The dipole anisotropy of the 2 Micron All-Sky Redshift Survey |
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| Authors: | P Erdo&#;du J P Huchra O Lahav M Colless R M Cutri E Falco T George T Jarrett D H Jones C S Kochanek L Macri J Mader N Martimbeau M Pahre Q Parker A Rassat W Saunders |
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| Institution: | Department of Physics, Middle East Technical University, 06531 Ankara, Turkey;School of Physics &Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD;Harvard-Smithsonian Center of Astrophysics, 60 Garden Street, MS-20, Cambridge, MA 02138, USA;Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT;Anglo-Australian Observatory, PO Box 296, Epping, NSW 2052, Australia;Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA;California Institute of Technology, 4800 Oak Grove Drive, 302-231, Pasadena, CA 91109, USA;Research School of Astronomy and Astrophysics, Mount Stromlo, and Siding Spring Observatories, Cotter Road, Weston Creek, ACT 2611, Australia;Department of Astronomy, Ohio State University, 4055 McPherson Lab, 140 West 18th Avenue, Columbus, OH 43221, USA;National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85726, USA;W.M. Keck Observatory, Kamuela, HI 96743, USA;Department of Physics, Macquarie University, Sydney, NWS 2109, Australia;Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ |
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| Abstract: | We estimate the acceleration on the Local Group (LG) from the 2 Micron All-Sky Redshift Survey (2MRS). The sample used includes about 23 200 galaxies with extinction-corrected magnitudes brighter than K s= 11.25 and it allows us to calculate the flux-weighted dipole. The near-infrared flux-weighted dipoles are very robust because they closely approximate a mass-weighted dipole, bypassing the effects of redshift distortions and require no preferred reference frame. This is combined with the redshift information to determine the change in dipole with distance. The misalignment angle between the LG and the cosmic microwave background (CMB) dipole drops to 12°± 7° at around 50 h ?1 Mpc , but then increases at larger distances, reaching 21°± 8° at around 130 h ?1 Mpc . Exclusion of the galaxies Maffei 1, Maffei 2, Dwingeloo 1, IC342 and M87 brings the resultant flux dipole to 14°± 7° away from the CMB velocity dipole. In both cases, the dipole seemingly converges by 60 h ?1 Mpc . Assuming convergence, the comparison of the 2MRS flux dipole and the CMB dipole provides a value for the combination of the mass density and luminosity bias parameters Ω0.6m/ b L= 0.40 ± 0.09 . |
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| Keywords: | methods: data analysis Local Group cosmology: observations large-scale structure of Universe infrared: galaxies |
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