The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
Daniel P Stark - One of the best experts on this subject based on the ideXlab platform.
-
a keck adaptive optics survey of a representative sample of gravitationally lensed Star forming galaxies high spatial resolution studies of kinematics and metallicity gradients
The Astrophysical Journal, 2016Co-Authors: Nicha Leethochawalit, Richard S Ellis, Daniel P Stark, Tucker Jones, J Richard, Adi Zitrin, Matthew W AugerAbstract:We discuss spatially resolved emission line spectroscopy secured for a total sample of 15 gravitationally lensed Star-forming galaxies at a mean redshift of z≃2 based on Keck laser-assisted adaptive optics observations undertaken with the recently improved OSIRIS integral field unit (IFU) spectrograph. By exploiting gravitationally lensed sources drawn primarily from the CASSOWARY survey, we sample these sub-L^* galaxies with source-plane resolutions of a few hundred parsecs ensuring well-sampled 2D velocity data and resolved variations in the gas-phase metallicity. Such high spatial resolution data offer a critical check on the structural properties of larger samples derived with coarser sampling using multiple-IFU instruments. We demonstrate how kinematic complexities essential to understanding the maturity of an Early Star-forming galaxy can often only be revealed with better sampled data. Although we include four sources from our earlier work, the present study provides a more representative sample unbiased with respect to emission line strength. Contrary to earlier suggestions, our data indicate a more diverse range of kinematic and metal gradient behavior inconsistent with a simple picture of well-ordered rotation developing concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydrodynamical simulations suggests that gas and metals have been mixed by outflows or other strong feedback processes, flattening the metal gradients in Early Star-forming galaxies.
-
a keck adaptive optics survey of a representative sample of gravitationally lensed Star forming galaxies high spatial resolution studies of kinematics and metallicity gradients
arXiv: Astrophysics of Galaxies, 2015Co-Authors: Nicha Leethochawalit, Richard S Ellis, Daniel P Stark, Tucker Jones, J Richard, Adi Zitrin, Matthew W AugerAbstract:We discuss spatially resolved emission line spectroscopy secured for a total sample of 15 gravitationally lensed Star-forming galaxies at a mean redshift of $z\simeq2$ based on Keck laser-assisted adaptive optics observations undertaken with the recently-improved OSIRIS integral field unit (IFU) spectrograph. By exploiting gravitationally lensed sources drawn primarily from the CASSOWARY survey, we sample these sub-L$^{\ast}$ galaxies with source-plane resolutions of a few hundred parsecs ensuring well-sampled 2-D velocity data and resolved variations in the gas-phase metallicity. Such high spatial resolution data offers a critical check on the structural properties of larger samples derived with coarser sampling using multiple-IFU instruments. We demonstrate how serious errors of interpretation can only be revealed through better sampling. Although we include four sources from our earlier work, the present study provides a more representative sample unbiased with respect to emission line strength. Contrary to earlier suggestions, our data indicates a more diverse range of kinematic and metal gradient behavior inconsistent with a simple picture of well-ordered rotation developing concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydrodynamical simulations suggests that strong feedback plays a key role in flattening metal gradients in Early Star-forming galaxies.
-
spectroscopic detections of c iii λ1909 a at z 6 7 a new probe of Early Star forming galaxies and cosmic reionization
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: Daniel P Stark, Brant E Robertson, Richard S Ellis, Johan Richard, Stephane Charlot, Benjamin Clement, Brian Siana, Matthew A Schenker, Julia GutkinAbstract:Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper, we demonstrate the validity of a new way forward via the detection of an alternative diagnostic line, C iii] λ1909 A, seen in spectroscopic exposures of a Star-forming galaxy at zLyα = 6.029. We also report tentative detection of C iii] λ1909 A in a galaxy at z_Lyα = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J125 = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J140 = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C iii] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where C iii] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our C iii] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
The Astrophysical Journal, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen-ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z ~ 6 the population of Star-forming galaxies at redshifts z ~ 7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M UV ~ –13 or fainter. Moreover, low levels of Star formation extending to redshifts z ~ 15-25, as suggested by the normal UV colors of z ≃ 7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z ≃ 10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
arXiv: Cosmology and Nongalactic Astrophysics, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicates reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z~6 the population of Star-forming galaxies at redshifts z~7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M_UV\sim -13 or fainter. Moreover, low levels of Star formation extending to redshifts z~15-25, as suggested by the normal UV colors of z\simeq7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z\simeq10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
Richard S Ellis - One of the best experts on this subject based on the ideXlab platform.
-
a keck adaptive optics survey of a representative sample of gravitationally lensed Star forming galaxies high spatial resolution studies of kinematics and metallicity gradients
The Astrophysical Journal, 2016Co-Authors: Nicha Leethochawalit, Richard S Ellis, Daniel P Stark, Tucker Jones, J Richard, Adi Zitrin, Matthew W AugerAbstract:We discuss spatially resolved emission line spectroscopy secured for a total sample of 15 gravitationally lensed Star-forming galaxies at a mean redshift of z≃2 based on Keck laser-assisted adaptive optics observations undertaken with the recently improved OSIRIS integral field unit (IFU) spectrograph. By exploiting gravitationally lensed sources drawn primarily from the CASSOWARY survey, we sample these sub-L^* galaxies with source-plane resolutions of a few hundred parsecs ensuring well-sampled 2D velocity data and resolved variations in the gas-phase metallicity. Such high spatial resolution data offer a critical check on the structural properties of larger samples derived with coarser sampling using multiple-IFU instruments. We demonstrate how kinematic complexities essential to understanding the maturity of an Early Star-forming galaxy can often only be revealed with better sampled data. Although we include four sources from our earlier work, the present study provides a more representative sample unbiased with respect to emission line strength. Contrary to earlier suggestions, our data indicate a more diverse range of kinematic and metal gradient behavior inconsistent with a simple picture of well-ordered rotation developing concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydrodynamical simulations suggests that gas and metals have been mixed by outflows or other strong feedback processes, flattening the metal gradients in Early Star-forming galaxies.
-
a keck adaptive optics survey of a representative sample of gravitationally lensed Star forming galaxies high spatial resolution studies of kinematics and metallicity gradients
arXiv: Astrophysics of Galaxies, 2015Co-Authors: Nicha Leethochawalit, Richard S Ellis, Daniel P Stark, Tucker Jones, J Richard, Adi Zitrin, Matthew W AugerAbstract:We discuss spatially resolved emission line spectroscopy secured for a total sample of 15 gravitationally lensed Star-forming galaxies at a mean redshift of $z\simeq2$ based on Keck laser-assisted adaptive optics observations undertaken with the recently-improved OSIRIS integral field unit (IFU) spectrograph. By exploiting gravitationally lensed sources drawn primarily from the CASSOWARY survey, we sample these sub-L$^{\ast}$ galaxies with source-plane resolutions of a few hundred parsecs ensuring well-sampled 2-D velocity data and resolved variations in the gas-phase metallicity. Such high spatial resolution data offers a critical check on the structural properties of larger samples derived with coarser sampling using multiple-IFU instruments. We demonstrate how serious errors of interpretation can only be revealed through better sampling. Although we include four sources from our earlier work, the present study provides a more representative sample unbiased with respect to emission line strength. Contrary to earlier suggestions, our data indicates a more diverse range of kinematic and metal gradient behavior inconsistent with a simple picture of well-ordered rotation developing concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydrodynamical simulations suggests that strong feedback plays a key role in flattening metal gradients in Early Star-forming galaxies.
-
spectroscopic detections of c iii λ1909 a at z 6 7 a new probe of Early Star forming galaxies and cosmic reionization
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: Daniel P Stark, Brant E Robertson, Richard S Ellis, Johan Richard, Stephane Charlot, Benjamin Clement, Brian Siana, Matthew A Schenker, Julia GutkinAbstract:Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper, we demonstrate the validity of a new way forward via the detection of an alternative diagnostic line, C iii] λ1909 A, seen in spectroscopic exposures of a Star-forming galaxy at zLyα = 6.029. We also report tentative detection of C iii] λ1909 A in a galaxy at z_Lyα = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J125 = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J140 = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C iii] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where C iii] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our C iii] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.
-
cosmic reionization and Early Star forming galaxies a joint analysis of new constraints from planck and the hubble space telescope
The Astrophysical Journal, 2015Co-Authors: Brant E Robertson, Richard S Ellis, Steven R Furlanetto, J S DunlopAbstract:We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high-redshift Star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z≃ 6–8 QSOs, gamma-ray bursts, and galaxies expected to host Lyα emission. However, the most stringent constraints on its duration have come from the integrated optical depth, τ, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value τ = 0.066 ± 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 ≾ z ≾ 10, thereby reducing the requirement for a significant population of very high redshift (z ≫ 10) galaxies. Our analysis strengthens the conclusion that Star-forming galaxies dominated the reionization process and has important implications for upcoming 21 cm experiments and searches for Early galaxies with the James Webb Space Telescope.
-
cosmic reionization and Early Star forming galaxies a joint analysis of new constraints from planck and hubble space telescope
arXiv: Cosmology and Nongalactic Astrophysics, 2015Co-Authors: Brant Robertson, Richard S Ellis, Steven R Furlanetto, J S DunlopAbstract:We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high redshift Star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z~6-8 QSOs, gamma-ray bursts and galaxies expected to host Lyman-alpha emission. However, the most stringent constraints on its duration have come from the integrated optical depth, tau, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value tau=0.066 +/- 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 >10) galaxies. Our analysis strengthens the conclusion that Star-forming galaxies dominated the reionization process and has important implications for upcoming 21cm experiments and searches for Early galaxies with James Webb Space Telescope.
Brant E Robertson - One of the best experts on this subject based on the ideXlab platform.
-
spectroscopic detections of c iii λ1909 a at z 6 7 a new probe of Early Star forming galaxies and cosmic reionization
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: Daniel P Stark, Brant E Robertson, Richard S Ellis, Johan Richard, Stephane Charlot, Benjamin Clement, Brian Siana, Matthew A Schenker, Julia GutkinAbstract:Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper, we demonstrate the validity of a new way forward via the detection of an alternative diagnostic line, C iii] λ1909 A, seen in spectroscopic exposures of a Star-forming galaxy at zLyα = 6.029. We also report tentative detection of C iii] λ1909 A in a galaxy at z_Lyα = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J125 = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J140 = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C iii] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where C iii] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our C iii] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.
-
cosmic reionization and Early Star forming galaxies a joint analysis of new constraints from planck and the hubble space telescope
The Astrophysical Journal, 2015Co-Authors: Brant E Robertson, Richard S Ellis, Steven R Furlanetto, J S DunlopAbstract:We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high-redshift Star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z≃ 6–8 QSOs, gamma-ray bursts, and galaxies expected to host Lyα emission. However, the most stringent constraints on its duration have come from the integrated optical depth, τ, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value τ = 0.066 ± 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 ≾ z ≾ 10, thereby reducing the requirement for a significant population of very high redshift (z ≫ 10) galaxies. Our analysis strengthens the conclusion that Star-forming galaxies dominated the reionization process and has important implications for upcoming 21 cm experiments and searches for Early galaxies with the James Webb Space Telescope.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
The Astrophysical Journal, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen-ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z ~ 6 the population of Star-forming galaxies at redshifts z ~ 7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M UV ~ –13 or fainter. Moreover, low levels of Star formation extending to redshifts z ~ 15-25, as suggested by the normal UV colors of z ≃ 7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z ≃ 10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
arXiv: Cosmology and Nongalactic Astrophysics, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicates reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z~6 the population of Star-forming galaxies at redshifts z~7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M_UV\sim -13 or fainter. Moreover, low levels of Star formation extending to redshifts z~15-25, as suggested by the normal UV colors of z\simeq7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z\simeq10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
-
Early Star forming galaxies and the reionization of the universe
Nature, 2010Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P StarkAbstract:Star-forming galaxies trace cosmic history. Recent observational progress with the NASA Hubble Space Telescope has led to the discovery and study of the earliest known galaxies, which correspond to a period when the Universe was only ~800 million years old. Intense ultraviolet radiation from these Early galaxies probably induced a major event in cosmic history: the reionization of intergalactic hydrogen.
J S Dunlop - One of the best experts on this subject based on the ideXlab platform.
-
cosmic reionization and Early Star forming galaxies a joint analysis of new constraints from planck and the hubble space telescope
The Astrophysical Journal, 2015Co-Authors: Brant E Robertson, Richard S Ellis, Steven R Furlanetto, J S DunlopAbstract:We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high-redshift Star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z≃ 6–8 QSOs, gamma-ray bursts, and galaxies expected to host Lyα emission. However, the most stringent constraints on its duration have come from the integrated optical depth, τ, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value τ = 0.066 ± 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 ≾ z ≾ 10, thereby reducing the requirement for a significant population of very high redshift (z ≫ 10) galaxies. Our analysis strengthens the conclusion that Star-forming galaxies dominated the reionization process and has important implications for upcoming 21 cm experiments and searches for Early galaxies with the James Webb Space Telescope.
-
cosmic reionization and Early Star forming galaxies a joint analysis of new constraints from planck and hubble space telescope
arXiv: Cosmology and Nongalactic Astrophysics, 2015Co-Authors: Brant Robertson, Richard S Ellis, Steven R Furlanetto, J S DunlopAbstract:We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high redshift Star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z~6-8 QSOs, gamma-ray bursts and galaxies expected to host Lyman-alpha emission. However, the most stringent constraints on its duration have come from the integrated optical depth, tau, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value tau=0.066 +/- 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 >10) galaxies. Our analysis strengthens the conclusion that Star-forming galaxies dominated the reionization process and has important implications for upcoming 21cm experiments and searches for Early galaxies with James Webb Space Telescope.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
The Astrophysical Journal, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen-ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z ~ 6 the population of Star-forming galaxies at redshifts z ~ 7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M UV ~ –13 or fainter. Moreover, low levels of Star formation extending to redshifts z ~ 15-25, as suggested by the normal UV colors of z ≃ 7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z ≃ 10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
arXiv: Cosmology and Nongalactic Astrophysics, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicates reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z~6 the population of Star-forming galaxies at redshifts z~7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M_UV\sim -13 or fainter. Moreover, low levels of Star formation extending to redshifts z~15-25, as suggested by the normal UV colors of z\simeq7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z\simeq10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
-
Early Star forming galaxies and the reionization of the universe
Nature, 2010Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P StarkAbstract:Star-forming galaxies trace cosmic history. Recent observational progress with the NASA Hubble Space Telescope has led to the discovery and study of the earliest known galaxies, which correspond to a period when the Universe was only ~800 million years old. Intense ultraviolet radiation from these Early galaxies probably induced a major event in cosmic history: the reionization of intergalactic hydrogen.
Steven R Furlanetto - One of the best experts on this subject based on the ideXlab platform.
-
the global 21 cm signal in the context of the high z galaxy luminosity function
Monthly Notices of the Royal Astronomical Society, 2017Co-Authors: Jordan Mirocha, Steven R Furlanetto, Guochao SunAbstract:We build a new model for the global 21-cm signal that is calibrated to measurements of the high-z galaxy luminosity function (LF) and further tuned to match the Thomson scattering optical depth of the cosmic microwave background, τe. Assuming that the z ≲ 8 galaxy population can be smoothly extrapolated to higher redshifts, the recent decline in best-fitting values of τe and the inefficient heating induced by X-ray binaries (the presumptive sources of the high-z X-ray background) imply that the entirety of cosmic reionization and reheating occurs at z ≲ 12. In contrast to past global 21-cm models, whose z ∼ 20 (ν ∼ 70 MHz) absorption features and strong ∼25 mK emission features were driven largely by the assumption of efficient Early Star formation and X-ray heating, our new models peak in absorption at ν ∼ 110 MHz at depths ∼−160 mK and have negligible emission components. Current uncertainties in the faint-end of the LF, binary populations in Star-forming galaxies, and UV and X-ray escape fractions introduce ∼20 MHz (∼50 mK) deviations in the trough's frequency (amplitude), while emission signals remain weak (≲10 mK) and are confined to ν ≳ 140 MHz. These predictions, which are intentionally conservative, suggest that the detection of a 21-cm absorption minimum at frequencies below ∼90 MHz and/or emission signals stronger than ∼10mK at ν ≲ 140 MHz would provide strong evidence for ‘new’ sources at high redshifts, such as Population III Stars and their remnants.
-
cosmic reionization and Early Star forming galaxies a joint analysis of new constraints from planck and the hubble space telescope
The Astrophysical Journal, 2015Co-Authors: Brant E Robertson, Richard S Ellis, Steven R Furlanetto, J S DunlopAbstract:We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high-redshift Star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z≃ 6–8 QSOs, gamma-ray bursts, and galaxies expected to host Lyα emission. However, the most stringent constraints on its duration have come from the integrated optical depth, τ, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value τ = 0.066 ± 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 ≾ z ≾ 10, thereby reducing the requirement for a significant population of very high redshift (z ≫ 10) galaxies. Our analysis strengthens the conclusion that Star-forming galaxies dominated the reionization process and has important implications for upcoming 21 cm experiments and searches for Early galaxies with the James Webb Space Telescope.
-
cosmic reionization and Early Star forming galaxies a joint analysis of new constraints from planck and hubble space telescope
arXiv: Cosmology and Nongalactic Astrophysics, 2015Co-Authors: Brant Robertson, Richard S Ellis, Steven R Furlanetto, J S DunlopAbstract:We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high redshift Star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z~6-8 QSOs, gamma-ray bursts and galaxies expected to host Lyman-alpha emission. However, the most stringent constraints on its duration have come from the integrated optical depth, tau, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value tau=0.066 +/- 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 >10) galaxies. Our analysis strengthens the conclusion that Star-forming galaxies dominated the reionization process and has important implications for upcoming 21cm experiments and searches for Early galaxies with James Webb Space Telescope.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
The Astrophysical Journal, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen-ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z ~ 6 the population of Star-forming galaxies at redshifts z ~ 7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M UV ~ –13 or fainter. Moreover, low levels of Star formation extending to redshifts z ~ 15-25, as suggested by the normal UV colors of z ≃ 7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z ≃ 10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
-
new constraints on cosmic reionization from the 2012 hubble ultra deep field campaign
arXiv: Cosmology and Nongalactic Astrophysics, 2013Co-Authors: Brant E Robertson, Richard S Ellis, J S Dunlop, R J Mclure, Daniel P Stark, Steven R Furlanetto, Stephane Charlot, Evan E Schneider, A M Koekemoer, Matthew A SchenkerAbstract:Understanding cosmic reionization requires the identification and characterization of Early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicates reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of Early Star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z~6 the population of Star-forming galaxies at redshifts z~7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M_UV\sim -13 or fainter. Moreover, low levels of Star formation extending to redshifts z~15-25, as suggested by the normal UV colors of z\simeq7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z\simeq10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.
