LBT Science at the University of Virginia - PowerPoint Presentation

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LBT Science at the University of Virginia - PPT Presentation

Some ongoing and recent UVa LBT programs Solar System Volcanism on Io LMIRcam ALES Skrutskie et al Dwarf planet composition LUCI Verbiscer Exoplanets Atmospheric ID: 657506

amp lbc proper luci lbc amp luci proper galaxies fritz mods kallivayalil high motion leakage thuan primordial dwarf segue

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Slide1

LBT Science at the University of Virginia

Some ongoing and recent UVa LBT programs:

Solar System: Volcanism on Io (LMIRcam/ALES; Skrutskie et al) Dwarf planet composition (LUCI; Verbiscer)Exoplanets: Atmospheric Composition from Exoplanet Transits (MODS; Turner, Johnson) Exoplanet IDs from the APOGEE survey (LMIRcam; Troup, Majewski)Local Group: Proper Motion of dwarf galaxy, Segue I (LBC; Kallivayalil, Fritz) Proper motion of Palomar 5 (LBC; Kallivayalil, Fritz, Lokken)Extragalactic: Ultra-faint dwarfs in small groups (LBC; Johnson, Stierwalt, Kalivayalil) Primordial He abundance from BCD galaxies (LUCI; Thuan) Lyman escape fraction in primordial galaxies (MODS; Thuan) Feedback in obscured quasars (LBC, MODS, LUCI; Whittle, Lonsdale)



Slide2

1) Volcanic resurfacing at Io’s Loki PateradeKleer, Skrutskie,

Leisenring et al (Nature 2017)

Io is most active object in the Solar System (tidal heating by Jupiter). Large caldera – Loki Patera – resurfaced every ~3yr since 1980s. Prior data from Voyager & Galileo, and AO from Keck and Gemini, but nature of resurfacing still unclear. Use LMIRcam at 4.5-5μm in AO and Fizeau LBTI interferometry:Observe during an eclipse of Io by Europa, to obtain light curve.Slide3

LBTI resolution = 30mas = 100km.

Not sufficient…

120ms time sample = 2.4 km resolution. LBTI boosts S/N for rapid sampling.Light profile needs careful modelingThermal gradients show two resurfacing events, one on each side.Consistent with crustal sinking…Slide4
Slide5

2) LyC leakage from low-z analogs of primordial galaxies Izotov, Thuan & Guseva (2017)

Select 5 from SDSS (z < 0.07) with high [OIII]/[OII] ratio (23-43) which may indicate density bounded HII regions, hence LyC leakage.High S/N spectra with MODS.

Cosmic reionization at z~5-10 still not well understood. Young star forming galaxies likely play an important role. However, LyC leakage fraction is critical factor – what is it?Study low-z analogs: Compact Star Forming Galaxies: CSFGs; BCDs12”Slide6

Young (<3

Myr

) SF. Low mass: M★~106 M Low abundance high-z analogsAll have broad Hα base Dynamically active, SN winds, possibly facilitating LyC leakage.Slide7

Model spectra using CLOUDY

Explore use of Helium lines as diagnostic of density bounded HII regions and hence HI column. CLOUDY models confirm its diagnostic value.

Results: 3 of 5 show NHI < 1017.5 cm-2 suggesting >20% LyC leakage.Strengthens case that high-z CSFG cause/contribute to reionization.

Previous emphasis on O32 as diagnostic of HI column.

However: O32 also depends on metallicity, SB age, and radiation parameter.

So, ambiguous.(Earlier conclusions of little leakage should be reexamined)Slide8

3) J0811

+4730: The Lowest

Metallicity SF Galaxy Known Izotov, Thuan, Guseva, & Liss (2017)Search SDSS DR13 for high [OIII]/[OII] CSFGsHunt for low metallicity: high-z analogs & primordial He abundance.2/17: 90 min MODS1/2 binocular: High S/N (e.g. [OIII] 4363)Slide9

Find: 12+Log [O/H] = -6.98±0.02

lowest ever for SFG

. MB = -15.4 Mstars = 106 Msun tage = 3 Myr z = 0.044  close analog to z > 3 dwarf SFGs.Quite different from normal (low-z) SFGs, due to lower metalicity. Displaced from normal SFG locus on BPT diagrams; Also overluminous (nebular emisson), and unevolved.Normal SFGs

Low-Z SFGsSlide10

4) Proper

motion of globular Palomar 5

epoch: 1999 SDSS DR9 positions

epoch: 2014 LBC images

Results (see

Fritz &

Kallivayalil

2015

= -2.25±0.19 mas/

-2.21±0.18 mas/

18'

Significant improvement on earlier measurements using photographic plates.

MW Satellites can be used to measure the structure and shape of the MW halo. Obtaining proper motions (PM) has been difficult, with only a few so far.

Pal-5 important because relatively close, so PM possible.

Also has a measured stream, which allows additional constraints.

LBC Fields

Tobias Fritz &

Nitya

Kallivayalil

(2015)Slide11

Milky Way halo is spherical

Previous halo models unable to provide strong constraints on halo shape.

New proper motion helps greatly and

strongly favors a spherical halo

c/a =1.05 ±0.14. (See

Bovy

Bahmanyar

, Fritz &

Kallivayalil

2016

)Slide12

5) Segue

1 is well bound

Modeling reveals (see

Fritz et al, 2017 in prep

Orbit properties different from the other satellites:

more tightly bound

; different orbital plane; non-circular with

peri

–

apocenter

: 22 – 34

kpc

Analogs to Segue 1 are found in FIRE simulations:

Form early and

infall

early (~10

Gyr

ago).

epoch: 2006 SDSS positions

epoch: 2016 LBC

Proper Motion:

= 0.85±0.47 mas/

= -2.74±0.44 mas/

Segue 1 is one of faintest dwarf galaxies with the highest M/L ratio:

= 340

sun

; M/L = 3400 ;

dist.

~23

kpc

Such galaxies help

understand the

missing

satellite problem. What is their origin? Find orbit from proper motion…

First measurement of such a faint galaxy.

LBC fields

Tobias Fritz,

Nitya

Kallivayalil

, & Martine

Lokken

(2017 in prep)Slide13

6) Luminous, Obscured, Radio Quasars

Mark Whittle, Carol Lonsdale, Mark Lacy, Pallavi

Patil.Use WISE & NVSS to select luminous obscured AGN at z ~ 0.5 – 3, with powerful kpc-scale radio sources (final sample 150).Young systems with powerful jets in massive ISM.Aim to study jet-related feedback. Radiointermediate& powerful

SB/LIRGs



AGN/QSO

Also: optically faint

 distant

“red”

Extensive ALMA, VLA and VLBA data already

acquried

Subset of 12 with interesting VLBA chosen for LBT follow-up:

LBC

g,r

; LUCI J,Ks done