SPECTROPOLARIMETRY CONFIRMS CENTRAL POWERING IN A Lyα NEBULA AT z = 3.09

Journal Article · Sat Feb 20 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/818/2/138· OSTI ID:22521516

Beck, Melanie; Scarlata, Claudia; Jones, Terry J. ^[1]; Hayes, Matthew ^[2]; Dijkstra, Mark ^[3]

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1. Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 116 Church Street, Minneapolis, MN 55455 (United States)
2. Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden)
3. Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo (Norway)

We present a follow-up study to the imaging polarimetry performed by Hayes et al. on LAB1 in the SSA22 protocluster region. Arguably the most well-known Lyα “blob,” this radio-quiet emission-line nebula likely hosts a galaxy that either is undergoing significant star formation or hosts an active galactic nucleus, or both. We obtain deep, spatially resolved spectropolarimetry of the Lyα emission and detect integrated linear polarization of 9%–13% ± 2%–3% at a distance of approximately 15 kpc north and south of the peak of the Lyα surface brightness with polarization vectors lying tangential to the galactic central source. In these same regions, we also detect a wavelength dependence in the polarization that is low at the center of the Lyα line profile and rises substantially in the wings of the profile. These polarization signatures are easily explained by a weak outflowing shell model. The spectral dependence of the polarization presented here provides a framework for future observations and interpretations of the southern portion of LAB1 in that any model for this system must be able to reproduce this particular spectral dependence. However, questions still remain for the northernmost spur of LAB1. In this region we detect total linear polarization of between 3% and 20% at the 5% significance level. Simulations predict that polarization should increase with radius for a symmetric geometry. That the northern spur does not suggests either that this region is not symmetric (which is likely) and exhibits variations in columns density or that it is kinematically distinct from the rest of LAB1 and powered by another mechanism altogether.

• OSTI ID: 22521516
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 818; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
APPROXIMATIONS
BRIGHTNESS
DENSITY
FREQUENCY DEPENDENCE
GALAXIES
GALAXY NUCLEI
NEBULAE
POLARIMETRY
POLARIZATION
RED SHIFT
STAR CLUSTERS
STARS
SURFACES
SYMMETRY