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This is a special venue for me!

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Time Domain Astronomy: The Next Decade

S. R. Kulkarni Caltech Optical Observatories

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MAJOR DIVISION: VARIABLE OBJECTS & TRANSIENTS

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Variable Objects

• Key measurement: Light Curves– Photometric Precision

• Low: RR Lyrae, Cepheids, AGN, Type Ia • Moderate: Eclipsing Binaries, Gravitational Lensing• High: Planetary Transits, Asteroseismology

• What is of value?– Total number of visits usually matters more than cadence

• Spectroscopy (followup)– In most cases rapid follow up is not essential– In many cases spectroscopy helps but is not crucial

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Transient Objects• Imaging surveys provide the starting point for investigation

– Supernova investigations are triggered by detection of a rising object – For many studies the follow up is decoupled from the initial detection

of a GRB (at high energies) • Cadence control is critical

– On the first night of an imaging survey the detected transients are dominated by old supernovae

– Conversely lack of cadence control presents significant opportunity costs (negative)

• Cadence directly determines the phase space that is being explored– “Universal” cadence simply means that everyone is equally unhappy

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This Talk• Focused entirely on transient object astronomy

• Main thesis: – Transient object astronomy is served best by sharply focused time domain

surveys – Conversely, the returns from a generic time domain survey are likely to be quite

poor (and wasteful of follow up resources)

• Transient Object Astronomy has a bright future in this decade and likely to continue into the next decade (when TMT will become operational)– However, TMT time is precious– Transient object astronomy has its own learning curve– The TMT collaboration must start preparing now

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AN EXEMPLAR

The Intermediate Palomar Transient Facility (iPTF)

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P48

P60

P200

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The Palomar Observatory

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P48Discovery

P60Confirmation

P200Spectroscopy

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1232

Kasli

wal

201

1 (P

hDT)

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Super-luminous Supernovae (no Hydrogen)

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Death Omen!

PTF10tel

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Double degenerates: The new frontier

Source: LISA Mission, NASA

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ON TO LOW LATENCY(SAME NIGHT)

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PTF11kly: A nearby Ia Explosion(Rosetta Stone)

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Progenitor of a Ib Supernova!

What next?

S. R. Kulkarni

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Short timescale is terra incognito

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PTF11agg: Dirty Fireball?

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Same night arcsecond localization of error region of 72 square degrees!

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As we go to press! GRB131011A

M. KasliwalL. Singer

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• TITLE: GCN CIRCULARNUMBER: 15324SUBJECT: Fermi403206457: iPTF detection of a possible optical afterglowDATE: 13/10/12 12:09:55 GMTFROM: Mansi M. Kasliwal at Caltech/Carnegie <mansikasliwal@gmail.com>

M. M. Kasliwal (Carnegie Observatories/Princeton), L. P. Singer (Caltech) and S. B. Cenko (NASA/GSFC) report on behalf of the intermediate PalomarTransient Factory (iPTF) collaboration:

Starting 2013-10-12 05:26 UT, we imaged about 70 deg^2 in the vicinity of the localization of the Fermi-GBM trigger 403206457 with the Palomar 48-inch Oschin telescope (P48). Sifting through 10,816 candidate variable sources in the GBM error circle using standard iPTF vetting procedures including Palomar 60-inch follow-up, we identify iPTF13dsw as a possibleoptical afterglow candidate:

RA(J2000) = 02h 10m 06.38s DEC(J2000) = -04d 24' 40.3" Light Curve: R=19.7mag @ 05:26 UT (P48), R=20.2mag @ 08:07 UT (P60)

iPTF13dsw is 3.4 deg away from the center of the final GBM localization(68% statistical confidence radius of 2.75 deg). Nothing was detected atthis location to a limiting magnitude of 20.6 mag on 2013 Sep 25.

At 08:56 UT, we obtained a Gemini-South/GMOS spectrum in twilight. Thespectrum is mostly featureless, with no prominent emission or absorptionlines between 5100-9300A.

.

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WHAT IS THE METRIC OF SYNOPTIC SURVEYS?

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Proposed Metrics

• The “Reach” Etendue, AΔΩ• Point source sensitivity, AΔΩ/θ2

• These metrics make sense only for static surveys. • Not relevant for transient surveys• For transients mere detection in itself is limited

value• Classification and follow up is the key

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Fundamental Parameters of a Time Domain Survey (Transients)

• Field-of-view (FOV), ΔΣ • Sensitivity (6σ), Sl

• Time to move one FOV, τm

• Cadence: typical time separation between re-visit to the same FOV

• Basic Integration time, τs (frame time)– Assume 60-s for all surveys

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Areal Rate• Short Duration Transients (T<τs)

• Long Duration Transients (T>τs)

• If follow up is essential then all that matters is Sl (set by follow up) and the parameters shown above. For 21-mag ZTF is 250 times faster than say HSC.

Zwicky Transient Facility

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47-sq degree camera for P48

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The SED Machine for P60

7 arcminute30 arcsec

PI: Nick Konidaris, PS: Robert QuimbyIn collaboration with NCU-Taiwan

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A Proposal: TMT Community based Transient Object Facilities

• Recognizing that transient object astronomy is a growing field with great promise the TMT community should ensure that it has access to quality transients

• Transient searches have three fundamental parameters and as such the idea that a single facility (equipped with “Universal Cadence”) can provide the transient stream is incorrect

• The preparation for this should start now so that the event streams will be ready by 2022.

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ZTF Annual Workshops

• The ZTF consortium will be holding yearly meetings (along the lines of the very successful iPTF 2013 Workshop)– We plan to invite key players from TMT

consortium to attend these meetings• http://ptf.caltech.edu/iptf/iptf_workshop/