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49 results on '"Fabbiano, Giuseppina"'

8. Wide-Field Hubble Space Telescope Observations of the Globular Cluster System in NGC 1399*

Author

Puzia, Thomas H, Paolillo, Maurizio, Goudfrooij, Paul, Maccarone, Thomas J, Fabbiano, Giuseppina, and Angelini, Lorella

Subjects
Astrophysics, Astronomy
Abstract

We present a comprehensive high spatial resolution imaging study of globular clusters (GCs) in NGC 1399, thecentral giant elliptical cD galaxy in the Fornax galaxy cluster, conducted with the Advanced Camera for Surveys(ACS) aboard theHubble Space Telescope(HST).Using a novel technique to construct drizzled point-spreadfunction libraries for HSTACS data, we accurately determine the fidelity of GC structural parameter measurementsfrom detailed artificial star cluster experiments and show the superior robustness of the GC half-light radius,rh,compared with other GC structural parameters, such as King core and tidal radius. The measurement ofrhfor themajor fraction of the NGC 1399 GC system reveals a trend of increasingrhversus galactocentric distance,Rgal,out to about 10 kpc and a flat relation beyond. This trend is very similar for blue and red GCs, which are found tohave a mean size ratio ofrh,redrh,blue0.820.11 at all galactocentric radii from the core regions of the galaxyout to40 kpc. This suggests that the size difference between blue and red GCs is due to internal mechanismsrelated to the evolution of their constituent stellar populations. Modeling the mass density profile of NGC 1399shows that additional external dynamical mechanisms are required to limit the GC size in the galaxy halo regionstorh2 pc. We suggest that this may be realized by an exotic GC orbit distribution function, an extended darkmatter halo, andor tidal stress induced by the increased stochasticity in the dwarf halo substructure at largergalactocentric distances. We compare our results with the GCrhdistribution functions in various galaxies and findthat the fraction of extended GCs withrh5 pc is systematically larger in late-type galaxies compared with GCsystems in early-type galaxies. This is likely due to the dynamically more violent evolution of early-type galaxies.We match our GCrhmeasurements with radial velocity data from the literature and split the resulting sample at themedianrhvalue into compact and extended GCs. We find that compact GCs show a significantly smaller line-of-sight velocity dispersion,cmp22525 km s1, than their extended counterparts,ext31721 km s1.Considering the weaker statistical correlation in the GCrhcolor and the GCrhRgalrelations, the more significantGC sizedynamics relation appears to be astrophysically more relevant and hints at the dominant influence of theGC orbit distribution function on the evolution of GC structural parameters.

Published
2014
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11. Disturbed Fossil Group Galaxy NGC 1132

Author

Kim, Dong-Woo, primary, Anderson, Craig, additional, Burke, Doug, additional, Fabbiano, Giuseppina, additional, Fruscione, Antonella, additional, Lauer, Jen, additional, McCollough, Michael, additional, Morgan, Doug, additional, Mossman, Amy, additional, O’Sullivan, Ewan, additional, Paggi, Alessandro, additional, Vrtilek, Saeqa, additional, and Trinchieri, Ginevra, additional

Published
2018
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13. Constraining the Physical State of the Hot Gas Halos in NGC 4649 and NGC 5846

Author

Paggi, Alessandro, primary, Kim, Dong-Woo, additional, Anderson, Craig, additional, Burke, Doug, additional, D’Abrusco, Raffaele, additional, Fabbiano, Giuseppina, additional, Fruscione, Antonella, additional, Gokas, Tara, additional, Lauer, Jen, additional, McCollough, Michael, additional, Morgan, Doug, additional, Mossman, Amy, additional, O’Sullivan, Ewan, additional, Trinchieri, Ginevra, additional, Vrtilek, Saeqa, additional, Pellegrini, Silvia, additional, Romanowsky, Aaron J., additional, and Brodie, Jean, additional

Published
2017
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14. X-Ray Emission from the Nuclear Region of Arp 220

Author

Paggi, Alessandro, primary, Fabbiano, Giuseppina, additional, Risaliti, Guido, additional, Wang, Junfeng, additional, Karovska, Margarita, additional, Elvis, Martin, additional, Maksym, W. Peter, additional, McDowell, Jonathan, additional, and Gallagher, Jay, additional

Published
2017
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23. THE DENSEST GALAXY

Author

Strader, Jay, primary, Seth, Anil C., additional, Forbes, Duncan A., additional, Fabbiano, Giuseppina, additional, Romanowsky, Aaron J., additional, Brodie, Jean P., additional, Conroy, Charlie, additional, Caldwell, Nelson, additional, Pota, Vincenzo, additional, Usher, Christopher, additional, and Arnold, Jacob A., additional

Published
2013
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46. XMM-Newton Observations of NGC 507: Supersolar Metal Abundances in the Hot Interstellar Medium

Author

Kim, Woo and Fabbiano, Giuseppina

Abstract

We present the results of the X-ray XMM-Newton observations of NGC 507, a dominant elliptical galaxy in a small group of galaxies, and report supersolar metal abundances of both Fe and a-elements in the hot interstellar medium (ISM) of this galaxy. These results are robust in that we considered all possible systematic effects in our analysis. We find ZFe = 2-3 times solar inside the D25 ellipse of NGC 507. This is the highest ZFe reported so far for the hot halo of an elliptical galaxy; this high iron abundance is fully consistent with the predictions of stellar evolution models, which include the yield of both Type II and Type Ia supernovae (SNe). Our analysis shows that abundance measurements are critically dependent on the selection of the proper emission model. The spatially resolved, high-quality XMM-Newton spectra provide enough statistics to formally require at least three emission components in each of four circumnuclear concentric shells (within 5' or 100 kpc): two soft thermal components indicating a range of temperatures in the hot ISM plus a harder component, consistent with the integrated output of low-mass X-ray binaries (LMXBs) in NGC 507. The two-component (thermal+LMXB) model customarily used in past studies yields a much lower ZFe, consistent with previous reports of subsolar metal abundances. This model, however, gives a significantly worse fit to the data (F-test probability < 0.0001). The abundance of a-elements (most accurately determined by Si) is also found to be supersolar. The a-element-to-Fe abundance ratio is close to the solar ratio, suggesting that ~70% of the iron mass in the hot ISM originated from Type Ia SNe. The a-element-to-Fe abundance ratio remains constant out to at least 100 kpc, indicating that Types II and Ia SN ejecta are well mixed on a scale much larger than the extent of the stellar body.

Published
2004

48. A DEEP CHANDRA ACIS STUDY OF NGC 4151. I. THE X-RAY MORPHOLOGY OF THE 3 kpc DIAMETER CIRCUM-NUCLEAR REGION AND RELATION TO THE COLD INTERSTELLAR MEDIUM

Author

Wang, Junfeng, Fabbiano, Giuseppina, Risaliti, Guido, Elvis, Martin, Karovska, Margarita, Zezas, Andreas, Mundell, Carole G., Dumas, Gaelle, and Schinnerer, Eva

Abstract

We report on the imaging analysis of [?]200 ks sub-arcsecond resolution Chandra Advanced CCD Imaging Spectrometer (ACIS-S) observations of the nearby Seyfert 1 galaxy NGC 4151. Bright, structured soft X-ray emission is observed to extend from 30 pc to 1.3 kpc in the southwest from the nucleus, much farther than seen in earlier X-ray studies. The terminus of the northeastern X-ray emission is spatially coincident with a CO gas lane, where the outflow likely encounters dense gas in the host galactic disk. X-ray emission is also detected outside the boundaries of the ionization cone, which indicates that the gas there is not completely shielded from the nuclear continuum, as would be the case for a molecular torus collimating the bicone. In the central r < 200 pc region, the subpixel processing of the ACIS data recovers the morphological details on scales of <30 pc (<0.''5) first discovered in Chandra High Resolution Camera images. The X-ray emission is more absorbed toward the boundaries of the ionization cone, as well as perpendicular to the bicone along the direction of a putative torus in NGC 4151. The innermost region where X-ray emission shows the highest hardness ratio is spatially coincident with the near-infrared-resolved H2 emission and dusty spirals we find in an Hubble Space Telescope V - H color image. The agreement between the observed H2 line flux and the value predicted from X-ray-irradiated molecular cloud models supports photo-excitation by X-rays from the active nucleus as the origin of the H2 line, although contribution from UV fluorescence or collisional excitation cannot be ruled out with current data. The discrepancy between the mass of cold molecular gas inferred from recent CO and near-infrared H2 observations may be explained by the anomalous CO abundance in this X-ray-dominated region. The total H2 mass derived from the X-ray observation agrees with the recent measurement by Storchi-Bergmann et al.

Published
2011

49. REVISITING WITH CHANDRA THE SCALING RELATIONS OF THE X-RAY EMISSION COMPONENTS (BINARIES, NUCLEI, AND HOT GAS) OF EARLY-TYPE GALAXIES

Author

Boroson, Bram, Kim, Woo, and Fabbiano, Giuseppina

Abstract

We have selected a sample of 30 normal (non-cD) early-type galaxies, for all of which optical spectroscopy is available and which have been observed with Chandra to a depth such as to ensure the detection of bright low-mass X-ray binaries (LMXBs) with LX > 1038 erg s-1. This sample includes a larger fraction of gas-poor galaxies than previously studied samples and covers a wide range of stellar luminosity (LK ), velocity dispersion (s*), globular cluster specific frequency (SN ), and stellar age. We derive X-ray luminosities (or upper limits) from the different significant X-ray components of these galaxies: nuclei, detected and undetected LMXBs, coronally active binaries (ABs), cataclysmic variables (CVs), and hot gas. The ABs and CVs contribution is estimated from the LX -LK scaling relation of M31 and M32. The contribution of undetected LMXBs is estimated both by fitting the spectra of the unresolved X-ray emission and by extrapolating the LMXB X-ray luminosity function. On average, the X-ray luminosity of LMXBs is a factor of [?]10 higher than that of ABs+CVs. By spectral fitting the emission (also considering gas emission in the regions of point sources), we estimate the contribution of the hot gas. We find our sample equally divided among galaxies with LX (gas) > LX (LMXB), LX (ABCV) [?] LX (gas) [?] LX (LMXB), and LX (gas) < LX (ABCV). The results for the nuclei are consistent with those discussed by Pellegrini. We derive a revised scaling relation between the integrated X-ray luminosity of LMXBs in a galaxy and the LK luminosity of the host galaxy: LX (LMXB)/LK [?] 1029 erg s-1 LK -1 with 50% 1s rms; moreover, we also obtain a tighter LX (LMXB)/LK -SN relation than previously published. We revisit the relations between hot gas content and other galaxy parameters (LK , s*), which in most previous work was based on the integrated total X-ray luminosity of the galaxy, finding a steeper LX (gas)-LK relation with larger scatter than reported in the literature. We find a positive correlation between the luminosity and temperature of the hot interstellar medium, significantly tighter than reported by earlier studies. This relation is particularly well defined in the subsample with s*>240 km s-1, where it may be related to the analogous correlation found in cD galaxies and groups/clusters. However, the gas-poor galaxies with the shallowest potentials (s* < 200 km s-1) also follow this relation, contrary to the expected anti-correlation in a simple outflow/wind scenario. Galaxies with intermediate values of s* instead tend to have the same kT, while LX (gas) spans a factor of [?]20; among these galaxies, we find a moderate, positive correlation between LX (gas) and the average stellar age, possibly suggesting a transition from halo retention to outflow caused by rejuvenated star formation associated with recent mergers.

Published
2011

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