Finding the smallest gas-rich galaxies Betsey Adams ASTRON / - PowerPoint PPT Presentation

Finding the smallest gas-rich galaxies Betsey Adams ASTRON / Kapteyn Astronomical Institute Small Galaxies, Cosmic Questions 1 Aug 2019 John Cannon, Riccardo Giovanelli, Martha Haynes, Bill Janesh, Lilly Bralts-Kelly, Steven Janowiecki, Tom Oosterloo, Susie Paine, Kathy Rhode, John Salzer, Nick Smith

The gas-rich (HI) Universe • Observables: Flux • Recessional velocity (distance) • Internal kinematics (total mass) Velocity ALFALFA HI Survey • HI line flux -> HI mass • Features: • Field galaxies: isolated, blue, star- forming • Disentangle environmental influence Mancera-Piña+ submitted vs. intrinsic properties

The gas-rich (HI) Universe • Observables: • Recessional velocity (distance) • Internal kinematics (total mass) • HI line flux -> HI mass • Features: • Field galaxies: isolated, blue, star- forming • Disentangle environmental influence Spekkens+ 2014 vs. intrinsic properties

What dwarf galaxies do we see in HI? • SHIELD: Nearby, bonafide low-mass dwarf galaxies • Distances ~ 5 -12 Mpc • M HI ~ 3-50 x 10 6 M sun • M star ~ 3-50 x 10 6 M sun • HI-bearing ultra-di ff use galaxies: distant, low surface McQuinn+ 2014 brightness dwarfs • Distances ~50-100 Mpc • M HI ~ 10 8 - 10 9 M sun • M star ~ 10 7 - 10 8 M sun Leisman+ 2017

What about the ultra-faint regime? • Leo T • Most distant UFD • Only one that is gas-rich • M star ~ 2 x 10 5 M sun • M HI ~ 4 x 10 5 M sun • Fill out parameter space pre- LSST? Tollerud+ 2008

What about the ultra-faint regime? • Leo T • Most distant UFD • Only one that is gas-rich • M star ~ 2 x 10 5 M sun • M HI ~ 4 x 10 5 M sun • Fill out parameter space pre- LSST? Tollerud+ 2008

What about the ultra-faint regime? • Leo T • Most distant UFD • Only one that is gas-rich • M star ~ 2 x 10 5 M sun • M HI ~ 4 x 10 5 M sun • Fill out parameter space pre- LSST? Ryan-Weber+ 2008 Tollerud+ 2008 Tollerud+ 2008

What about the ultra-faint regime? • Leo T • Most distant UFD • Only one that is gas-rich • M star ~ 2 x 10 5 M sun • M HI ~ 4 x 10 5 M sun • Fill out parameter space pre- LSST? Ryan-Weber+ 2008 Tollerud+ 2008

Leo P: Pushing to the field UFD limit • Extreme, nearby galaxy discovered as an HI source in ALFALFA • D=1.62 Mpc • M HI = 8.1 x 10 5 M sun • M star = 5.6 x 10 5 M sun • v rot = 15 km/s • 12 + log[O/H] = 7.17 (~3% solar) • Single star-formation region

Leo P: Pushing to the field UFD limit • Extreme, nearby galaxy discovered as an HI source in ALFALFA • D=1.62 Mpc • M HI = 8.1 x 10 5 M sun • M star = 5.6 x 10 5 M sun • v rot = 15 km/s • 12 + log[O/H] = 7.17 (~3% solar) • Single star-formation region Bernstein-Cooper+ 2014

Isolated HI clouds as candidate LG galaxies By design: No apparent optical counterpart in SDSS data Feature: Confusion with Galactic HI halo cloud population Higher resolution HI to discriminate ′ 00 . 0 ′′ 40 ′ 00 . 0 ′′ ′ 00 . 0 ′′ 36 ′ 00 . 0 ′′ Dec (J2000) ′ 00 . 0 ′′ 32 ′ 00 . 0 ′′ ′ 00 . 0 ′′ 28 ′ 00 . 0 ′′ ′ 00 . 0 ′′ +17 ◦ 24 ′ 00 . 0 ′′ 15 . 00 s 18 m 00 . 00 s 45 . 00 s 30 . 00 s 14 h 17 m 15 . 00 s 45 . 00 s 30 . 00 s 15 . 00 s 30 m 00 . 00 s 9 h 29 m 45 . 00 s RA (J2000) RA (J2000) E. A. K. Adams+ 2013

Isolated HI clouds as candidate LG galaxies By design: No apparent optical counterpart in SDSS data Feature: Confusion with Galactic HI & halo cloud population Higher resolution HI to discriminate 54 . 0 156 . 0 20 ′ 00 . 0 ′′ 40 ′ 00 . 0 ′′ 155 . 2 52 . 5 154 . 4 51 . 0 16 ′ 00 . 0 ′′ 153 . 6 36 ′ 00 . 0 ′′ 49 . 5 152 . 8 48 . 0 cz (km s − 1 ) Dec (J2000) Dec (J2000) 152 . 0 12 ′ 00 . 0 ′′ 46 . 5 32 ′ 00 . 0 ′′ 151 . 2 45 . 0 150 . 4 08 ′ 00 . 0 ′′ 43 . 5 28 ′ 00 . 0 ′′ 149 . 6 42 . 0 148 . 8 +24 ◦ 04 ′ 00 . 0 ′′ 40 . 5 +17 ◦ 24 ′ 00 . 0 ′′ 148 . 0 15 . 00 s 18 m 00 . 00 s 45 . 00 s 30 . 00 s 14 h 17 m 15 . 00 s 45 . 00 s 30 . 00 s 15 . 00 s 30 m 00 . 00 s 9 h 29 m 45 . 00 s RA (J2000) RA (J2000) N HI,peak ~ 5 x 10 19 atoms cm -2 N HI,peak ≲ 10 19 atoms cm -2 E. A. K. Adams+ 2016

Isolated HI clouds as candidate LG galaxies By design: No apparent optical counterpart in SDSS data Feature: Confusion with Galactic HI & halo cloud population Higher resolution HI to discriminate 54 . 0 156 . 0 20 ′ 00 . 0 ′′ 40 ′ 00 . 0 ′′ 155 . 2 52 . 5 154 . 4 51 . 0 16 ′ 00 . 0 ′′ 153 . 6 36 ′ 00 . 0 ′′ 49 . 5 152 . 8 48 . 0 Possible HI in a "disk" -- cz (km s − 1 ) Dec (J2000) Dec (J2000) Likely Galactic halo cloud 152 . 0 12 ′ 00 . 0 ′′ 46 . 5 potential "galaxy" 32 ′ 00 . 0 ′′ 151 . 2 45 . 0 150 . 4 08 ′ 00 . 0 ′′ 43 . 5 28 ′ 00 . 0 ′′ 149 . 6 42 . 0 148 . 8 +24 ◦ 04 ′ 00 . 0 ′′ 40 . 5 +17 ◦ 24 ′ 00 . 0 ′′ 148 . 0 15 . 00 s 18 m 00 . 00 s 45 . 00 s 30 . 00 s 14 h 17 m 15 . 00 s 45 . 00 s 30 . 00 s 15 . 00 s 30 m 00 . 00 s 9 h 29 m 45 . 00 s RA (J2000) RA (J2000) N HI,peak ~ 5 x 10 19 atoms cm -2 N HI,peak ≲ 10 19 atoms cm -2 E. A. K. Adams+ 2016

Isolated HI clouds as candidate LG galaxies By design: No apparent optical counterpart in SDSS data Feature: Confusion with Galactic HI & halo cloud population Higher resolution HI to discriminate 54 . 0 40 ′ 00 . 0 ′′ 52 . 5 51 . 0 36 ′ 00 . 0 ′′ 49 . 5 48 . 0 cz (km s − 1 ) Dec (J2000) 46 . 5 32 ′ 00 . 0 ′′ 45 . 0 43 . 5 28 ′ 00 . 0 ′′ 42 . 0 40 . 5 +17 ◦ 24 ′ 00 . 0 ′′ 15 . 00 s 18 m 00 . 00 s 45 . 00 s 30 . 00 s 14 h 17 m 15 . 00 s RA (J2000) N HI,peak ~ 5 x 10 19 atoms cm -2 Garrison-Kimmel+ 2014 E. A. K. Adams+ 2016

Isolated HI clouds as candidate LG galaxies By design: No apparent optical counterpart in SDSS data Feature: Confusion with Galactic HI & halo cloud population Higher resolution HI to discriminate 54 . 0 156 . 0 20 ′ 00 . 0 ′′ 40 ′ 00 . 0 ′′ 155 . 2 52 . 5 154 . 4 51 . 0 16 ′ 00 . 0 ′′ 153 . 6 36 ′ 00 . 0 ′′ 49 . 5 152 . 8 48 . 0 cz (km s − 1 ) Dec (J2000) Dec (J2000) 152 . 0 12 ′ 00 . 0 ′′ 46 . 5 32 ′ 00 . 0 ′′ 151 . 2 45 . 0 150 . 4 RELHICs - column density 08 ′ 00 . 0 ′′ 43 . 5 28 ′ 00 . 0 ′′ 149 . 6 corresponds to halo mass 42 . 0 148 . 8 +24 ◦ 04 ′ 00 . 0 ′′ 40 . 5 +17 ◦ 24 ′ 00 . 0 ′′ of ~few x 10 9 M sun 148 . 0 15 . 00 s 18 m 00 . 00 s 45 . 00 s 30 . 00 s 14 h 17 m 15 . 00 s 45 . 00 s 30 . 00 s 15 . 00 s 30 m 00 . 00 s 9 h 29 m 45 . 00 s RA (J2000) RA (J2000) N HI,peak ~ 5 x 10 19 atoms cm -2 N HI,peak ≲ 10 19 atoms cm -2 Benítez-Llambay+ 2017 E. A. K. Adams+ 2016

Kinematics of galaxy candidates v rot ~ 6 km/s 54 . 0 Preliminary v circ ~ 10 km/s 40 ′ 00 . 0 ′′ 52 . 5 51 . 0 36 ′ 00 . 0 ′′ 49 . 5 48 . 0 cz (km s − 1 ) Dec (J2000) 46 . 5 32 ′ 00 . 0 ′′ 45 . 0 43 . 5 28 ′ 00 . 0 ′′ 42 . 0 40 . 5 +17 ◦ 24 ′ 00 . 0 ′′ 15 . 00 s 18 m 00 . 00 s 45 . 00 s 30 . 00 s 14 h 17 m 15 . 00 s RA (J2000) Lily Bralts-Kelly, in progress

Distances to candidate galaxies Deep optical imaging with WIYN/pODI reveals potential stellar component Janesh+ 2017

Properties of candidate galaxies Deep optical imaging with WIYN/pODI reveals potential stellar component AGC 249525 • 98% significance • D = 1.64 Mpc • M star ~ 0.2 - 4 x10 5 M sun • M HI = 3 x 10 6 M sun • D HI ~ 4 kpc • M dyn ~ 10 8 M sun Janesh+ 2017

Properties of candidate galaxies Deep optical imaging with WIYN/pODI reveals potential stellar component AGC 249525 • 98% significance • D = 1.64 Mpc • M star ~ 0.2 - 4 x10 5 M sun • M HI = 3 x 10 6 M sun • D HI ~ 4 kpc • M dyn ~ 10 8 M sun Janesh+ 2017

Properties of candidate galaxies Deep optical imaging with WIYN/pODI reveals potential stellar component 5/29 detections in total (Janesh+ 2019) • D = .35 - 1.6 Mpc • M HI ~ 0.2 - 30 x10 5 M sun • M star ~ 0.04 - 40 x 10 4 M sun • Only old stellar populations Janesh+ 2017

Looking to the future Apertif: Phased-array feed on WSRT MeerKAT: sensitive single-pixel feeds ASKAP: Phased-array feed FAST, Arecibo w/ ALPACA (40 beams)

The data is flowing MIGHTEE (MeerKAT) 
 Apertif Early Science Data Early Science Data UGC 8914 dwarf galaxy companion M star = 10 6 M sun no previous redshi fu M HI = 3 x 10 8 M sun MIGHTEE-HI and IDIA Pipelines Team Apertif Imaging Team

Take-away messages • HI o ff ers an important perspective on dwarf galaxies • HI surveys o ff er possibility of finding gas-bearing field ultra- faint dwarf galaxies • Have found several (~2-5) potential candidates in ALFALFA • AGC 249525 is an excellent candiate with promising HI properties and a potential stellar counterpart • Exciting times ahead with SKA pathfinders coming online