time domain astronomy - hou.usra.edu · cara battersby (moderator) is an assistant professor of...

Time Domain AstronomyCara Battersby (University of Connecticut), ModeratorBrad Cenko (NASA Goddard Space Flight Center)Julie McEnery (NASA Goddard Space Flight Center)Daryl Haggard (McGill University)

Our Panel

Cara Battersby (moderator) is an Assistant Professor of Astrophysics at the University of Connecticut, specializing in extreme star formation, particularly in our Galactic Center

Brad Cenko is a Research Astrophysicist at NASA Goddard Space Flight Center. He is the PI of the Neil Gehrels Swift Observatory, and part of the Zwicky Transient Facility (ZTF) and Large Synoptic Survey Telescope (LSST) teams

Daryl Haggard is an Assistant Professor of Physics at McGill University, specializing in AGN and their host galaxies, Galactic Center and SgrA*, EM counterparts to GW sources, accretion onto compact objects, multi-wavelength and time domain surveys

Julie McEnery is an Astrophysicist at the NASA Goddard Space Flight Center. She is WIRST deputy Project Scientist and was project scientist for the Fermi Gamma-ray Space Telescope until last Monday.

Our Panel

Exoplanet Person! Expert on your exact research area! and also has the same favorite flavor of ice cream as you!

Knower of all Things! AKA a deity Knower of all Things! AKA a theorist

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Our Panel

Exoplanet Person! Such an expert on all the things!

Expert on your exact research area! Thinks all your thoughts and also has the same favorite flavor of ice cream!

Knower of all Things! AKA a deity Knower of all Things! AKA a theorist

X X

X XYou!

Schematic of Transients and Variables


★ Many science areas


★ Many science areas★ Multiwavelength


★ Many science areas★ Multiwavelength★ Need dedicated

wide-field surveys...



wide-field surveys...★ ...and fast, detailed

follow-up




follow-up★ Build for what we

know...




follow-up★ Build for what we

know...★ … and what we

don’t. Huge discovery space.

Far-IR Variability is mostly untapped● Growth of dust in supernova remnants● Detailed time-monitoring of Solar System objects (comets, asteroids...)● Gravitational wave follow-up● The growth of young stars

Herschel Gould Belt

How do Stars Gain their Mass?

(Fischer et al. 2019 White Paper:2019arXiv190307628F ) Info from Will Fischer, Doug Johnstone, Mike Dunham, Joel Green, Jenny Hatchell….See also high-mass case in Hunter et al. 2019 White Paper

Important for understanding origin of the IMF and how planets form and evolve

https://ui.adsabs.harvard.edu/#abs/2019arXiv190307628F/abstract

Herschel Gould Belt



Important for understanding origin of the IMF and how planets form and evolve

Star formation… from a snapshot to a movie


● Variability is well-established ○ In mid-IR (e.g. YSOVAR Morales-Calderon+ 2011 and Caratti o Garatti 2011, Safron+ 2015, Fischer+ 2019)○ In Far-IR (e.g. SOFIA, Herschel: Billot+ 2012, )○ In sub-mm (JCMT, Herczeg+ 2017, Johnstone+ 2018a)○ Even extragalactically (Spitzer SAGE survey from Meixner+2006 showed variability in 1% of protoclusters in 3

months, Vijh+ 2009)● Time range of days to years


ALMA

(Fischer et al. 2019 White Paper… See also high-mass case in Hunter et al. 2019 White Paper


● Variability is well-established ○ In mid-IR (e.g. YSOVAR Morales-Calderon+ 2011 and Caratti o Garatti 2011, Safron+ 2015, Fischer+ 2019)○ In Far-IR (e.g. SOFIA, Herschel: Billot+ 2012, )○ In sub-mm (JCMT, Herczeg+ 2017, Johnstone+ 2018a)○ Even extragalactically (Spitzer SAGE survey from Meixner+2006 showed variability in 1% of protoclusters in 3

months, Vijh+ 2009)● Time range of days to years

HOPS 383 in Orion, Sarfon+ 2015

EC 53 (Yoo+ 2017; Johnstone+ 2018b)

(Fischer et al. 2019 White Paper… See also high-mass case in Hunter et al. 2019 White Paper


Need dedicated, high-cadence observations of many stars. Light from protostars peaks in far-IR, making it the most direct tracer of variable accretion




Origins is designed to map large areas, quickly, and it can deal with the large dynamic range in Galactic targets.

Herzchel Gould Belt(Fischer et al. 2019 White Paper:2019arXiv190307628F ) Info from Will Fischer, Doug Johnstone, Mike Dunham, Joel Green, Jenny Hatchell….See also high-mass case in Hunter et al. 2019 White Paper



Origins is designed to map large areas, quickly, and it can deal with the large dynamic range in Galactic targets.

Herzchel Gould Belt

★ Consider time domain discovery science when designing your missions!



The Ground-Based Time-Domain Context:Optical Surveys

● Wide-area optical imaging surveys are near “saturation”○ Bright (< 18 mag) - TESS 30 min cadence over 2500

deg2, ASAS-SN ~ daily cadence over whole sky○ Medium (< 21 mag) - ZTF, ATLAS, Pan-STARRS

imaging Northern Sky every 2-3 days, BlackGem will do similar in the South in few years

○ Faint (< 24 mag) - LSST imaging Southern Sky every 3-4 days

● Major investments from NASA (TESS, ATLAS) and NSF (ZTF, LSST)

The Ground-Based Time-Domain Context: Radio Surveys

● Next frontier will be at radio wavelengths○ Low-frequency arrays in existence or soon coming

online (LOFAR, CHIME, LWA, …)○ Higher frequencies under development (Square

Kilometer Array Phase 1)○ Sensitive to both coherent and incoherent emission

processes● Many (but not all) projects funded outside US

The Ground-Based Time-Domain Context: Scientific Opportunities

● Wide-area survey instruments at complementary wavelengths (“co-observing”)○ High Energies: Current facilities (Fermi, Swift, INTEGRAL) provide complementarity, but unlikely

to be around for entire 10 year duration of LSST○ Infared: WFIRST (somewhat smaller FOV)○ Ultraviolet: Completely lacking (current largest FOV instrument: 18’ x 18’)○ Co-observing extremely powerful for classification (e.g., relativistic ejecta)

● Multi-wavelength Follow-up○ Target-of-Opportunity capabilities on existing missions○ Most (but not all) large missions not well matched to this science (e.g., JWST)○ Swift lesson: fast slewing, UV/X-ray powerful combination○ Spectroscopy is particularly important need

The IceCube experiment in Antarctica has been observing Astrophysical high energy neutrinos since XXX - Where do they come from?

The answer will unambiguously identify acceleration sites of very high energy protons

Where do the highest energy particles in the Universe come from?

The High Energy Sky seen by Fermi-LAT

The Variable Gamma-ray Sky

TXS 0506+056 in months long outburst

Follow up observations across the EM spectrum

IceCube, Fermi-LAT, MAGIC,

AGILE, ASAS-SN, HAWC,

H.E.S.S, INTEGRAL, Kapteyn,

Kanata, Kiso, Liverpool,

Subaru, Swift, VERITAS, VLA,

Science 2018

Some takeaways

Neither the neutrino nor gamma-ray observation were interesting by themselves

Identification of the counterpart with Fermi relied on knowing the past history of the blazar

Timescales were relatively long - didn’t need to rush, but did need long baseline observations

Getting full science interpretation relied on many observations across the EM spectrum with a mix of large and small facilities

Gravitational Waves and Gamma-ray Bursts

Gravitational waves and GRB

Gamma-ray burst was not especially interesting by itself -humdrum phenomena can be groundbreaking when combined with new observation capabilities

Prompt dissemination of Fermi-GBM GRB enabled rapid identification of the gravitational wave signal

Observations of (nearly) simultaneous short duration phenomena only possible for instruments with large FoV

The X-ray Time Domain Context: Our Poster Child GW170817

● Multiwavelength LCs of GW170817

up to ~30 days post-merger

● Confirms NS merger origin for KNe

● Early peak in the UV and blue LCs

● UV for ”blue” KNe, shock break out

● Kilonova evolves rapidly from blue

to red in photom. and

spectroscopy

● UV spectroscopy offer constraints

on r-process elemental

abundances

The X-ray Time Domain Context: Our Poster Child GW170817

● Multiwavelength coverage up to

~600 days post-merger shows non-

thermal synchrotron

● Fit is for an off-axis (∼30deg)

structured relativistic jet in a low

density medium

● Exquisite PL from radio to X-ray

● No break detected thus far

● Ongoing work to place GW170817

into SGRB context and to search

archives for similar sources

Time Domain Deserati in the 2020++

Ground-based GW Detectors for 2020s

LIGO-Virgo O3Public Alerts!GCN, ATEL, GW Events (iPhone)

GW’s Across the Mass Scale

Questions for the coming decade 1. What space missions/wavelengths/modes are critical? Do we need a suite of

missions? Which ones? How soon?2. In addition to space missions, how do we support other necessary capabilities

(cyberinfrastructure, archives, theory)?3. How do we better coordinate with large projects from different funding

agencies?4. How do we handle orders of magnitude difference in relevant timescales

(seconds to years)? How much can we do if we miss the “prompt” emission? Will GW localization be enough?

5. How do we coordinate observatories in space and on the ground? (E.g., monitor LIGO-Virgo high confidence regions, vs. all sky monitors, vs. rapid response, … ?) Are TACs ready?

6. What are the implications for observatory schedulers? Should we support VO standards for visibility/scheduling?

7. What archives must we curate?

Takeaway messages

★ Time domain astronomy is a key future discovery space. ★ All future facilities should be considering the needs of time

domain astronomy … both what we know already, and the open discovery space in wavelength and time baseline.

★ Key needs:○ Dedicated, wide-field survey facilities○ High-resolution, multiwavelength facilities for detailed

follow-up studies

time domain astronomy - hou.usra.edu · cara battersby (moderator) is an assistant professor of...

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