional, Serra, Paolo, additional, Oosterloo, Thomas A., additional, Sancisi, Renzo, additional, Fraternali, Filippo, additional, Rand, Richard J., additional, Walterbos, Rene A. M., additional, Jütte, Eva, additional, Gentile, Gianfranco, additional, Debattista, Victor P., additional, and Popescu, C. C., additional

Published
2010
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79. An HI view of galaxy conformity: HI-rich environment around HI-excess galaxies.

Author

Jing Wang, Serra, Paolo, Józsa, Gyula I. G., Koribalski, Bärbel, van der Hulst, Thijs, Kamphuis, Peter, Cheng Li, Jian Fu, Ting Xiao, Overzier, Roderik, Wieringa, Mark, and Wang, Enci

Subjects
INTERSTELLAR medium, GALAXY spectra, STELLAR mass, ACCRETION (Astrophysics), RADIO telescopes
Abstract

Using data taken as part of the Bluedisk project, we study the connection between neutral hydrogen (H I) in the environment of spiral galaxies and that in the galaxies themselves. We measure the total H I mass present in the environment in a statistical way by studying the distribution of noise peaks in the H I data cubes obtained for 40 galaxies observed with Westerbork Synthesis Radio Telescope. We find that galaxies whose H I mass fraction is high relative to standard scaling relations have an excess H I mass in the surrounding environment as well. Gas in the environment consists of gas clumps which are individually below the detection limit of our H I data. These clumps may be hosted by small satellite galaxies and/or be the high-density peaks of a more diffuse gas distribution in the intergalactic medium. We interpret this result as an indication for a picture in which the [Math Processing Error]-rich central galaxies accrete gas from an extended gas reservoir present in their environment. [ABSTRACT FROM AUTHOR]

Published
2015
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81. Probing quasar shutdown timescales with Hanny's Voorwerp.

Author

Evans, Daniel A., Schawinski, Kevin, Virani, Shanil, Urry, C. Megan, Keel, William C., Natarajan, Priyamvada, Lintott, Chris J., Manning, Anna, Coppi, Paolo, Kaviraj, Sugata, Bamford, Steven P., Józsa, Gyula I. G., Garrett, Michael, van Arkel, Hanny, Gay, Pamela, and Fortson, Lucy

Subjects
GALAXY formation, MODULATION theory, BLACK holes, SUPERMASSIVE stars, STELLAR luminosity function, HANNY'S Voorwerp
Abstract

Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition into and out of such phases is, however, unknown. We present the first measurement of the shutdown timescale for an individual quasar using Suzaku and XMM-Newton X-ray observations of the nearby galaxy IC 2497, which hosted a luminous quasar no more than ~230,000 years ago that is still seen as a light echo in 'Hanny's Voorwerp', but whose presentday radiative output is lower by at least 2 and more likely by over 4 orders of magnitude. This extremely rapid shutdown provides new insights into the physics of accretion in supermassive black holes, and may signal a transition of the accretion disk to a radiatively inefficient state. These results were first presented by [1]. [ABSTRACT FROM AUTHOR]

Published
2012
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82. An observational and theoretical view of the radial distribution of H i gas in galaxies.

Author

Wang, Jing, Fu, Jian, Aumer, Michael, Kauffmann, Guinevere, Józsa, Gyula I. G., Serra, Paolo, Huang, Mei-ling, Brinchmann, Jarle, van der Hulst, Thijs, and Bigiel, Frank

Subjects
ASTRONOMICAL observations, RADIAL distribution function, RADIAL velocity of galaxies, GALACTIC evolution, GALAXY spectra, DARK matter
Abstract

We analyse the radial distribution of H i gas for 23 disc galaxieswith unusually high H i content from the Bluedisk sample, along with a similar-sized sample of ‘normal’ galaxies. We propose an empirical model to fit the radial profile of the H i surface density, an exponential function with a depression near the centre. The radial H i surface density profiles are very homogeneous in the outer regions of the galaxy; the exponentially declining part of the profile has a scalelength of ∼0.18 R1, where R1 is the radius where the column density of the H i is 1 M⊙ pc−2. This holds for all galaxies, independent of their stellar or H i mass. The homogenous outer profiles, combined with the limited range in H i surface density in the non-exponential inner disc, results in the well-known tight relation between H i size and H i mass. By comparing the radial profiles of the H i-rich galaxies with those of the control systems, we deduce that in about half the galaxies, most of the excess gas lies outside the stellar disc, in the exponentially declining outer regions of the H i disc. In the other half, the excess is more centrally peaked. We compare our results with existing smoothed particle hydrodynamical simulations and semi-analytic models of disc galaxy formation in a Λ cold dark matter universe. Both the hydro simulations and the semi-analytic models reproduce the H i surface density profiles and the H i size–mass relation without further tuning of the simulation and model inputs. In the semi-analytic models, the universal shape of the outer H i radial profiles is a consequence of the assumption that infalling gas is always distributed exponentially. [ABSTRACT FROM AUTHOR]

Published
2014
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83. The WSRT HALOGAS Survey.

Author

Heald, George, Józsa, Gyula I. G., Serra, Paolo, Oosterloo, Thomas A., Sancisi, Renzo, Fraternali, Filippo, Rand, Richard J., Walterbos, Rene A. M., Jütte, Eva, and Gentile, Gianfranco

Subjects
*SPIRAL galaxies, *RADIO telescopes, *ASTRONOMY, *HYDROGEN, *METAPHYSICAL cosmology
Abstract

The WSRT Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) survey, now being conducted with the Westerbork Synthesis Radio Telescope (WSRT), aims at performing the first systematic investigation of cold gas accretion in nearby spiral galaxies. In the scope of this new WSRT survey, we will observe neutral hydrogen gas in 22 nearby spiral galaxies with a wide spread in morphological type, with an integration time of 120 hours per target. This is sufficient to detect faint, neutral gas in the outskirts of the target galaxies. The telescope design enables us to achieve a significantly better picture of the diffuse HI structure and its kinematics in the outskirts of the observed galaxies than has been achieved in most other HI surveys of nearby spiral galaxies. The detected amount of anomalous gas, indicative of either gas accretion or a fountain mechanism, varies significantly from galaxy to galaxy. [ABSTRACT FROM AUTHOR]

Published
2010
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84. HALOGAS Observations of NGC 4559: Anomalous and Extraplanar H I and its Relation to Star Formation

Author

Rene A. M. Walterbos, Maria T. Patterson, Filippo Fraternali, Paolo Serra, G. Gentile, George Heald, Gyula I. G. Józsa, Richard J. Rand, Carlos J. Vargas, Astronomy, Vargas, Carlos J., Heald, George, Walterbos, René A. M., Fraternali, Filippo, Patterson, Maria T., Rand, Richard J., Józsa, Gyula I. G., Gentile, Gianfranco, Serra, Paolo, Physics, and Astronomy and Astrophysics Research Group

Subjects
galaxies: spiral, DWARF GALAXIES, Milky Way, galaxies: halos, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, EXTRA-PLANAR GAS, 01 natural sciences, Spectral line, DIFFUSE IONIZED-GAS, 0103 physical sciences, GASEOUS HALOS, NEARBY GALAXIES, galaxies: halos, galaxies: ISM, galaxies: spiral, HIGH-VELOCITY CLOUDS, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, Physics, Spiral galaxy, 010308 nuclear & particles physics, Star formation, Astronomy, Astronomy and Astrophysics, Scale height, DISK GALAXIES, Galaxy, NEUTRAL HYDROGEN, Stars, Space and Planetary Science, MILKY-WAY, SPIRAL GALAXIES, galaxies: ISM
Abstract

We use new deep 21 cm H i observations of the moderately inclined galaxy NGC 4559 in the HALOGAS survey to investigate the properties of extraplanar gas. We use TiRiFiC to construct simulated data cubes to match the H i observations. We find that a thick-disk component of scale height ∼2 kpc, characterized by a negative vertical gradient in its rotation velocity (lag) of ∼13 ± 5 km s −1 kpc −1 is an adequate fit to extraplanar gas features. The tilted ring models also present evidence for a decrease in the magnitude of the lag outside R 25 , and a radial inflow of ∼10 km s −1 . We extracted lagging extraplanar gas through Gaussian velocity profile fitting. From both the 3D models and extraction analyses we conclude that ∼10%–20% of the total H i mass is extraplanar. Most of the extraplanar gas is spatially coincident with regions of star formation in spiral arms, as traced by H α and GALEX FUV images, so it is likely due to star formation processes driving a galactic fountain. We also find the signature of a filament of a kinematically “forbidden” H i feature, containing ∼1.4 × 10 6 M ⊙ of H i , and discuss its potential relationship to a nearby H i hole. We discover a previously undetected dwarf galaxy in H i located ∼0.°4 (∼58 kpc) from the center of NGC 4559, containing ∼4 × 10 5 M ⊙ . This dwarf has counterpart sources in SDSS with spectra typical of H ii regions, and we conclude that it is two merging blue compact dwarf galaxies.

Published
2017
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