arXiv subjects

C. R. Lawrence

Publications and source records attributed to C. R. Lawrence.

At least 55 records · Page 3Linked to original sources

arXiv2016

Planck intermediate results. XLIII. The spectral energy distribution of dust in clusters of galaxies

Although infrared (IR) overall dust emission from clusters of galaxies has been statistically detected using data from the Infrared Astronomical Satellite (IRAS), it has not been possible to sample the spectral energy distribution (SED) of this emission over its peak, and thus to break the degeneracy between dust temperature and mass. By complementing the IRAS spectral coverage with Planck satellite data from 100 to 857 GHz, we provide new constraints on the IR spectrum of thermal dust emission in clusters of galaxies. We achieve this by using a stacking approach for a sample of several hundred objects from the Planck cluster sample; this procedure averages out fluctuations from the IR sky, allowing us to reach a significant detection of the faint cluster contribution. We also use the large frequency range probed by Planck, together with component-separation techniques, to remove the contamination from both cosmic microwave background anisotropies and the thermal Sunyaev-Zeldovich effect (tSZ) signal, which dominate below 353 GHz. By excluding dominant spurious signals or systematic effects, averaged detections are reported at frequencies between 353 and 5000 GHz. We confirm the presence of dust in clusters of galaxies at low and intermediate redshifts, yielding an SED with a shape similar to that of the Milky Way. Planck's beam does not allow us to investigate the detailed spatial distribution of this emission (e.g., whether it comes from intergalactic dust or simply the dust content of the cluster galaxies), but the radial distribution of the emission appears to follow that of the stacked SZ signal, and thus the extent of the clusters. The recovered SED allows us to constrain the dust mass responsible for the signal, as well as its temperature. We additionally explore the evolution of the IR emission as a function of cluster mass and redshift.

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arXiv2016

Planck Intermediate Results. XXXVI. Optical identification and redshifts of Planck SZ sources with telescopes in the Canary Islands Observatories

We present the results of approximately three years of observations of Planck Sunyaev-Zeldovich (SZ) sources with telescopes at the Canary Islands observatories as part of the general optical follow-up programme undertaken by the Planck collaboration. In total, 78 SZ sources are discussed. Deep-imaging observations were obtained for most of these sources; spectroscopic observations in either in long-slit or multi-object modes were obtained for many. We effectively used 37.5 clear nights. We found optical counterparts for 73 of the 78 candidates. This sample includes 53 spectroscopic redshift determinations, 20 of them obtained with a multi-object spectroscopic mode. The sample contains new redshifts for 27 Planck clusters that were not included in the first Planck SZ source catalogue (PSZ1).

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arXiv2016

Planck intermediate results. XXXI. Microwave survey of Galactic supernova remnants

The all-sky Planck survey in 9 frequency bands was used to search for emission from all 274 known Galactic supernova remnants. Of these, 16 were detected in at least two Planck frequencies. The radio-through-microwave spectral energy distributions were compiled to determine the emission mechanism for microwave emission. In only one case, IC 443, is there high-frequency emission clearly from dust associated with the supernova remnant.In all cases, the low-frequency emission is from synchrotron radiation. A single power law, as predicted for a population of relativistic particles with energy distribution that extends continuously to high energies, is evident for many sources, including the Crab and PKS 1209-51/52. A decrease in flux density relative to the extrapolation of radio emission is evident in several sources. Their spectral energy distributions can be approximated as broken power laws, $S_ν\proptoν^{-α}$, with the spectral index, alpha, increasing by 0.5-1 above a break frequency in the range 10-60 GHz. The break could be due to synchrotron losses.

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arXiv2016

Planck 2015 results. III. LFI systematic uncertainties

We present the current accounting of systematic effect uncertainties for the Low Frequency Instrument (LFI) that are relevant to the 2015 release of the Planck cosmological results, showing the robustness and consistency of our data set, especially for polarization analysis. We use two complementary approaches: (i) simulations based on measured data and physical models of the known systematic effects; and (ii) analysis of difference maps containing the same sky signal ("null-maps"). The LFI temperature data are limited by instrumental noise. At large angular scales the systematic effects are below the cosmic microwave background (CMB) temperature power spectrum by several orders of magnitude. In polarization the systematic uncertainties are dominated by calibration uncertainties and compete with the CMB $E$-modes in the multipole range 10--20. Based on our model of all known systematic effects, we show that these effects introduce a slight bias of around $0.2\,σ$ on the reionization optical depth derived from the 70\,GHz $EE$ spectrum using the 30 and 353\,GHz channels as foreground templates. At 30\,GHz the systematic effects are smaller than the Galactic foreground at all scales in temperature and polarization, which allows us to consider this channel as a reliable template of synchrotron emission. We assess the residual uncertainties due to LFI effects on CMB maps and power spectra after component separation and show that these effects are smaller than the CMB amplitude at all scales. We also assess the impact on non-Gaussianity studies and find it to be negligible. Some residuals still appear in null maps from particular sky survey pairs, particularly at 30 GHz, suggesting possible straylight contamination due to an imperfect knowledge of the beam far sidelobes.

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arXiv2015

Planck intermediate results. XXXVII. Evidence of unbound gas from the kinetic Sunyaev-Zeldovich effect

By looking at the kinetic Sunyaev-Zeldovich effect (kSZ) in Planck nominal mission data, we present a significant detection of baryons participating in large-scale bulk flows around central galaxies (CGs) at redshift $z\approx 0.1$. We estimate the pairwise momentum of the kSZ temperature fluctuations at the positions of the CGC (Central Galaxy Catalogue) samples extracted from Sloan Digital Sky Survey (DR7) data. For the foreground-cleaned maps, we find $1.8$-$2.5σ$ detections of the kSZ signal, which are consistent with the kSZ evidence found in individual Planck raw frequency maps, although lower than found in the WMAP-9yr W band ($3.3σ$). We further reconstruct the peculiar velocity field from the CG density field, and compute for the first time the cross-correlation function between kSZ temperature fluctuations and estimates of CG radial peculiar velocities. This correlation function yields a $3.0$-$3.7$$σ$ detection of the peculiar motion of extended gas on Mpc scales, in flows correlated up to distances of 80-100 $h^{-1}$ Mpc. Both the pairwise momentum estimates and kSZ temperature-velocity field correlation find evidence for kSZ signatures out to apertures of 8 arcmin and beyond, corresponding to a physical radius of $> 1$ Mpc, more than twice the mean virial radius of halos. This is consistent with the predictions from hydro simulations that most of the baryons are outside the virialized halos. We fit a simple model, in which the temperature-velocity cross-correlation is proportional to the signal seen in a semi-analytic model built upon N-body simulations, and interpret the proportionality constant as an "effective" optical depth to Thomson scattering. We find $τ_T=(1.4\pm0.5)\times 10^{-4}$; the simplest interpretation of this measurement is that much of the gas is in a diffuse phase, which contributes little signal to X-ray or thermal SZ observations.

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arXiv2015

Planck 2015 results. IV. Low Frequency Instrument beams and window functions

This paper presents the characterization of the in-flight beams, the beam window functions, and the associated uncertainties for the Planck Low Frequency Instrument (LFI). The structure of the paper is similar to that presented in the 2013 Planck release; the main differences concern the beam normalization and the delivery of the window functions to be used for polarization analysis. The in-flight assessment of the LFI main beams relies on measurements performed during observations of Jupiter. By stacking data from seven Jupiter transits, the main beam profiles are measured down to -25 dB at 30 and 44 GHz, and down to -30 dB at 70 GHz. It has been confirmed that the agreement between the simulated beams and the measured beams is better than 1% at each LFI frequency band (within the 20 dB contour from the peak, the rms values are 0.1% at 30 and 70 GHz; 0.2% at 44 GHz). Simulated polarized beams are used for the computation of the effective beam window functions. The error budget for the window functions is estimated from both main beam and sidelobe contributions, and accounts for the radiometer band shapes. The total uncertainties in the effective beam window functions are 0.7% and 1% at 30 and 44 GHz, respectively (at $\ell \approx 600$); and 0.5% at 70 GHz (at $\ell \approx 1000$).

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arXiv2015

Planck intermediate results. XXXVIII. E- and B-modes of dust polarization from the magnetized filamentary structure of the interstellar medium

The quest for a B-mode imprint from primordial gravity waves on the polarization of the cosmic microwave background (CMB) requires the characterization of foreground polarization from Galactic dust. We present a statistical study of the filamentary structure of the 353 GHz Planck Stokes maps at high Galactic latitude, relevant to the study of dust emission as a polarized foreground to the CMB. We filter the intensity and polarization maps to isolate filaments in the range of angular scales where the power asymmetry between E-modes and B-modes is observed. Using the Smoothed Hessian Major Axis Filament Finder, we identify 259 filaments at high Galactic latitude, with lengths larger or equal to 2° (corresponding to 3.5 pc in length for a typical distance of 100 pc). These filaments show a preferred orientation parallel to the magnetic field projected onto the plane of the sky, derived from their polarization angles. We present mean maps of the filaments in Stokes I, Q, U, E, and B, computed by stacking individual images rotated to align the orientations of the filaments. Combining the stacked images and the histogram of relative orientations, we estimate the mean polarization fraction of the filaments to be 11 %. Furthermore, we show that the correlation between the filaments and the magnetic field orientations may account for the E and B asymmetry and the $C_{\ell}^{TE}/C_{\ell}^{EE}$ ratio, reported in the power spectra analysis of the Planck 353 GHz polarization maps. Future models of the dust foreground for CMB polarization studies will need to take into account the observed correlation between the dust polarization and the structure of interstellar matter.

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arXiv2015

Planck intermediate results. XXXIX. The Planck list of high-redshift source candidates

The Planck mission, thanks to its large frequency range and all-sky coverage, has a unique potential for systematically detecting the brightest, and rarest, submillimetre sources on the sky, including distant objects in the high-redshift Universe traced by their dust emission. A novel method, based on a component-separation procedure using a combination of Planck and IRAS data, has been applied to select the most luminous cold submm sources with spectral energy distributions peaking between 353 and 857GHz at 5' resolution. A total of 2151 Planck high-z source candidates (the PHZ) have been detected in the cleanest 26% of the sky, with flux density at 545GHz above 500mJy. Embedded in the cosmic infrared background close to the confusion limit, these high-z candidates exhibit colder colours than their surroundings, consistent with redshifts z>2, assuming a dust temperature of 35K and a spectral index of 1.5. First follow-up observations obtained from optical to submm have confirmed that this list consists of two distinct populations. A small fraction (around 3%) of the sources have been identified as strongly gravitationally lensed star-forming galaxies, which are amongst the brightest submm lensed objects (with flux density at 545GHz ranging from 350mJy up to 1Jy) at redshift 2 to 4. However, the vast majority of the PHZ sources appear as overdensities of dusty star-forming galaxies, having colours consistent with z>2, and may be considered as proto-cluster candidates. The PHZ provides an original sample, complementary to the Planck Sunyaev-Zeldovich Catalogue; by extending the population of the virialized massive galaxy clusters to a population of sources at z>1.5, the PHZ may contain the progenitors of today's clusters. Hence the PHZ opens a new window on the study of the early ages of structure formation, and the understanding of the intensively star-forming phase at high-z.

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arXiv2015

Planck 2013 results. XXXI. Consistency of the Planck data

The Planck design and scanning strategy provide many levels of redundancy that can be exploited to provide tests of internal consistency. One of the most important is the comparison of the 70GHz and 100GHz channels. Based on different instrument technologies, with feeds located differently in the focal plane, analysed independently by different teams using different software, and near the minimum of diffuse foreground emission, these channels are in effect two different experiments. The 143GHz channel has the lowest noise level on Planck, and is near the minimum of unresolved foreground emission. In this paper, we analyse the level of consistency achieved in the 2013 Planck data. We concentrate on comparisons between the 70/100/143GHz channel maps and power spectra, particularly over the angular scales of the first and second acoustic peaks, on maps masked for diffuse Galactic emission and for strong unresolved sources. Difference maps covering angular scales from 8deg-15arcmin are consistent with noise, and show no evidence of cosmic microwave background structure. Including small but important corrections for unresolved-source residuals, we demonstrate agreement between 70 and 100GHz power spectra averaged over 70<l<390 at the 0.8% level, and agreement between 143 and 100GHz power spectra of 0.4% over the same l range. These values are within and consistent with the overall uncertainties in calibration given in the Planck 2013 results. We also present results based on the 2013 likelihood analysis showing consistency at the 0.35% between the 100/143/217GHz power spectra. We analyse calibration procedures and beams to determine what fraction of these differences can be accounted for by known approximations or systematic errors that could be controlled even better in the future, reducing uncertainties still further. Several possible small improvements are described...(abridged)

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arXiv2015

The Q/U Imaging ExperimenT: Polarization Measurements of the Galactic Plane at 43 and 95 GHz

We present polarization observations of two Galactic plane fields centered on Galactic coordinates (l,b)=(0 deg,0 deg) and (329 deg, 0 deg) at Q- (43 GHz) and W-band (95 GHz), covering between 301 and 539 square degrees depending on frequency and field. These measurements were made with the QUIET instrument between 2008 October and 2010 December, and include a total of 1263 hours of observations. The resulting maps represent the deepest large-area Galactic polarization observations published to date at the relevant frequencies with instrumental rms noise varying between 1.8 and 2.8 uK deg, 2.3-6 times deeper than corresponding WMAP and Planck maps. The angular resolution is 27.3' and 12.8' FWHM at Q- and W-band, respectively. We find excellent agreement between the QUIET and WMAP maps over the entire fields, and no compelling evidence for significant residual instrumental systematic errors in either experiment, whereas the Planck 44 GHz map deviates from these in a manner consistent with reported systematic uncertainties for this channel. We combine QUIET and WMAP data to compute inverse-variance-weighted average maps, effectively retaining small angular scales from QUIET and large angular scales from WMAP. From these combined maps, we derive constraints on several important astrophysical quantities, including a robust detection of polarized synchrotron spectral index steepening of ~0.2 off the plane, as well as the Faraday rotation measure toward the Galactic center (RM=-4000 +/- 200 rad m^-2), all of which are consistent with previously published results. Both the raw QUIET and the co-added QUIET+WMAP maps are made publicly available together with all necessary ancillary information.

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arXiv2015

Planck 2013 results. XXVII. Doppler boosting of the CMB: Eppur si muove

Our velocity relative to the rest frame of the cosmic microwave background (CMB) generates a dipole temperature anisotropy on the sky which has been well measured for more than 30 years, and has an accepted amplitude of v/c = 0.00123, or v = 369km/s. In addition to this signal generated by Doppler boosting of the CMB monopole, our motion also modulates and aberrates the CMB temperature fluctuations (as well as every other source of radiation at cosmological distances). This is an order 0.1% effect applied to fluctuations which are already one part in roughly one hundred thousand, so it is quite small. Nevertheless, it becomes detectable with the all-sky coverage, high angular resolution, and low noise levels of the Planck satellite. Here we report a first measurement of this velocity signature using the aberration and modulation effects on the CMB temperature anisotropies, finding a component in the known dipole direction, (l,b)=(264, 48) [deg], of 384km/s +- 78km/s (stat.) +- 115km/s (syst.). This is a significant confirmation of the expected velocity.

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arXiv2015

Planck intermediate results. XXXIII. Signature of the magnetic field geometry of interstellar filaments in dust polarization maps

Planck observations at 353GHz provide the first fully-sampled maps of the polarized dust emission towards interstellar filaments and their backgrounds. The polarization data provide insight on the structure of their magnetic field (B). We present the polarization maps of three nearby star forming filament of moderate column density (NH~10^22cm^-2): Musca, B211, and L1506. We use the spatial information to separate Stokes I, Q, and U of the filaments from those of their backgrounds, an essential step to measure the intrinsic polarization fraction (p) and angle (psi) of each emission component. We find that the polarization angles in the three filaments (psi_fil) are coherent along their lengths and not the same as in their backgrounds (psi_bg). The differences between psi_fil and psi_bg are 12deg, 6deg, and 54deg for Musca, B211, and L1506, respectively. These differences for Musca and L1506 are larger than the dispersions of psi, both along the filaments and in their backgrounds. The observed changes of psi are direct evidence for variations of the orientation of the plane of the sky (POS) projection of the B-field. As in previous studies, we find a decrease of several percent of p with NH. We show that the drop in p cannot be explained by random fluctuations of the orientation of B within the filaments because they are too small (sigma_psi<10deg). We recognize the degeneracy between dust alignment efficiency and the structure of B in causing variations in p, but we argue that the decrease of p from the backgrounds to the filaments results in part from depolarization associated with the 3D structure of B: both its orientation in the POS and with respect to the POS. We do not resolve the inner structure of the filaments, but at the smallest scales accessible with Planck (~0.2pc), the observed changes of psi and p hold information on the B-field structure within filaments.

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arXiv2015

Planck intermediate results. XXIII. Galactic plane emission components derived from Planck with ancillary data

Planck data when combined with ancillary data provide a unique opportunity to separate the diffuse emission components of the inner Galaxy. The purpose of the paper is to elucidate the morphology of the various emission components in the strong star-formation region lying inside the solar radius and to clarify the relationship between the various components. The region of the Galactic plane covered is l=300-0-60deg where star-formation is highest and the emission is strong enough to make meaningful component separation. The latitude widths in this longitude range lie between 1deg and 2deg, which correspond to FWHM z-widths of 100-200pc at a typical distance of 6kpc. The four emission components studied here are synchrotron, free-free, anomalous microwave emission (AME), and thermal (vibrational) dust emission. These components are identified by constructing spectral energy distributions (SEDs) at positions along the Galactic plane using the wide frequency coverage of Planck (28.4-857GHz) in combination with low-frequency radio data at 0.408-2.3GHz plus WMAP data at 23-94GHz, along with far-infrared (FIR) data from DIRBE and IRAS. The free-free component is determined from radio recombination line (RRL) data. AME is found to be comparable in brightness to the free-free emission on the Galactic plane in the frequency range 20-40GHz with a width in latitude similar to that of the thermal dust; it comprises 45+/-1% of the total 28.4GHz emission in the longitude range l=300-0-60deg. The free-free component is the narrowest, reflecting the fact that it is produced by current star-formation as traced by the narrow distribution of OB stars. It is the dominant emission on the plane between 60 and 100GHz. RRLs from this ionized gas are used to assess its distance, leading to a free-free z-width of FWHM ~100pc...(abridged)

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arXiv2015

Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization

Planck has mapped the intensity and polarization of the sky at microwave frequencies with unprecedented sensitivity. We make use of the Planck 353 GHz I, Q, and U Stokes maps as dust templates, and cross-correlate them with the Planck and WMAP data at 12 frequencies from 23 to 353 GHz, over circular patches with 10 degree radius. The cross-correlation analysis is performed for both intensity and polarization data in a consistent manner. We use a mask that focuses our analysis on the diffuse interstellar medium at intermediate Galactic latitudes. We determine the spectral indices of dust emission in intensity and polarization between 100 and 353 GHz, for each sky-patch. The mean values, $1.59\pm0.02$ for polarization and $1.51\pm0.01$ for intensity, for a mean dust temperature of 19.6 K, are close, but significantly different ($3.6\,σ$). We determine the mean spectral energy distribution (SED) of the microwave emission, correlated with the 353 GHz dust templates, by averaging the results of the correlation over all sky-patches. We find that the mean SED increases for decreasing frequencies at $ν< 60$ GHz, for both intensity and polarization. The rise of the polarization SED towards low frequencies may be accounted for by a synchrotron component correlated with dust, with no need for any polarization of the anomalous microwave emission. We use a spectral model to separate the synchrotron and dust polarization and to characterize the spectral dependence of the dust polarization fraction. The polarization fraction ($p$) of the dust emission decreases by $(21\pm6)$ % from 353 to 70 GHz. The decrease of $p$ could indicate differences in polarization efficiency among components of interstellar dust (e.g., carbon versus silicate grains). Our observational results provide inputs to quantify and optimize the separation between Galactic and cosmological polarization.

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arXiv2015

Planck intermediate results. XXVII. High-redshift infrared galaxy overdensity candidates and lensed sources discovered by Planck and confirmed by Herschel-SPIRE

[Abridged] We use the Planck all-sky submm and mm maps to search for rare sources distinguished by extreme brightness, a few hundreds of mJy, and their potential for being situated at high redshift. These "cold" Planck sources, selected using the High Frequency Instrument (HFI) directly from the maps and from the Planck Catalogue of Compact Sources (PCCS), all satisfy the criterion of having their rest-frame far-infrared peak redshifted to the frequency range 353 and 857 GHz. This colour-selection favours galaxies in the redshift range z=2-4, which we consider as cold peaks in the cosmic infrared background (CIB). We perform a dedicated Herschel-SPIRE follow-up of 234 such Planck targets, finding a significant excess of red 350 and 500um sources, in comparison to reference SPIRE fields. About 94% of the SPIRE sources in the Planck fields are consistent with being overdensities of galaxies peaking at 350um. About 3% are candidate lensed systems, all 12 of which have secure spectroscopic confirmations, placing them at redshifts z>2.2. The galaxy overdensities are detected with high significance, half of the sample showing statistical significance above 10sigma. The SPIRE photometric redshifts of galaxies in overdensities suggest a peak at z~2. Under the Td=35K assumption, we derive an infrared (IR) luminosity for each SPIRE source of about 4x10^12 Lsun, yielding star formation rates of typically 700 Msun.yr^-1. If the observed overdensities are actual gravitationally-bound structures, the total total star formation rates reaches 7x10^3 Msun.yr^-1. Taken together, these sources show the signatures of high-z (z>$) protoclusters of intensively star-forming galaxies. All these observations confirm the uniqueness of our sample and demonstrate the ability of the all-sky Planck-HFI cold sources to select populations of cosmological and astrophysical interest for structure formation studies.

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arXiv2015

Planck intermediate results. XXI. Comparison of polarized thermal emission from Galactic dust at 353 GHz with interstellar polarization in the visible

The Planck survey provides unprecedented full-sky coverage of the submillimetre polarized emission from Galactic dust, bringing new constraints on the properties of dust. The dust grains that emit the radiation seen by Planck in the submillimetre also extinguish and polarize starlight in the visible. Comparison of the polarization of the emission and of the interstellar polarization on selected lines of sight probed by stars provides unique new diagnostics of the emission and light scattering properties of dust. Using ancillary catalogues of interstellar polarization and extinction of starlight, we obtain the degree of polarization, $p_V$ , and the optical depth in the V band to the star, $τ_V$. Toward these stars we measure the submillimetre polarized intensity, $P_S$, and total intensity, $I_S$, in the Planck 353 GHz channel. For those lines of sight through the diffuse interstellar medium with comparable values of the estimated column density and polarization directions close to orthogonal, we correlate properties in the submillimetre and visible to find two ratios, $R_{S/V} = (P_S/I_S)/(p_V/τ_V)$ and $R_{P/p} = P_S/p_V$ , the latter focusing directly on the polarization properties of the aligned grain population alone. We find $R_{S/V}$ = 4.2, with statistical and systematic uncertainties 0.2 and 0.3, respectively, and $R_{P/p}$ = 5.4 MJy sr$^{-1}$, with uncertainties 0.2 and 0.3 MJy sr$^{-1}$, respectively. Our estimate of $R_{S/V}$ is compatible with predictions based on a range of polarizing dust models that have been developed for the diffuse interstellar medium. However, our estimate of $R_{P/p}$ is not compatible with predictions, which are too low by a factor of about 2.5. This more discriminating diagnostic, $R_{P/p}$, indicates that changes to the optical properties in the models of the aligned grain population are required.

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arXiv2015

Planck 2015 results. VI. LFI mapmaking

This paper describes the mapmaking procedure applied to Planck LFI (Low Frequency Instrument) data. The mapmaking step takes as input the calibrated timelines and pointing information. The main products are sky maps of $I,Q$, and $U$ Stokes components. For the first time, we present polarization maps at LFI frequencies. The mapmaking algorithm is based on a destriping technique, enhanced with a noise prior. The Galactic region is masked to reduce errors arising from bandpass mismatch and high signal gradients. We apply horn-uniform radiometer weights to reduce effects of beam shape mismatch. The algorithm is the same as used for the 2013 release, apart from small changes in parameter settings. We validate the procedure through simulations. Special emphasis is put on the control of systematics, which is particularly important for accurate polarization analysis. We also produce low-resolution versions of the maps, and corresponding noise covariance matrices. These serve as input in later analysis steps and parameter estimation. The noise covariance matrices are validated through noise Monte Carlo simulations. The residual noise in the map products is characterized through analysis of half-ring maps, noise covariance matrices, and simulations.

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arXiv2014

Monopole and dipole estimation for multi-frequency sky maps by linear regression

We describe a simple but efficient method for deriving a consistent set of monopole and dipole corrections for multi-frequency sky map data sets, allowing robust parametric component separation with the same data set. The computational core of this method is linear regression between pairs of frequency maps, often called "T-T plots". Individual contributions from monopole and dipole terms are determined by performing the regression locally in patches on the sky, while the degeneracy between different frequencies is lifted when ever the dominant foreground component exhibits a significant spatial spectral index variation. Based on this method, we present two different, but each internally consistent, sets of monopole and dipole coefficients for the 9-year WMAP, Planck 2013, SFD 100 um, Haslam 408 MHz and Reich & Reich 1420 MHz maps. The two sets have been derived with different analysis assumptions and data selection, and provides an estimate of residual systematic uncertainties. In general, our values are in good agreement with previously published results. Among the most notable results are a relative dipole between the WMAP and Planck experiments of 10-15 uK (depending on frequency), an estimate of the 408 MHz map monopole of 8.9 +- 1.3 K, and a non-zero dipole in the 1420 MHz map of $0.15 +- 0.03 K pointing towards Galactic coordinates (l,b) = (308,-36) +- 14 degrees. These values represent the sum of any instrumental and data processing offsets, as well as any Galactic or extra-Galactic component that is spectrally uniform over the full sky.

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