COS-DIISC (P.I. Borthakur)

COS-DIISC is a large HST program designed to study how galaxies acquire gas to build their HI disk. We obtained 100 orbits of HST COS data under this program.

UV-DIISC program (P.I. Borthakur)

We are combing archival imaging from GALEX (FUV, NUV), WISE, and Spitzer to trace star formating in the extended disks for star forming HI-rich galaxies. Some of the early results were presented at the AAS 2019.

1. Tracing Young Stars in the Outer Disks of HI-rich Galaxies
Padave et al. 2019, AAS, 23420214

Halpha-DIISC program (P.I. Borthakur)

We are currently obtaining deep H-alpha imaging of the DISK sample with the Vatican Advanced Technology Telescope (VATT). We have 4 nights of data in hand and will be acquiring addition imaging in 2020+.

COS-GASS (P.I. Heckman)

COS-GASS is the first attempt to study the CGM of low redshift galaxies and connect the CGM properties to neutral gas properties that reside in the inner 10% of the galaxies. These galaxies have both 21cm HI data as well as GALEX data in addition to SDSS imaging and spectroscopy and are drawn from the THE GALEX ARECIBO SDSS SURVEY (GASS).

The COS-GASS program is designed to study a sample of 47 galaxy-QSO pairs with the Cosmic Origin Spectrograph (COS) aboard the Hubble Space Telescope. COS-GASS used 119 orbits of HST to probe the CGM with COS and another 72 parallel orbits was used to map out the stellar distribution with WFC3. Here are some of the publications:

1. The Properties of the Circumgalactic Medium in Red and Blue Galaxies: Results from the COS-GASS+COS-Halos Surveys
Borthakur, Heckman et al. 2016, ApJ, 833, 259

2. Connection Between the Circumgalactic Medium and the Interstellar Medium of Galaxies: Results from the COS-GASS Survey
Borthakur, Heckman, et al. 2015, ApJ, 813, 46

VLA-DIISC program (P.I. Borthakur)

We mounted the first controlled experiment that will use UV QSO absorption-line spectra obtained with the Hubble Space Telescope (COS-DIISC survey) in conjunction with HI 21cm line images from the VLA to probe the disk-halo interface. The VLA HI 21cm data will probe the structure, extent, and kinematics of the outer disks down to column densities of 10¹⁹ atoms cm^-2, while the UV spectra will probe HI columns of 10^20-14 atoms cm^-2 out to 3.5 times HI radius (~50-80kpc). The combination COS-DIISC and VLA-DIISC, together with data from the COS-GASS survey, will allow us to probe gas out to the virial radii of galaxies. We will compare our observations with state-of-the-art numerical simulations providing important constraints both on the physical prescriptions for gas cooling and stellar and black-hole feedback. We plan to generate mock data cubes of the HI and synthetic UV-absorption spectra of the disk-halo interface that will enable us to analyze the simulations in the same way as the observations.

The VLA-DIISC program has 180 hours of VLA data in D- and C-configurations mapping 35 nearby galaxies. Additional 330 hours of VLA data will be obrained to under program 21A-275 in 2021 and 2022 to map 14 of the DIISC galaxies at 6" resolution.

Simulations (led by Guinevere Kauffman, Dylan Nelson, & Thorsten Naab)

We plan to compare our results (from COS-GASS and COS-Disk Surveys) with cosmological simulations and as well idealized box simulations. Some of the papers in this direction led by our simulations team is listed below:

1. The morphology and kinematics of the gaseous circumgalactic medium of Milky Way mass galaxies - II. Comparison of IllustrisTNG and Illustris simulation results
Kauffman, Nelson, & Borthakur 2019, MNRAS, 486, 4686

2. The morphology and kinematics of neutral hydrogen in the vicinity of z = 0 galaxies with Milky Way masses - a study with the Illustris simulation
Kauffmann, Borthakur, & Nelson 2016, MNRAS, 462, 3751

GBT-DISK (P.I. Borthakur)

GBT-DIISC is a set of smaller programs with the GBT that aimed at detecting cold atomic gas in and around HI disk in HI 21cm absorption. Publication(s) associated with these programs are listed below:

1. Distribution of Cold Atomic Gas in Galaxies: Results from the GBT HI Absorption Survey Probing Inner Halos of Low-z Galaxies
Borthakur 2016, ApJ, 829, 128

Dwarfs-Survey

The program observed 40 nearby sub-L* galaxies in HI 21cm spin transition (L-band) and optical spectrsocopy to connect the properteos of the ISM and stars to the CGM.