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Mid- to far-infrared properties of star-forming galaxies and active galactic nuclei

Magdis, Georgios E.; Rigopoulou, Dimitra; Helou , George; Farrah, Duncan; Hurley, Pete; Alonso Herrero, Almudena; Bock , Jamie; Burgarella, Denis; Chapman, Scott; Charmandaris, Vassilis; Cooray, Asantha R.; Dai, Sophia; Dale, Daniel A.; Elbaz, David; Felt
Fonte: EDP Sciences Publicador: EDP Sciences
Tipo: info:eu-repo/semantics/article; publishedVersion
ENG
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We study the mid- to far-IR properties of a 24 μm-selected flux-limited sample (S24> 5 mJy) of 154 intermediate redshift (⟨ z ⟩ ~ 0.15), infrared luminous galaxies, drawn from the 5 Milli-Jansky Unbiased Spitzer Extragalactic Survey. By combining existing mid-IR spectroscopy and new Herschel SPIRE submm photometry from the Herschel Multi-tiered Extragalactic Survey, we derived robust total infrared luminosity (LIR) and dust mass (Mdust) estimates and infered the relative contribution of the AGN to the infrared energy budget of the sources. We found that the total (8−1000 μm) infrared emission of galaxies with weak 6.2 μm PAH emission (EW6.2 ≤ 0.2 μm) is dominated by AGN activity, while for galaxies with EW6.2> 0.2 μm more than 50% of the LIR arises from star formation. We also found that for galaxies detected in the 250–500 μm Herschel bands an AGN has a statistically insignificant effect on the temperature of the cold dust and the far-IR colours of the host galaxy, which are primarily shaped by star formation activity. For star-forming galaxies we reveal an anti-correlation between the LIR-to-rest-frame 8 μm luminosity ratio, IR8 ≡ LIR/L8  and the strength of PAH features. We found that this anti-correlation is primarily driven by variations in the PAHsemission...

The far-infrared properties of the most isolated galaxies

Lisenfeld, Ute; Verdes-Montenegro, L.; Leon, S.; Sulentic, J.
Fonte: Springer Publicador: Springer
Tipo: Conferência ou Objeto de Conferência
ENG
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Congress: "Island universes: structure and evolution of disk galaxies", Terschelling (The Netherlands), 3-8 july, 2005.; Although it is widely accepted that galaxy interactions stimulate secular evolutionary effects (e.g. enhanced star formation) the amplitude of this effect and the processes for accomplishing them, are not well quantified. The goal of the project AMIGA (Analysis of the Interstellar Medium of Isolated Galaxies) is to provide a sizable reference sample (n=1050) of the most isolated galaxies as a basis for the study of the influence of the environment on galaxy properties. Here, we present the far-infrared (FIR) properties of 1030 galaxies of the sample for which IRAS data are available. We improved the detection rate and accuracy of the IRAS data with respect to the Point Source and Faint Source Catalog by redoing the data reduction with the IPAC utility ADDSCAN/SCANPI. Comparing the FIR to the blue luminosities, we find a slightly non-linear relation. Furthermore, we find that interacting galaxies tend to have an enhanced FIR emission.

Infrared Properties of QCD from Dyson-Schwinger equations

Fischer, Christian S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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I review recent results on the infrared properties of QCD from Dyson-Schwinger equations. The topics include infrared exponents of one-particle irreducible Green's functions, the fixed point behaviour of the running coupling at zero momentum, the pattern of dynamical quark mass generation and properties of light mesons.; Comment: 47 pages, 19 figures, Topical Review to be published in J.Phys.G, v2: typos corrected and some references added

The Optical and Near-Infrared Properties of 2837 Quasars in the UKIRT Infrared Deep Sky Survey (UKIDSS)

Chiu, Kuenley; Richards, Gordon T.; Hewett, Paul C.; Maddox, Natasha
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/12/2006
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The UKIRT Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of hemispheric imaging projects to extend the work of the Two Micron All Sky Survey (2MASS) by reaching three magnitudes deeper in YJHK imaging, to K=18.2 (5-sigma, Vega) over wide fields. Better complementing existing optical surveys such as the Sloan Digital Sky Survey (SDSS), the resulting public imaging catalogues provide new photometry of rare object samples too faint to be reached previously. The first data release of UKIDSS has already surpassed 2MASS in terms of photons gathered, and using this new dataset we examine the near-infrared properties of 2837 quasars found in the SDSS and newly catalogued by the UKIDSS in ~189 square degrees. The matched quasars include the RA range 22hr to 4hr on the Southern Equatorial Stripe (SDSS Stripe 82), an area of significant future followup possibilities with deeper surveys and pointed observations. The sample covers the redshift and absolute magnitude ranges 0.08

Optical and infrared properties of active galactic nuclei in the Lockman Hole

Rovilos, E.; Fotopoulou, S.; Salvato, M.; Burwitz, V.; Egami, E.; Hasinger, G.; Szokoly, G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/02/2011
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We present the observed-frame optical, near- and mid-infrared properties of X-ray selected AGN in the Lockman Hole. Using a likelihood ratio method on optical, near-infrared or mid-infrared catalogues, we assigned counterparts to 401 out of the 409 X-ray sources of the XMM-Newton catalogue. Accurate photometry was collected for all the sources from U to 24um. We used X-ray and optical criteria to remove any normal galaxies, galactic stars, or X-ray clusters among them and studied the multi-wavelength properties of the remaining 377 AGN. We used a mid-IR colour-colour selection to understand the AGN contribution to the optical and infrared emission. Using this selection, we identified different behaviours of AGN-dominated and host-dominated sources in X-ray-optical-infrared colour-colour diagrams. More specifically, the AGN dominated sources show a clear trend in the f_x/f_R vs. R-K and f_24um/f_R vs. R-K diagrams, while the hosts follow the behaviour of non X-ray detected galaxies. In the optical-near-infrared colour-magnitude diagram we see that the known trend of redder objects being more obscured in X-rays is stronger for AGN-dominated than for host-dominated systems. This is an indication that the trend is more related to the AGN contaminating the overall colours than any evolutionary effects. Finally...

Infrared properties of blazars: putting the GASP-WEBT sources into context

Raiteri, C. M.; Villata, M.; Carnerero, M. I.; Acosta-Pulido, J. A.; Larionov, V. M.; D'Ammando, F.; Arévalo, M. J.; Arkharov, A. A.; Bueno, A. Bueno; Di Paola, A.; Efimova, N. V.; González-Morales, P. A.; Gorshanov, D. L.; Grinon-Marin, A. B.; Lázaro,
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 16/05/2014
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463.884%
The infrared properties of blazars can be studied from the statistical point of view with the help of sky surveys, like that provided by the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All Sky Survey (2MASS). However, these sources are known for their strong and unpredictable variability, which can be monitored for a handful of objects only. In this paper we consider the 28 blazars (14 BL Lac objects and 14 flat-spectrum radio quasars, FSRQs) that are regularly monitored by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) since 2007. They show a variety of infrared colours, redshifts, and infrared-optical spectral energy distributions (SEDs), and thus represent an interesting mini-sample of bright blazars that can be investigated in more detail. We present near-IR light curves and colours obtained by the GASP from 2007 to 2013, and discuss the infrared-optical SEDs. These are analysed with the aim of understanding the interplay among different emission components. BL Lac SEDs are accounted for by synchrotron emission plus an important contribution from the host galaxy in the closest objects, and dust signatures in 3C 66A and Mkn 421. FSRQ SEDs require synchrotron emission with the addition of a quasar-like contribution...

X-ray and infrared properties of galaxies and AGNs in the 9 square degree Bootes field

Hickox, R. C.; Jones, C.; Forman, W. R.; Murray, S. S.; Brodwin, M.; XBootes, the Chandra; Survey, Spitzer IRAC Shallow; AGES; Teams, NOAO DWFS
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/03/2006
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We examine the X-ray and infrared properties of galaxies and AGNs in the 9 square degree Bootes field, using data from the Chandra XBootes and Spitzer IRAC Shallow Surveys, as well as optical spectroscopy from the AGES survey. A sample of ~30,000 objects are detected in all four IRAC bands, of which ~2,000 are associated with X-ray sources. We also study X-ray fainter sources using stacking techniques, and find that X-ray fluxes are highest for objects with IRAC colors that are known to be characteristic of AGNs. Because these are shallow, wide-field surveys, they probe the bright end of the AGNluminosity function out to spectroscopic redshifts as high as z=3-4. We can use this multiwavelength dataset to explore the properties and redshift evolution of a large sample of luminous active galaxies.; Comment: 4 pages, 3 figures, to appear in the proceedings of "The Spitzer Science Center 2005 Conference: Infrared Diagnostics of Galaxy Evolution", Pasadena, November 2005

Near-Infrared Properties of Faint X-rays Sources from NICMOS Imaging in the Chandra Deep Fields

Colbert, James W.; Teplitz, Harry; Yan, Lin; Malkan, Matthew; McCarthy, Patrick
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 15/11/2004
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We measure the near-infrared properties of 42 X-ray detected sources from the Chandra Deep Fields North and South, the majority of which lie within the NICMOS Hubble Deep Field North and Ultra Deep Field. We detect all 42 Chandra sources with NICMOS, with 95% brighter than H = 24.5. We find that X-ray sources are most often in the brightest and most massive galaxies. Neither the X-ray fluxes nor hardness ratios of the sample show any correlation with near-infrared flux, color or morphology. This lack of correlation indicates there is little connection between the two emission mechanisms and is consistent with the near-infrared emission being dominated by starlight rather than a Seyfert non-stellar continuum. Near-infrared X-ray sources make up roughly half of all extremely red (J-H > 1.4) objects brighter than H > 24.5. These red X-ray sources have a range of hardness ratios similar to the rest of the sample, decreasing the likelihood of dust-obscured AGN activity as the sole explanation for their red color. Using a combination of spectroscopic and photometric redshifts, we find the red J-H objects are at high redshifts (z > 1.5), which we propose as the primary explanation for their extreme J-H color. Measurement of rest-wavelength absolute B magnitudes shows that X-ray sources are the brightest optical objects at all redshifts...

Near-infrared properties of classical novae: a perspective gained from Mount Abu Infrared Observatory

Banerjee, Dipankar P. K.; Ashok, N. M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/06/2013
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We review the near-infrared properties of classical novae in the J, H and K bands at wavelengths between 1.08 to 2.4 micron. A classification system exists for the early post-outburst optical spectra of novae on the basis of the strength of group of non-hydrogen emission lines. A similar scheme for the near-infrared regime, which is not available at present, is presented here. In the optical system there are two principal classes, namely, "Fe II" and "He/N" for novae with either prominent Fe II lines or prominent "He/N" lines. There is also a small subset of the hybrid Fe IIb type. From spectroscopic observations we show the differences and similarities between these classes of novae in the near-infrared. The spectral lines common to the two principal classes arise from H, He, N and O. However, the near-IR features that separate these two classes are the numerous, and often strong, Carbon lines which are seen only in the spectra of the Fe II class of novae. The dust formation process in novae is discussed based on broad-band observations. The first-overtone carbon monoxide (CO) detections in novae are analyzed to understand the formation and evolution of this molecule in the nova ejecta and to discuss the observed 12C/13C ratio.; Comment: Review article in Bulletin of the Astron. Soc. of India...

Near-Infrared properties of the X-ray emitting young stellar objects in the Carina Nebula

Preibisch, Thomas; Hodgkin, Simon; Irwin, Mike; Lewis, James R.; King, Robert R.; McCaughrean, Mark J.; Zinnecker, Hans; Townsley, Leisa; Broos, Patrick
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/03/2011
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Abbreviated Abstract: The near-infrared study of the Carina Nebula in this paper builds on the results of the Chandra Carina Complex Project (CCCP), that detected 14368 X-ray sources in the 1.4 square-degree survey region, an automatic source classification study that classified 10714 of these as very likely young stars in Carina, and an analysis of their clustering properties. We used HAWK-I at the ESO VLT to conduct a very deep near-IR survey with sub-arcsecond angular resolution, covering about 1280 square-arcminutes. The HAWK-I images reveal more than 600000 individual infrared sources, whereby objects as faint as J ~ 23, H ~ 22, and Ks ~ 21 are detected at S/N >= 3. While less than half of the Chandra X-ray sources have counterparts in the 2MASS catalog, the ~5 mag deeper HAWK-I data reveal infrared counterparts to 6636 (= 88.8%) of the 7472 Chandra X-ray sources in the HAWK-I field. We analyze near-infrared color-color and color-magnitude diagrams to derive information about the extinctions, infrared excesses, ages, and masses of the X-ray selected objects. The near-infrared properties agree well with the results of the automatic X-ray source classification. The shape of the K-band luminosity function of the X-ray selected Carina members agrees well with that derived for the Orion Nebula Cluster...

Characterising the Far-infrared Properties of Distant X-ray Detected AGNs: Evidence for Evolution in the Infrared--X-ray Luminosity Ratio

Mullaney, J. R.; Alexander, D. M.; Huynh, M.; Goulding, A. D.; Frayer, D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/09/2009
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(Abridged) We investigate the far-infrared properties of X-ray sources detected in the Chandra Deep Field-South (CDF-S) survey using the ultra-deep 70um and 24um Spitzer observations taken in this field. We rely on stacking analyses of the 70um data to characterise the average 70um properties of the X-ray sources. Using Spitzer-IRS data of the Swift-BAT sample of z~0 active galactic nuclei (hereafter, AGNs), we show that the 70um/24um flux ratio can distinguish between AGN-dominated and starburst-dominated systems out to z~1.5. From stacking analysis we find that both high redshift and z~0 AGNs follow the same tendency toward warmer 70um/24um colours with increasing X-ray luminosity (L_X). We also show that the 70um flux can be used to determine the infrared (8-1000um) luminosities of high redshift AGNs. We use this information to show that L_X=10^{42-43} erg/s AGNs at high redshifts (z=1-2) have infrared to X-ray luminosity ratios (hereafter, L_IR/L_X) that are, on average, 4.7_{-2.0}^{+10.2} and 12.7^{+7.1}_{-2.6} times higher than AGNs with similar X-ray luminosities at z=0.5-1 and z~0, respectively. By comparison, we find that the L_IR/L_X ratios of L_X=10^{43-44} erg/s AGNs remain largely unchanged across this same redshift interval. We explore the consequences that these results may have on the identification of distant...

Mid-infrared properties of X-ray sources in the Extended Groth Strip

Barmby, P.; Alonso-Herrero, A.; Donley, J. L.; Egami, E.; Fazio, G. G.; Georgakakis, A.; Huang, J. -S.; Laird, E. S.; Miyazaki, S.; Nandra, K.; Park, S. Q.; Perez-Gonzalez, P. G.; Rieke, G. H.; Rigby, J. R.; Willner, S. P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Mid-infrared observations of Active Galactic Nuclei (AGN) are important for understanding of the physical conditions around the central accretion engines. Chandra and XMM-Newton X-ray observations of a 300 arcmin^2 region in the Extended Groth Strip are used to select a sample of~150 AGN. The Spitzer instruments IRAC and MIPS detect 68-80% of these sources, which show a wide range of mid-infrared properties. About 40% of the sources have red power-law spectral energy distributions (f_nu ~ nu^alpha, alpha<0) in the 3.6-8 um IRAC bands. In these sources the central engine dominates the emission at both X-ray and IR wavelengths. Another 40% of the sources have blue mid-IR spectral energy distributions (alpha>0) with their infrared emission dominated by the host galaxy; the remaining 20% are not well-fit by a power law. Published IRAC color criteria for AGN select most of the red sources, but only some of the blue sources. As with all other known methods, selecting AGN with mid-IR colors will not produce a sample that is simultaneously complete and reliable. The IRAC SED type does not directly correspond to X-ray spectral type (hard/soft). The mid-IR properties of X-ray-detected Lyman-break, radio, submillimeter, and optically-faint sources vary widely and...

Herschel-ATLAS: far-infrared properties of radio-selected galaxies

Hardcastle, M. J.; Virdee, J. S.; Jarvis, M. J.; Bonfield, D. G.; Dunne, L.; Rawlings, S.; Stevens, J. A.; Christopher, N. M.; Heywood, I.; Mauch, T.; Rigopoulou, D.; Verma, A.; Baldry, I. K.; Bamford, S. P.; Buttiglione, S.; Cava, A.; Clements, D. L.; Co
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/09/2010
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We use the Herschel-ATLAS science demonstration data to investigate the star-formation properties of radio-selected galaxies in the GAMA-9h field as a function of radio luminosity and redshift. Radio selection at the lowest radio luminosities, as expected, selects mostly starburst galaxies. At higher radio luminosities, where the population is dominated by AGN, we find that some individual objects are associated with high far-infrared luminosities. However, the far-infrared properties of the radio-loud population are statistically indistinguishable from those of a comparison population of radio-quiet galaxies matched in redshift and K-band absolute magnitude. There is thus no evidence that the host galaxies of these largely low-luminosity (Fanaroff-Riley class I), and presumably low-excitation, AGN, as a population, have particularly unusual star-formation histories. Models in which the AGN activity in higher-luminosity, high-excitation radio galaxies is triggered by major mergers would predict a luminosity-dependent effect that is not seen in our data (which only span a limited range in radio luminosity) but which may well be detectable with the full Herschel-ATLAS dataset.; Comment: 10 pages, 4 colour figures. Accepted for publication in MNRAS (Herschel special issue)

The Infrared Properties of Massive Stars in the Magellanic Clouds

Bonanos, A. Z.; Lennon, D. J.; Massa, D. L.; Sewilo, M.; Köhlinger, F.; Panagia, N.; van Loon, J. Th.; Evans, C. J.; Smith, L. J.; Meixner, M.; Gordon, K.; teams, the SAGE
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/10/2010
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We present results of our study of the infrared properties of massive stars in the Large and Small Magellanic Clouds, which are based on the Spitzer SAGE surveys of these galaxies. We have compiled catalogs of spectroscopically confirmed massive stars in each galaxy, as well as photometric catalogs for a subset of these stars that have infrared counterparts in the SAGE database, with uniform photometry from 0.3 to 24 microns in the UBVIJHKs+IRAC+MIPS24 bands. These catalogs enable a comparative study of infrared excesses of OB stars, classical Be stars, yellow and red supergiants, Wolf-Rayet stars, Luminous Blue Variables and supergiant B[e] stars, as a function of metallicity, and provide the first roadmaps for interpreting luminous, massive, resolved stellar populations in nearby galaxies at infrared wavelengths.; Comment: 5 pages, 1 figure, contribution to 39th Liege Astrophysical Colloquium, 'The multi-wavelength view of hot, massive stars'

The Great Observatories All-Sky LIRG Survey: Comparison of Ultraviolet and Far-Infrared Properties

Howell, Justin H.; Armus, Lee; Mazzarella, Joseph M.; Evans, Aaron S.; Surace, Jason A.; Sanders, David B.; Petric, Andreea; Appleton, Phil; Bothun, Greg; Bridge, Carrie; Chan, Ben H. P.; Charmandaris, Vassilis; Frayer, David T.; Haan, Sebastian; Inami, H
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/04/2010
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The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 Luminous Infrared Galaxies (LIRGs) selected from the IRAS Revised Bright Galaxy Sample (RBGS). The galaxies span the full range of interaction stages, from isolated galaxies to interacting pairs to late stage mergers. We present a comparison of the UV and infrared properties of 135 galaxies in GOALS observed by GALEX and Spitzer. For interacting galaxies with separations greater than the resolution of GALEX and Spitzer (2-6"), we assess the UV and IR properties of each galaxy individually. The contribution of the FUV to the measured SFR ranges from 0.2% to 17.9%, with a median of 2.8% and a mean of 4.0 +/- 0.4%. The specific star formation rate of the GOALS sample is extremely high, with a median value (3.9*10^{-10} yr^{-1}) that is comparable to the highest specific star formation rates seen in the Spitzer Infrared Nearby Galaxies Survey sample. We examine the position of each galaxy on the IR excess-UV slope (IRX-beta) diagram as a function of galaxy properties, including IR luminosity and interaction stage. The LIRGs on average have greater IR excesses than would be expected based on their UV colors if they obeyed the same relations as starbursts with L_IR < 10^{11}L_0 or normal late-type galaxies. The ratio of L_IR to the value one would estimate from the IRXg-beta relation published for lower luminosity starburst galaxies ranges from 0.2 to 68...

An ALMA Survey of Submillimetre Galaxies in the Extended Chandra Deep Field South: The Far-Infrared Properties of SMGs

Swinbank, Mark; Simpson, James; Smail, Ian; Harrison, Chris; Hodge, Jacqueline; Karim, Alex; Walter, Fabian; Alexander, Dave; Brandt, Niel; de Breuck, Carlos; da Cunha, Elizabete; Chapman, Scott; Coppin, Kristen; Danielson, Alice; Dannerbauer, Helmut; Dec
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We exploit ALMA 870um (345GHz) observations of submillimetre sources in the Extended Chandra Deep Field South to investigate the far-infrared properties of high-redshift submillimetre galaxies (SMGs). Using the precisely located 870um ALMA positions of 99 SMGs, together with 24um and radio imaging of this field, we deblend the Herschel/SPIRE imaging of this region to extract their far-infrared fluxes and colours. The median photometric redshifts for ALMA LESS (ALESS) SMGs which are detected in at least two SPIRE bands increases with wavelength of the peak in their SEDs, with z=2.3+/-0.2, 2.5+/-0.3 and 3.5+/-0.5 for the 250, 350 and 500-um peakers respectively. We find that 34 ALESS SMGs do not have a >3-sigma counterpart at 250, 350 or 500-um. These galaxies have a median photometric redshift of z=3.3+/-0.5, which is higher than the full ALESS SMG sample; z=2.5+/-0.2. Using the photometric redshifts together with the 250-870um photometry, we estimate the far-infrared luminosities and characteristic dust temperature of each SMG. The median infrared luminosity of the S_870um>2mJy SMGs is L_IR=(3.0+/-0.3)x10^{12}Lo(SFR=300+/-30Mo/yr). At a fixed luminosity, the characteristic dust temperature of these high-redshift SMGs is 2-3K lower than comparably luminous galaxies at z=0...

The Great Observatories All-sky LIRG Survey: Comparison of Ultraviolet and Far-infrared Properties

Howell, Justin H.; Armus, Lee; Mazzarella, Joseph M.; Evans, Aaron S.; Surace, Jason A.; Sanders, David B.; Petric, Andreea; Appleton, Phil; Bothun, Greg; Bridge, Carrie; Chan, Ben H. P.; Charmandaris, Vassilis; Frayer, David T.; Haan, Sebastian; Inami, H
Fonte: American Astronomical Society Publicador: American Astronomical Society
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 20/05/2010
Relevância na Pesquisa
467.21684%
The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 luminous infrared galaxies (LIRGs) selected from the IRAS Revised Bright Galaxy Sample (RBGS). The galaxies span the full range of interaction stages, from isolated galaxies to interacting pairs to late stage mergers. We present a comparison of the UV and infrared properties of 135 galaxies in GOALS observed by GALEX and Spitzer. For interacting galaxies with separations greater than the resolution of GALEX and Spitzer (~2"-6"), we assess the UV and IR properties of each galaxy individually. The contribution of the FUV to the measured star formation rate (SFR) ranges from 0.2% to 17.9%, with a median of 2.8% and a mean of 4.0% ± 0.4%. The specific star formation rate (SSFR) of the GOALS sample is extremely high, with a median value (3.9 × 10^(–10) yr^(–1)) that is comparable to the highest SSFRs seen in the Spitzer Infrared Nearby Galaxies Survey sample. We examine the position of each galaxy on the IR excess-UV slope (IRX-β) diagram as a function of galaxy properties, including IR luminosity and interaction stage. The LIRGs on average have greater IR excesses than would be expected based on their UV colors if they obeyed the same relations as starbursts with L_(IR) < 10^(11) L_☉ or normal late-type galaxies. The ratio of L_(IR) to the value one would estimate from the IRX-β relation published for lower luminosity starburst galaxies ranges from 0.2 to 68...

Spitzer Infrared Properties of Lyman α Emitters

Colbert, James W.; Scarlata, Claudia; Atek, Hakim; Teplitz, Harry
Fonte: Astronomical Society of the Pacific Publicador: Astronomical Society of the Pacific
Tipo: Book Section; PeerReviewed Formato: application/pdf
Publicado em //2011
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465.4141%
We present results on the infrared properties of Lyman α emitters. At z=0.3 we demonstrate that our sample of 50 GALEX-identified emitters possess the same extinction properties as similarly ultraviolet-bright galaxies at the same redshift. The AGN fraction for these z=0.3 sources is low, 10-20%, and they show no correlation between Lyα flux and total infrared luminosity. At z=2.4-3.1 we discuss a sample of Lyman α blobs. Roughly two thirds of these blobs have infrared counterparts with infrared and sub-mm colors indicating they are dominated by star formation. Of the six IRS spectra taken of blob counterparts, four show PAH features. Their equivalent widths indicate two are strongly star formation dominated, while the other two are mixed sources with a significant contribution from an AGN.

Near-infrared and Brg observations of post-AGB stars

van de Steene, Griet; van Hoof, Peter A M; Wood, Peter R
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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In this article we report further investigations of the IRAS selected sample of Planetary Nebula (PN) candidates that was presented in Van de Steene & Pottasch (1993). About 20% of the candidates in that sample have been detected in the radio and/or Ha and later confirmed as PNe. Here we investigate the infrared properties of the IRAS sources not confirmed as PNe. We observed 28 objects in the N-band of which 20 were detected and 5 were resolved, despite adverse weather conditions. We obtained medium resolution Brγ spectra and we took high resolution JHKL images of these 20 objects. We critically assessed the identification of the IRAS counterpart in the images and compared our identification with others in the literature. High spatial resolution and a telescope with very accurate pointing are crucial for correct identification of the IRAS counterparts in these crowded fields. Of sixteen positively identified objects, seven show Brγ in absorption. The absorption lines are very narrow in six objects, indicating a low surface gravity. Another six objects show Brγ in emission. Two of these also show photospheric absorption lines. All emission line sources have a strong underlying continuum, unlike normal PNe. In another three objects...

Herschel-ATLAS: Far-infrared properties of radio-selected galaxies

Hardcastle, M; Virdee, J S; Jarvis, M; Bonfield, D G; Dunne, L; Rawlings, Steve; Stevens, J A; Christopher, N. M.; Heywood, I; Mauch, Thomas; Sharp, Robert
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
460.61656%
We use the Herschel-Astrophysical Terahertz Large Area Survey (ATLAS) science demonstration data to investigate the star formation properties of radio-selected galaxies in the GAMA-9h field as a function of radio luminosity and redshift. Radio selection at the lowest radio luminosities, as expected, selects mostly starburst galaxies. At higher radio luminosities, where the population is dominated by active galactic nuclei (AGN), we find that some individual objects are associated with high far-infrared luminosities. However, the far-infrared properties of the radio-loud population are statistically indistinguishable from those of a comparison population of radio-quiet galaxies matched in redshift and K-band absolute magnitude. There is thus no evidence that the host galaxies of these largely low-luminosity (Fanaroff-Riley class I), and presumably low-excitation, AGN, as a population, have particularly unusual star formation histories. Models in which the AGN activity in higher luminosity, high-excitation radio galaxies is triggered by major mergers would predict a luminosity-dependent effect that is not seen in our data (which only span a limited range in radio luminosity) but which may well be detectable with the full Herschel-ATLAS data set.