Nikole M. Nielsen
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View article: Ultrastrong Mg <scp>ii</scp> absorbers trace both inflowing and outflowing gas: insights from dual down-the-barrel and quasar sightlines
Ultrastrong Mg <span>ii</span> absorbers trace both inflowing and outflowing gas: insights from dual down-the-barrel and quasar sightlines Open
We present Keck/Low-Resolution Imaging Spectrometer spectroscopy of seven isolated galaxy–quasar pairs at $0.4 \le z \le 0.6$, each exhibiting ultrastrong Mg ii absorption ($W_{\mathrm{ r},2796} \ge 3$ Å), probing both down-the-barrel and …
View article: 13 Billion Years of MgII Absorber Evolution
13 Billion Years of MgII Absorber Evolution Open
Applying "apportioned integrals," we use dN/dX measurements to determine the MgII absorber equivalent width distribution function for Wr > 0.03 [angstroms] and 0 < z < 7. Adopting a Schechter distribution, f(z,W)dW = Phi* (W/W*)^alpha e^{-…
View article: COS-EDGES: Co-rotation and Kinematic Stratification of the Multi-Phase CGM Around Edge-On Galaxies
COS-EDGES: Co-rotation and Kinematic Stratification of the Multi-Phase CGM Around Edge-On Galaxies Open
We present the first results from the COS-EDGES survey, targeting the kinematic connection between the ISM and multi-phase circumgalactic medium (CGM) in nine isolated, edge-on galaxies at z~0.2, each probed along its major axis by a backg…
View article: The AGEL Survey Data Release 2: A Gravitational Lens Sample for Galaxy Evolution and Cosmology
The AGEL Survey Data Release 2: A Gravitational Lens Sample for Galaxy Evolution and Cosmology Open
The ASTRO 3D Galaxy Evolution with Lenses (AGEL) Survey is an ongoing effort to spectroscopically confirm a diverse sample of gravitational lenses with high spatial resolution imaging, to facilitate a broad range of science outcomes. The A…
View article: COS-EDGES: Co-rotation and kinematic stratification of the multi-phase CGM around edge-on galaxies
COS-EDGES: Co-rotation and kinematic stratification of the multi-phase CGM around edge-on galaxies Open
We present the first results from the COS-EDGES survey, targeting the kinematic connection between the interstellar medium and multi-phase circumgalactic medium (CGM) in nine isolated, near-edge-on galaxies at $z\sim0.2$ , each probed alon…
View article: DUVET: sub-kiloparsec resolved star formation driven outflows in a sample of local starbursting disc galaxies
DUVET: sub-kiloparsec resolved star formation driven outflows in a sample of local starbursting disc galaxies Open
We measure resolved (kiloparsec-scale) outflow properties in a sample of 10 starburst galaxies from the Deep near-UV observations of Entrained gas in Turbulent (DUVET) galaxies sample, using Keck/KCWI observations of H $\beta$ and [O iii] …
View article: Signatures of gas flows – II. Connecting the kinematics of the multiphase circumgalactic medium to galaxy rotation
Signatures of gas flows – II. Connecting the kinematics of the multiphase circumgalactic medium to galaxy rotation Open
The multiphase circumgalactic medium (CGM) hosts critical processes that affect galaxy evolution such as accretion and outflows. We searched for evidence of these phenomena by using the EW co-rotation fraction ($f_{\rm EWcorot}$) to study …
View article: Gravitational lensing reveals cool gas within 10-20 kpc around a quiescent galaxy
Gravitational lensing reveals cool gas within 10-20 kpc around a quiescent galaxy Open
While quiescent galaxies have comparable amounts of cool gas in their outer circumgalactic medium (CGM) compared to star-forming galaxies, they have significantly less interstellar gas. However, open questions remain on the processes causi…
View article: Gravitational Lensing Reveals Cool Gas within 10-20 kpc around a Quiescent Galaxy
Gravitational Lensing Reveals Cool Gas within 10-20 kpc around a Quiescent Galaxy Open
While quiescent galaxies have comparable amounts of cool gas in their outer circumgalactic medium (CGM) compared to star-forming galaxies, they have significantly less interstellar gas. However, open questions remain on the processes causi…
View article: Signatures of gas flows – I. Connecting the kinematics of the H <scp>i</scp> circumgalactic medium to galaxy rotation
Signatures of gas flows – I. Connecting the kinematics of the H <span>i</span> circumgalactic medium to galaxy rotation Open
The circumgalactic medium (CGM) hosts many physical processes with different kinematic signatures that affect galaxy evolution. We address the CGM–galaxy kinematic connection by quantifying the fraction of H i that is aligned with galaxy r…
View article: Unveiling the complex circumgalactic medium: a comparative study of merging and non-interacting galaxy groups
Unveiling the complex circumgalactic medium: a comparative study of merging and non-interacting galaxy groups Open
While most galaxies live in group environments where they undergo an accelerated evolution, the characteristics of their circumgalactic medium (CGM) remain uncertain. We present an analysis of the CGM of two galaxy groups in different stag…
View article: Unveiling the Complex Circumgalactic Medium: A Comparative Study of Merging and Non-Interacting Galaxy Groups
Unveiling the Complex Circumgalactic Medium: A Comparative Study of Merging and Non-Interacting Galaxy Groups Open
While most galaxies live in group environments where they undergo an accelerated evolution, the characteristics of their circumgalactic medium (CGM) remain uncertain. We present an analysis of the CGM of two galaxy groups in different stag…
View article: DUVET: Resolved direct metallicity measurements in the outflow of starburst galaxy NGC 1569
DUVET: Resolved direct metallicity measurements in the outflow of starburst galaxy NGC 1569 Open
We present the results of direct-method metallicity measurements in the disc and outflow of the low-metallicity starburst galaxy NGC 1569. We use Keck Cosmic Web Imager observations to map the galaxy across 54″ (800 pc) along the major axi…
View article: Cloud-by-cloud multiphase investigation of the circumgalactic medium of low-redshift galaxies
Cloud-by-cloud multiphase investigation of the circumgalactic medium of low-redshift galaxies Open
The pervasive presence of warm gas in galaxy haloes suggests that the circumgalactic medium (CGM) is multiphase in its ionization structure and complex in its kinematics. Some recent state-of-the-art cosmological galaxy simulations predict…
View article: DUVET: Resolved direct metallicity measurements in the outflow of starburst galaxy NGC 1569
DUVET: Resolved direct metallicity measurements in the outflow of starburst galaxy NGC 1569 Open
We present the results of direct-method metallicity measurements in the disk and outflow of the low-metallicity starburst galaxy NGC 1569. We use Keck Cosmic Web Imager observations to map the galaxy across 54$\arcsec$ (800 pc) along the m…
View article: Cloud-by-cloud Multiphase Investigation of the Circumgalactic Medium of Low-redshift Galaxies
Cloud-by-cloud Multiphase Investigation of the Circumgalactic Medium of Low-redshift Galaxies Open
The pervasive presence of warm gas in galaxy halos suggests that the circumgalactic medium (CGM) is multiphase in its ionization structure and complex in its kinematics. Some recent state-of-the-art cosmological galaxy simulations predict …
View article: DUVET: sub-kiloparsec resolved star formation driven outflows in a sample of local starbursting disk galaxies
DUVET: sub-kiloparsec resolved star formation driven outflows in a sample of local starbursting disk galaxies Open
We measure resolved (kiloparsec-scale) outflow properties in a sample of 10 starburst galaxies from the DUVET (Deep near-UV observations of Entrained gas in Turbulent galaxies) sample, using Keck/KCWI observations of H$β$ and [OIII]~$λ$500…
View article: The Relation between Galaxy ISM and Circumgalactic O vi Gas Kinematics Derived from Observations and ΛcDM Simulations
The Relation between Galaxy ISM and Circumgalactic O vi Gas Kinematics Derived from Observations and ΛcDM Simulations Open
We present the first galaxy-O vi absorption kinematic study for 20 absorption systems (EW > 0.1 å) associated with isolated galaxies (0.15 ≤ z ≤ 0.55) that have accurate redshifts and rotation curves obtained using Keck/ESI. Our sample is …
View article: MAGiiCAT IV. KINEMATICS of the CIRCUMGALACTIC MEDIUM and EVIDENCE for QUIESCENT EVOLUTION AROUND RED GALAXIES
MAGiiCAT IV. KINEMATICS of the CIRCUMGALACTIC MEDIUM and EVIDENCE for QUIESCENT EVOLUTION AROUND RED GALAXIES Open
The equivalent widths of Mg II absorption in the circumgalactic medium (CGM) trace the global star formation rate up to z < 6, are larger for star-forming galaxies than passively evolving galaxies, and decrease with increasing distance fro…
View article: MAG iiCAT VI. the Mg ii Intragroup Medium Is Kinematically Complex
MAG iiCAT VI. the Mg ii Intragroup Medium Is Kinematically Complex Open
By comparing Mg II absorption in the circumgalactic medium (CGM) of group environments to isolated galaxies, we investigated the impact of environment on the CGM. An Mg II absorber is associated with a group if there are two or more galaxi…
View article: The Impact of the Group Environment on the O VI Circumgalactic Medium
The Impact of the Group Environment on the O VI Circumgalactic Medium Open
We present a study comparing O vi λλ1031, 1037 doublet absorption found toward group galaxy environments to that of isolated galaxies. The O vi absorption in the circumgalactic medium (CGM) of isolated galaxies has been studied previously …
View article: Examining quasar absorption-line analysis methods: the tension between simulations and observational assumptions key to modelling clouds
Examining quasar absorption-line analysis methods: the tension between simulations and observational assumptions key to modelling clouds Open
A key assumption in quasar absorption-line studies of the circumgalactic medium (CGM) is that each absorption component maps to a spatially isolated ‘cloud’ structure that has single valued properties (e.g. density, temperature, metallicit…
View article: Signatures of gas flows-II: Connecting the kinematics of the multiphase circumgalactic medium to galaxy rotation
Signatures of gas flows-II: Connecting the kinematics of the multiphase circumgalactic medium to galaxy rotation Open
The multiphase CGM hosts critical processes that affect galaxy evolution such as accretion and outflows. We searched for evidence of these phenomena by using the EW co-rotation fraction ($f_{\rm EWcorot}$) to study the kinematic connection…
View article: Signatures of gas flows-I: Connecting the kinematics of the HI circumgalactic medium to galaxy rotation
Signatures of gas flows-I: Connecting the kinematics of the HI circumgalactic medium to galaxy rotation Open
The CGM hosts many physical processes with different kinematic signatures that affect galaxy evolution. We address the CGM-galaxy kinematic connection by quantifying the fraction of HI that is aligned with galaxy rotation with the equivale…
View article: An emission map of the disk-circumgalactic medium transition in starburst IRAS 08339+6517
An emission map of the disk-circumgalactic medium transition in starburst IRAS 08339+6517 Open
Most of a galaxy's mass is located out to hundreds of kiloparsecs beyond its stellar component. This diffuse reservoir of gas, the circumgalactic medium (CGM), acts as the interface between a galaxy and the cosmic web that connects galaxie…
View article: DUVET Survey: Mapping Outflows in the Metal-Poor Starburst Mrk 1486
DUVET Survey: Mapping Outflows in the Metal-Poor Starburst Mrk 1486 Open
We present a method to characterize star-formation driven outflows from edge-on galaxies and apply this method to the metal-poor starburst galaxy, Mrk 1486. Our method uses the distribution of emission line flux (from H$β$ and [OIII] 5007)…
View article: DUVET: Spatially Resolved Observations of Star Formation Regulation via Galactic Outflows in a Starbursting Disk Galaxy
DUVET: Spatially Resolved Observations of Star Formation Regulation via Galactic Outflows in a Starbursting Disk Galaxy Open
We compare 500 pc scale, resolved observations of ionized and molecular gas for the z ∼ 0.02 starbursting disk galaxy IRAS08339+6517, using measurements from KCWI and NOEMA. We explore the relationship of the star-formation-driven ionized …
View article: A complex multiphase DLA associated with a compact group at <i>z</i> = 2.431 traces accretion, outflows, and tidal streams
A complex multiphase DLA associated with a compact group at <i>z</i> = 2.431 traces accretion, outflows, and tidal streams Open
As part of our program to identify host galaxies of known z = 2–3 Mg ii absorbers with the Keck Cosmic Web Imager (KCWI), we discovered a compact group giving rise to a z = 2.431 DLA with ultrastrong Mg ii absorption in quasar field J23462…
View article: Extreme Variation in Star Formation Efficiency across a Compact, Starburst Disk Galaxy
Extreme Variation in Star Formation Efficiency across a Compact, Starburst Disk Galaxy Open
We report on the internal distribution of star formation efficiency in IRAS 08339+6517 (hereafter IRAS08), using ∼200 pc resolution CO(2 − 1) observations from NOEMA. The molecular gas depletion time changes by 2 orders-of-magnitude from d…
View article: Examining quasar absorption-line analysis methods: the tension between simulations and observational assumptions key to modelling clouds
Examining quasar absorption-line analysis methods: the tension between simulations and observational assumptions key to modelling clouds Open
A key assumption in quasar absorption line studies of the circumgalactic medium (CGM) is that each absorption component maps to a spatially isolated "cloud" structure that has single valued properties (e.g. density, temperature, metallicit…