Periodically variable quasars have been suggested as close binary supermassive black holes. We pr... more Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed quasars with a median redshift of 1.8 in a 4.6 deg2 overlapping region of the Dark Energy Survey Supernova (DES-SN) fields and the Sloan Digital Sky Survey Stripe 82 (SDSS-S82). Our sample has a unique 20-year long multi-color (griz) light curve enabled by combining DES-SN Y6 observations with archival SDSS-S82 data. The deep imaging allows us to search for periodic light curves in less luminous quasars (down to r ∼23.5 mag) powered by less massive black holes (with masses ≳ 108.5M⊙) at high redshift for the first time. We find five candidates with significant (at >99.74% single-frequency significance in at least two bands with a global p-value of ∼7 × 10−4–3× 10−3 accounting for the look-elsewhere effect) periodicity with observed periods of ∼3–5 years (i.e., 1–2 years in rest frame) having ∼4–6 cy...
We present far-UV imaging of the Hubble Deep Field North (HDF-N) taken with the Solar Blind Chann... more We present far-UV imaging of the Hubble Deep Field North (HDF-N) taken with the Solar Blind Channel of the Advanced Camera for Surveys (ACS/SBC) on board HST. Combined with archival STIS imaging, the full WFPC2 deep field has now been observed at 1500 Å. We detect 111 objects, with redshifts 0.07 < z < 0.85. A high fraction of galaxies
What drives the correlations between galaxy properties and environment? How do they evolve with t... more What drives the correlations between galaxy properties and environment? How do they evolve with time? We combine ACS imaging with ground-based optical spectroscopy for 3 clusters at z ˜ 0.8 to investigate the evolution of the correlation of galaxy properties, such as color, morphology, and star-formation rates, and environment. The clusters, CL0152-1357, CL1604+4304, and CL1604+ 4321 were chosen to cover a range of X-ray luminosity, and thus mass. Here we present preliminary results for CL0152-1357. Of the sample of 102 cluster members, we find 33 star-forming galaxies and 2 AGN. We have morphological information for 24 of the star-forming galaxies. Five of these are compact early-type galaxies, and seven are red cluster sequence spiral galaxies. The remaining 12 are blue spiral and irregular galaxies.
In this letter we address the problem of the origin of blue cores and inverse color gradients in ... more In this letter we address the problem of the origin of blue cores and inverse color gradients in early-type galaxies reported in the Hubble Deep Field North and South (HDFs) by Menanteau, Abraham & Ellis 2001. We use a multi-zone single collapse model. This model accounts for the observed blue cores by adopting a broad spread in formation redshifts for ellipticals, allowing some of these galaxies begin forming no more than ~1 Gyr before the redshift of observation. The single-zone collapse model then produces cores that are bluer than the outer regions because of the increase of the local potential well toward the center which makes star-formation more extended in the central region of the galaxy. We compare the predicted V-I(r) color gradients with the observed ones using the redshift of formation ($z_F$) of the elliptical as the only free parameter. We find that the model can account with relatively good agreement for the blue cores and inverse color gradients found in many spheroidals and at the same time for the red and smooth colors profiles reported. Based on the model our analysis suggests two populations of field ellipticals, one formed recently, within $\lesssim1$Gyr and another much older formed $\gtrsim4$Gyr since the redshift of observation.
We investigate the internal color properties of a sample of ˜ 85 (i775 < 25.5) morphol... more We investigate the internal color properties of a sample of ˜ 85 (i775 < 25.5) morphologically selected spheroid galaxies in the Hubble Ultra Deep Field. The unprecedented deep multicolor BViz information enables us to study in great detail the resolved galaxy colors. We augment our database of spectroscopic redshifts with Bayesian photometric estimates from the BViz and NICMOS J and
Using an iz dropout criterion, we determine the space density of z � 6 galaxies from two deep ACS... more Using an iz dropout criterion, we determine the space density of z � 6 galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of 23 objects are found over 46 arcmin2 ,o r� 0:5 � 0:1 objects arcmin� 2 down to zAB � 27: 3( 6� ), or a completeness-corrected � 0:5 � 0:2 objects arcmin�
We propose to obtain deep g- and r-band Blanco/MOSAIC imaging of three optically-rich and X-ray b... more We propose to obtain deep g- and r-band Blanco/MOSAIC imaging of three optically-rich and X-ray bright clusters, Abell S0592, Abell S0295, and RXC J0217.2-5244, that have been selected based on their detection by the Atacama Cosmology Telescope (ACT) in the Sunyaev- Zel'dovich effect (SZE) at 145 GHz. The clear signature of the SZE is being used to produce a unique
Observatory Operations: Strategies, Processes, and Systems V, 2014
ABSTRACT The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding ... more ABSTRACT The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding the accelerating expansion of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the 5000 sq-degree wide field and 30 sq-degree supernova surveys, the DES Collaboration built the Dark Energy Camera (DECam), a 3 square-degree, 570-Megapixel CCD camera that was installed at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO). DES started its first observing season on August 31, 2013 and observed for 105 nights through mid-February 2014. This paper describes DES "Year 1" (Y1), the strategy and goals for the first year's data, provides an outline of the operations procedures, lists the efficiency of survey operations and the causes of lost observing time, provides details about the quality of the first year's data, and hints at the "Year 2" plan and outlook.
Periodically variable quasars have been suggested as close binary supermassive black holes. We pr... more Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed quasars with a median redshift of 1.8 in a 4.6 deg2 overlapping region of the Dark Energy Survey Supernova (DES-SN) fields and the Sloan Digital Sky Survey Stripe 82 (SDSS-S82). Our sample has a unique 20-year long multi-color (griz) light curve enabled by combining DES-SN Y6 observations with archival SDSS-S82 data. The deep imaging allows us to search for periodic light curves in less luminous quasars (down to r ∼23.5 mag) powered by less massive black holes (with masses ≳ 108.5M⊙) at high redshift for the first time. We find five candidates with significant (at >99.74% single-frequency significance in at least two bands with a global p-value of ∼7 × 10−4–3× 10−3 accounting for the look-elsewhere effect) periodicity with observed periods of ∼3–5 years (i.e., 1–2 years in rest frame) having ∼4–6 cy...
We present far-UV imaging of the Hubble Deep Field North (HDF-N) taken with the Solar Blind Chann... more We present far-UV imaging of the Hubble Deep Field North (HDF-N) taken with the Solar Blind Channel of the Advanced Camera for Surveys (ACS/SBC) on board HST. Combined with archival STIS imaging, the full WFPC2 deep field has now been observed at 1500 Å. We detect 111 objects, with redshifts 0.07 < z < 0.85. A high fraction of galaxies
What drives the correlations between galaxy properties and environment? How do they evolve with t... more What drives the correlations between galaxy properties and environment? How do they evolve with time? We combine ACS imaging with ground-based optical spectroscopy for 3 clusters at z ˜ 0.8 to investigate the evolution of the correlation of galaxy properties, such as color, morphology, and star-formation rates, and environment. The clusters, CL0152-1357, CL1604+4304, and CL1604+ 4321 were chosen to cover a range of X-ray luminosity, and thus mass. Here we present preliminary results for CL0152-1357. Of the sample of 102 cluster members, we find 33 star-forming galaxies and 2 AGN. We have morphological information for 24 of the star-forming galaxies. Five of these are compact early-type galaxies, and seven are red cluster sequence spiral galaxies. The remaining 12 are blue spiral and irregular galaxies.
In this letter we address the problem of the origin of blue cores and inverse color gradients in ... more In this letter we address the problem of the origin of blue cores and inverse color gradients in early-type galaxies reported in the Hubble Deep Field North and South (HDFs) by Menanteau, Abraham & Ellis 2001. We use a multi-zone single collapse model. This model accounts for the observed blue cores by adopting a broad spread in formation redshifts for ellipticals, allowing some of these galaxies begin forming no more than ~1 Gyr before the redshift of observation. The single-zone collapse model then produces cores that are bluer than the outer regions because of the increase of the local potential well toward the center which makes star-formation more extended in the central region of the galaxy. We compare the predicted V-I(r) color gradients with the observed ones using the redshift of formation ($z_F$) of the elliptical as the only free parameter. We find that the model can account with relatively good agreement for the blue cores and inverse color gradients found in many spheroidals and at the same time for the red and smooth colors profiles reported. Based on the model our analysis suggests two populations of field ellipticals, one formed recently, within $\lesssim1$Gyr and another much older formed $\gtrsim4$Gyr since the redshift of observation.
We investigate the internal color properties of a sample of ˜ 85 (i775 < 25.5) morphol... more We investigate the internal color properties of a sample of ˜ 85 (i775 < 25.5) morphologically selected spheroid galaxies in the Hubble Ultra Deep Field. The unprecedented deep multicolor BViz information enables us to study in great detail the resolved galaxy colors. We augment our database of spectroscopic redshifts with Bayesian photometric estimates from the BViz and NICMOS J and
Using an iz dropout criterion, we determine the space density of z � 6 galaxies from two deep ACS... more Using an iz dropout criterion, we determine the space density of z � 6 galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of 23 objects are found over 46 arcmin2 ,o r� 0:5 � 0:1 objects arcmin� 2 down to zAB � 27: 3( 6� ), or a completeness-corrected � 0:5 � 0:2 objects arcmin�
We propose to obtain deep g- and r-band Blanco/MOSAIC imaging of three optically-rich and X-ray b... more We propose to obtain deep g- and r-band Blanco/MOSAIC imaging of three optically-rich and X-ray bright clusters, Abell S0592, Abell S0295, and RXC J0217.2-5244, that have been selected based on their detection by the Atacama Cosmology Telescope (ACT) in the Sunyaev- Zel'dovich effect (SZE) at 145 GHz. The clear signature of the SZE is being used to produce a unique
Observatory Operations: Strategies, Processes, and Systems V, 2014
ABSTRACT The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding ... more ABSTRACT The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding the accelerating expansion of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the 5000 sq-degree wide field and 30 sq-degree supernova surveys, the DES Collaboration built the Dark Energy Camera (DECam), a 3 square-degree, 570-Megapixel CCD camera that was installed at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO). DES started its first observing season on August 31, 2013 and observed for 105 nights through mid-February 2014. This paper describes DES "Year 1" (Y1), the strategy and goals for the first year's data, provides an outline of the operations procedures, lists the efficiency of survey operations and the causes of lost observing time, provides details about the quality of the first year's data, and hints at the "Year 2" plan and outlook.
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Papers by Felipe Menanteau