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Your search keyword '"Morales, Miguel F."' showing total 6 results
Start Over Author "Morales, Miguel F." Publisher blackwell publishing ltd
6 results on '"Morales, Miguel F."'

1. First limits on the 21 cm power spectrum during the Epoch of X-ray heating

Author

Ewell-Wice, A., Dillon, Joshua, Hewitt, Jacqueline N, Loeb, Abraham, Mesinger, A., Neben, A R, Offringa, A., Tegmark, Max, Barry, N, Beardsley, A. P., Bernardi, G, Briggs, Franklin, Bowman, Judd D, Feng, Lu, Greenhill, Lincoln, Johnston-Hollitt, M, Jacobs, Daniel C., Kaplan, D L, Thyagarajan, Nithyanandan, Oberoi, D, Pindor, B., Prabu, T, Rogers, Alan, Udaya Shankar, N., Srivani, K. S., Whitney, Alan, Williams, Christopher L, Cappallo, R. J, Carroll, P, Corey, B.E, de Oliveira-Costa,, A, Emrich, David, Gaensler, B M, Goeke, R, Hazelton, B, Hurley-Walker, Natasha, Kasper, J.C., Kim, HS, Kratzenberg, Eric, Lenc, E, Line, J, Lonsdale, Colin J, Lynch, Mervyn J, McKinley, B, McWhirter, S.R., Mitchell, D.A., Morales, Miguel F, Morgan, Edward H, Ord, S M, Paul, S, Pober, J. C., Procopio, P., Riding, J, Roshi, A., Sethi, Shiv K, Subrahmanyan, R., Sullivan, I S, Tingay, S.J., Trott, C. M., Waterson, Mark, Wayth, Randall, B., Webster, Rachel L, Williams, A, Wu, Chen, Wyithe, J Stuart B, Ewell-Wice, A., Dillon, Joshua, Hewitt, Jacqueline N, Loeb, Abraham, Mesinger, A., Neben, A R, Offringa, A., Tegmark, Max, Barry, N, Beardsley, A. P., Bernardi, G, Briggs, Franklin, Bowman, Judd D, Feng, Lu, Greenhill, Lincoln, Johnston-Hollitt, M, Jacobs, Daniel C., Kaplan, D L, Thyagarajan, Nithyanandan, Oberoi, D, Pindor, B., Prabu, T, Rogers, Alan, Udaya Shankar, N., Srivani, K. S., Whitney, Alan, Williams, Christopher L, Cappallo, R. J, Carroll, P, Corey, B.E, de Oliveira-Costa,, A, Emrich, David, Gaensler, B M, Goeke, R, Hazelton, B, Hurley-Walker, Natasha, Kasper, J.C., Kim, HS, Kratzenberg, Eric, Lenc, E, Line, J, Lonsdale, Colin J, Lynch, Mervyn J, McKinley, B, McWhirter, S.R., Mitchell, D.A., Morales, Miguel F, Morgan, Edward H, Ord, S M, Paul, S, Pober, J. C., Procopio, P., Riding, J, Roshi, A., Sethi, Shiv K, Subrahmanyan, R., Sullivan, I S, Tingay, S.J., Trott, C. M., Waterson, Mark, Wayth, Randall, B., Webster, Rachel L, Williams, A, Wu, Chen, and Wyithe, J Stuart B

Published
2016

2. Limits on Fast Radio Bursts and other transient sources at 182 MHz using the Murchison Widefield Array

Author

Rowlinson, A., Bell, M. E., Murphy, Tara, Trott, C. M., Hurley-Walker, Natasha, Johnston, S., Tingay, S.J., Kaplan, D. L., Carbone, D., Hancock, P.J., Feng, Lu, Offringa, A., Bernardi, G, Bowman, J D, Briggs, Franklin, Cappallo, R. J, Deshpande, Avinash, Gaensler, B M, Greenhill, Lincoln, Hazelton, B, Johnston-Hollitt, M, Lonsdale, Colin J, McWhirter, S.R., Mitchell, Daniel A, Morales, Miguel F, Morgan, Edward H, Oberoi, D, Ord, S M, Prabu, T, Udaya Shankar, N., Srivani, K. S., Subrahmanyan, R., Williams, Christopher L, Rowlinson, A., Bell, M. E., Murphy, Tara, Trott, C. M., Hurley-Walker, Natasha, Johnston, S., Tingay, S.J., Kaplan, D. L., Carbone, D., Hancock, P.J., Feng, Lu, Offringa, A., Bernardi, G, Bowman, J D, Briggs, Franklin, Cappallo, R. J, Deshpande, Avinash, Gaensler, B M, Greenhill, Lincoln, Hazelton, B, Johnston-Hollitt, M, Lonsdale, Colin J, McWhirter, S.R., Mitchell, Daniel A, Morales, Miguel F, Morgan, Edward H, Oberoi, D, Ord, S M, Prabu, T, Udaya Shankar, N., Srivani, K. S., Subrahmanyan, R., and Williams, Christopher L

Published
2016

3. A high reliability survey of discrete Epoch of Reionization foreground sources in the MWA EoR0 field

Author

Carroll, P, Line, J, Morales, Miguel F, Barry, N, Beardsley, A, Hazelton, B, Jacobs, D. C., Pober, J. C., Sullivan, I S, Webster, Rachel L, Bernardi, Gianni, Bowman, J. D., Briggs, Franklin, Ewall-Wice, Aaron, Feng, Lu, Gaensler, B M, Pindor, B., Procopio, P., Riding, J, Rogers, Alan, Whitney, Alan, Williams, Christopher L, Carroll, P, Line, J, Morales, Miguel F, Barry, N, Beardsley, A, Hazelton, B, Jacobs, D. C., Pober, J. C., Sullivan, I S, Webster, Rachel L, Bernardi, Gianni, Bowman, J. D., Briggs, Franklin, Ewall-Wice, Aaron, Feng, Lu, Gaensler, B M, Pindor, B., Procopio, P., Riding, J, Rogers, Alan, Whitney, Alan, and Williams, Christopher L

Abstract

Detection of the epoch of reionization H I signal requires a precise understanding of the intervening galaxies and AGN, both for instrumental calibration and foreground removal. We present a catalogue of 7394 extragalactic sources at 182 MHz detected in the RA = 0 field of the Murchison Widefield Array Epoch of Reionization observation programme. Motivated by unprecedented requirements for precision and reliability we develop new methods for source finding and selection. We apply machine learning methods to self-consistently classify the relative reliability of 9490 source candidates. A subset of 7466 are selected based on reliability class and signal-to-noise ratio criteria. These are statistically cross-matched to four other radio surveys using both position and flux density information. We find 7369 sources to have confident matches, including 90 partially resolved sources that split into a total of 192 sub-components. An additional 25 unmatched sources are included as new radio detections. The catalogue sources have a median spectral index of −0.85. Spectral flattening is seen towards lower frequencies with a median of −0.71 predicted at 182 MHz. The astrometric error is 7 arcsec compared to a 2.3 arcmin beam FWHM. The resulting catalogue covers ∼1400 deg2 and is complete to approximately 80 mJy within half beam power. This provides the most reliable discrete source sky model available to date in the MWA EoR0 field for precision foreground subtraction.

Published
2016

4. Quantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield Array

Author

Loi, Shyeh Tjing, Murphy, Tara, Bell, Martin E., Kaplan, D L, Lenc, E, Offringa, Andre, Hurley-Walker, Natasha, Bernardi, G, Bowman, J D, Briggs, Franklin, Cappallo, Roger C, Corey, Brian E, Deshpande, Avinash, Emrich, David, Gaensler, B M, Goeke, R, Greenhill, Lincoln, Hazelton, B, Johnston-Hollitt, M, Kasper, J.C., Kratzenberg, Eric, Lonsdale, Colin J, Lynch, Mervyn J, McWhirter, S.R., Mitchell, D.A., Morales, Miguel F, Morgan, Edward H, Oberoi, D, Ord, S M, Prabu, T, Rogers, Alan, Roshi, A., Udaya Shankar, N., Srivani, K. S., Subrahmanyan, R., Tingay, S.J., Waterson, Mark, Wayth, Randall, Webster, Rachel L, Whitney, Alan, Williams, Andrew J., Williams, Christopher L, Kasper, Justin, Loi, Shyeh Tjing, Murphy, Tara, Bell, Martin E., Kaplan, D L, Lenc, E, Offringa, Andre, Hurley-Walker, Natasha, Bernardi, G, Bowman, J D, Briggs, Franklin, Cappallo, Roger C, Corey, Brian E, Deshpande, Avinash, Emrich, David, Gaensler, B M, Goeke, R, Greenhill, Lincoln, Hazelton, B, Johnston-Hollitt, M, Kasper, J.C., Kratzenberg, Eric, Lonsdale, Colin J, Lynch, Mervyn J, McWhirter, S.R., Mitchell, D.A., Morales, Miguel F, Morgan, Edward H, Oberoi, D, Ord, S M, Prabu, T, Rogers, Alan, Roshi, A., Udaya Shankar, N., Srivani, K. S., Subrahmanyan, R., Tingay, S.J., Waterson, Mark, Wayth, Randall, Webster, Rachel L, Whitney, Alan, Williams, Andrew J., Williams, Christopher L, and Kasper, Justin

Abstract

Refraction and diffraction of incoming radio waves by the ionosphere induce time variability in the angular positions, peak amplitudes and shapes of radio sources, potentially complicating the automated cross-matching and identification of transient and variable radio sources. In this work, we empirically assess the effects of the ionosphere on data taken by the Murchison Widefield Array (MWA) radio telescope. We directly examine 51 h of data observed over 10 nights under quiet geomagnetic conditions (global storm index Kp < 2), analysing the behaviour of short-time-scale angular position and peak flux density variations of around ten thousand unresolved sources. We find that while much of the variation in angular position can be attributed to ionospheric refraction, the characteristic displacements (10-20 arcsec) at 154 MHz are small enough that search radii of 1-2 arcmin should be sufficient for crossmatching under typical conditions. By examining bulk trends in amplitude variability, we place upper limits on the modulation index associated with ionospheric scintillation of 1-3 per cent for the various nights. For sources fainter than ~1 Jy, this variation is below the image noise at typical MWA sensitivities. Our results demonstrate that the ionosphere is not a significant impediment to the goals of time-domain science with the MWA at 154 MHz.

Published
2015

5. The EoR sensitivity of the murchison widefield array

Author

Waterson, Mark, Beardsley, A, Hazelton, B, Morales, Miguel F, Arcus, W, Barnes, David G, Bernardi, G, Briggs, Franklin, Bowman, J D, Bunton, John D., Cappallo, Roger C, Corey, Brian E, Deshpande, Avinash, Desouza, Ludi, Emrich, David, Greenhill, Lincoln, Kincaid, Barton B, Prabu, T, Rogers, Alan, Roshi, Anish, Srivani, K. S., Whitney, Alan, Williams, Andrew, Williams, Christopher L, Waterson, Mark, Beardsley, A, Hazelton, B, Morales, Miguel F, Arcus, W, Barnes, David G, Bernardi, G, Briggs, Franklin, Bowman, J D, Bunton, John D., Cappallo, Roger C, Corey, Brian E, Deshpande, Avinash, Desouza, Ludi, Emrich, David, Greenhill, Lincoln, Kincaid, Barton B, Prabu, T, Rogers, Alan, Roshi, Anish, Srivani, K. S., Whitney, Alan, Williams, Andrew, and Williams, Christopher L

Abstract

Using the final 128 antenna locations of the MurchisonWidefield Array (MWA), we calculate its sensitivity to the epoch of reionization (EoR) power spectrum of redshifted 21 cm emission for a fiducial model and provide the tools to calculate the sensitivit

Published
2013

6. A new layout optimization technique for interferometric arrays, applied to the Murchison Widefield Array

Author

Beardsley, A, Hazelton, B, Morales, Miguel F, Cappallo, Roger C, Goeke, R, Emrich, David, Lonsdale, Colin J, Arcus, W, Barnes, David G, Bernardi, G, Waterson, Mark, Bowman, J D, Bowman, Judd D, Deshpande, Avinash, Gaensler, B M, Greenhill, Lincoln, Kaplan, D L, Kincaid, Barton B, Prabu, T, Rogers, Alan, Roshi, Anish, Shankar, N.Udaya, Srivani, K. S., Whitney, Alan, Williams, Andrew, Williams, Christopher L, Beardsley, A, Hazelton, B, Morales, Miguel F, Cappallo, Roger C, Goeke, R, Emrich, David, Lonsdale, Colin J, Arcus, W, Barnes, David G, Bernardi, G, Waterson, Mark, Bowman, J D, Bowman, Judd D, Deshpande, Avinash, Gaensler, B M, Greenhill, Lincoln, Kaplan, D L, Kincaid, Barton B, Prabu, T, Rogers, Alan, Roshi, Anish, Shankar, N.Udaya, Srivani, K. S., Whitney, Alan, Williams, Andrew, and Williams, Christopher L

Abstract

Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21-cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed - even at the remote Australian location of the Murchison Widefield Array (MWA) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhances the PSF sidelobes and reduces the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution. This method not only outperforms random placement algorithms that avoid exclusion zones, but surprisingly outperforms random placement algorithms without constraints to provide what we believe are the smoothest constrained baseline distributions developed to date. We use our new algorithm to determine antenna placements for the originally planned MWA, and present the antenna locations, baseline distribution and snapshot PSF for this array choice.

Published
2012

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