C. M. Gutierrez

Universidad de La Laguna, San Cristóbal de La Laguna, Canary Islands, Spain

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Publications (108)339.83 Total impact

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    ABSTRACT: QUIJOTE (Q-U-I JOint TEnerife) is a new polarimeter aimed to characterize the polarization of the Cosmic Microwave Background and other Galactic and extragalactic signals at medium and large angular scales in the frequency range 10-40 GHz. The multi-frequency (10-20~GHz) instrument, mounted on the first QUIJOTE telescope, saw first light on November 2012 from the Teide Observatory (2400~m a.s.l). During 2014 the second telescope has been installed at this observatory. A second instrument at 30~GHz will be ready for commissioning at this telescope during summer 2015, and a third additional instrument at 40~GHz is now being developed. These instruments will have nominal sensitivities to detect the B-mode polarization due to the primordial gravitational-wave component if the tensor-to-scalar ratio is larger than r=0.05.
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    ABSTRACT: From the Sloan Digital Sky Survey Data Release 12, which covers the full Baryonic Oscillation Spectroscopic Survey (BOSS) footprint, we investigate the possible variation of the fine-structure constant over cosmological time scales. We analyze the largest quasar sample considered so far in the literature, which contains 10,363 spectra with $z<1$. All the BOSS quasar spectra are selected from a visually inspected quasar catalog. We apply the emission line method on the [O III] doublet (4960, 5008 A) and obtain $\Delta\alpha/\alpha= \left(1.4 \pm 2.3\right)\times10^{-5}$ for the relative variation of the fine-structure constant. We also investigate the possible sources of systematics: misidentification of the lines, sky OH lines, H$\beta$ and broad line contamination, optimal wavelength range for the Gaussian fits, chosen polynomial order for the continuum spectrum, signal-to-noise ratio and good quality of the fits. The uncertainty of the measurement is dominated by the sky subtraction. The results presented in this work, being systematics limited, have sufficient statistics to constrain robustly the variation of the fine structure constant in redshift bins ($\Delta z\approx 0.06$) over the last 7.9 Gyr. In addition, we study the [Ne III] doublet (3870, 3969 A) present in 462 quasar spectra; and discuss the systematic effects on using these emission lines to constrain the fine-structure constant variation. Better constraints on $\Delta\alpha/\alpha\ (<10^{-6})$ using the emission line method would be possible with high resolution spectroscopy.
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    ABSTRACT: The QUIJOTE (Q-U-I JOint Tenerife) CMB Experiment is designed to observe the polarization of the Cosmic Microwave Background and other Galactic and extragalactic signals at medium and large angular scales in the frequency range of 10-40 GHz. The first of the two QUIJOTE telescopes and the multi-frequency (10-20 GHz) instrument have been in operation since November 2012. In 2014 a second telescope and a new instrument at 30GHz will be ready for commissioning, and an additional instrument at 40 GHz is in its final design stages. After three years of effective observations, the data obtained by these telescopes and instruments will have the required sensitivity to detect a primordial gravitational-wave component if the tensor-to-scalar ratio is larger than r = 0.05. At the moment, we have completed half of the wide Galactic survey with the multi-frequency instrument covering 18 000 square degrees of the Northern hemisphere. When we finish this survey in early 2014, we shall have reached approximately 14{\mu}K per one degree beam at 11, 13, 17 and 19 GHz, in both Q and U.
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    ABSTRACT: The Anomalous microwave emission (AME) has been proved to be an important component of the Galactic diffuse emission in the range from 20 to 60 GHz. To discriminate between different models of AME low frequency microwave data from 10 to 20 GHz are needed. We present here a re-analysis of published and un-published Tenerife data from 10 to 33 GHz at large angular scales (from 5 to 15 degrees). We cross-correlate the Tenerife data to templates of the main Galactic diffuse emissions: synchrotron, free-free and thermal dust. We find evidence of dust correlated emission in the Tenerife data that could be explained as spinning dust grain emission.
    Advances in Astronomy 01/2013; 2013. DOI:10.1155/2013/780407 · 1.23 Impact Factor
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    Martín López-Corredoira, Carlos M. Gutiérrez
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    ABSTRACT: There are extremely luminous quasi stellar objects (QSOs) at high redshift which are absent at low redshift. The lower luminosities at low redshifts can be understood as the external manifestation of either a lower Eddington ratio or a lower mass. To distinguish between both effects, we determine the possible dependence of masses and Eddington ratios of QSOs with a fixed luminosity as a function of redshifts; this avoids the Malmquist bias or any other selection effect. For the masses and Eddington ratios derived for a sample of QSOs in the Sloan Digital Sky Survey, we model their evolution by a double linear fit separating the dependence on redshifts and luminosities. The validity of the fits and possible systematic effects were tested by the use of different estimators of masses or bolometric luminosities, and possible intergalactic extinction effects. The results do not show any significant evolution of black hole masses or Eddington ratios for equal luminosity QSOs. The black hole mass only depends on the bolometric luminosity without significant dependence on the redshift as M_{BH}(10^9 M_sun) = 3.4[L_{bol}(10^{47} erg/s})]^{0.65} on average for z<5. This must not be confused with the possible evolution in the formation of black holes in QSOs. The variations of environment might influence the formation of the black holes but not its subsequent accretion. It also leaves a question to be solved: Why are there not QSOs with very high mass at low redshift? A brief discussion of the possible reasons for this is tentatively pointed out.
    Research in Astronomy and Astrophysics 12/2011; 12(3). DOI:10.1088/1674-4527/12/3/002 · 1.64 Impact Factor
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    ABSTRACT: We present a study of the spatial and redshift distributions of Sloan Digital Sky Survey (SDSS) galaxies towards the position of CrB-H, a very deep and extended decrement in the cosmic microwave background (CMB), located within the Corona Borealis supercluster (CrB-SC). It was found in a survey with the Very Small Array (VSA) interferometer at 33 GHz, with a peak negative brightness temperature of −230μK, and deviates 4.4σ from the Gaussian CMB (Génova-Santos et al.). Observations with the Millimeter and Infrared Testa Grigia Observatory (MITO) suggested that 25+21−18 per cent of this decrement may be caused by the thermal Sunyaev-Zel'dovich (tSZ) effect (Battistelli et al.). Here, we investigate whether the galaxy distribution could be tracing either a previously unnoticed galaxy cluster or a warm/hot intergalactic medium (WHIM) filament that could build up this tSZ effect. We find that the projected density of galaxies outside Abell clusters and with redshifts 0.05 < z < 0.12 at the position of CrB-H is the highest in the area encompassed by the CrB-SC. Most of these galaxies are located around redshifts z= 0.07 and 0.11, but no clear connection in the form of a filamentary structure is appreciable in between. While the galaxy distribution at z= 0.07 is sparse, we find evidence at z= 0.11 of a galaxy group or a low-mass galaxy cluster. We estimate that this structure could produce a thermal Sunyaev-Zel'dovich (tSZ) effect of ≈−18μK. The remaining VSA signal of ≈−212μK is still a significant 4.1σ deviation from the Gaussian CMB. However, the MITO error bar allows for a larger tSZ effect, which could be produced by galaxy clusters or superclusters beyond the sensitivity of the SDSS. Contributions from other possible secondary anisotropies associated with these structures are also discussed.
    Monthly Notices of the Royal Astronomical Society 04/2010; 403(3):1531 - 1540. DOI:10.1111/j.1365-2966.2010.16222.x · 5.23 Impact Factor
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    Carlos M. Gutierrez, Martin Lopez-Corredoira
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    ABSTRACT: The optical spectra of objects classified as QSOs in the SDSS DR6 are analyzed with the aim of determining the value of the fine structure constant in the past and then check for possible changes in the constant over cosmological timescales. The analysis is done by measuring the position of the fine structure lines of the [OIII] doublet (4959 and 5008) in QSO nebular emission. From the sample of QSOs at redshifts z < 0.8 a subsample was selected on the basis of the amplitude and width of the [OIII] lines. Two different method were used to determine the position of the lines of the [OIII] doublet, both giving similar results. Using a clean sample containing 1568 of such spectra, a value of Delta alpha /alpha=(+2.4 +-2.5) x 10^{-5} (in the range of redshifts 0-0.8) was determined. The use of a larger number of spectra allows a factor ~5 improvement on previous constraints based on the same method. On the whole, we find no evidence of changes in alpha on such cosmological timescales. The mean variation compatible with our results is 1/ Delta alpha/alpha=(+0.7 +- 0.7) x 10^{-14} yr^{-1}. The analysis was extended to the [NeIII] and [SII] doublets, although their usefulness is limited due to the fact that all these doublets in QSOs tend to be fainter than [OIII], and that some of them are affected by systematics. Comment: 22 pages, 10 figures. Accepted for publication in Astrophysical Journal
    The Astrophysical Journal 02/2010; 713(1). DOI:10.1007/978-3-642-19397-2_8 · 6.28 Impact Factor
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    ABSTRACT: In a 24deg2 survey for baryonic matter at 33GHz in the Corona Borealis supercluster (CrB-SC) of galaxies (z=0.07), with the Very Small Array (VSA) interferometer (Génova-Santos et al. 2005, MNRAS 363, 79; 2008, arXiv: 0804.0199), we found a very strong temperature decrement in the Cosmic Microwave Background (CMB). It has an amplitude of−230±23μK and is located near the center of the supercluster, in a position with no known galaxy clusters, and without a significant X-ray emission in the ROSAT All-Sky Survey. Monte-Carlo simulations discard the primordial CMB Gaussian field as a possible explanation for this decrement at a level of 99.6%. We therefore concluded that this could be indicative of a Sunyaev–Zel’dovich (SZ) effect produced either by a warm/hot gas distribution in the intercluster medium or by a farther unknown galaxy cluster. Here we present an optical study of the galaxy distribution in this region, aiming at elucidating whether it traces a possible warm/hot gas filamentary distribution or a galaxy cluster. First, we have studied the galaxy population down to r≤20 magnitudes in the SDSS. This reveals an overdensity by a factor of 2 with respect to nearby control fields, but lower than in the galaxy clusters member of the CrB–SC. This indicates that the associated gas could at least be partially responsible for the observed CMB decrement. Second, we obtained spectroscopic redshifts, with the William Herschel Telescope (WHT), for a sample of galaxies in the region of the cold spot, and found evidence of a substructure with redshifts extending from 0.07 to 0.10. This suggests the existence of a dense filamentary structure with a length of several tens of Mpc. Finally, we investigated the presence of at least one farther cluster in the same line-of-sight, at z≈0.11.
    12/2009: pages 329-329;
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    ABSTRACT: We study the spatial distribution and colours of galaxies within the region covered by the cold spot in the cosmic microwave background recently detected by the Very Small Array interpherometer (VSA) towards the Corona Borealis supercluster (CrB-SC). The spot is in the northern part of a region with a radius ∼1° (∼5 Mpc at the redshift of CrB-SC) enclosing the clusters Abell 2056, 2065, 2059 and 2073, and where the density of galaxies, excluding the contribution from those clusters, is approximately two times higher than the mean value in typical intercluster regions of the CrB-SC. Two of such clusters (Abell 2056 and 2065) are members of the CrB-SC, while the other two are in the background. This high-density intercluster region is quite inhomogeneous, being the most remarkable feature a large concentration of galaxies in a narrow filament running from Abell 2065 with a length of ∼35 arcmin (∼3 Mpc at the redshift of CrB-SC) in the SW–NE direction. This intercluster population of galaxies probably results from the interaction of clusters Abell 2065 and 2056. The area subtended by the VSA cold spot shows an excess of faint (21 < r < 22) and red (1.1 < r−i < 1.3) galaxies as compared with typical values within the CrB-SC intercluster regions. This overdensity of galaxies shows a radial dependence and extends out to ∼15 arcmin. This could be the signature of a previously unnoted cluster in the background.
    Monthly Notices of the Royal Astronomical Society 06/2009; 396(1):53 - 60. DOI:10.1111/j.1365-2966.2009.14785.x · 5.23 Impact Factor
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    ABSTRACT: We study the spatial distribution and colours of galaxies within the region covered by the cold spot in the cosmic microwave background (CMB) recently detected by the Very Small Array (VSA; Genova-Santos et al. 2005, 2008) towards the Corona Borealis supercluster (CrB-SC). The spot is in the northern part of a region with a radius ~1 degree (~5 Mpc at the redshift of CrB-SC) enclosing the clusters Abell 2056, 2065, 2059 and 2073, and where the density of galaxies, excluding the contribution from those clusters, is ~2 times higher than the mean value in typical intercluster regions of the CrB-SC. Two of such clusters (Abell 2056 and 2065) are members of the CrB-SC, while the other two are in the background. This high density intercluster region is quite inhomogeneous, being the most remarkable feature a large concentration of galaxies in a narrow filament running from Abell 2065 with a length of ~35 arcmin (~3 Mpc at the redshift of CrB-SC) in the SW-NE direction. This intercluster population of galaxies probably results from the interaction of clusters Abell 2065 and 2056. The area subtended by the VSA cold spot shows an excess of faint (21<r<22) and red (1.1<r-i<1.3) galaxies as compared with typical values within the CrB-SC intercluster regions. This overdensity of galaxies shows a radial dependence and extends out to ~15 arcmin. This could be signature of a previously unnoticed cluster in the background.
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    ABSTRACT: In a recent survey at 33 GHz for baryonic matter at large scales in the Corona Borealis Supercluster (CrB-SC) of galaxies (z = 0.07) using the Very Small Array interferometer (VSA), covering 24^2, two strongs decrements in temperature (CrB-B and CrB-H) near the centre of the supercluster were detected. The amplitudes are -157+/-27 and -230+/-23muK for decrements CrB-B and CrB-H respectively. There are no known clusters of galaxies coincident with the position of either of these decrements. Monte-Carlo simulations show that only CrB-B can be produced by primary anisotropies in the Cosmic Microwave Background (CMB) radiation. To explain the origen of CrB-H, a combination of both CMB perturbations and the Sunyaev-Zel'dovich effect (SZE) is required. We explore the possibility that this SZE could be produced by warm/hot gas on superclusters scales. ROSAT images do not show X-ray emission in these regions. We study the distribution of galaxies down to r
    Proceedings of the International Astronomical Union 05/2009; 2(S235). DOI:10.1017/S1743921306006363
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    F. Prada, C. M. Gutiérrez
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    ABSTRACT: We present a detailed study of the stellar kinematics in the barred galaxy NGC 5728 based on I-band photometry and long-slit spectroscopic observations in the region of the near-IR Ca II triplet. The analysis of the stellar line-of-sight velocity distribution (LOSVD) has revealed, in the central regions of the bar, the presence of a cold (v/σ~2.5), prograde, S-shaped velocity component that coexists in the central 4 kpc, with a fainter and hotter (v/σ~0.5) counterrotating component. Beyond 4 kpc from the nucleus, the LOSVD shows the stellar bar kinematics. The comparison of the radial surface brightness profile of the velocity components with that obtained from an I-band image shows that the counterrotating core follows a r1/4 profile, while the S-shaped component does not follow the flat-bar surface brightness profile. Several possible scenarios accounting for such kinematic signatures found in the center of the bar in NGC 5728 are discussed. The data presented in this paper show for the first time the presence of extended retrograde motions in barred systems that, together with previous discoveries, seem to indicate that the stellar counterrotation is a phenomenon present all along the Hubble sequence.
    The Astrophysical Journal 01/2009; 517(1):123. DOI:10.1086/307199 · 6.28 Impact Factor
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    ABSTRACT: In this article we demonstrate that PKS J1037–2705 has a weak accretion flow luminosity, well below the Seyfert 1/QSO dividing line, weak broad emission lines (BELs), and moderately powerful FR II extended radio emission. It is one of the few documented examples of a broad-line object in which the time-averaged jet kinetic luminosity, , is larger than the total thermal luminosity (IR to X-ray) of the accretion flow, Lbol. The blazar nucleus dominates the optical and near-ultraviolet emission and is a strong source of hard X-rays. The strong blazar emission indicates that the relativistic radio jet is presently active. The implication is that even weakly accreting AGNs can create powerful jets. Kinetically dominated () broad-line objects provide important constraints on the relationship between the accretion flow and the jet production mechanism.
    The Astrophysical Journal 12/2008; 687(1):162. DOI:10.1086/591650 · 6.28 Impact Factor
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    C. M. Gutiérrez, M. López-Corredoira
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    ABSTRACT: Spectroscopy and deep imaging of the group NEQ3 are presented. This system is formed by three compact objects with relative separations of ~26 and ~28 and a lenticular galaxy at ~17'' from the geometric center of the group. A diffuse filament is located on a line joining the three compact objects and the main galaxy. Analysis of these observations confirms the redshift previously known for three of the objects (z = 0.1239 for the main galaxy, and z = 0.1935 and 0.1939 for two of the compact objects). We have also determined the previously unknown redshift of the third compact object as z = 0.2229. Using the relative strength and width of the main spectral lines we have classified the compact objects as two H II galaxies and one QSO (the object at z = 0.1935). With cross-correlation techniques, we have tentatively estimated the redshift of the filament as z = 0.19 (although a weaker component also appears at z = 0.12), so that it is probably associated with the halo of the two compact objects at this redshift. The two objects at redshift ~0.19 represent possibly one of the more clear examples of starburst (and perhaps QSO activity) driven by interaction. These considerations and the relation between these objects and the other two at reshifts ~0.12 and ~0.22 make the nature of the system intriguing, being difficult to explain the whole association in conventional scenarios.
    The Astrophysical Journal 12/2008; 605(1):L5. DOI:10.1086/383346 · 6.28 Impact Factor
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    ABSTRACT: The results of the Tenerife cosmic microwave background (CMB) experiments are presented. These observations cover 5000 and 6500 deg2 on the sky at 10 and 15 GHz, respectively, centered on decl. ~ +35°. The experiments are sensitive to multipoles l = 10-30 that correspond to the Sachs-Wolfe plateau of the CMB power spectra. The sensitivity values of the data are ~31 and ~12 μK at 10 and 15 GHz, respectively, in a beam-size region (5° × 5°). The data at 15 GHz show clear detection of structure at high Galactic latitude; the results at 10 GHz are compatible with these, but at lower significance. A likelihood analysis of the 10 and 15 GHz data at high Galactic latitude, assuming a flat CMB band power spectrum, gives a signal ΔTℓ = 30 μK (68% C.L.). Including the possible contaminating effect due to the diffuse Galactic component, the CMB signal is ΔTℓ = 30 μK. These values are stable against the Galactic cut chosen. Assuming a Harrison-Zeldovich spectrum for the primordial fluctuations, the above values imply an expected quadrupole Qrms-ps = 20 μK, which agrees with previous results from these experiments, and which are compatible with the COBE DMR data in the case of the standard inflationary cold dark matter models.
    The Astrophysical Journal 12/2008; 529(1):47. DOI:10.1086/308246 · 6.28 Impact Factor
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    C. M. Gutiérrez, M. López-Corredoira
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    ABSTRACT: We present spectroscopic observations of six optical counterparts of ultraluminous X-ray sources (ULXs) around nearby galaxies. The spectra of the six objects show the presence of broad emission features. The identification of these allow us to classify all of the objects as quasars at higher redshift than their assigned parent galaxy. This is one of the first and largest identifications of such objects using unambigous optical spectral features. These results, in conjuction with previous similar identifications of other sources, indicate that high-redshift quasars represent an important fraction of cataloged ULX sources. We estimate the density of such sources and compare this with expectations for a population of randomly distributed background quasars.
    The Astrophysical Journal 12/2008; 622(2):L89. DOI:10.1086/429616 · 6.28 Impact Factor
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    ABSTRACT: We describe a new high-sensitivity experiment for observing cosmic microwave background (CMB) anisotropies. The instrument is a two-element interferometer operating at 33 GHz with a ∼3 GHz bandwidth. It is installed on the high and dry Teide Observatory site on Tenerife where successful beam-switching observations have been made at this frequency. Two realizations of the interferometer have been tested with element separations of 11.9λ and 16.7λ. The resulting angular resolution of ∼2° was chosen to explore the amplitude of CMB structure on the large angular scale side of the Doppler (acoustic) peak. It is found that observations are unaffected by water vapour for more than 70 per cent of the time when the sensitivity is limited by the receiver noise alone. Observations over several months are expected to give an rms noise level of ∼10--20 2 μK covering ∼100 resolution elements. Preliminary results show stable operation of the interferometer with the detection of discrete radio sources as well as the Galactic plane at Dec. =+41° and −29°.
    Monthly Notices of the Royal Astronomical Society 09/2008; 305(2):399 - 408. DOI:10.1046/j.1365-8711.1999.02440.x · 5.23 Impact Factor
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    ABSTRACT: In this article, we demonstrate that PKSJ 1037-2705 has a weak accretion flow luminosity, well below the Seyfert1/QSO dividing line, weak broad emission lines (BELs) and moderately powerful FRII extended radio emission. It is one of the few documented examples of a broad-line object in which the time averaged jet kinetic luminosity, $\bar{Q}$, is larger than the total thermal luminosity (IR to X-ray) of the accretion flow, $L_{bol}$. The blazar nucleus dominates the optical and near ultraviolet emission and is a strong source of hard X-rays. The strong blazar emission indicates that the relativistic radio jet is presently active. The implication is that even weakly accreting AGN can create powerful jets. Kinetically dominated ($\bar{Q}>L_{bol}$) broad-line objects provide important constraints on the relationship between the accretion flow and the jet production mechanism. Comment: To appear in ApJ November 1, 2008, v687n1 issue
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    ABSTRACT: Aims.A recent catalogue by Flesch & Hardcastle presents two major anomalies in the spatial distribution of QSO candidates: $i)$ an apparent excess of such objects near bright galaxies, and $ii)$ an excess of very bright QSO candidates compared to random background expectations in several regions of the sky. Because anyone of these anomalies would be relevant in a cosmological context, we carried out an extensive analysis of the probabilities quoted in that catalogue.Methods.We determine the nature and redshift of a subsample of 30 sources in that catalogue by analysing their optical spectra (another 11 candidates were identified from existing public databases). These have allowed us to statistically check the reliability of the probabilities QSO status quoted by Flesch & Hardcastle for their candidates.Results.Only 12 of the 41 candidates turned out QSOs (7 of which have been identified here for the first time).Conclusions.The probabilities of the QSOs' being the candidates given by Flesch & Hardcastle are overestimated for $m_B$ $\le$ 17 and for objects projected near ($\le$1 arcmin) bright galaxies. This is the cause of the anomalies mentioned above.
    Astronomy and Astrophysics 03/2008; DOI:10.1051/0004-6361:20078164 · 4.48 Impact Factor
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    ABSTRACT: We present observations with the new 11-GHz radiometer of the COSMOSOMAS experiment at the Teide Observatory (Tenerife). The sky region between 0° <= RA <= 360° and 26° <= Dec. <= 49° (ca. 6500 deg2) was observed with an angular resolution of . Two orthogonal independent channels in the receiving system measured total power signals from linear polarizations with a 2-GHz bandwidth. Maps with an average sensitivity of 50 μK per beam have been obtained for each channel. At high Galactic latitude (|b| > 30°) the 11-GHz data are found to contain the expected cosmic microwave background (CMB) as well as extragalactic radiosources, galactic synchrotron and free-free emission, and a dust-correlated component which is likely of Galactic origin. At the angular scales allowed by the window function of the experiment, the 100-240 μm dust-correlated component presents an amplitude ΔT ~ 9-13 μK while the CMB signal is of the order of 27 μK. The spectral behaviour of the dust-correlated signal is examined in the light of previous COSMOSOMAS data at 13-17 GHz and Wilkinson Microwave Anisotropy Probe data at 22-94 GHz in the same sky region. We detect a flattening in the spectral index of this signal below 20 GHz which rules out synchrotron radiation as being responsible for the emission. This anomalous dust emission can be described by a combination of free-free emission and spinning dust models with a flux density peaking around 20 GHz.
    Monthly Notices of the Royal Astronomical Society 12/2007; 382(2):594-608. DOI:10.1111/j.1365-2966.2007.12380.x · 5.23 Impact Factor