Angelica de Oliveira-Costa

My current research is focused on the Cosmic Microwave Background (CMB), where by combining theoretical work with new measurements I do data mining and constrain cosmological models.

Topology of the Universe:

The CMB is a unique probe of cosmological parameters and conditions, and allows us to constrain not only models of structure formation, but also the large-scale properties of space itself. For instance, there is a connection between the anisotropy in the CMB and the topology of the Universe: only a discrete set of modes can be excited if space is compact, much like in a crystal of finite size. I wrote some of the first papers constraining the topology using COBE/DMR data, showing that if the Universe has the structure of a general 3-dimensional torus, then none of the three directions could be much smaller than the horizon scale.

CMB Data Mining:

I am very interested in data mining techniques and how they can be applied to CMB analysis. A large part of my recent work has been on such issues, for instance developing mapmaking methods, improving measurements of the CMB power spectrum, and studying the spatial structure of Galactic foreground contamination. Mapmaking is an important step of any CMB pipeline, where huge time-ordered data sets can be reduced to a manageable size without losing any cosmological information. Using new mapmaking methods developed by me and my co-authors, combining Fourier methods and large matrix operations to remove correlated noise and scan-synchronous offsets, we made the Saskatoon, HACME and QMAP maps. The power spectrum, used to constrain cosmological models, is another important step of a CMB pipeline. As an example of my work on this topic, we produced the recently published power spectrum data points from the QMAP experiment. Another useful data mining technique that I have frequently employed is that of cross-correlating data sets with templates of potential contaminants, as described below.

Galactic Structure and Microwave Foregrounds:

I am interested in the structure and composition of the interstellar medium (ISM), both as a problem in its own right and because of its effects as a foreground contaminant to CMB measurements by producing synchrotron, free-free and dust emission.

Galactic free-free emission is believed to originate mainly within a few hundred pc of the Galactic plane, whereas diffuse synchrotron and dust emission extends further from the plane, with a scale height of a several kpc. Nearby supernova remnants can complicate the picture with synchrotron emission also at high galactic latitudes, often highly polarized. We are unfortunately a long way from having a self-consistent three-dimensional model of the the ISM and the magnetic field, including a model for the variations in density, temperature and magnetic field on various scales. However, upcoming multifrequency CMB measurements at various Galactic latitudes (both unpolarized and polarized) will offer a valuable tool for building such a model, especially when combined with maps of radio, dust and H-alpha emission. As a long-term project, I am interested in using such measurements to refine our knowledge of the structure of the Milky Way.

Our ability to measure cosmological parameters from upcoming CMB experiments will only be as good as our understanding of microwave foregrounds. By cross-correlating different CMB maps with foreground templates, I have quantified the level of foreground contamination at 10 and 15 GHz, 19 GHz, 30 and 40 GHz, evaluating its effect on published CMB measurements. My detection of a dust-correlated component at 30 and 40 GHz (with the Saskatoon data), also detected by Kogut et al using the COBE/DMR maps, puzzled many people in the community and triggered Draine & Lazarian to investigate the possibility of a fourth component of Galactic emission, from rotating dust grains. I am currently continuing my work on CMB foregrounds, quantifying the contamination in the QMAP (30-40 GHz) and MAT (30, 40 and 120 GHz) data sets to hopefully determine whether this observed correlation of CMB and dust maps is due to the free-free or rotational dust emission.

Because of the above-mentioned work and results from the COBE team and other groups during the last few years, models of unpolarized forergrounds went from being based largely on extrapolations to being founded on actual foreground detections at CMB frequencies. I am now focusing my attention on what I see as the next major challenge: to do the same with polarized foregrounds, i.e., to detect them and measure their power spectrum at CMB frequencies. I have also worked on the foreground contamination due to extragalactic point sources, and plan to do further work on this topic using the FIRST survey.

CMB Polarization:

Recently, I also started to study CMB polarization. CMB polarization is important for two reasons: first, polarization measurements can substantially improve the accuracy with which parameters are measured by breaking the degeneracy between certain parameter combinations; besides, it also offers an independent test of the basic assumptions that underly the standard cosmological model.

• INPE, Undergraduate Fellowship in Astrophysics, 1985-1987
  
• CNPq, M.Sc. Fellowship in Astrophysics, 1989-1992
  
• CNPq, Ph.D. Fellowship in Astrophysics, 1993-1996
  
• NASA, LTSA Research Program, 1997-2002
  
• NASA, LTSA Research Program, 2002-200?
  
• NSF, Astronomy and Astrophysics Research Grants, 2006-Today
  

• INPE (B.S. work on Observational Extragalactic Astronomy), 1987-1988
  
• Lawrence Berkeley National Laboratory (Ph.D. work on COBE/DMR data analysis - Ph.D. Supervisor: George F. Smoot), 1993-1995
  
• Princeton University/Institute for Advanced Study (postdoc work on CMB with the Princeton Cosmology Group), 1996-1999
  
• Penn (Research Faculty), January 2000-December 2004
• MIT (Principal Research Scientist), September 2004-Today

• Organizer (with W.Hu, A.Refregier, D.Spergel and M.Tegmark) of IAS CMB workshop, Nov 14-15, 1998
  

Books:

1. "Microwave Foregrounds" Ed. A. de Oliveira-Costa & M. Tegmark 1999 (ASP: San Francisco)

   Journal Articles:

2. "Constraints on the topology of the universe from the 2-yr COBE data" de Oliveira-Costa & Smoot 1995, ApJ, 448:477.
3. "Can the lack of symmetry in the COBE/DMR maps constrain the topology of the universe?" de Oliveira-Costa, Smoot & Starobinsky 1996, ApJ, 468:457.
4. "A high-resolution map of the Cosmic Microwave Background around the North Celestial Pole" Tegmark, de Oliveira-Costa, Devlin, Netterfield, Page & Wollack 1997, ApJ, 474:L77.
5. "Galactic emission at degree angular scales" de Oliveira-Costa, Kogut, Devlin, Netterfield, Page & Wollack 1997, ApJ, 482:L17.
6. "Removing point sources from CMB maps" Tegmark & de Oliveira-Costa 1998, ApJ, 500:L83.
7. "Galactic emission at 19 GHz" de Oliveira-Costa, Tegmark, Page & Boughn 1998, ApJ, 509:L9.
8. "Mapping the CMB Anisotropy: The First Flight of the QMAP Experiment" Devlin, de Oliveira-Costa, Herbig, Miller, Netterfield, Page & Tegmark 1998, ApJ, 509:L69.
9. "Mapping the CMB Anisotropy: The Second Flight of the QMAP Experiment" Herbig, de Oliveira-Costa, Devlin, Miller, Netterfield, Page & Tegmark 1998, ApJ, 509:L73.
10. "Mapping the CMB Anisotropy: Combined Analysis of QMAP Flights" de Oliveira-Costa, Devlin, Herbig, Miller, Netterfield, Page & Tegmark 1998, ApJ, 509:L77.
11. "Cross-correlation of Tenerife data with Galactic templates - evidence for spinning dust?" de Oliveira-Costa, Tegmark, Gutierrez, Jones, Davies, Lasenby, Rebolo, & Watson 1999, ApJ, 527:L9.
12. "Foregrounds and Forecasts for the CMB" Tegmark, Eisenstein, Hu & de Oliveira-Costa 2000, ApJ, 530:133.
13. "A Spin Modulated Telescope to Make Two Dimensional CMB Maps" Staren, Meinhold, Childers, Lim, Levy, Lubin, Seiffert, Gaier, Figueiredo, Villela, Wuensche, Tegmark & de Oliveira-Costa 2000, ApJ, 539:52.
14. "Cosmic microwave background maps from the HACME experiment" Tegmark, de Oliveira-Costa, Staren, Meinhold, Lubin, Childers, Figueiredo, Gaier, Lim, Seiffert, Villela & Wuensche 2000, ApJ, 541:535.
15. "Galactic contamination in the QMAP experiment" de Oliveira-Costa, Tegmark, Devlin, Haffner, Herbig, Miller, Page, Reynolds, Tufte 2000, ApJ, 542:L5.
16. "Comparing and combining the Saskatoon, QMAP and COBE CMB maps" Xu, Tegmark, de Oliveira-Costa, Devlin, Herbig, Miller, Netterfield & Page 2001, Phy.Rev.D, 63:103002.
17. "How to measure CMB polarization power spectra without losing information" Tegmark & de Oliveira-Costa 2001, Phy.Rev.D, 64:63001.
18. "A Limit on the Large Angular Scale Polarization of the Cosmic Microwave Background" Keating, O'Dell, de Oliveira-Costa, Klawikowski, Stebor, Piccirillo, Tegmark & Timbie 2001, ApJL, 560:L1.
19. "A New Spin on Galactic Dust" de Oliveira-Costa, Tegmark, Finkbeiner, Davies, Gutierrez, Haffner, Jones, Lasenby, Reynolds, Tufte & Watson 2002, ApJ, 567:363.
20. "The CMB power spectrum at l=30-200 from QMASK" Xu, Tegmark & de Oliveira-Costa 2002, Phy.Rev.D 65:083002
21. "First attempt at measuring the CMB cross-polarization" de Oliveira-Costa, Tegmark, Zaldarriaga, Barkats, Gundersen, Hedman, Staggs & Winstein 2002, Phys. Rev. D. 67:023003.
22. "E/B decomposition of finite pixelized CMB maps" Bunn, Zaldarriaga, Tegmark & de Oliveira-Costa 2002, Phys. Rev. D. 67:023501.
23. "CMB Polarization at Large Angular Scales: Data Analysis of the POLAR Experiment" O'Dell, Keating, de Oliveira-Costa, Tegmark & Timbie 2003, Phys. Rev. D. 68:042002.
24. "The Large-Scale Polarization of the Microwave Background and Foreground" de Oliveira-Costa, Tegmark, O'Dell, Keating, Timbie, Efstathiou & Smoot 2003, Phys. Rev. D. 68:083003.
25. "A high resolution foreground cleaned CMB map from WMAP" Tegmark, de Oliveira-Costa & Hamilton 2003, Phys. Rev. D. 68:123523.
26. "The significance of the largest scale CMB fluctuations in WMAP" de Oliveira-Costa, Tegmark, Zaldarriaga & Hamilton 2004, Phys. Rev. D. 69:063516.
27. "The Quest for Microwave Foreground X" de Oliveira-Costa, Tegmark, Davies, Gutierrez, Lasenby, Rebolo & Watson 2004, ApJL 606:L89.
28. "How accurately can suborbital experiments measure the CMB?" de Oliveira-Costa, Tegmark, Devlin, Page, Miller, Netterfield & Xu 2005, Phys. Rev. D. 71:043004.
29. "Cosmological Parameters from the 2003 Flight of BOOMERanG" MacTavish & the BOOMERanG Collaboration 2006, ApJ, 647:799.
30. "A Measurement of the CMB EE Spectrum from the 2003 Flight of BOOMERanG" Montroy & the BOOMERanG Collaboration 2006, ApJ, 647:813.
31. "A Measurement of the Angular Power Spectrum of the CMB Temperature Anisotropy from the 2003 Flight of BOOMERanG" Jones & the BOOMERanG Collaboration 2006, ApJ, 647:823.
32. "A Measurement of the Polarization-Temperature Angular Cross Power Spectrum of the CMB from the 2003 Flight of BOOMERanG" Piacentini & the BOOMERanG Collaboration 2006, ApJ, 647:833.
33. "CMB Multipole Measurements in the Presence of Foregrounds" de Oliveira-Costa & Tegmark 2006, Phys. Rev. D. 74:023005.
34. "Instrument, Method, Brightness and Polarization Maps from the 2003 Flight of BOOMERanG" Masi & the BOOMERanG Collaboration 2006, A&A, 458(3):687.
35. "Searching for non Gaussian signals in the BOOMERanG 2003 CMB maps" de Troia & the BOOMERanG Collaboration 2007, ApJ, in press

    Preprints:

    Proceedings:

36. "Search for structures in the CMBR" de Oliveira-Costa & Villela 1993, Rev. Mex. Astron. Astrofis., 26:127 (Just Abstract).
37. "Does COBE rule out a toroidal Universe?" de Oliveira-Costa & Smoot 1995, Nuc. Phys. B, 43:299.
38. "Constraining topology with the CMB" de Oliveira-Costa, Smoot & Starobinsky 1996. Proceedings from "XXXIst Recontres de Moriond: Future CMB missions", Ed F. Bouchet.
39. "Foreground contamination around the North Celestial Pole" de Oliveira-Costa, Kogut, Devlin, Netterfield, Page & Wollack 1997, Proceedings from "18th Texas Symposium on Relativistic Astrophysics: Texas in Chicago", Ed. A. Olinto, J. Frieman & D. Schramm.
40. "New Techniques for Making CMB Maps" de Oliveira-Costa & Tegmark 1998, Proceedings from "Wide Field Surveys in Cosmology, 14th IAP meeting", Ed. F. Bouchet.
41. "Are we observing spinning dust grains?" de Oliveira-Costa, Tegmark, Gutierrez, Jones, Davies, Lasenby, Rebolo, & Watson 1999, Proceedings from "Microwave Foregrounds", Ed. A. de Oliveira-Costa & M. Tegmark.
42. "Overview of Foregrounds and their Impact" Tegmark, Eisenstein, Hu & de Oliveira-Costa 1999, Proceedings from "Microwave Foregrounds", Ed. A. de Oliveira-Costa & M. Tegmark.
43. "CMB Satellites: Forecasts and Foregrounds" Eisenstein, Tegmark, Hu & de Oliveira-Costa 1999, Proceedings from "American Astronomical Society Meeting 194" (Just Abstract).
44. "POLAR: Instrument and Results" Keating, de Oliveira-Costa, O'Dell, Piccirillo, Stebor, Tegmark & Timbie 2002, Proceedings from "Experimental Cosmology at Millimetre Wavelengths, AIP Conference Proceedings 616", Ed. M. De Petris & M. Gervasi.
45. "BOOMERanG" Masi & the BOOMERanG Collaboration 2003, MSAIS, v.2, p.54
46. "BOOMERanG returns" Mauskopf & the BOOMERanG Collaboration 2003, NewAR, v.47, p.733-740
47. "The Large-Scale Polarization of the Microwave Foreground" de Oliveira-Costa, Tegmark, O'Dell, Keating, Timbie, Efstathiou & Smoot 2003, Proceedings from "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, Eds. S. Hanany and K.A. Olive.
48. "Measuring CMB Polarization with BOOMERANG" Montroy & the BOOMERanG Collaboration 2003, NewAR, v.47, p.1057-1065
49. "Maps of the millimetre sky from the BOOMERanG experiment" de Bernardis & the BOOMERanG Collaboration 2003, Proceedings from "IAU Symposium 216: Maps of the Cosmos", Sydney, July 14-17.
50. "The Cosmic Microwave Background and Its Polarization" de Oliveira-Costa 2004, Review to be published in the proceedings of "Astronomical Polarimetry - Current Status and Future Directions'', Hawaii, March 15-19.
51. "BOOMERANG Results" Polenta & the BOOMERanG Collaboration 2005, AdSpR, 36(6):1064.
52. "Observations of the temperature and polarization anisotropies with BOOMERANG 2003" Jones & the BOOMERanG Collaboration 2007, NewAR, v.50, p.945-950
53. "The millimeter sky as seen with BOOMERanG" Masi & the BOOMERanG Collaboration 2007, NewAR, v.51, p.236-243
54. "CMB polarization with BOOMERANG 2003" Piacentini & the BOOMERanG Collaboration 2007, NewAR, v.51, p.244-249
55. "Searching for non-Gaussian signals in the BOOMERanG 2003 CMB map: Preliminary results" de Troia & the BOOMERanG Collaboration 2007, NewAR, v.51, p.250-255

    Other Publications:

56. "Eolipila" de Oliveira-Costa 1986, First Experimental Catalog of Physics of USP (In Portuguese)
57. "Structures in the CMB: hot and cold spots in the microwave sky" de Oliveira-Costa 1993, M.Sc. Thesis published by INPE, INPE-5491-TDI/508 (In Portuguese).
58. "CMB data analysis: constraints on the topology of the Universe" de Oliveira-Costa 1996, Ph.D. Thesis published by INPE.
59. "Book Review: Microwave Foregrounds" de Oliveira-Costa & Tegmark 2000, Irish Astron. J., 27(1):107.
60. "Book Review: Microwave Foregrounds" de Oliveira-Costa & Tegmark 2000, The Observatory, 120(1157):272.