Joaquin Vieira | University of Illinois at Urbana-Champaign (original) (raw)

Papers by Joaquin Vieira

The South Pole Telescope (SPT) has recently discovered a new population of extraordinarily bright... more The South Pole Telescope (SPT) has recently discovered a new population of extraordinarily bright, dusty, star-forming galaxies in a wide field millimeter-wave survey of the southern sky. Our extensive follow-up campaign indicates that they are high-redshift, strongly-lensed, sub-mm galaxies (SMGs). ATCA is playing a central role in these observations by providing precise locations and in some cases resolving multiple images. Here we propose observations of 6 targets from 2008 SPT observations. ATCA imaging will provide unambiguous identification of the IR counterparts of these sources and enable spectroscopic followup, and resolve lensed structure in several sources. Only through these observations can we advance our understanding of these objects and use them to probe extreme galaxy formation processes in the early universe.

We propose to obtain RIJK imaging with the 4m Southern Astrophysical Research (SOAR) telescope of... more We propose to obtain RIJK imaging with the 4m Southern Astrophysical Research (SOAR) telescope of 16 millimeter-bright sources discovered by the South Pole Telescope (SPT). We also propose to obtain optical spectroscopy and imaging with the 8m Gemini telescope of an additional 3 sources, also discovered by the SPT, and identified in the Blanco Cosmology Survey (BCS) as strong z>4 candidates via griz photometry. Together, these 19 sources are the empirically brightest and rarest members of the population commonly referred to as sub-millimeter galaxies (SMGs). Our targets are expected to have a higher median redshift than objects currently in the literature. Theoretical estimates suggest that we are detecting a significant number of lensed sources, some of which should lie at z>5. Our proposed photometric observations will allow us to identify the optical counterparts out to z~5 and maximize return by taking advantage of previous imaging of half of these objects by the BCS survey. The proposed observations will provide optical identification, characterization, and spectroscopic redshifts for this unique sample of galaxies. It is likely that one of these candidates will be the highest redshift SMG ever observed.

We propose to obtain IRAC imaging of 40 rare millimeter sources discovered by the South Pole Tele... more We propose to obtain IRAC imaging of 40 rare millimeter sources discovered by the South Pole Telescope (SPT). These sources are the observably brightest, rarest members of the population commonly referred to as sub-millimeter galaxies (SMGs) and will provide a new window on galaxy formation in the early universe. Because our targets are selected at longer wavelengths than typical SMG surveys, and are an order of magnitude brighter than the typical SMGs, they are expected to have a higher median redshift than objects currently in the literature. Simulations suggest that we are detecting a significant number of lensed sources, some of which should lie at z>6. The proposed observations, when combined with precise positions from ATCA 3 mm interferometric images, will enable photometric redshifts and measurements of total luminosity, star formation rates, and stellar masses for this unique sample of galaxies.

This proposal requests observing time to determine the properties of sources detected in the Sout... more This proposal requests observing time to determine the properties of sources detected in the South Pole Telescope Sunyaev-Zel'dovich Survey (SPT-SZ). This is a deep millimeter-wave survey at 90, 150 and 220 GHz of the extragalactic sky south of decl = -30 degrees from RA = 22h to 24h and 0h to 7h. Among the objects detected are submillimeter-bright galaxies and Sunyaev-Zel'dovich effect from clusters of galaxies. In this proposal, we request observing time to observe these newly-detected objects. During the best observing weather, we will observe about 40 SMGs at 3mm to determine accurate positions. This will allow positive optical identification of these objects and is essential to their further study. During less-than-optimal weather, we will observe SZ-selected clusters at 12mm to determine the log N - log S relation for AGNs inside the cluster galaxies. This information will be used to better understand the dynamics of galaxy clusters, and possibly indicate corrections needed in the cluster method for the determination of cosmological parameters.

Journal of Low Temperature Physics, 2008

The implementation of TES based microbolometer arrays will achieve unprecedented sensitivities fo... more The implementation of TES based microbolometer arrays will achieve unprecedented sensitivities for mm and sub-mm astronomy through fabrication of large format arrays and improved linearity and stability arising from strong electro-thermal feedback. We report on progress in developing TES microbolometers using Mo/Au thin films and Au absorbing structures. We present measurements of suppressing the thermal conductance through the etching of features on a continuous Silicon-Nitride window.

We present millimeter-wave (mm) number counts and spectral indices from a new survey taken with t... more We present millimeter-wave (mm) number counts and spectral indices from a new survey taken with the 10 m South Pole Telescope located at the Amundsen-Scott South Pole Station in Antarctica. Extragalactic mm sources are expected to be the dominant contaminant in the current generation of fine-scale cosmic microwave background and Sunyaev-Zel'dovich effect experiments. Here we characterize the spectral and flux distributions of mm sources down to a few mJy at 150 and 225 GHz from an 80 square degree field with uniform coverage. Two distinct populations of mm sources are observed, characterized by their spectral indices: (1) a population of bright sources with falling or flat spectra and cm-wave counterparts and (2) a population of sources with positive spectral indices with number counts consistent with previous observations of submillimeter galaxies.

When and how did galaxies form and their metals accumulate? Over the last decade, this has moved ... more When and how did galaxies form and their metals accumulate? Over the last decade, this has moved from an archeological question to a live investigation: there is now a broad picture of the evolution of galaxies in dark matter halos: their masses, stars, metals and supermassive blackholes. Galaxies have been found and studied in which these formation processes are taking place most vigorously, all the way back in cosmic time to when the intergalactic medium (IGM) was still largely neutral. However, the details of how and why the interstellar medium (ISM) in distant galaxies cools, is processed, recycled and enriched in metals by stars, and fuels active galactic nuclei (AGNs) remain uncertain. In particular, the cooling of gas to fuel star formation, and the chemistry and physics of the most intensely active regions is hidden from view at optical wavelengths, but can be seen and diagnosed at mid-& far-infrared (IR) wavelengths. Rest-frame IR observations are important first to identify the most luminous, interesting and important galaxies, secondly to quantify accurately their total luminosity, and finally to use spectroscopy to trace the conditions in the molecular and atomic gas out of which stars form. In order to map out these processes over the full range of environments and large-scale structures found in the universe -from the densest clusters of galaxies to the emptiest voids -we require tools for deep, large area surveys, of millions of galaxies out to z~5, and for detailed follow-up spectroscopy. The necessary tools can be realized technically. Here, we outline the requirements for gathering the crucial information to build, validate and challenge models of galaxy evolution.

IEEE Transactions on Applied Superconductivity, 2009

We propose a program to image the first sample of galaxy clusters selected at mm-wavelengths via ... more We propose a program to image the first sample of galaxy clusters selected at mm-wavelengths via the Sunyaev-Zeldovich Effect (SZE). We have chosen a sample of 84 robust, high-significance clusters (S/N >D 4.5) from the first 350 deg^2 of the ongoing > 1000 deg^2 South Pole Telescope (SPT) SZE survey. These clusters are selected on total mass, independently of redshift, and as such form the ideal sample for studies of massive galaxies in rich environments over a wide range of redshifts. The IRAC data will provide photometric redshifts and stellar mass estimates for both field galaxies and cluster members, allowing studies of the cluster IR luminosity and stellar mass function evolution over the last 10 Gyr in a unique, unbiased cluster sample. Finally, in concert with our ongoing, extensive multiwavelength and spectroscopic follow-up programs, the proposed data will allow empirical calibration of the relationship between SZE, X-ray, IR and dynamical measures of cluster mass, which will ultimately allow accurate constraints to be placed on the equation of state of dark energy.

IEEE Transactions on Applied Superconductivity, 2009

The South Pole Telescope (SPT) is conducting a deep millimeter-wave survey at 90, 150 and 220 GHz... more The South Pole Telescope (SPT) is conducting a deep millimeter-wave survey at 90, 150 and 220 GHz of the extragalactic sky south of decl = -30 degrees from RA = 22h to 24h and 0h to 7h. We have detected a new class of sub-millimeter galaxies (SMGs) that have no previously-known radio, infrared, or optical counterpart. Photometric redshifts for a few of these SMGs show them to be highly redshifted (z>4). They may be unusually bright because of lensing: one of these candidates may be the highest-z SMG ever observed. Multi-wavelength observations are planned. The SPT beam of 1' cannot locate the SMGs with sufficient precision for optical studies: ATCA can provide the requisite resolution and sensitivity to enable followup. Observations with Spitzer have been approved, for which ATCA positions are essential. May 2009 CABB observations at 3mm, made under average-to-poor conditions, detected a small number of SMGs. We now propose further ATCA 3mm studies to locate additional SMGs. A backup project utilizes poor weather to determine the log N-log S relation for radio sources in newly-discovered clusters: data that is essential to make new, highly accurate measures of cosmological parameters.

The South Pole Telescope (SPT) has surveyed hundreds of square degrees to milli-Jansky levels at ... more The South Pole Telescope (SPT) has surveyed hundreds of square degrees to milli-Jansky levels at 1.4 mm and 2.0 mm. We report here on sources of point- like emission detected in the 1.4 and 2.0 mm bands in an 87 deg 2 field, centered at R.A. 5 h 30 m , decl. -55°, and observed in 2008. Based on the ratio of flux in these two bands, we are able to separate the detected sources into two populations, one consistent with synchrotron emission from active galactic nuclei (AGN) and one consistent with thermal emission from dust. We present source counts for each population from 11 to 640 mJy at 1.4 mm and from 4.4 to 800 mJy at 2.0 mm. We detect 119 synchrotron-dominated sources and 49 dust-dominated sources at S/N > 4.5 in at least one band. All of the most significantly detected members of the synchrotron-dominated population are associated with sources in previously published radio catalogs and/or in our own long-wavelength follow-up observations. Some of the dust-dominated sources are associated with nearby ( z [Special characters omitted.] 1) galaxies whose dust emission is also detected by the Infrared Astronomy Satellite (IRAS). However, most of the bright, dust-dominated sources have no counterparts in any existing catalog. We argue that these sources represent the rarest, brightest, and possibly strongly-lensed members of the population commonly referred to as sub-millimeter galaxies (SMGs). Because these sources are selected at longer wavelengths than in typical SMG surveys, they are expected to have a higher mean redshift distribution than objects currently in the literature, and may provide a new window on galaxy formation in the early universe.

The South Pole Telescope (SPT) has recently discovered a new population of extraordinarily bright... more The South Pole Telescope (SPT) has recently discovered a new population of extraordinarily bright, dusty, star-forming galaxies in a wide field millimeter-wave survey of the southern sky. Our extensive follow-up campaign indicates that they are high-redshift, strongly-lensed, sub-mm galaxies (SMGs). ATCA is playing a central role in these observations by providing precise locations and in some cases resolving multiple images. Here we propose observations of 6 targets from 2008 SPT observations. ATCA imaging will provide unambiguous identification of the IR counterparts of these sources and enable spectroscopic followup, and resolve lensed structure in several sources. Only through these observations can we advance our understanding of these objects and use them to probe extreme galaxy formation processes in the early universe.

We propose to obtain RIJK imaging with the 4m Southern Astrophysical Research (SOAR) telescope of... more We propose to obtain RIJK imaging with the 4m Southern Astrophysical Research (SOAR) telescope of 16 millimeter-bright sources discovered by the South Pole Telescope (SPT). We also propose to obtain optical spectroscopy and imaging with the 8m Gemini telescope of an additional 3 sources, also discovered by the SPT, and identified in the Blanco Cosmology Survey (BCS) as strong z>4 candidates via griz photometry. Together, these 19 sources are the empirically brightest and rarest members of the population commonly referred to as sub-millimeter galaxies (SMGs). Our targets are expected to have a higher median redshift than objects currently in the literature. Theoretical estimates suggest that we are detecting a significant number of lensed sources, some of which should lie at z>5. Our proposed photometric observations will allow us to identify the optical counterparts out to z~5 and maximize return by taking advantage of previous imaging of half of these objects by the BCS survey. The proposed observations will provide optical identification, characterization, and spectroscopic redshifts for this unique sample of galaxies. It is likely that one of these candidates will be the highest redshift SMG ever observed.

We propose to obtain IRAC imaging of 40 rare millimeter sources discovered by the South Pole Tele... more We propose to obtain IRAC imaging of 40 rare millimeter sources discovered by the South Pole Telescope (SPT). These sources are the observably brightest, rarest members of the population commonly referred to as sub-millimeter galaxies (SMGs) and will provide a new window on galaxy formation in the early universe. Because our targets are selected at longer wavelengths than typical SMG surveys, and are an order of magnitude brighter than the typical SMGs, they are expected to have a higher median redshift than objects currently in the literature. Simulations suggest that we are detecting a significant number of lensed sources, some of which should lie at z>6. The proposed observations, when combined with precise positions from ATCA 3 mm interferometric images, will enable photometric redshifts and measurements of total luminosity, star formation rates, and stellar masses for this unique sample of galaxies.

This proposal requests observing time to determine the properties of sources detected in the Sout... more This proposal requests observing time to determine the properties of sources detected in the South Pole Telescope Sunyaev-Zel'dovich Survey (SPT-SZ). This is a deep millimeter-wave survey at 90, 150 and 220 GHz of the extragalactic sky south of decl = -30 degrees from RA = 22h to 24h and 0h to 7h. Among the objects detected are submillimeter-bright galaxies and Sunyaev-Zel'dovich effect from clusters of galaxies. In this proposal, we request observing time to observe these newly-detected objects. During the best observing weather, we will observe about 40 SMGs at 3mm to determine accurate positions. This will allow positive optical identification of these objects and is essential to their further study. During less-than-optimal weather, we will observe SZ-selected clusters at 12mm to determine the log N - log S relation for AGNs inside the cluster galaxies. This information will be used to better understand the dynamics of galaxy clusters, and possibly indicate corrections needed in the cluster method for the determination of cosmological parameters.

Journal of Low Temperature Physics, 2008

The implementation of TES based microbolometer arrays will achieve unprecedented sensitivities fo... more The implementation of TES based microbolometer arrays will achieve unprecedented sensitivities for mm and sub-mm astronomy through fabrication of large format arrays and improved linearity and stability arising from strong electro-thermal feedback. We report on progress in developing TES microbolometers using Mo/Au thin films and Au absorbing structures. We present measurements of suppressing the thermal conductance through the etching of features on a continuous Silicon-Nitride window.

We present millimeter-wave (mm) number counts and spectral indices from a new survey taken with t... more We present millimeter-wave (mm) number counts and spectral indices from a new survey taken with the 10 m South Pole Telescope located at the Amundsen-Scott South Pole Station in Antarctica. Extragalactic mm sources are expected to be the dominant contaminant in the current generation of fine-scale cosmic microwave background and Sunyaev-Zel'dovich effect experiments. Here we characterize the spectral and flux distributions of mm sources down to a few mJy at 150 and 225 GHz from an 80 square degree field with uniform coverage. Two distinct populations of mm sources are observed, characterized by their spectral indices: (1) a population of bright sources with falling or flat spectra and cm-wave counterparts and (2) a population of sources with positive spectral indices with number counts consistent with previous observations of submillimeter galaxies.

When and how did galaxies form and their metals accumulate? Over the last decade, this has moved ... more When and how did galaxies form and their metals accumulate? Over the last decade, this has moved from an archeological question to a live investigation: there is now a broad picture of the evolution of galaxies in dark matter halos: their masses, stars, metals and supermassive blackholes. Galaxies have been found and studied in which these formation processes are taking place most vigorously, all the way back in cosmic time to when the intergalactic medium (IGM) was still largely neutral. However, the details of how and why the interstellar medium (ISM) in distant galaxies cools, is processed, recycled and enriched in metals by stars, and fuels active galactic nuclei (AGNs) remain uncertain. In particular, the cooling of gas to fuel star formation, and the chemistry and physics of the most intensely active regions is hidden from view at optical wavelengths, but can be seen and diagnosed at mid-& far-infrared (IR) wavelengths. Rest-frame IR observations are important first to identify the most luminous, interesting and important galaxies, secondly to quantify accurately their total luminosity, and finally to use spectroscopy to trace the conditions in the molecular and atomic gas out of which stars form. In order to map out these processes over the full range of environments and large-scale structures found in the universe -from the densest clusters of galaxies to the emptiest voids -we require tools for deep, large area surveys, of millions of galaxies out to z~5, and for detailed follow-up spectroscopy. The necessary tools can be realized technically. Here, we outline the requirements for gathering the crucial information to build, validate and challenge models of galaxy evolution.

IEEE Transactions on Applied Superconductivity, 2009

We propose a program to image the first sample of galaxy clusters selected at mm-wavelengths via ... more We propose a program to image the first sample of galaxy clusters selected at mm-wavelengths via the Sunyaev-Zeldovich Effect (SZE). We have chosen a sample of 84 robust, high-significance clusters (S/N >D 4.5) from the first 350 deg^2 of the ongoing > 1000 deg^2 South Pole Telescope (SPT) SZE survey. These clusters are selected on total mass, independently of redshift, and as such form the ideal sample for studies of massive galaxies in rich environments over a wide range of redshifts. The IRAC data will provide photometric redshifts and stellar mass estimates for both field galaxies and cluster members, allowing studies of the cluster IR luminosity and stellar mass function evolution over the last 10 Gyr in a unique, unbiased cluster sample. Finally, in concert with our ongoing, extensive multiwavelength and spectroscopic follow-up programs, the proposed data will allow empirical calibration of the relationship between SZE, X-ray, IR and dynamical measures of cluster mass, which will ultimately allow accurate constraints to be placed on the equation of state of dark energy.

IEEE Transactions on Applied Superconductivity, 2009

The South Pole Telescope (SPT) is conducting a deep millimeter-wave survey at 90, 150 and 220 GHz... more The South Pole Telescope (SPT) is conducting a deep millimeter-wave survey at 90, 150 and 220 GHz of the extragalactic sky south of decl = -30 degrees from RA = 22h to 24h and 0h to 7h. We have detected a new class of sub-millimeter galaxies (SMGs) that have no previously-known radio, infrared, or optical counterpart. Photometric redshifts for a few of these SMGs show them to be highly redshifted (z>4). They may be unusually bright because of lensing: one of these candidates may be the highest-z SMG ever observed. Multi-wavelength observations are planned. The SPT beam of 1' cannot locate the SMGs with sufficient precision for optical studies: ATCA can provide the requisite resolution and sensitivity to enable followup. Observations with Spitzer have been approved, for which ATCA positions are essential. May 2009 CABB observations at 3mm, made under average-to-poor conditions, detected a small number of SMGs. We now propose further ATCA 3mm studies to locate additional SMGs. A backup project utilizes poor weather to determine the log N-log S relation for radio sources in newly-discovered clusters: data that is essential to make new, highly accurate measures of cosmological parameters.

The South Pole Telescope (SPT) has surveyed hundreds of square degrees to milli-Jansky levels at ... more The South Pole Telescope (SPT) has surveyed hundreds of square degrees to milli-Jansky levels at 1.4 mm and 2.0 mm. We report here on sources of point- like emission detected in the 1.4 and 2.0 mm bands in an 87 deg 2 field, centered at R.A. 5 h 30 m , decl. -55°, and observed in 2008. Based on the ratio of flux in these two bands, we are able to separate the detected sources into two populations, one consistent with synchrotron emission from active galactic nuclei (AGN) and one consistent with thermal emission from dust. We present source counts for each population from 11 to 640 mJy at 1.4 mm and from 4.4 to 800 mJy at 2.0 mm. We detect 119 synchrotron-dominated sources and 49 dust-dominated sources at S/N > 4.5 in at least one band. All of the most significantly detected members of the synchrotron-dominated population are associated with sources in previously published radio catalogs and/or in our own long-wavelength follow-up observations. Some of the dust-dominated sources are associated with nearby ( z [Special characters omitted.] 1) galaxies whose dust emission is also detected by the Infrared Astronomy Satellite (IRAS). However, most of the bright, dust-dominated sources have no counterparts in any existing catalog. We argue that these sources represent the rarest, brightest, and possibly strongly-lensed members of the population commonly referred to as sub-millimeter galaxies (SMGs). Because these sources are selected at longer wavelengths than in typical SMG surveys, they are expected to have a higher mean redshift distribution than objects currently in the literature, and may provide a new window on galaxy formation in the early universe.