The Clustering Dipole of the Local Universe from the Two Micron All Sky Survey

The unprecedented sky coverage and photometric uniformity of the Two MicronAll Sky Survey (2MASS) provides a rich resource for investigating the galaxiespopulating the local Universe. A full characterization of the large-scaleclustering distribution is important for theoretical studies of structureformation. 2MASS offers an all-sky view of the local galaxy population at 2.15micron, unbiased by young stellar light and minimally affected by dust. We use2MASS to map the local distribution of galaxies, identifying the largeststructures in the nearby universe. The inhomogeneity of these structures causesan acceleration on the Local Group of galaxies, which can be seen in the dipoleof the Cosmic Microwave Background (CMB). We find that the direction of the2MASS clustering dipole is 11 degrees from the CMB dipole, confirming that thelocal galaxy distribution accelerates the Local Group. From the magnitude ofthe dipole we find a value of the linear bias parameter b=1.37 +/- 0.3 in theK_s-band. The 2MASS clustering dipole is 19 degrees from the latest measurementof the dipole using galaxies detected by the Infrared Astronomical Satellite(IRAS) suggesting that bias may be non-linear in some wavebands.