Liverpool Telescope 2

Transcription

1 Liverpool Telescope 2 Chris Copperwheat Liverpool Telescope group: Iain Steele, Chris Davis, Rob Barnsley, Stuart Bates, Neil Clay, Steve Fraser, Jon Marchant, Chris Mottram, Robert Smith, Mike Tomlinson

2 The Liverpool Telescope The Liverpool Telescope is a robotic 2m alt-az telescope currently in operation on La Palma Not 'remote controlled' operated autonomously without night-time supervision Software decides what and how to observe and is responsible for safe operation of telescope throughout the night

3 Liverpool Telescope Instrumentation IO O: Main imaging camera: 10' FoV; 12 optical filters FRODOspec: 12x '' lenslet IFU R~2500/5500; 400 < λ < 940nm RINGO3: Fast-readout tri-band polarimetry RISE: Rapid readout (0.6sec) photometry; 10' FoV IO THOR: High cadence photometry (~7ms); 2.25' FoV Coming this year: IO I: Infrared (Y, J, H) imager. 6x6' FoV SPRAT: R~500 spectrograph

4 LT Science Flexible nature of LT observing modes makes it ideal for time domain work High-impact science 36 citations/paper average (for papers > 3yr old) 15 publications in Nature/Science (86 citations on average)

5 GRB Polarimetry Polarisation evolution of GRB A (Mundell et al., 2013) Results indicate that GRBs contain magnetized baryonic jets with large-scale uniform fields that can survive long after the initial explosion (See also Mundell et al., 2007; Steele et al., 2009)

6 Eclipsing binaries CSS Eclipsing white dwarf M dwarf binary. Porb ~3.59 hrs Eclipses timed to sub-second precision Variations in orbital period due to magnetic variability or circumbinary planets (e.g. Beuermann et al. 2010) (Data from Bours et al.)

7 Long period binaries Subdwarf-B star with FGK-type MS companion Orbital period (~months years) measured via radial velocity shifts Example of the type of project which would be impossible on a classically scheduled telescope

8 Liverpool Telescope 2 The Liverpool Telescope is now a mature facility which is expected to stay competitive until at least 2020 The next decades will see an increased emphasis worldwide on time domain science, with many new facilities and missions coming on line We aim to build a new 'Liverpool Telescope 2' facility designed to capitalise on this exciting new era, to come into operation ~2020 LJMU has committed 200,000 to fund the feasibility and initial design study for LT2. We are 15 months into that process and things are proceeding well No real preconceptions other than that LT2 will build on the existing strengths of the LT

9 Operational strengths of the LT Low operational cost (robotic observing) 10.5 staff; 500k/year or 10k/paper Rapid response to transient alerts (avg ~180s) Robotic telescope Design telescope, enclosure, software Instrumentation Diverse suite of instruments Quick instrument changes Rapid deployment of new instruments to meet new needs

10 LT2 key science objectives

11 Transient science Transients (of various types) a key research area at LJMU, and in astronomy groups worldwide An area of study well matched to robotic observing Synoptic surveys such as PTF, Pan-STARRS, Skymapper provide large numbers of transients detected at early times Number of detections to increase significantly with next generation of surveys (LSST) For fast fading transients like GRBs, rapid response more important than aperture Next decades will see the discovery of exotic transients across the EM spectrum

12 Early time spectra of SN2011fe Light curve (Fulton/LCOGT/PTF) High velocity OI feature detected in LT+Frodospec spectrum, 1.18 days after explosion (Nugent et al. 2011)

13 LSST Sited at Cerro Pachón, Chile (Gemini South) Engineering first light 2020, 10 yr survey begins m primary mirror, 9.6 deg2 field of view 1000 visits to each patch of sky in 10 years. Each visit 2 x 15 sec exposures Single visit depth r ~ 24.5 Total survey covers 20,000 deg2 in ugrizy Coadded depth r ~ 26.5 ~ 1e6 transient alerts per night Alerts published 60 s after observation

14 Transient science in LSST (and the other synoptic surveys) will provide Large, unbiased and statistically complete samples Very early detections (many objects like SN2011fe). New parameter space CC SNe: progenitors (pre-explosion imaging), relative frequencies of rare subtypes, unusual environments Potentially new types of stellar explosions (combined with radio, high energy, GW, neutrino detections) Many photometric monitoring programmes running on the LT currently these data will be provided 'for free' by next gen synoptic surveys Will not provide Spectroscopy (low R for classification, intermediate R for most science) Photometry optimised to the SN light curve: LSST 3-4 days between visits (even longer for same filter) High cadence observations at early time and over peak

15 Transient spectroscopy in Current synoptic surveys such as PTF provide large numbers of transients detected at early times Spectroscopic follow-up is the bottleneck The need for flexible spectroscopic follow-up will become even more acute in the next decade Only ~10% of PTF detections get a spectral classification LSST will issue ~1e6 alerts per night! Even accounting for variable stars and NEOs, still 1000s of targets Programmes like PESSTO are showing that large scale optical follow-up of transients with 4m class telescopes can be very productive. A telescope dedicated primarily to transient spectroscopy with the speed and flexibility of robotic operations would be a powerful tool

16 Gamma-ray bursts A topic well matched to the LT's capabilities, so no surprise it has been a productive area GRB science 2020: High z bursts Cosmological parameters, reionisation, star formation history Requires 8m+ class facilities unless you catch afterglow very early (seconds - minutes) Low to intermediate z bursts GRB-supernova associations Prompt phase particle acceleration, radiation processes, internal shocks Short GRBs nature of the binary merger components

17 Gamma-ray bursts With rapidly fading transients like GRB afterglows, slew time is incredibly important perhaps even more important than aperture! LT can get on target in 2-3 min a facility which could better this time with a larger aperture would provide a powerful capability Instrumentation Multiband imager, something along the lines of GROND, optical-infrared for SED Spectroscopy requires extremely rapid response Afterglow polarimetry a specialisation of the current facility In where will the triggers come from?

18 SVOM Joint French/Chinese mission Payload very similar to Swift Optical and X-ray telescopes for afterglow Ground based component for quick localisation and photometric redshifts Array of wide field cameras (a la SuperWASP) Wide field gamma ray detector improved energy range and sensitivity compared to Swift BAT 2x 1m robotic telescopes Some political issues, but I hear things are back on track...

19 Variability across the EM spectrum X-ray: LOFT is a ESA M3 candidate (launch ~2022) Wide Field Monitor: X-ray transient detections and triggers Optical: Gaia final catalogue will be published in e9 stars with accurate positions and distances, limited photometry and very limited spectroscopy Millions of variables and binaries. Statistically complete samples, rare subclasses... Radio: SKA full science operations 2020 (phase 1), 2024 (phase 2) Pulsars, RRATs, AXPs, SGRs, NS-NS binaries, synchrotron emission from jets, coherent emission from flare stars, brown dwarfs and hot Jupiters... High energies: Cherenkov Telescope Array begins construction ~2018 Northern site (Tenerife?): AGN, GRBs, clusters Southern site:galactic centre, SNR, pulsars, SFR, XRBs

20 Astrophysical Neutrino Searches IceCube completed 2010 and currently operational at the south pole Most sensitive to muon neutrinos Vast majority of detections due to atmospheric muons and neutrinos from cosmic ray showers Best sensitivity for northern hemisphere (Earth serves as filter for atmospheric muons) Companion KM3NeT detector planned for the north Science: point sources of high energy neutrinos, coincident GRBs, galactic SNe, decay products from WIMPs...

21 Detection of 28 astrophysical neutrino events reported in 2013 Science paper Upgrades planned for increased sensitivity Capability for triggered EM follow-up in place. No coincident detections yet...

22 Gravitational wave counterparts ALIGO commissioning 2015 full sensitivity 2022 Key problems for detection of electromagnetic counterparts are Localisation (hopeless in 2015, extremely difficult in 2022!) Nature of counterpart is unclear, but potentially faint and fast-fading From 'Commissioning and Observing Scenarios for the Advanced LIGO and Advanced Virgo Gravitational-Wave Observatories by The LIGO Scientific Collaboration and the Virgo Collaboration (2012)'

23 GW electromagnetic counterparts For an NS-NS or NS-BH merger, counterpart might consist of sgrb - prompt emission and afterglow, harder to detect further off axis 'kilonova' - SN like, isotropic component powered by radioactive decay of heavy elements synthesised in ejecta (GRB130603B, Tanvir et al. 2013) Non-thermal radio afterglow. Long time delay Metzger and Berger (2012)

24 Exoplanet science Plenty to do, for example: Hot Jupiters migration or scattering? Planetary formation and evolution: Planets of same radius have vastly different masses Atmospheres Rings, moons, binary planets Smaller objects (Neptunes, super Earths) Stellar systems rather than individual objects Multi-planet systems from RV surveys (Lovis and Fischer, 2010)

25 Future exoplanet facilities Kepler host stars typically 14.5 > mv > 13.5 New facilities will concentrate on brighter (mv ~ 8-13) stars to maximise follow-up potential Millions of stars surveyed, tens of thousands of transiting planets Neptunes / super-earths / Earths NGTS ( ) under construction at Paranal TESS approved by NASA for a 2017 launch PLATO potential ESA M3 mission (~2022) decision this year From

26 Exoplanet instrumentation Transit photometry simultaneous multiband imager High resolution spectroscopy HARPS type instrument Secondary eclipses. As far infrared as possible Transmission spectroscopy (transit depth as a function of wavelength). Stable, high throughput Water, biomarkers Transmission spectroscopy with FORS (Bean et al. 2010) Is there a role for LT2 in the 2020 exoplanet landscape?

27 LT2 site and telescope design

28 Site Northern and southern sites both viable for our science: synoptic transient surveys in both hemispheres, targets from space facilities, GW detections over whole sky, etc. Some important infrastructure will be in the south, but LSST for example will cover the sky up to +15 in dec, so northern telescopes will still have a significant follow-up role. At this stage our preferred site is La Palma, and we are developing this option in collaboration with the IAC From La Palma: Dec -30, 1.5h TOT at airmass < 2.0 Dec -20, 4h TOT at airmass < 2.0 1h TOT at airmass < 1.5 Dec -10, 6.5h TOT at airmass < 2.0 4h TOT at airmass < 1.5

29 GW localisation (BNS at 80Mpc) (BNS at 80Mpc) (BNS at 160Mpc) (BNS at 160Mpc) From 'Commissioning and Observing Scenarios for the Advanced LIGO and Advanced Virgo Gravitational-Wave Observatories by The LIGO Scientific Collaboration and the Virgo Collaboration (2012)'

30 LT2 user requirements Liverpool Telescope 2 will be a robotic telescope designed for extremely rapid follow-up of transients detected by other facilities Fast slewing: aiming to be taking data within 30 seconds of alert Includes blind pointing, mirror settling and mechanical movement of enclosure Excellent open loop tracking performance (image elongation no greater than 0.2'' in ten minutes) so we don't have to be slowed down by autoguider Important for fast-fading transients, but also reduced overhead for efficient monitoring of large numbers of targets The most pressing follow-up need will be for intermediate resolution (R<10,000) spectroscopy Main instrument will be an opt/ir spectrograph, down to at least 2 micron Does not include acquisition of target onto IFU/slit Focal stations for simultaneous mounting of at least 4 other instruments Aperture of 4 metres will put us at the bright end for LSST follow-up, but still 100s of targets per night!

31 Signal-to-noise models

32 Telescope slew models

33 Telescope Design We have commissioned some preliminary optical design studies based on our user requirements Key challenges are mechanical, in order to meet fast slewing requirement One possible option for reducing weight is a segmented primary A short distance from Liverpool, Technium OpTIC in North Wales are currently developing large optics fabrication methods for the ELT mirror segments and can fabricate segments up to ~2m in size Location of focal stations another important issue. Everything on Nasmyth platforms?

34 A new role for the LT? If LT2 will be colocated on La Palma with the existing LT, one exciting possibility is to combine both telescopes into a single facility Replace existing LT instrument suite with prime focus wide field imager 2x2 deg FoV Use the LT to discover our own transients and time variable sources, which are then fed to LT2 for spectroscopic follow-up A new PTF type facility, with the benefits of modern telescopes and the rapid reaction capability of robotic operations Also maintain (increase?) commitment to Schools Observatory

35 Novel instrumentation EM (electron multiplying) CCDs are seeing increasing use at various observatories Effectively zero read noise Spectroscopic format chips imminent CMOS detectors Very fast. QE historically a problem, things now improving MKIDS: Microwave Kinetic Inductance Detectors Surface impedance of superconductor changed by incident photon through kinetic inductance effect Photon counting with spectral information Largish arrays now possible, although energy resolution still poor (R~10-15) As you go to larger arrays the key challenges are computational and cooling

36 Summary We intend to build a new 4m class telescope to come into operation at the beginning of the next decade Our preferred site is the ORM on La Palma Telescope will be fully robotic with all the versatility that entails Time domain science with a focus on transients Very rapid response for fast-fading objects Intermediate resolution spectroscopy, but provision for a diverse instrument suite Future of LT? We would hope to keep it operational. Replace instrument suite with prime focus wide field (2x2 deg) camera? LT2 website:

37 Cherenkov Telescope Array (CTA) Array consists of three types of telescope combined energy range 10s of GeV 100 TeV 5 10 improvement in sensitivity over HESS, MAGIC, VERITAS Construction begins ~2018 Sites not yet determined Northern site: focus on extragalactic astronomy AGN, GRBs, clusters Southern site: focus on Galactic sources Galactic centre, SNR, pulsars, SFR, XRBs

38 X-ray transients with LOFT RXTE successor Potential ESA M3 mission (decision this year) High-time resolution X-ray mission for compact objects, bright AGN Launch date would be ~ 2022 Simultaneous optical/x-ray: TDEs, echo outbursts in XRBs Transient detections from Wide Field Monitor Much larger effective area than RXTE ASM 2-50 kev energy range Observes 50% of available sky Point source location accuracy (10σ) ~ 1'

39 Gaia Launch October, operational lifetime of 5 years, final catalogue published 2020 So no LT2 overlap with the Gaia alerts programme, although LT will participate 1e9 stars with accurate positions and distances, limited photometry and very limited spectroscopy Huge numbers of variable stars and binaries for spectroscopic follow-up! - statistically complete samples, rare subclasses...

40 Radio transients SKA Phase 1 full science operations 2020 SKA Phase 2 full science operations 2024 Transient science: Pulsars Exotic related objects: RRATs, AXPs, SGRs Strong-field tests of gravity with pulsar BH binaries NS-NS / NS-BH binaries. Mergers. Synchrotron emission in jets from Cvs, XRBs, SNe and GRBs Coherent emission from flare stars, brown dwarfs, hot Jupiters Characteristics of radio transient sky currently quite unclear SKA pathfinders will be very useful (LOFAR follow-up with LT)

41 GW optical counterpart models Metzger and Berger (2012)