Krumholz, Mark R., Ellison, Sara L., Prochaska, J. Xavier, Tumlinson, Jason
We argue that the lack of observed damped Lyman alpha (DLA) systems that simultaneously have high HI columns densities and high metallicities results naturally from the formation of molecules in the...
Ellison, Sara L., Lopez, Sebastian
The Complete Optical and Radio Absorption Line System (CORALS) survey has previously been used to demonstrate that the number density, gas and metals content of z>1.6 damped Lyman alpha systems is...
Revisiting the origin of the high metallicities of sub-damped Lyman-alpha systems (2009)
Dessauges-Zavadsky, Miroslava, Ellison, Sara L., Murphy, Michael T.
Sub-damped Lyman-alpha systems (sub-DLAs) have previously been found to exhibit a steeper metallicity evolution than the classical damped Lyman-alpha systems (DLAs), evolving to close to solar...
Ellison, Sara L., Simard, Luc, Cowan, Nicolas B., Baldry, Ivan K., Patton, David R., McConnachie, Alan W.
Using a large (14,857), homogenously selected sample of cluster galaxies identified in the Sloan Digital Sky Survey Data Release 4 (SDSS DR4), we investigate the impact of cluster membership and...
Ellison, Sara L., Murphy, Michael T., Dessauges-Zavadsky, Miroslava
Using a sample of 21 damped Lyman alpha systems (DLAs) and 35 sub-DLAs, we evaluate the D-index from high-resolution spectra of the Mg ii λ 2796 profile. This sample represents an increase in...
Revisiting the origin of the high metallicities of sub-damped Lyman-alpha systems (2009)
Dessauges-Zavadsky, Miroslava, Ellison, Sara L., Murphy, Michael T.
Sub-damped Lyman-alpha systems (sub-DLAs) have previously been found to exhibit a steeper metallicity evolution than the classical damped Lyman-alpha systems (DLAs), evolving to close to solar...
Ellison, Sara L., Murphy, Michael T., Dessauges-Zavadsky, Miroslava
Using a sample of 21 damped Lyman alpha systems (DLAs) and 35 sub-DLAs, we evaluate the D-index from high-resolution spectra of the Mg ii λ 2796 profile. This sample represents an increase in...
Revisiting the origin of the high metallicities of sub-damped Lyman-alpha systems (2009)
Dessauges-Zavadsky, Miroslava, Ellison, Sara L., Murphy, Michael T.
Sub-damped Lyman-alpha systems (sub-DLAs) have previously been found to exhibit a steeper metallicity evolution than the classical damped Lyman-alpha systems (DLAs), evolving to close to solar...
Ellison, Sara L., Murphy, Michael T., Dessauges-Zavadsky, Miroslava
Using a sample of 21 damped Lyman alpha systems (DLAs) and 35 sub-DLAs, we evaluate the D-index = EW / Delta v x 1000 from high resolution spectra of the MgII lambda 2796 profile. This sample...
Brasseur, Crystal M., McConnachie, Alan W., Ellison, Sara L., Patton, David R.
We examine the properties of galaxies in compact groups identified in a mock galaxy catalogue based upon the Millennium Run simulation. The overall properties of groups identified in projection are...
A search for damped Lyman-alpha systems towards radio-loud quasars I: The optical survey (2008)
Ellison, Sara L., York, Brian A., Pettini, Max, Kanekar, Nissim
We present the results from the optical component of a survey for damped Lyman-alpha systems (DLAs) towards radio-loud quasars. Our quasar sample is drawn from the Texas radio survey with the...
Compact groups in theory and practice - I. The spatial properties of compact groups (2008)
McConnachie, Alan W., Ellison, Sara L., Patton, David R.
We use a mock galaxy catalogue based upon the Millennium Run simulation to investigate the intrinsic spatial properties of compact groups of galaxies. We find that approximately 30% of galaxy...
Ellison, Sara L., Patton, David R., Simard, Luc, McConnachie, Alan W.
(Abridged). We present a sample of 1716 galaxies with companions within Delta v < 500 km/s, r_p < 80 kpc and stellar mass ratio 0.1 < M_1/M_2 < 10 from the Sloan Digital Sky Survey (SDSS) Data...
Metallicity Calibrations and the Mass-Metallicity Relation for Star-Forming Galaxies (2008)
Kewley, Lisa J., Ellison, Sara L.
(Abridged) We investigate the effect of metallicity calibrations, AGN classification, and aperture covering fraction on the local mass-metallicity (MZ) relation using 27,730 star-forming galaxies...
Lawton, Brandon, Churchill, Christopher W., York, Brian A., Ellison, Sara L., Snow, Theodore P., Johnson, Rachel A., ...
We present equivalent width measurements and limits of six diffuse interstellar bands (DIBs) in seven damped Ly-alpha absorbers (DLAs) over the redshift range 0.091
Diffuse interstellar bands in z < 0.6 Ca ii absorbers (2008)
Ellison, Sara L., York, Brian A., Murphy, Michael T., Zych, Berkeley J., Smith, Arfon M., Sarre, Peter J.
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(H i), and dust reddening, E(...
Diffuse interstellar bands in z < 0.6 Ca ii absorbers (2008)
Ellison, Sara L., York, Brian A., Murphy, Michael T., Zych, Berkeley J., Smith, Arfon M., Sarre, Peter J.
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(H i), and dust reddening, E(...
Diffuse interstellar bands in z < 0.6 Ca ii absorbers (2008)
Ellison, Sara L., York, Brian A., Murphy, Michael T., Zych, Berkeley J., Smith, Arfon M., Sarre, Peter J.
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(H i), and dust reddening, E(...
Diffuse interstellar bands in z < 0.6 Ca ii absorbers (2008)
Ellison, Sara L., York, Brian A., Murphy, Michael T., Zych, Berkeley J., Smith, Arfon M., Sarre, Peter J.
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(H i), and dust reddening, E(...
Diffuse interstellar bands in z < 0.6 Ca ii absorbers (2008)
Ellison, Sara L., York, Brian A., Murphy, Michael T., Zych, Berkeley J., Smith, Arfon M., Sarre, Peter J.
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(H i), and dust reddening, E(...
Ellison, Sara L., Patton, David R., Simard, Luc, McConnachie, Alan W.
We use a sample of 43,690 galaxies selected from the Sloan Digital Sky Survey Data Release 4 to study the systematic effects of specific star formation rate (SSFR) and galaxy size (as measured by the...
York, Brian A., Kanekar, Nissim, Ellison, Sara L., Pettini, Max
We report the detection of HI 21 cm absorption from the $z=2.289$ damped Lyman-$\alpha$ system (DLA) towards TXS 0311+430, with the Green Bank Telescope. The 21 cm absorption has a velocity spread...
Diffuse Interstellar Bands in z < 0.6 CaII Absorbers (2007)
Ellison, Sara L., York, Brian A., Murphy, Michael T., Zych, Berkeley J., Smith, Arfon M., Sarre, Peter J.
The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(HI), and dust reddening,...
The Galactic Deuterium Abundance and Dust Depletion: Insights From an Expanded Ti/H Sample (2007)
Ellison, Sara L., Prochaska, Jason X., Lopez, Sebastian
The primordial abundance of deuterium (D/H) yields a measure of the density of baryons in the universe and is an important complement to determinations from cosmic microwave background (CMB)...
The host galaxies of strong CaII QSO absorption systems at z (2007)
Zych, Berkeley J., Murphy, Michael T., Pettini, Max, Hewett, Paul C., Ryan-Weber, Emma V., Ellison, Sara L.
We present new imaging and spectroscopic observations of the fields of five QSOs with very strong intervening CaII absorption systems at redshifts z
Ellison, Sara L., Hennawi, Joseph F., Martin, Crystal L., Sommer-Larsen, Jesper
We report coincident damped Lyman alpha (DLA) and sub-DLA absorption at z = 2.66 and z = 2.94 towards the z ~ 3 13.8 arcsecond separation binary quasar SDSS 1116+4118 AB. At the redshifts of the...
The host galaxies of strong CaII quasar absorption systems at z < 0.5 (2007)
Zych, Berkeley J., Murphy, Michael T., Pettini, Max, Hewett, Paul C., Ryan-Weber, Emma V., Ellison, Sara L.
We present new imaging and spectroscopic observations of the fields of five quasars with very strong intervening Ca II absorption systems at redshifts z(abs) < 0.5 selected from the Sloan Digital Sky...
The host galaxies of strong CaII quasar absorption systems at z < 0.5 (2007)
Zych, Berkeley J., Murphy, Michael T., Pettini, Max, Hewett, Paul C., Ryan-Weber, Emma V., Ellison, Sara L.
We present new imaging and spectroscopic observations of the fields of five quasars with very strong intervening Ca II absorption systems at redshifts z(abs) < 0.5 selected from the Sloan Digital Sky...
The host galaxies of strong CaII quasar absorption systems at z < 0.5 (2007)
Zych, Berkeley J., Murphy, Michael T., Pettini, Max, Hewett, Paul C., Ryan-Weber, Emma V., Ellison, Sara L.
We present new imaging and spectroscopic observations of the fields of five quasars with very strong intervening Ca II absorption systems at redshifts z(abs) < 0.5 selected from the Sloan Digital Sky...
The host galaxies of strong CaII quasar absorption systems at z < 0.5 (2007)
Zych, Berkeley J., Murphy, Michael T., Pettini, Max, Hewett, Paul C., Ryan-Weber, Emma V., Ellison, Sara L.
We present new imaging and spectroscopic observations of the fields of five quasars with very strong intervening Ca II absorption systems at redshifts z(abs) < 0.5 selected from the Sloan Digital Sky...
The host galaxies of strong CaII quasar absorption systems at z < 0.5 (2007)
Zych, Berkeley J., Murphy, Michael T., Pettini, Max, Hewett, Paul C., Ryan-Weber, Emma V., Ellison, Sara L.
We present new imaging and spectroscopic observations of the fields of five quasars with very strong intervening Ca II absorption systems at redshifts z(abs) < 0.5 selected from the Sloan Digital Sky...
Dust, Metals and Diffuse Interstellar Bands in Damped Lyman Alpha Systems (2006)
Although damped Lyman alpha (DLA) systems are usually considered metal-poor, it has been suggested that this could be due to observational bias against metal-enriched absorbers. I review recent...
Three intervening galaxy absorbers towards GRB060418: faint and dusty? (2006)
Ellison, Sara L., Vreeswijk, Paul, Ledoux, Cedric, Willis, Jon P., Jaunsen, Andreas, ...
We present an analysis of three strong, intervening Mg II absorption systems (z_abs = 0.603, 0.656, 1.107) towards the optical afterglow of gamma-ray burst (GRB) 060418. From high resolution UVES...
The Metal-Strong Damped Lyman-alpha Systems (2006)
Herbert-Fort, Stéphane, Prochaska, Jason X., Dessauges-Zavadsky, Miroslava, Ellison, Sara L., Howk, J. Chris, Wolfe, Arthur M., ...
We have identified a metal-strong (logN(Zn+) > 13.15 or logN(Si+) > 15.95) DLA (MSDLA) population from an automated quasar (QSO) absorber search in the Sloan Digital Sky Survey Data Release 3...
York, Brian A., Ellison, Sara L., Lawton, Brandon, Churchill, Christopher W., Snow, Theodore P., Johnson, Rachel A., ...
We report the first detection of the 5705 and 5780 A Diffuse Interstellar Bands (DIBs) in a moderate redshift Damped Lyman alpha (DLA) system. We measure a rest frame equivalent width of 63.2 +- 8.7...
An efficient technique for pre-selecting low redshift damped Lyman alpha systems (2006)
The number of z ~ 1 damped Lyman alpha systems (DLAs, log N(HI) >= 20.3) per unit redshift is approximately 0.1, making them relatively rare objects. Large, blind QSO surveys for low redshift DLAs...
An excess of damped Lyman alpha galaxies near QSOs (2005)
Russell, David M., Ellison, Sara L., Benn, Chris R.
We present a sample of 33 damped Lyman alpha systems (DLAs) discovered in the Sloan Digital Sky Survey (SDSS) whose absorption redshifts (z_abs) are within 6000 km/s of the QSO's systemic redshift...
Strong Line Metallicity Calibrators Applied to SDSS Galaxies (2005)
Ellison, Sara L., Kewley, Lisa J.
We calculate the oxygen abundances for ~45,000 star-forming galaxies selected from the SDSS using nine popular `strong-line' metallicity diagnostics. We find that individual galaxies can have...
Ellison, Sara L., Hall, Patrick B., Lira, Paulina
The presence of dust in quasar absorbers, such as damped Lyman alpha (DLA) systems, may cause the background QSO to appear reddened. We investigate the extent of this potential reddening by comparing...
Zn and Cr abundances in damped Lyman alpha systems from the CORALS survey (2005)
Akerman, Chris J., Ellison, Sara L., Pettini, Max, Steidel, Charles C.
We present metal abundances in 15 damped Lyman alpha systems (DLAs) from the Complete Optical and Radio Absorption Line System (CORALS) survey, designed to be free from any biasing effects due to...
A Search For Organic Molecules in Intermediate Redshift DLAs (2005)
Lawton, Brandon, York, Brian, Ellison, Sara L., Churchill, Christopher W., Johnson, Rachel A., Snow, Theodore P.
There has been a renewed interest in searching for diffuse interstellar bands (DIBs) due to their probable connection to organic molecules and, thus, their possible link to life in the Universe. Our...
Absorption Systems In Radio-Selected QSO Surveys (2005)
Radio-selected samples of quasars with complete optical identifications offer an ideal dataset with which to investigate dust bias associated with intervening absorption systems. Here, we review our...
Emission Line Abundances of Absorption Selected Galaxies at z (2004)
Ellison, Sara L., Kewley, Lisa J., Mallen-Ornelas, Gabriela
We have obtained optical spectra of four galaxies associated with MgII QSO absorbers at redshifts 0.10 < z < 0.45. We calculate the gas-phase oxygen abundance of these galaxies using the empirical...
Ellison, Sara L., Churchill, Chris W., Rix, Samantha A., Pettini, Max
The goal of the Complete Optical and Radio Absorption Line System (CORALS) survey is to quantify the potential impact on QSO absorber statistics from dust in intervening galaxies. Dust may introduce...
Ellison, Sara L., Ibata, Rodrigo, Pettini, Max, Lewis, Geraint F., Aracil, Bastien, Petitjean, Patrick, ...
We have obtained spatially resolved spectra of the z=3.911 triply imaged QSO APM08279+5255 using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). We study...
The Structure of High Redshift Galactic Halos (2003)
Ellison, Sara L., Ibata, Rodrigo, Pettini, Max, Lewis, Geraint F., Aracil, Bastien, Petitjean, Patrick, ...
Observations of multiple or lensed QSOs at high redshift can be used to probe transverse structure in intervening absorption systems. Here we present results obtained from STIS spectroscopy of the...
The C IV Mass Density of the Universe at Redshift 5 (2003)
Pettini, Max, Madau, Piero, Bolte, Michael, Prochaska, Jason X., Ellison, Sara L., Fan, Xiaohui
In order to search for metals in the Lyman alpha forest at redshifts z > 4, we have obtained spectra of high S/N and resolution of three QSOs at z > 5.4 discovered by the Sloan Digital Sky Survey....
Ellison, Sara L., Pettini, Max, Churchill, Chris W., Hook, Isobel M., Lopez, Sebastian, Rix, Samantha A., ...
We present a brief overview of the ongoing Complete Optical and Radio Absorption Line System (CORALS) survey. We review the results of our survey for z>2.2 damped Lyman alpha systems (DLAs) and...
Lopez, Sebastian, Ellison, Sara L.
(abridged) Following our previous work on metal abundances of a double damped Ly-alpha system with a line-of-sight separation ~2000 km/s (Ellison & Lopez 2001), we present VLT UVES abundances of 3...
The Absorption and Emission Kinematics in the z=0.7450 Mg II Absorber Towards Q1331+17 (2003)
Ellison, Sara L., Mallen-Ornelas, Gabriela, Sawicki, Marcin
(Abridged) We present a comparative analysis of the galaxy emission and QSO absorption kinematics of a z~0.7450 MgII system and its candidate absorbing galaxy (G5) located 3.86 arcsecs (28.3 h-1 kpc)...
The Abundances of Nitrogen and Oxygen in Damped Lyman Alpha Systems (2002)
Pettini, Max, Ellison, Sara L., Bergeron, Jacqueline, Petitjean, Patrick
We take a fresh look at the abundance of nitrogen in DLAs with oxygen abundances between 1/10 and 1/100 of solar. This is a metallicity regime poorly sampled in the local universe and where QSO...
Lewis, Geraint F., Ibata, Rodrigo A., Ellison, Sara L., Aracil, Bastien, Petitjean, Patrick, Pettini, Max, ...
While gravitationally lensed quasars are expected to display an odd number of images, invariably systems are observed with an even number of quasars. For this, lensing galaxies must have very small...
Ellison, Sara L., Yan, Lin, Hook, Isobel M., Pettini, Max, Wall, Jasper V., Shaver, Peter
We present a list of z_abs ~ z_em (Delta v < 3000 km/s) DLAs discovered during the CORALS survey for absorbers in a radio-selected QSO sample. On the assumption that z_abs ~ z_em DLAs are neither...
Unusual Metal Abundances in a Pair of Damped Lyman Alpha Systems at z~2 (2001)
Ellison, Sara L., Lopez, Sebastian
We present high resolution spectroscopic observations of two neighbouring damped Lya systems (DLAs) along the same line of sight towards B2314-409. Due to their separation (v ~ 2000 km/s) and the...
Ellison, Sara L., Yan, Lin, Hook, Isobel M., Pettini, Max, Wall, Jasper V., Shaver, Peter
(Abridged) We present the first results from the Complete Optical and Radio Absorption Line System (CORALS) survey. We have compiled a homogeneous sample of radio-selected QSOs from the Parkes...
Ellison, Sara L., Yan, Lin, Hook, Isobel M., Pettini, Max, Wall, Jasper V., Shaver, Peter
We present the first results from the Complete Optical and Radio Absorption Line System (CORALS) survey for Damped Lyman Alpha (DLA) systems based on a radio-selected sample of quasars. We find that...
The First Detection of Co in a Damped Lyman Alpha System (2001)
Ellison, Sara L., Ryan, Sean G., Prochaska, Jason X.
The study of elemental abundances in Damped Lyman Alpha systems (DLAs) at high redshift represents one of our best opportunities to probe galaxy formation and chemical evolution at early times. By...
The First Detection of Cobalt in a Damped Lyman Alpha System (2001)
Ellison, Sara L., Ryan, Sean G., Prochaska, Jason X.
We present the first ever detection of Cobalt in a Damped Lyman Alpha system (DLA) at z = 1.92. In addition to providing important clues to the star formation history of these high redshift galaxies,...
Ellison, Sara L., Pettini, Max, Steidel, Charles C., Shapley, Alice E.
We present the results of a series of imaging and spectroscopic observations aimed at identifying and studying the galaxy responsible for the z = 3.38639 damped lya system in the z = 3.61 QSO...
Ellison, Sara L., Songaila, Antoinette, Schaye, Joop, Pettini, Max
We have obtained an exceptionally high S/N, high resolution spectrum of the gravitationally lensed quasar Q1422+231 in order to investigate the metal enrichment of the IGM. A column density...
Mining for Metals in the Lyman Alpha Forest (2000)
Ellison, Sara L., Songaila, Antoinette, Schaye, Joop, Pettini, Max
In order to ascertain the extent of metal enrichment in the Ly alpha forest, we have analysed a very high S/N spectrum of the z = 3.625 QSO Q1422+231. We find that in high column density Ly alpha...
LA Palma Night-Sky Brightness (1999)
Benn, Chris R., Ellison, Sara L.
The brightness of the moonless night sky above La Palma was measured on 427 CCD images taken with the Isaac Newton and Jacobus Kapteyn Telescopes on 63 nights during 1987 - 1996. The median sky...
KECK HIRES Spectroscopy of APM 08279+5255 (1999)
Ellison, Sara L., Lewis, Geraint F., Pettini, Max, Sargent, Wallace L. W., Chaffee, Frederic H., Foltz, Craig B., ...
With an optical R-band magnitude of 15.2, the recently discovered z=3.911 BAL quasar APM 08279+5255 is an exceptionally bright high redshift source. Its brightness has allowed us to acquire a high...
Metal Abundances in the Lyman Alpha Forest (1999)
Ellison, Sara L., Lewis, Geraint F., Pettini, Max, Sargent, Wallace L. W., Chaffe, Frederic H., Irwin, Mike J.
We present high S/N echelle spectra of the recently discovered ultraluminous QSO APM 08279+5255 and use these data to re-examine the abundance of Carbon in Ly alpha forest clouds. In agreement with...
Pettini, Max, Ellison, Sara L., Steidel, Charles C., Bowen, David V.
We explore the redshift evolution of the metal content of damped Lyman alpha systems (DLAs) with new observations of four absorbers at z < 1.5 . The main conclusion is that the column...