相关论文: Dark Halos of Spiral Galaxies: ISO photometry

We present a search for near-infrared (3.5-5 micron) emission from baryonic dark matter in the form of low-mass stars and/or brown dwarfs in the halo of the nearby edge-on spiral galaxy NGC 5907. The observations were made using a 256 by…

The presence of unseen halos of ``dark matter'' has long been inferred from the high rotation speeds of gas and stars in the outer parts of spiral galaxies$^{1}$. The volume density of this dark matter decreases less quickly from the…

NGC 2915 is a nearby blue compact dwarf with the HI properties of a late-type spiral. Its large, rotating HI disk (extending out to R ~ 22 B-band scale lengths) and apparent lack of stars in the outer HI disk make it a useful candidate for…

We have used dedicated 0.7m telescopes in California and Israel to image the halos of ~200 galaxies in the Local Volume to 29 mag/sq arcsec, the sample mainly drawn from the 2MASS Large Galaxy Atlas (LGA). We supplement the LGA sample with…

Galaxies are thought to grow through accretion; as less massive galaxies are disrupted and merge over time, their debris results in diffuse, clumpy stellar halos enveloping the central galaxy. Here we present a study of the variation in the…

This study presents first results from an X-ray mini-survey carried out with XMM-Newton to investigate the diffuse Hot Ionized Medium in the halos of nine nearby star-forming edge-on spiral galaxies. Diffuse gaseous X-ray halos are detected…

We present H-band images obtained with NICMOS of a field 75'' (5kpc) above the plane of the disk of the edge-on spiral galaxy NGC 5907. Ground-based observations have shown that NGC 5907 has a luminous halo with a shallow radial profile…

NGC 2915 is a blue compact dwarf galaxy embedded in an extended, low surface brightness HI disk exhibiting a two-armed spiral structure and a central bar-like component. Commonly accepted mechanisms are unable to explain the existence of…

Abridged abstract: We present HI synthesis observations of the weak blue compact dwarf (BCD) galaxy NGC~2915. NGC~2915 has the HI properties of a late type spiral galaxy (Sd - Sm), including a double horn global profile, and HI spiral arms.…

Hot gaseous halos are predicted around all large galaxies and are critically important for our understanding of galaxy formation, but they have never been detected at distances beyond a few kpc around a spiral galaxy. We used the Chandra…

Dwarf galaxies are dominated by dark matter even in the innermost regions and, therefore, provide excellent probes for the investigation of dark halos. To that purpose, we analyse ROSAT PSPC-data of the dwarf galaxy NGC 247. We focus in…

We derive the oblateness parameter q of the dark matter halo of a sample of gas rich, face-on disk galaxies. We have assumed that the halos are triaxial in shape but their axes in the disk plane (a and b) are equal, so that q=c/a measures…

Various theoretical models predict the existence of extended $\gamma$-ray halo around normal galaxies that could be produced by interactions of cosmic rays with the circumgalactic medium or by annihilation or decay of hypothetical dark…

Recent HST and ISO observations provide very severe limits on any compact baryonic contributions to galactic (dark) halos. When combined with Milky Way Galaxy microlensing results, almost the entire plausible range of massive compact…

Galaxy halos appear to be missing a large fraction of their baryons, most probably hiding in the circumgalactic medium (CGM), a diffuse component within the dark matter halo that extends far from the inner regions of the galaxies. A…

The opacity of spiral galaxies is examined by modelling the dust and stellar content of individual galaxies. The model is applied to five late-type spiral galaxies (NGC 4013, IC 2531, UGC 1082, NGC 5529 and NGC 5907). Having analyzed a…

The Circum-Galactic Medium of MASsive Spirals (CGM-MASS) is a project studying the overall content, physical and chemical properties, and spatial distributions of the multi-phase circum-galactic medium (CGM) around a small sample of the…

We report HI observations of eight spiral galaxies that are strongly lensing background sources. Our targets were selected from the Sloan WFC (Wide Field Camera) Edge-on Late-type Lens Survey (SWELLS) using the Arecibo, Karl G. Jansky Very…

(Abridged) We present H-alpha images of five edge-on galaxies: NGC 891, NGC 4631, NGC 4244, NGC 3003, and UGC 9242. We also analyze [SII] 6717+6731A and [OIII] 5007A images of NGC 4631. We analyze the ionized gas content, with particular…

We present a direct detection of the stellar halo of the edge-on S0 galaxy NGC 3957, using ultra-deep VLT/VIMOS V and R images. This is achieved with a sky subtraction strategy based on infrared techniques. These observations allow us to…