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MAPPING THE POLARIZATION OF THE RADIO-LOUD Ly<i>α</i>NEBULA B3 J2330+3927
You, Chang,Zabludoff, Ann,Smith, Paul,Yang, Yujin,Kim, Eunchong,Jannuzi, Buell,Prescott, Moire K. M.,Matsuda, Yuichi,Lee, Myung Gyoon American Astronomical Society 2017 The Astrophysical journal Vol.834 No.2
<P>Ly alpha nebulae, or 'Ly alpha blobs,' are extended (up to similar to 100 kpc), bright (L-Ly alpha greater than or similar to 10(43) erg s(-1)) clouds of Lya emitting gas that tend to lie in overdense regions at z similar to 2-5. The origin of the Lya emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband imaging polarimetry of a radio-loud Lya nebula, B3 J2330+3927, at z - 3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob's Lya emission peak, and its radio lobes align roughly with the blob's major axis. With the SPOL polarimeter on the 6.5 m MMT telescope, we map the total (Ly alpha + continuum) polarization in a grid of circular apertures of a radius of 0.'' 6 (4.4 kpc), detecting a significant (>2 sigma) polarization fraction P-% in nine apertures and achieving strong upper limits (as low as 2%) elsewhere. P-% increases from <2% at similar to 5 kpc from the blob center to 17% at similar to 15-25 kpc. The detections are distributed asymmetrically, roughly along the nebula's major axis. The polarization angles theta are mostly perpendicular to this axis. Comparing the Ly alpha flux to that of the continuum and conservatively assuming that the continuum is highly polarized (20%-100%) and aligned with the total polarization, we place lower limits on the polarization of the Lya emission P-%,P-Ly alpha ranging from no significant polarization at similar to 5 kpc from the blob center to 3%-17% at 10-25 kpc. Like the total polarization, the Ly alpha polarization detections occur more often along the blob's major axis.</P>
Discovery of a Very Large (≈20 kpc) Galaxy at <i>z</i> = 3.72
Lee, Kyoung-Soo,Dey, Arjun,Matheson, Thomas,Shi, Ke,Hung, Chao-Ling,Xue, Rui,Inami, Hanae,Huang, Yun,Lee, Khee-Gan,Ashby, Matthew L. N.,Jannuzi, Buell,Reddy, Naveen,Hong, Sungryong,Mo, Wenli,Malavasi, American Astronomical Society 2018 The Astrophysical journal Vol.862 No.1
<P>We report the discovery and spectroscopic confirmation of a very large star-forming galaxy, G6025, at z(spec) = 3.721 +/- 0.003. In the rest frame approximate to 2100 angstrom, G6025 subtends approximate to 24 kpc in physical extent when measured from the 1.5 sigma isophote, in agreement with the parametric size measurements that yield a half-light radius of 4.9 +/- 0.5 kpc and a semimajor axis of 12.5 +/- 0.1 kpc. It is also very UV-luminous (approximate to 5L(UV,z similar to 4)*) and young (approximate to 140 +/- 60 Myr). Despite its unusual size and luminosity, the stellar population parameters and dust reddening (M-star similar to M-z similar to 4*( )and E(B - V) similar to 0.18 +/- 0.05) estimated from the integrated light are similar to those of smaller galaxies at comparable redshifts. The ground-based morphology and spectroscopy show two dominant components, both located off-center, embedded in more diffuse emission. We speculate that G6025 may be a scaled-up version of chain galaxies seen in deep HST imaging or, alternatively, a nearly equal-mass merger involving two super-L* galaxies in its early stage. It lies close to but not within a known massive protocluster at z = 3.78. We find four companions within 6 Mpc from G6025, two of which lie within 1.6 Mpc. While the limited sensitivity of the existing spectroscopy does not allow us to robustly characterize the local environment of G6025, it likely resides in a locally overdense environment. The luminosity, size, and youth of G6025 make it uniquely suited to study the early formation of massive galaxies in the universe.</P>