Publications (26)
The chemodynamical signature of coherent metal-poor inflow and enriched recycled accretion in the cool circumgalactic medium
Glenn G. Kacprzak, Jerrard Doran, Sameer +7
The paper analyzes how metallicity, ionisation state, and kinematics of circumgalactic gas vary with azimuthal angle around galaxies, finding metal-poor inflow along the disk plane…
Studying the gaseous outskirts of galaxy groups with coherent Ly alpha absorption patterns
P. Richter, J. C. Charlton, A. J. Fox +2
In this study, we explore the properties of diffuse intergalactic gas residing in the outskirts of the four nearby, low-mass galaxy groups NGC1052, NGC5866, NGC4631, and NGC3992 (a…
The COS CGM Compendium V: The Dichotomy of OVI Associated with Low- and High-Metallicity Cool Gas at z < 1
Sameer, Nicolas Lehner, J. Christopher Howk +3
We analyze the \ovi\ content and kinematics for 126 {\hi}-selected absorbers at for which the metallicities of their cool photoionized phase have be…
Unveiling the Complex Circumgalactic Medium: A Comparative Study of Merging and Non-Interacting Galaxy Groups
Antonia Fernandez-Figueroa, Glenn G. Kacprzak, Nikole M. Nielsen +5
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…
Multiwavelength observations of a VHE gamma-ray flare from PKS 1510-089 in 2015
MAGIC Collaboration, M. L. Ahnen, S. Ansoldi +172
Context. PKS 1510-089 is one of only a few flat spectrum radio quasars detected in the VHE (very-high-energy, > 100 GeV) gamma-ray band. Aims. We study the broadband spectral and t…
X-ray and multi-epoch optical/UV investigations of BAL to non-BAL quasar transformations
Sameer, W. N. Brandt, S. Anderson +10
We report on an X-ray and optical/UV study of eight Broad Absorption Line (BAL) to non-BAL transforming quasars at 1.7-2.2 over 0.29-4.95 rest-frame years with at lea…
Kinematic analysis of an Ultra-Strong MgII absorber at z~1.13 linking to Circumgalactic Gas Structures
Purvi Udhwani, Sameer, Anand Narayanan +3
We present a spectroscopic and imaging analysis of the ultra-strong MgII absorption system identified in the /UVES spectrum of a background quasar loc…
Cloud-by-cloud, multiphase, Bayesian modeling: Application to four weak, low ionization absorbers
Sameer, J. C. Charlton, J. M. Norris +8
We present a new method aimed at improving the efficiency of component by component ionization modeling of intervening quasar absorption line systems. We carry out cloud-by-cloud,…
Cloud-by-cloud Multiphase Investigation of the Circumgalactic Medium of Low-redshift Galaxies
Sameer, Jane C. Charlton, Bart P. Wakker +10
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 recen…
The Halo21 Absorption Modeling Challenge: Lessons From "Observing" Synthetic Circumgalactic Absorption Spectra
Zachary Hafen, Sameer, Cameron Hummels +7
In the Halo21 absorption modeling challenge we generated synthetic absorption spectra of the circumgalactic medium (CGM), and attempted to estimate the metallicity, temperature, an…
Using cosmological simulations and synthetic absorption spectra to assess the accuracy of observationally derived CGM metallicities
Rachel Marra, Christopher W. Churchill, Caitlin Doughty +6
We used adaptive mesh refinement hydrodynamic cosmological simulations of a Milky Way-type galaxy and a Dwarf galaxy and generated synthetic quasar absorption-line spec…
Project AMIGA: The Inner Circumgalactic Medium of Andromeda from Thick Disk to Halo
Nicolas Lehner, J. Christopher Howk, Lucy Collins +22
The inner circumgalactic medium (CGM) of galaxies, where disk and halo processes intersect, remains poorly characterized despite its critical role in regulating galaxy evolution. W…
Signatures of gas flows-I: Connecting the kinematics of the HI circumgalactic medium to galaxy rotation
Hasti Nateghi, Glenn G. Kacprzak, Nikole M. Nielsen +5
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 o…
A Complex Multiphase DLA Associated with a Compact Group at z=2.431 Traces Accretion, Outflows, and Tidal Streams
Nikole M. Nielsen, Glenn G. Kacprzak, Sameer +4
As part of our program to identify host galaxies of known z=2-3 MgII absorbers with the Keck Cosmic Web Imager (KCWI), we discovered a compact group giving rise to a z=2.431 DLA wi…
Stochastic modeling of multiwavelength variability of the classical BL Lac object OJ 287 on timescales ranging from decades to hours
A. Goyal, L. Stawarz, S. Zola +109
We present the results of our power spectral density analysis for the BL Lac object OJ\,287, utilizing the {\it Fermi}-LAT survey at high-energy -rays, {\it Swift}-XRT in X-ray…
Multi-wavelength study of flaring activity in HBL 1ES 1959+650 during 2015-16
Navpreet Kaur, S. Chandra, Kiran S Baliyan +2
We present the results from a multiwavelength study of the flaring activity in HBL, 1ES 1959+650, during January 2015-June 2016. The source underwent significant flux enhancements…
Improving blazar redshift constraints with the edge of the Ly forest: 1ES 1553+113 and implications for observations of the WHIM
J. Dorigo Jones, S. D. Johnson, Sowgat Muzahid +6
Blazars are some of the brightest UV and X-ray sources in the sky and are valuable probes of the elusive warm-hot intergalactic medium (WHIM; K). However, man…
A partial Lyman limit system tracing intragroup gas at towards HE1003+0149
Anand Narayanan, Sameer, Sowgat Muzahid +6
We present an analysis of the galaxy environment and physical properties of a partial Lyman limit system at z = 0.83718 with HI and metal line components closely separated in redsh…
COS-EDGES: Co-rotation and Kinematic Stratification of the Multi-Phase CGM Around Edge-On Galaxies
Glenn G. Kacprzak, Benjamin D. Oppenheimer, Nikole M. Nielsen +10
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 gal…
Optical variability in IBL S5 0716+714 during the 2013-2015 outburst
Navpreet Kaur, Kiran S. Baliyan, S. Chandra +2
With an aim to explore optical variability at diverse timescales in BL Lac source S5 0716+714, it was observed for 46 nights during 2013 January 14 to 2015 June 01 when it underwen…
MAGIC observations of variable very-high-energy gamma-ray emission from PKS1510-089 during May 2015 outburst
Julian Sitarek, Josefa Becerra González, Vandad Fallah Ramazani Elina Lindfors +11
PKS1510-089 is a flat spectrum radio quasar located at a redshift of 0.36. It is one of only a few such sources detected in very-high-energy (VHE, >100 GeV) gamma rays. Though PKS1…
Probing the physicochemical properties of the Leo Ring and the Leo I group
Sameer, Jane Charlton, Glenn Kacprzak +6
We present an absorption line study of the physical and chemical properties of the Leo HI Ring and the Leo I Group as traced by 11 quasar sightlines spread over a 600 kpc X 800 kpc…
Signatures of gas flows-II: Connecting the kinematics of the multiphase circumgalactic medium to galaxy rotation
Hasti Nateghi, Glenn G. Kacprzak, Nikole M. Nielsen +4
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 fra…
Broad absorption line disappearance/emergence in multiple ions in a weak emission-line quasar
Weimin Yi, M. Vivek, W. N. Brandt +9
We report the discovery of disappearance of Mg ii, Al iii, C iv, and Si iv broad absorption lines (BALs) at the same velocity, accompanied by a new Civ BAL emerging at a higher vel…
Optical intra-day variability in 3C 66A: 10 years of observations
Navpreet Kaur, Sameer, Kiran S. Baliyan +1
We present results based on the observations of the blazar 3C 66A from 2005 November 06 to 2016 February 14 in the BVR and I broadbands using 1.2m telescope of the Mt. Abu InfraRed…
Solar-Metallicity Gas in the Extended Halo of a Galaxy at
Jayadev Pradeep, Sriram Sankar, T. M. Umasree +5
We present the detection and analysis of a weak low-ionization absorber at along the blazar sightline PG~, using spectroscopic data from both /COS and…