共查询到20条相似文献,搜索用时 15 毫秒
1.
The relationships between the monochromatic luminosity of Seyfert galaxies at frequencies of 0.408, 1.49, and 4.85 GHz and the integrated luminosity in the far infrared (IR) range are investigated. At all radio frequencies they are linear and equally close. Some Seyfert galaxies, of morphological types S0/a, E, and S0, have a far higher radio luminosity than Seyfert spiral galaxies with the same IR luminosity. Most of them are found to have compact central radio components. Seyfert spiral galaxies follow the same relationship between radio and IR emission as non-Seyfert spiral galaxies. The relationships between radio and IR luminosity for the individual groups of galaxies of spectral types Sy 1-Sy 1.5 and Sy 1.8-Sy 2 are also linear. 相似文献
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F01 CONDOR – 1.4 THz Hetrodyne Receiver for APEX and for GREAT on SOFIA F02 FLASH – a First Light APEX Submillimeter Heterodyne instrument F03 GREAT – The German first light heterodyne instrument for SOFIA F04 CHAMP+ – A powerfull submillimeter array for the APEX telescope F05 The JamesWebb Space Telescope (JWST) and its Mid Infrared Instrument (MIRI) F06 CHARM – a Compact Heterodyne Array Receiver Module for KOSMA with Scalable Fully Reflective Focal Plane Array Optics F07 Science with Herschel‐PACS F08 CI/CO Mapping of IC 348 & Cepheus B using SMART on KOSMA F09 The warm and dense interstellar medium observed with Herschel F10 Intelligent Detectors – On‐Board Data Reduction for Future Missions F11 The Herschel Photodetector Array Camera & Spectrometer PACS F12 Why Astromineralogy Should Care about the Far‐infrared Range F13 ESI: A European Imaging Far‐Infrared Spectrometer for the Japanese SPICA space observatory F14 STAR – A 16 Pixel Terahertz Array Receiver for SOFIA F15 FIFI LS, a Field‐Imaging Far‐Infrared Line‐Spectrometer for SOFIA F16 Characterization of high‐ and low‐stressed Ge:Ga array cameras for Herschel's PACS instrument F17 Herschel / PACS Guaranteed Time Programs at MPIA F18 NANTEN2: CI and mid‐J CO surveys of clouds and galaxies of the southern sky 相似文献
4.
The relationships among the monochromatic luminosities at 0.408, 1.4, and 4.85 GHz and the integrated luminosity in the far-infrared (IR) range for galaxies of the liner type (galaxies with low-ionization, narrow-emission regions) are investigated. At all the frequencies there is a close correlation between radio luminosity and IR luminosity for liners. The character of the relationship between the radio and IR luminosities of spiral liners differs from that for spiral normal and spiral Seyfert galaxies. For the latter this relationship is linear in a wide radio range. For spiral liners it may have a nonlinear character. The scatter (standard deviation) around the regression line for the relationship between radio and IR luminosities is considerably larger for spiral liners. The ratio of the emission fluxes in the far-IR range and in the radio range is larger, on the average, for spiral liners than for normal and Seyfert spiral galaxies. 相似文献
5.
Results of radio observations of luminous and ultraluminous infrared galaxies are discussed. The declining or flattening of the radio spectra of compact and (in some cases) extended sources found using interplanetary scintillation observations at 102 MHz is accounted for by absorption in thermal plasma, in agreement with the observed brightness of optical emission lines. It is argued that a region of violent star formation occupies the area of a molecular disc 1 kpc in size. The discrepancy between the linear sizes of the compact radio sources and the star forming regions is discussed. 相似文献
6.
IRAS在12,25,60和100μm的巡天,给我们提供了研究各类星系红外辐射特性的可能。为了研究具有尘带的E和SO星系的红外辐射特性,我们利用了E.Sadler给出的完备的E和SO星系表。在该星系表中共列出248个夭体,其中38个被证记为IRAS点源,且又有确切的60和100μm的流量值。在这38个天体中有6个被列在K.Ebneter和B.Balik最新发表的具有全带的椭圆星系表中。我们以这6个星系作为具有尘带的E和SO星系的样本,其它32个没有尘带的E和SO星系即作为对照样本。为了讨论具有尘带的椭圆星系的红外辐射特性,我们利用非参数Mann-Whitney检验,对这两个样本的LIR和FIR/FB的分布作了讨论,结果是在对于置信度α=0.05的水平上,我们不能拒绝另一假设:这两个样本的LIR和FIR/FB的分布是相同的。对于同时具有25,60和100μm确切流量的E和SO星系我们讨论了它们的双色图,结果发现,不具尘带的E和SO星系都处于Rowan-Robinson.et al所指出的正常星系区,而一些具有尘和带的ESO星系,则远离这一区域,它们是LINER和SEYFERT星系。 相似文献
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Roberto Fusco-Femiano 《Astrophysics and Space Science》2004,294(1-2):37-43
The most evident signature for the presence of non-thermal elements (magnetic fields and relativistic electrons) in clusters
of galaxies is given by the presence of diffuse radio regionspresent so far in a limited number of objects. We review the
recent discoveries of new spectral components by EUVE and BeppoSAX in the spectra of some clusters of galaxies that allow to better determine the non-thermalquantities by relating radio and
X-ray data.
In collaboration with: M. Orlandini, G. Brunetti, L. Feretti, G. Giovannini, P. Grandi, & G. Setti. 相似文献
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D.A. Dale 《Astrophysics and Space Science》2001,277(1):63-66
We have developed a new phenomenological model for the spectral energy distribution of normal star-forming galaxies between 3 and 1100 μm. These model spectra allow us to determine the infrared energy budget for normal galaxies, and in particular to translate far-infrared fluxes into total (bolometric) infrared fluxes. The 20 to 42 m range appears to show the most significant growth in relative terms as the activity level increases, suggesting that the 20–42 m continuum may be the best dust emission tracer of current star formation in galaxies. 相似文献
9.
D. Lutz R. Genzel D. Kunze D. Rigopoulou H.W.W. Spoon E. Sturm D. Tran A.F.M. Moorwood 《Astrophysics and Space Science》1999,266(1-2):85-90
Spectroscopy from the Infrared Space Observatory ISO has for the first timeprovided the sensitivity to exploit the diagnostic power ofmid-infrared fine structure lines and PAH features for the study ofultraluminous infrared galaxies (LIR >1012
L
). We report on observations obtainedwith SWS, ISOPHOT-S, and the CVF option of ISOCAM. From both fine structure lines and PAH features, we find that the majority of ULIRGs is predominantlypowered by star formation. Our total sample of about 75 ULIRGs allows tosearch for trends within the class of ULIRGs: The fraction of AGNs increaseswith luminosity above 3 × 1012L but there is no obvioustrend for ULIRGs to be more AGN-like with more advanced merger phase. 相似文献
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D.L. Clements 《Astrophysics and Space Science》1999,266(1-2):233-242
We discuss two significant recent developments in the far-IRwith relevance to the study of Ultraluminous Infrared Galaxies(ULIRGs). The first of these is the discovery of an isotropiccosmological infrared background radiation (CIB). This has beendetected in observations by two different instruments (FIRAS (Puget etal. 1996, Hauser et al. 1998) and DIRBE (Fixsen et al. 1998)) aboardthe COBE satellite, with consistent results. The second concernsobservations with the ISO satellite at 175m. Several groups haveconducted deep surveys with ISO at its most sensitive, longwavelength, 175m. If one assumes that the CIB is a coaddition ofdiscrete sources, it is entirely possible that deep long wavelengthobservations with ISO can detect these objects (Guiderdoni et al.1997). Several groups have undertaken such observations (eg. Puget etal. 1998, Kawara et al. 1998), and it would appear that a large numberof faint far-IR sources have been found. For the FIRBACK survey, whichis discussed in detail, covering about 4 sq. deg. to 175m fluxlimits of 100mJy, we are detecting 100 sources persq. deg., which amounts to about 10% of the CIB. The presence of theCIB at these flux levels, and its apparent origin as the integratedflux from numerous point sources, suggests that dust obscuration playsan important role in the early universe. We speculate that the sourcescontributing to the CIB may be a population of ULIRG-like objects atmoderate to high redshift. 相似文献
11.
M. S. Yun J. E. Hibbard J. J. Condon Naveen Reddy 《Astrophysics and Space Science》1999,266(1-2):29-34
An analysis of radio and FIR emission in over 1500IRAS selected galaxies produces a good linear correlationbetween radio and FIR luminosity, indicating that star formationin normal field galaxies dominates the infrared luminosityin the local volume. Galaxies with clear radio-excess (definedas having at least5 times larger radio flux over expected from FIR) are identified as hosting a radio AGN, and they account for onlyabout 1% of the whole sample. This fraction increases to 10% among themore luminous galaxies with L
1.4GHz 1023 W Hz-1 (equivalently L
60m 1011 L), however. The characteristic mid-IR excess of a Seyfert nucleus is ubiquitously present amongthe radio-excess objects, suggesting that mid-IR excess isa robust tracer of an AGN despite the high mid-IR opacity.We conclude that about 30% of the luminous infrared galaxies(L
60m 1011 L) host an AGN based on themid-IR excess, and about 40% of the mid-IR excess AGNs alsohost a radio AGN. A VLA imaging survey of a distance limited sample of IR luminousgalaxies has revealed the presence of 100 kpc scale giant radioplumes in 3 out of 9 cases (Mrk 231, Mrk 273, NGC 6240). Theirlarge spatial extent, energetics, and presence of a powerful AGN in each case suggests that an AGN is the power source. Such plumesare not detected in other ultraluminous infrared galaxies which lack clear evidence for an AGN, such as Arp 220. 相似文献
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根据25μm和60μm间的红外谱指数及60μm和100μm的相对流量选择了6个天体,在1994年9月9日至11日期间,利用北京天文台2.16m望远镜观测了它们的光谱。经处理后,发现了一个新的Seyfert2和一个Seyfert3星系,另外还有一个HII星系。 相似文献
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Jian-Ling Wang 《中国天文和天体物理学报》2008,8(6)
We used the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) to study the morphological properties of 1137 nearby infrared (IR) galaxies, most of which are brighter than 15.9 mag in r-band. This sample was drawn from a cross-correlation of the Infra-Red Astronomical Satellite (IRAS) point source catalog redshift survey with DR5 at z(≤)0.08. Based on this IR galaxy sample, we constructed five volume-limited sub-samples with IR luminosity ranging from 109.5L⊙ to 1012L⊙. By deriving the IR luminosity functions (LF) for different morphological types, we found that normal spiral galaxies are the dominant population below LIR~ 8 × 1010 L⊙; while the fraction of barred spiral galaxies increases with increasing IR luminosity and becomes dominant in spiral galaxies beyond LIR(≈) 5×1010L⊙. As the IR luminosity decreases, the IR galaxies become more compact and have lower stellar masses. The analysis also shows that normal spiral galaxies give the dominant contribution to the total comoving IR energy density in the nearby universe, while, in contrast, the contribution from peculiar galaxies is only 39%. 相似文献
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We present HST (WFPC2 and FOC) images and UV GHRS spectraplus ground-based optical spectra of four Luminous Infrared Galaxies (LIRGs) that have Seyfert 2nuclei (Mrk 477, NGC 7130, NGC 5135 and IC 3639). The data provide direct evidence of the existence of a central nuclearstarburst that dominates the UV and optical light and are dusty and compact. The bolometricluminosity ( 1010 L) of these starbursts is similar to the estimated bolometric luminosities of their obscured Seyfert 1 nuclei, and thus they contributein the same amount to the overall energetics of these galaxies. An extended work based on ground-based optical spectra of the 20 brightest nuclei known indicate that at least 40%of the Seyfert 2 galaxies harbor a nuclear starburst. The eight Seyfert 2 nuclei thatharbor a starburst are strong IR emitters. This suggests that nuclear starbursts can make a significant contribution or even dominate the UV and optical light of LIRGs. 相似文献
16.
In recent years the evolution of dust-enshrouded galaxies has become an important issue in cosmology. We present the results
of a study linking the high- and low-redshift populations of such galaxies. Previously, a simple hierarchical clustering model
was found to be successful in describing the high-redshift populations of dusty galaxies. This study showed that strong evolution
could not be avoided in order to satisfy all the high-redshift infrared and submillimetre constraints. We now apply the same
model to the low-redshift data available, and find that the strong evolution inferred is compatible with the count and redshift
data we have from IRAS and ISO.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
17.
This study introduces a novel convolutional neural network, the WISE Galaxy Classification Network (WGC), for classifying spiral and elliptical galaxies using Wide-field Infrared Survey Explorer (WISE) images. WGC attains an accuracy of 89.03%, surpassing the combined use of K-means or SVM with the Color–Color method in more accurately identifying galaxy morphologies. The enhanced variant, WGC_mag, integrates magnitude parameters with image features, further boosting the accuracy to 89.89%. The ... 相似文献
18.
从1981年开始,北京天文台开展了发射线星系的物端稜镜巡天。用60/90cm Schmidt望远镜加5.°3的物端稜镜在敏化的ⅢaJ底片上可以得到亮于16~m的星系光谱像。本文公布了第一批巡天结果:在覆盖天区约220平方度的12张底片上证认出50个发射线天体,47个河外星系(其中3个可能是新的Seyfert星系),3个行星状星云(其中一个N2242以前被当作河外星系)。文中给出了这些天体的名称、坐标、星等及光谱结构分类等资料,并比较系统地讨论了发射线星系的证认及光谱结构分类。我们还将本巡天的结果与其他天文台的结果作了比较。这些天体的证认图见图版Ⅰ—Ⅱ。 相似文献
19.
Lei Shi Qiu-Sheng Gu Department of Astronomy Nanjing University Nanjing qsgu@nju.edu.cn 《中国天文和天体物理学报》2005,5(2):117-125
We present a study of the origin of infrared (IR) emission in the optically normal, infrared luminous galaxy NGC 4418. By decomposing the stellar absorption features and continua in the range of 3600-8000 A from the Sloan Digital Sky Survey into a set of simple stellar populations, we derive the stellar properties for the nuclear region of NGC 4418. We compare the observed infrared luminosity with the one derived from the starburst model, and find that star-forming activity contributes only 7% to the total IR emission, that as the IR emission region is spatially very compact, the most possible source for the greater part of the IR emission is a deeply embedded AGN, though an AGN component is found to be unnecessary for fitting the optical spectrum. 相似文献
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The rest-frame UV-to-optical flux ratio, which characterizes the "UV upturn" phenomenon, is potentially the most sensitive tracer of age in elliptical galaxies; models predict that it may change by orders of magnitude over the course of a few gigayears. In order to trace the evolution of the UV upturn as a function of redshift, we have used the far-UV camera on the Space Telescope Imaging Spectrograph to image the galaxy cluster CL 0016+16 at z=0.55. Our 25"x25" field includes four bright elliptical galaxies, spectroscopically confirmed to be passively evolving cluster members. The weak UV emission from the galaxies in our image demonstrates that the UV upturn is weaker at a look-back time approximately 5.6 Gyr earlier than our own, as compared to measurements of the UV upturn in cluster E and S0 galaxies at z=0 and z=0.375. These images are the first with sufficient depth to demonstrate the fading of the UV upturn expected at moderate redshifts. We discuss these observations and the implications for the formation history of galaxies. 相似文献