Study Of The Far Infrared Emission Of Nearby Spiral Galaxies

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Study Of The Far Infrared Emission Of Nearby Spiral Galaxies

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Author : Willie Drouhet
language : en
Publisher:
Release Date : 2013

Study Of The Far Infrared Emission Of Nearby Spiral Galaxies written by Willie Drouhet and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.

In my PHD work I explored the links between the physical properties of interstellar dust and other components of nearby spiral galaxies especially their stellar content. I worked on 46 disk galaxies from KINGFISH with IRAC/MIPS/PACS/SPIRE maps (3.6 - 500 microns). A bias is usually introduced in estimating disk orientations by using only a single surface brightness isophote. Thus I devised different surface brightness levels separated by constant steps in surface brightness and extracted isophotes at these levels in all FIR maps as well as in all IRAC 4.5 microns maps. To further assess the coherence of the shapes of isophotes across galactic disks, I built a quantitative indicator of the difference in shape between two ellipses with same center and same semi-major axis.I defined an acceptable level of difference between isophote shapes, by comparing disk orientations found in litterature. Using this level, I found regions inside the galactic disks where the isophotal shapes are similar. From these, I extracted one disk orientation per wavelength band. I found in the vast majority of the disk galaxy maps, be it dominated by stellar or dust emission, that a large fraction of the isophotes I extracted are coherent with the idea of an underlying disk. Comparing, for each galaxy, disk orientations extracted at all wavelengths, I found evidence in 20 galaxies out of 46, that on radial ranges as large as 1/3 of the visible disk (as measured by R25), the shapes of isophotes are morphologically similar. Thus for these 20 galaxies I devised consistent disk orientations both for the stellar and dust content. These 20 galaxies are less luminous, less emitting in the IR w.r.t. the optical, less barred, and characterized by later stage types than average. I also found that the disk orientations devised by my photometric method yield results more similar to H-alpha kinematic orientations than other photometric studies based on a single isophote level.Using the orientations I found and H-alpha dynamics disk orientations, I averaged azimuthally surface brightnesses to produce radial spectral energy distributions (SED) profiles. Once fitted with a cosmic dust emission model, they resulted in radial profiles of dust and stellar content properties. I found the dust intercepted power to be proportionnal to the product of the total dust mass and the average ISRF shining on dust. This former quantity is better correlated with the bolometric stellar luminosity than any of the dust mass or the dust heating ISRF separately. Thus the old stellar populations may be an important heating source for dust. The power intercepted by dust is also very well correlated with the total infrared power. The dust intercepts a larger quantity of power coming from stars in more actively star forming galaxies.Dust exhibit radial mass surface density profiles less well described by Sersic functions than stellar ones. When both profiles are well fitted by Sersic functions, stellar density profiles have smaller half mass radii than the isophotal optical radius (R25) separately in later type galaxies, but also in more quiescent galaxies. Sersic index and half mass radius distributions have larger widths for dust than for stellar surface density profiles.I also found that the ratio of dust over stellar surface density is an important factor to explain the variations with galactic morphological type of the ratio of dust intercepted power over the power emitted by old stellar populations. This later link could be intertwined with spiral structure strength in stage types later than 2.

Modelling The Far Infrared Emission In Spiral Galaxies

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Author : Simone Bianchi
language : en
Publisher:
Release Date : 1999

Modelling The Far Infrared Emission In Spiral Galaxies written by Simone Bianchi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with categories.

Study Of The Far Infrared Fadio Correlation For An Optically Selected Sample Of Spiral Galaxies

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Author : Melanie L. Anderson
language : en
Publisher:
Release Date : 1990

Study Of The Far Infrared Fadio Correlation For An Optically Selected Sample Of Spiral Galaxies written by Melanie L. Anderson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with categories.

An Investigation Of The Source Of The Far Infrared Radiation In Spiral Galaxies Using Near Infrared Hydrogen Recombination Lines As A Probe Of Star Formation

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Author : Lauren V. Jones
language : en
Publisher:
Release Date : 2000

An Investigation Of The Source Of The Far Infrared Radiation In Spiral Galaxies Using Near Infrared Hydrogen Recombination Lines As A Probe Of Star Formation written by Lauren V. Jones and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.

Far Infrared Emission From Rich Clusters Of Galaxies

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Author : Caroline Virginia Cox
language : en
Publisher:
Release Date : 1995

Far Infrared Emission From Rich Clusters Of Galaxies written by Caroline Virginia Cox and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.

Far Infrared And Radio Continuum Spatial Correlations In Ten Nearby Spiral Galaxies

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Author : Bryant Charles Heikkila
language : en
Publisher:
Release Date : 1995

Far Infrared And Radio Continuum Spatial Correlations In Ten Nearby Spiral Galaxies written by Bryant Charles Heikkila and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Radio astronomy categories.

The Interpretation Of Modern Synthesis Observations Of Spiral Galaxies

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Author : Nebojsa Duric
language : en
Publisher:
Release Date : 1991

The Interpretation Of Modern Synthesis Observations Of Spiral Galaxies written by Nebojsa Duric and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with Science categories.

Far Infrared Emission From Galaxies And Quasars

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Author : Girish Kumar Beeharry
language : en
Publisher:
Release Date : 1997

Far Infrared Emission From Galaxies And Quasars written by Girish Kumar Beeharry and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with categories.

The Effect Of Environment On The Radio Far Infrared Correlation In Spiral Galaxies

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Author : Victor Andersen
language : en
Publisher:
Release Date : 1992

The Effect Of Environment On The Radio Far Infrared Correlation In Spiral Galaxies written by Victor Andersen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Infrared radiation categories.

Infrared Observations Of The Spiral Galaxy Ngc 891

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Author : Cynthia Whaley
language : en
Publisher:
Release Date : 2007

Infrared Observations Of The Spiral Galaxy Ngc 891 written by Cynthia Whaley and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.

This thesis is a detailed, multi-waveband study of the inner 14 kpc of the famous spiral galaxy, NCG 891. The primary data have come from the Infrared Space Observatory's Camera. These data are images of the galaxy in 9 different mid-infrared wavebands. We have supported these data with archived data from the Spitzer Infrared Array Camera in 4 similar wavebands. Surface brightness contour maps of the galaxy were created and examined to determine where the mid-infrared emitters are located with respect to the galactic plane. We have determined that the main mid-infrared emission, due to warm dust and PAHs, lies in a thin disk of width 700 - 800 pc, but has faint emission that reaches up to about 2.3 kpc into the halo. The infrared spectral energy distribution (SED) for four environments in NGC 891 were created from the above mentioned wavebands as well as measurements from Spitzer's Multiband Imaging Photometer (3 Far-Infrared wavebands), the Two Micron All Sky Survey J, H, and K near-infrared wavebands, and the Sub-millimeter Common User Bolometer Array 450 and 850 $\mu$m bands. These spectra were fit with a SED model created by Frederic Galliano, and the physical properties of these environments were computed. The maps and SED show that while there is a relatively large amount of dust in NGC 891's halo, there is a depletion of PAHs beyond 2.3 kpc from the mid-plane. This is only the fourth galaxy to date that has PAH emission discovered in the halo, and it is the first in which the SED has been modeled for the halo.