Thomas J. Cox's research while affiliated with The University of Arizona and other places
What is this page?
This page lists the scientific contributions of an author, who either does not have a ResearchGate profile, or has not yet added these contributions to their profile.
It was automatically created by ResearchGate to create a record of this author's body of work. We create such pages to advance our goal of creating and maintaining the most comprehensive scientific repository possible. In doing so, we process publicly available (personal) data relating to the author as a member of the scientific community.
If you're a ResearchGate member, you can follow this page to keep up with this author's work.
If you are this author, and you don't want us to display this page anymore, please let us know.
It was automatically created by ResearchGate to create a record of this author's body of work. We create such pages to advance our goal of creating and maintaining the most comprehensive scientific repository possible. In doing so, we process publicly available (personal) data relating to the author as a member of the scientific community.
If you're a ResearchGate member, you can follow this page to keep up with this author's work.
If you are this author, and you don't want us to display this page anymore, please let us know.
Publications (135)
Two-dimensional integral field surveys such as ATLAS^3D are producing rich
observational data sets yielding insights into galaxy formation. These new
kinematic observations have highlighted the need to understand the evolutionary
mechanisms leading to a spectrum of fast-rotators and slow-rotators in
early-type galaxies. We address the formation of...
We present an analysis of the spatial distribution of star formation in
a sample of 60 visually identified galaxy merger candidates at z > 1.
Our sample, drawn from the 3D-HST survey, is flux limited and was
selected to have high star formation rates based on fits of their
broad-band, low spatial resolution spectral energy distributions. It
include...
We analyze the link between active galactic nuclei (AGN) and mid-infrared
flux using dust radiative transfer calculations of starbursts realized in
hydrodynamical simulations. Focusing on the effects of galaxy dust, we evaluate
diagnostics commonly used to disentangle AGN and star formation in
ultraluminous infrared galaxies (ULIRGs). We examine th...
High-redshift submillimetre galaxies (SMGs) are some of the most rapidly
star-forming galaxies in the Universe. Historically, galaxy formation models
have had difficulty explaining the observed number counts of SMGs. We combine a
semi-empirical model with 3-D hydrodynamical simulations and 3-D dust radiative
transfer to predict the number counts of...
I discuss recent work in which we construct models of poststarburst galaxies by combining fully three-dimensional hydrodynamic simulations of galaxy mergers with radiative transfer calculations of dust attenuation. The poststarburst signatures can occur shortly after a bright starburst phase in gas-rich mergers, and thus offer a unique opportunity...
We use simulations with realistic models for stellar feedback to study galaxy
mergers. These high resolution (1 pc) simulations follow formation and
destruction of individual GMCs and star clusters. The final starburst is
dominated by in situ star formation, fueled by gas which flows inwards due to
global torques. The resulting high gas density res...
We study the future orbital evolution and merging of the MW-M31-M33 system,
using a combination of collisionless N-body simulations and semi-analytic orbit
integrations. Monte-Carlo simulations are used to explore the consequences of
varying the initial phase-space and mass parameters within their observational
uncertainties. The observed M31 trans...
The definition of homology for single-component galaxies is clear, but for multicomponent (luminous and dark matter) galaxies
there is some ambiguity. We attempt to clarify the situation by carefully separating the different concepts of homology that
have been used to date. We argue that the most useful definition is that a set of galaxies is homol...
(Abridged) We study relationships between the SFR and the nuclear properties
of X-ray selected AGNs out to z=2.5, using far-IR data in three extragalactic
deep fields as part of the PACS Evolutionary Probe (PEP) program. Guided by
studies of intrinsic infra-red AGN SEDs, we show that the majority of the FIR
emission in AGNs is produced by cold dust...
In recent work, we have suggested that the high-redshift (z∼ 2–4) bright submillimetre galaxy (SMG) population is heterogeneous, with major mergers contributing both at early stages,
where quiescently star-forming discs are blended into one submm source (‘galaxy-pair SMGs’), and at late stages, where mutual
tidal torques drive gas inflows and cause...
We present a novel pair of numerical models of the interaction history
between the Large and Small Magellanic Clouds (LMC and SMC, respectively) and
our Milky Way (MW) in light of recent high precision proper motions
(Kallivayalil et al. 2006a,b). Given the new velocities, cosmological
simulations of structure formation favor a scenario where the M...
Central supermassive black holes (SMBHs) are a ubiquitous feature of
locally-observed galaxies, and ample evidence suggests that the growth of SMBHs
and their host galaxies is closely linked. However, in the event of a merger,
gravitational-wave (GW) recoil may displace a SMBH from its galactic center, or
eject it entirely. To explore the consequen...
Calculating the galaxy merger rate requires both a census of galaxies
identified as merger candidates, and a cosmologically-averaged `observability'
timescale T_obs(z) for identifying galaxy mergers. While many have counted
galaxy mergers using a variety of techniques, T_obs(z) for these techniques
have been poorly constrained. We address this prob...
We employ hydrodynamical simulations to study the effects of dissipational
gas physics on the vertical heating and thickening of disc galaxies during
minor mergers. For the first time we present a suite of simulations that
includes a diffuse, rotating, cooling, hot gaseous halo, as predicted by
cosmological hydrodynamical simulations as well as mod...
Nuclear inflows of metal-poor interstellar gas triggered by galaxy
interactions can account for the systematically lower central oxygen abundances
observed in local interacting galaxies. Here, we investigate the metallicity
evolution of a large set of simulations of colliding galaxies. Our models
include cooling, star formation, feedback, and a new...
Central supermassive black holes (SMBHs) are a ubiquitous feature of locally-observed galaxies, and ample evidence suggests that the growth of SMBHs and their host galaxies is closely linked. However, in the event of a merger, gravitational-wave (GW) recoil may displace a SMBH from its galactic center, or eject it entirely. To explore the consequen...
Cosmological hydrodynamical simulations as well as observations indicate that
spiral galaxies are comprised of five different components: dark matter halo,
stellar disc, stellar bulge, gaseous disc and gaseous halo. While the first
four components have been extensively considered in numerical simulations of
binary galaxy mergers, the effect of a ho...
Gravitational-wave (GW) recoil of merging supermassive black holes
(SMBHs) may influence the co-evolution of SMBHs and their host galaxies.
We examine this possibility using SPH/N-body simulations of gaseous
galaxy mergers in which the merged BH receives a recoil kick. With our
suite of over 200 merger simulations, we identify systematic trends in...
Models of poststarburst (or "K+A") galaxies are constructed by combining
fully three-dimensional hydrodynamic simulations of galaxy mergers with
radiative transfer calculations of dust attenuation. Spectral line catalogs are
generated automatically from moderate-resolution optical spectra calculated as
a function of merger progress in each of a lar...
Recently, we have demonstrated the displacement of Luminous Infrared Galaxies on the K-band Fundamental Plane (FP) is due to the presence of bright Red Supergiants or Asymptotic Giant Branch stars. These stars reside in a central disk which reduces the observed CO (1.6 and 2.3 micron) velocity dispersions (sigma) by 30-50%. This causes LIRG mass me...
Gravitational-wave recoil of merging supermassive black holes (SMBHs) may influence the co-evolution of SMBHs and their host galaxies. We examine this possibility using smoothed particle hydrodynamic/N-body simulations of gaseous galaxy mergers, including SMBH accretion, in which the merged BH receives a recoil kick. This enables us to follow the t...
SDSS J1254+0846 is the first luminous, spatially resolved binary quasar that clearly inhabits an ongoing galaxy merger. These two luminous (z=0.44) radio quiet quasars, with a radial velocity difference of just 215 km/s, are separated on the sky by 21 kpc in a disturbed host galaxy merger showing broad, symmetrical tidal arm features spanning some...
We perform 3-D dust radiative transfer (RT) calculations on hydrodynamic
simulations of isolated and merging disk galaxies in order to quantitatively
study the dependence of observed-frame submillimeter (submm) flux density on
galaxy properties. We find that submm flux density and star formation rate
(SFR) are related in dramatically different ways...
Since the violent relaxation in hierarchical merging is incomplete, elliptical galaxies retain a wealth of information about their formation pathways in their present-day orbital structure. Recent advances in integral field spectroscopy, multi-slit infrared spectroscopy, and triaxial dynamical modeling techniques have greatly improved our ability t...
Gravitational-wave (GW) recoil of merging supermassive black holes (SMBHs) may influence the co-evolution of SMBHs and their host galaxies. We examine this possibility using SPH/N-body simulations of gaseous galaxy mergers in which the merged BH receives a recoil kick. This enables us to follow recoiling BHs in self-consistent, evolving merger remn...
Recent high-precision proper motions from the Hubble Space Telescope suggest that the Large and Small Magellanic Clouds (LMC and SMC, respectively) are either on their first passage or on an eccentric long period (>6 Gyr) orbit about the Milky Way (MW). This differs markedly from the canonical picture in which the Clouds travel on a quasi-periodic...
We present a physical model for the origin of z~2 Dust-Obscured Galaxies (DOGs), a class of high-redshift ULIRGs selected at 24 micron which are particularly optically faint (24/R>1000). By combining N-body/SPH simulations of high redshift galaxy evolution with 3D polychromatic dust radiative transfer models, we find that luminous DOGs (with F24 >...
We present an analysis of the large-scale galaxy distribution around two
possible warm-hot intergalactic medium (WHIM) absorption systems reported along
the Markarian 421 sightline. Using the Sloan Digital Sky Survey, we find a
prominent galaxy filament at the redshift of the z=0.027 X-ray absorption line
system. The filament exhibits a width of 3....
Theoretical models have had difficulty matching the observed number density of sub-millimeter galaxies (SMGs), causing some authors (e.g., Baugh et al. 2005) to suggest that SMGs provide evidence for a top-heavy initial mass function (IMF). To test this claim, we have, for the first time, combined high-resolution 3-D hydrodynamic simulations of iso...
We present a detailed analysis of the structure and resolved stellar populations of simulated merger remnants, and compare them to observations of compact quiescent galaxies at z ~ 2. We find that major merging is a viable mechanism to produce systems of ~ 10^11 Msun and ~ 1 kpc size, provided the gas fraction at the time of final coalescence is hi...
We discuss our ongoing project analyzing N-body/smoothed-particle hydrodynamics simulations of isolated and merging galaxies, performed using GADGET-2 (Springel 2005), with the 3-D adaptive grid, polychromatic Monte Carlo radiative transfer code SUNRISE (Jonsson 2006). We apply commonly used UV, optical, and IR star formation rate (SFR) indicators...
Recent observations of excited CO emission lines from z∼ 2 disc galaxies have shed light on the SFR ∝ρN relation at high z via observed ΣSFR–ΣαCOJ=2−1 and ΣSFR–ΣαCOJ=3−2 relations. Here, we describe a novel methodology for utilizing these observations of high-excitation CO to derive the underlying
Schmidt (SFR ∝ρN) relationship. To do this requires...
Gas-rich galaxy mergers are more easily identified by their disturbed morphologies than mergers with less gas. Because the typical gas fraction of galaxy mergers is expected to increase with redshift, the under-counting of low gas-fraction mergers may bias morphological estimates of the evolution of galaxy merger rate. To understand the magnitude o...
The outer regions of galactic disks have received increased attention since ultraviolet observations with GALEX demonstrated that nearly 30% of galaxies have UV emission beyond their optical extents, indicating star formation activity. These galaxies have been termed extended UV (XUV) disks. Here, we address whether these observations contradict th...
An updated version of the dust radiation-transfer code sunrise, including models for star-forming regions and a self-consistent calculation of the spatially dependent dust and PAH emission, is presented. Given a hydrodynamic simulation of a galaxy, this model can calculate a realistic 2D ultraviolet–submillimetre spectral energy distribution of the...
Author Joan M. Wrobel, who contributed substantially to the paper (primarily the section on radio observations and their implications) was inadvertently left off the author list in the original version.
We present the first luminous, spatially resolved binary quasar that clearly inhabits an ongoing galaxy merger. SDSS J125455.09+084653.9 and SDSS J125454.87+084652.1 (SDSS J1254+0846 hereafter) are two luminous z = 0.44 radio-quiet quasars, with a radial velocity difference of just 215 km s–1, separated on the sky by 21 kpc in a disturbed host gala...
We describe a model for the formation of z∼ 2 submillimetre galaxies (SMGs) which simultaneously accounts for both average and bright SMGs while providing a reasonable match to their mean observed spectral energy distributions (SEDs). By coupling hydrodynamic simulations of galaxy mergers with the high-resolution 3D polychromatic radiative transfer...
There is a large observational scatter toward low velocities in the stellar mass Tully-Fisher (TF) relation if disturbed and compact objects are included. However, this scatter can be eliminated if one replaces rotation velocity with S 0.5, a quantity that includes a velocity dispersion term added in quadrature with the rotation velocity. In this w...
Since the violent relaxation in hierarchical merging is incomplete, elliptical galaxies retain a wealth of information about their formation pathways in their present-day orbital structure. A variety of evidence indicates that gas-rich major mergers play an important role in the formation of elliptical galaxies. We simulate 1:1 disk mergers at seve...
Models of poststarburst galaxies are constructed by combining fully three-dimensional numerical simulations of galaxy mergers with three-dimensional polychromatic radiative transfer. Mergers between gas-rich disks of nearly equal mass on a variety of orbits can lead to the unique optical spectrum of a poststarburst (or "K+A") galaxy. The lifetime a...
We present a model for the CO molecular line emission from high-redshift Submillimetre Galaxies (SMGs). By combining hydrodynamic simulations of gas-rich galaxy mergers with the polychromatic radiative transfer code, sunrise, and the 3D non-LTE molecular line radiative transfer code, turtlebeach, we show that if SMGs are typically a transient phase...
The majority of galaxy mergers are expected to be minor mergers. The observational signatures of minor mergers are not well understood, thus there exist few constraints on the minor merger rate. This paper seeks to address this gap in our understanding by determining if and when minor mergers exhibit disturbed morphologies and how they differ from...
Massive galaxies at high-z have smaller effective radii than those today, but similar central densities. Their size growth therefore relates primarily to the evolving abundance of low-density material. Various models have been proposed to explain this evolution, which have different implications for galaxy, star, and BH formation. We compile observ...
Transformation of discs into spheroids via mergers is a well-accepted element of galaxy formation models. However, recent simulations have shown that the bulge formation is suppressed in increasingly gas-rich mergers. We investigate the global implications of these results in a cosmological framework, using independent approaches: empirical halo-oc...
Dwarf spheroidal galaxies are the most dark matter dominated systems in the nearby Universe and their origin is one of the outstanding puzzles of how galaxies form. Dwarf spheroidals are poor in gas and stars, making them unusually faint, and those known as ultra-faint dwarfs have by far the lowest measured stellar content of any galaxy. Previous t...
We present a comparison between the observed color distribution, number, and mass density of massive galaxies at 1.5 < z < 3 and a model by Hopkins et al. that relates the quasar and galaxy population on the basis of gas-rich mergers. In order to test the hypothesis that quiescent red galaxies are formed after a gas-rich merger involving quasar act...
An updated version of the dust radiation transfer code Sunrise, including models for star-forming regions and a self-consistent calculation of the spatially dependent dust and PAH emission, is presented. Given a hydrodynamic simulation of a galaxy, this model can calculate a realistic 2-dimensional ultraviolet--submillimeter spectral energy distrib...
We present a merger-driven evolutionary model for the production of luminous (LIRGs) and ultraluminous infrared galaxies (ULIRGs)
with warm infrared (IR) colours. Our results show that simulations of gas-rich major mergers including star formation, black
hole growth and feedback can produce warm (U)LIRGs. We also find that while the warm evolutiona...
We present a model for the CO molecular line emission from high redshift Submillimeter Galaxies (SMGs). By combining hydrodynamic simulations of gas rich galaxy mergers with the polychromatic radiative transfer code, Sunrise, and the 3D non-LTE molecular line radiative transfer code, Turtlebeach, we show that if SMGs are typically a transient phase...
We present a detailed analysis of our ability to determine stellar masses, ages, reddening, and extinction values, and star formation rates (SFRs) of high-redshift galaxies by modeling broadband spectral energy distributions (SEDs) with stellar population synthesis. In order to do so, we computed synthetic optical-to-NIR SEDs for model galaxies tak...
We present a detailed comparison of the CO (3-2) emitting molecular gas between a local sample of luminous infrared galaxies (U/LIRGs) and a high-redshift sample that comprises submm selected galaxies (SMGs), quasars, and Lyman Break Galaxies (LBGs). The U/LIRG sample consists of our recent CO (3-2) survey using the Submillimeter Array while the CO...
We describe a model for the formation of \zsim 2 Submillimeter Galaxies (SMGs) which simultaneously accounts for both average and bright SMGs while providing a reasonable match to their mean observed spectral energy distributions (SEDs). By coupling hydrodynamic simulations of galaxy mergers with the high resolution 3D polychromatic radiative trans...
We investigate how "extra" or "excess" central light in the surface brightness profiles of cusp or power-law elliptical galaxies relates to the profiles of ellipticals with cores. The envelopes of cusp ellipticals are established by violent relaxation in mergers acting on stars present in gas-rich progenitor disks, while their centers are structure...
The properties of elliptical galaxies are broadly consistent with simulated remnants of gas-rich mergers between spirals, motivating more detailed studies of the imprint of this formation mechanism on the remnant distribution function. Gas has a strong impact on the non-Gaussian shapes of the line-of-sight velocity distributions (LOSVDs) of the mer...
We study the origin and properties of 'extra' or 'excess' central light in the surface brightness profiles of cusp or power-law ellipticals. Dissipational mergers give rise to two-component profiles: an outer profile established by violent relaxation acting on stars present in the progenitors prior to the final merger, and an inner stellar populati...
We develop a physical model for how galactic disks survive and/or are destroyed in interactions. Based on dynamical arguments, we show gas primarily loses angular momentum to internal torques in a merger. Gas within some characteristic radius (a function of the orbital parameters, mass ratio, and gas fraction of the merging galaxies), will quickly...
A key obstacle to measuring the galaxy merger rate and its role in
galaxy evolution is the difficulty in constraining the merger properties
and time-scales from instantaneous snapshots of the real universe. We
present the first realistic constraints on the merger observability
timescales from a large suite of galaxy merger simulations which have
be...
Recent proper-motion measurements of the Large and Small Magellanic Clouds (LMC and SMC, respectively) by Kallivayalil and coworkers suggest that the 3D velocities of the Clouds are substantially higher (~100 km s-1) than previously estimated and now approach the escape velocity of the Milky Way (MW). Previous studies have also assumed that the Mil...
The hierarchical nature of the ΛCDM cosmology poses serious difficulties for the formation of disk galaxies. To help resolve these issues, we describe a new, merger-driven scenario for the cosmological formation of disk galaxies at high redshifts that supplements the standard dissipational collapse model. In this picture, large gaseous disks may be...
Based on numerical simulations of gas-rich galaxy mergers, we discuss a model in which quasar activity is tied to the self-regulated growth of supermassive black holes in galaxies. Nuclear inflow of gas attending a galaxy collision triggers a starburst and feeds black hole growth, but for most of the duration of the starburst, the black hole is hea...
We examine the evolution of the black hole mass-stellar velocity dispersion (MBH-σ) relation over cosmic time, using simulations of galaxy mergers that include feedback from supermassive black hole growth. For a range in redshifts z = 0-6, we modify the virial mass, gas fraction, interstellar medium equation of state, surface mass density, and conc...
We compare observed clustering of quasars and galaxies as a function of redshift, mass, luminosity, and color/morphology, to constrain models of quasar fueling and the co-evolution of spheroids and supermassive black holes (BHs). High-redshift quasars are shown to be drawn from the progenitors of local early-type galaxies, with the characteristic q...
We present a scenario for the production of dynamically cold rings around the Milky Way via a high-eccentricity, flyby encounter. These initial conditions are more cosmologically motivated than those considered in previous works. We find that the encounters we examine generically produce a series of nearly dynamically cold ringlike features on low-...
The discovery of luminous quasars at redshift z ~ 6 indicates the presence of supermassive black holes (SMBHs) of mass ~109 M☉ when the universe was less than 1 billion years old. This finding presents several challenges for theoretical models because whether such massive objects can form so early in the ΛCDM cosmology, the leading theory for cosmi...
We calculate multiwavelength spectral energy distributions (SEDs) from simulations of major galaxy mergers with black hole feedback that produce submillimeter bright galaxies (SMGs), using the self-consistent three-dimensional radiative transfer code RADISHE. These calculations allow us to predict multiwavelength correlations for this important cla...
We present the rest-frame ultraviolet through near-infrared spectral energy distribution for an interacting Lyman break galaxy at a redshift z = 4.42, the highest redshift merging system known with clearly resolved tidal features. The two objects in this system, HDF-G4 and its previously unidentified companion, are both B435-band dropouts, have sim...
We study the effects of feedback from active galactic nuclei (AGNs) on emission from molecular gas in galaxy mergers by combining hydrodynamic simulations that include black holes with a three-dimensional, non-local thermodynamic equilibrium (LTE) radiative transfer code. We find that molecular clouds entrained in AGN winds produce an extended CO m...
We examine the origin and evolution of correlations between properties of supermassive BHs and their host galaxies using simulations of major galaxy mergers, including the effects of gas dissipation, cooling, star formation, and BH accretion and feedback. We demonstrate that the simulations predict the existence of a BH "fundamental plane" (BHFP),...
We examine the fundamental scaling relations of elliptical galaxies formed through mergers. Using hundreds of simulations to judge the impact of progenitor galaxy properties on the properties of merger remnants, we find that gas dissipation provides an important contribution to tilt in the fundamental plane (FP) relation. Dissipationless mergers of...
We present new data obtained with the Submillimeter Array for a sample of 14 nearby luminous and ultraluminous infrared galaxies. The galaxies were selected to have distances DL < 200 Mpc and far-infrared luminosities log LFIR > 11.4. The galaxies were observed with spatial resolutions of order 1 kpc in the CO J = 3–2, CO J = 2–1,13CO J = 2–1, and...
Using a new model for quasar lifetimes and light curves derived from numerical simulations of galaxy mergers that incorporate black hole growth, we study the faint-end slope of the quasar luminosity function (QLF) and its evolution with redshift. Our model motivates a new interpretation of the QLF in which the bright end consists of quasars radiati...
We use numerical simulations to study the kinematic structure of remnants formed from mergers of equal-mass disk galaxies. In particular, we show that remnants of dissipational mergers, which include the radiative cooling of gas, star formation, feedback from supernovae, and the growth of supermassive black holes, are smaller, rounder, have, on ave...
The detection of large quantities of dust in z ~ 6 quasars by infrared and radio surveys presents puzzles for the formation and evolution of dust in these early systems. Previously, Li et al. showed that luminous quasars at z 6 can form through hierarchical mergers of gas-rich galaxies, and that these systems are expected to evolve from starburst t...
We derive a physical model for the observed relations between star formation rate (SFR) and molecular line (CO and HCN) emission in galaxies, and show how these observed relations are reflective of the underlying star formation law. We do this by combining 3D non-LTE radiative transfer calculations with hydrodynamic simulations of isolated disk gal...
We investigate the luminosity dependence of quasar clustering, inspired by numerical simulations of galaxy mergers that incorporate black hole growth. These simulations have motivated a new interpretation of the quasar luminosity function. In this picture, the bright end of the quasar luminosity function consists of quasars radiating nearly at thei...
We propose a model of quasar lifetimes in which longer periods of rapid black hole accretion are distinguished from observationally inferred lifetimes of quasars owing to gas and dust obscuration. In our picture, quasars are powered by gas funneled to galaxy centers, fueling starbursts and feeding black hole growth, but are "buried" until feedback...
We examine X-ray emission produced from hot gas during collisions and mergers of disk galaxies. To study this process, we employ simulations that incorporate cosmologically motivated disk-galaxy models and include the effects of radiative cooling, star formation, supernova feedback, and accreting supermassive black holes. We find that during a merg...