Global Extinction in Spiral Galaxies

Observations show that the slope of the inner part of the H$\alpha$/[NII] rotation curves of disk galaxies is depressed by extinction: at fixed luminosity, the observed slope is in fact seen to depend on the disk inclination to the line of sight. Using a simple extinction model, we are able to reproduce well the observed trends. The model assumes an exponential distribution, both in the radial and $z$ directions, identical for star--forming regions and dust. Fits to the data ...

The observed properties of galaxies vary with inclination; for most applications we would rather have properties that are independent of inclination, intrinsic properties. One way to determine inclination corrections is to consider a large sample of galaxies, study how the observed properties of these galaxies depend on inclination and then remove this dependence to recover the intrinsic properties. We perform such an analysis for galaxies selected from the Sloan Digital Sky ...

Based on our sample of 10095 galaxies with bulge-disc decompositions we derive the empirical B-band internal attenuation--inclination relation for galaxy discs and their associated central bulges. Our results agree well with the independently derived dust models of Tuffs et al., leading to a direct constraint on the mean opacity of spiral discs of Tau_B^f = 3.8 +/- 0.7 (central face-on B-band opacity). Depending on inclination, the B-band attenuation correction varies from 0....

This paper addresses the issue of how best to correct astronomical data for the wavelength-dependent effects of Galactic interstellar extinction. The main general features of extinction from the IR through the UV are reviewed, along with the nature of observed spatial variations. The enormous range of extinction properties found in the Galaxy, particularly in the UV spectral region, is illustrated. Fortunately, there are some tight constraints on the wavelength dependence of ...

We probe the dust extinction through the foreground disk of the overlapping galaxy pair UGC 5041 by analyzing B,I, and H band images. The inclined foreground disk of this infrared-selected pair is almost opaque in B at a projected distance of ~8kpc. From the images, we estimate directly the area-weighted distribution of differential near-IR extinction: it is nearly Gaussian with <tau_I-tau_H>=0.6 and sigma=0.27. For a homogenous dust distribution and a Milky Way extinction cu...

The inclination of galaxies induces both reddening and extinction to their observed spectral energy distribution, which in turn impact the derived properties of the galaxies. Here we report a significant dependence of the error in photometric redshift (photo-z) on the inclination of disk galaxies from the Sloan Digital Sky Survey. The bias in the photo-z based on the template-fitting approach increases from -0.015 in face-on to 0.021 in edge-on galaxies. A Principal Component...

Using the Millennium Galaxy Catalogue we quantify the dependency of the disc and bulge luminosity functions on galaxy inclination. Using a contemporary dust model we show that our results are consistent with galaxy discs being optically thick in their central regions (tau_B^f=3.8+/-0.7). As a consequence the measured B-band fluxes of bulges can be severely attenuated by 50% to 95% depending on disc inclination. We argue that a galaxy's optical appearance can be radically tran...

We analyze the absolute magnitude (M_r) and color (u-r) of low redshift (z<0.06) galaxies in the Sloan Digital Sky Survey Data Release 6. galaxies with nearly exponential profiles (Sloan parameter fracDeV < 0.1) fall on the blue sequence of the color - magnitude diagram; if, in addition, these exponential galaxies have M_r < -19, they show a dependence of u-r color on apparent axis ratio q expected for a dusty disk galaxy. By fitting luminosity functions for exponential galax...

The emerging light from a galaxy is under the influence of its own interstellar medium, as well as its spatial orientation. Considering a sample of 2,239 local spiral galaxies in optical (SDSS u, g, r, i, and z) and infrared bands (WISE W1, W1), we study the dependency of the global intrinsic attenuation in spiral galaxies on their morphologies, sizes, and spatial inclinations. Reddening is minimal at the extremes of low mass and gas depletion and maximal in galaxies that are...

We present $K'$-band surface photometry of a sample of 31 inclined Sa-Scd galaxies, together with additional $J$- and $H$-band data for four of them. In this first paper of a series, profiles are presented, together with global and isophotal parameters. Our profiles are compared to similar $B$, $R$ and $I$ data collected from other sources. Three galaxies exhibit previously unknown small bars in their center, while in five others, such bars may also be present. Four objects p...