the toros project to search for optical counterparts...

Frascati Workshop 2017, Palermo, 6/16/2017

Center for Gravitational Wave Astronomy

The TOROS project to search for optical counterparts of gravitational waves

Mario Díaz

The Amazing Life of the Stars, Cefalu, 10/ 8/ 2017


What is TOROS?• Transient Optical Robotic Observatory of the South.

• The original main goal: to deploy a wide FoV telescope in the Atacama plateau dedicated to follow up in the optical band triggers provided by the LIGO VIRGO collaboration.

• Until this noble goal succeeds pool different existing resources to engage in these activities with different strategies.


We are in the era of Gravitational Wave Astronomy!


But surprise: BH-BHs


BNS detection rates

LV Col. Living Rev. Relativity 19 (2016), 1


The next big challenge: BNS mergers

From Metzger 2013


What is a kilonova?• Merger of BNS (or NS-BH) produces moderate neutron-

rich ejecta (Mej ~ 10-3 - 10-1 M⊙ and 𝛽ej~0.1-0.3. (Rosswog 2009, Bauswein 2013)

• Radioactive decay of heavy elements powered by r-process nucleosynthesis may produce an isotropic quasi-thermal transient.(Li 1998, Metzger 2010, Grossman 2014)

• The emission will be reddened by the opacities 𝜅~10-100 cm2g-1 for 𝜆~0.3 - 3 𝜇m (Kasen et al 2013).

• L~ 1040 ergs/s, fast (t~few days), 𝜆peak ~ 1.5 microns.


RAJ2000=5 11 h 28 min 48.16 s, decJ2000=17∘ 4’ 18” lying slightly off a tidally distorted spiral arm. The host and its field at left. At right, the epoch-1 and epoch-2 and their difference in the 0.6 𝜇m (upper row) and 1.6 𝜇m bands

From: “A ‘kilonova’ associated with the short-duration γ-ray burst GRB 130603B” N. R. Tanvir et al, Nature Letter 500 (29 August 2013.)

GRB 130603B: the first kilonova?


Kilonova light curves

Kasen, Fernández & Metzger, 2014


NS-NS and BH-NS extremely rich astrophysics

• GRB BNS connections.

• Progenitor Astrophysics.

• NS eq of state.

• nuclear processes. Kilonova models.

• Independent measurements of Hubble constant.

• Multimessenger Astronomy will play a crucial role.


Localization probability map HLV 2016-2017

LV Col. Living Rev. Relativity 19 (2016), 1

The Amazing Life of the Stars, Cefalu, 10/ 8/ 2017 12

https://toros.utrgv.edu/TOROS/First_TOROS_Workshop.html

Transient Optical Robotic Observatory of the South (TOROS)


The TOROS CollaborationUSA• UTRGV-CGWA (M. Díaz, M. Beroiz, A. Zadrozny), • Texas A&M (L. Macri, D. Depoy, J. Marshall)

Argentina• U. of Córdoba (D. Garcia-Lambas and several members).

Mexico

INAOE (O. Lopez-Cruz).

Chile• La Serena U (A. Ramirez, JL Nilo Castellon), • Universidad Católica (N. Padilla)

Brasil • U. Sao Paulo (C. Mendes)


TOROS telescopes

Dedicated, Co. Macon TOO


Cordon Macon, ArgentinaTOROS location

Aprox. 1468 Km

379 km

4,650 ms asl seeing comparable to Paranal or better extremely low water vapor. More than 95% of the nights cloudless year round.


Life at more than 15,000 ft


Tolar Grande

9 km


ABRAS1.2 m telescope Infrared camera Spectrograph


TOROS telescope specs• 0.60 m telescope

• 4 elements main focal corrector capable of a 9 microns precision over entire FOV (1 200 mm CaFl corrector lens).

• CCD 10Kx10K, 9 microns/ pixel.

• focal length: 1815 mm.

• plate scale: 1arcs p/pixel.

• FOV: 3◦ x 3◦

• mag 22~23 w/ 15 min exposure.


GLOPT_010.zmxConfiguration 1 of 1

Layout4 LENS PRIME FOCUS CORRECTOR11/18/2013Total Axial Length: 2013.46175 mm


Spot diagram

Surface: IMA

100.00

OBJ: 0.0000 (deg)

IMA: 0.000 mm

OBJ: 0.3000 (deg)

IMA: 9.509 mm

OBJ: 0.5000 (deg)

IMA: 15.864 mm

OBJ: 1.0000 (deg)

IMA: 31.883 mm

OBJ: 1.5000 (deg)

IMA: 48.238 mm

OBJ: 2.0000 (deg)

IMA: 65.173 mm

0.5000

0.6000

0.7000

0.8000

GLOPT_010.zmxConfiguration 1 of 1

Spot Diagram4 LENS PRIME FOCUS CORRECTOR11/18/2013 Units are µm.Field : 1 2 3 4 5 6RMS radius : 5.924 4.998 4.967 5.490 6.660 9.235GEO radius : 16.311 16.749 17.558 20.254 23.243 30.011Scale bar : 100 Reference : Chief Ray


TOROS first stage• TOROS telescope (Planewave 0.60 m) has been

purchased and is under construction.

• Wind proof dome from Ashdome ready to ship.

• Construction of dome-wall and pier to start Summer 2018.

• Commissioning of the telescope March 2018.


Dome…ready, telescope soon


O1 E-M Follow-up• LVC established an E-M (and particle) follow-up

program. 74 groups signed up.

• 25 groups followed up the GCN circular for GW150914.

• TOROS performed observations of the skymaps provided using the 1.5 m telescope at EABA (Córdoba, Argentina).


Follow-up scheme

GW detectors

GCN w/skymapadvocates (veto)

E-M facilities


Electromagnetic Follow-up

25 group of astronomers participated

Abbott et al, ApJL, 2016, 826, L13


• Galaxy catalog can greatly increase the probability of finding an EM counterpart. (Nuttall & Sutton 2010; Abadie et al. 2012; Hanna et al. 2014).

• We used the Gravitational Wave Galaxy Catalog (GWGC; White et al. 2011), ∼53,000 galaxies within 100 Mpc (incompleteness starting at D ~ 40 Mpc).

• in-house “scheduler” (a Python module of the TOROS pipeline). The scheduler set a list of criteria: (1) observability from our location (30 > d > -70 ), (2) appar- ent magnitude B ≦ 21 mag, and (3) distance D < 60 Mpc.

• Target probabilities based on pixel values in the initial cWB map.


Skymap for GW150914

image credit:

LIGO/Axel Mellinger


Localization probability maps for GW150914 Red dots are the galaxies observed by TOROS


• We analyzed the observations using two independent implementations of difference-imaging algorithms, followed by a Random-Forest-based algorithm to discriminate between real and bogus transients.

• We did not find any bona fide transient event in the surveyed area down to a 5σ limiting magnitude of r = 21.7 mag (AB).

• Result is consistent with the LIGO detection of a binary black hole merger, for which no E-M counterparts are expected, and with the expected rates of other astrophysical transients.


O2 TOROS follow-up observations

• We performed several follow-up observations of triggers (GCN) provided by LVC.

• Among them GW170104.

• Telescopes in Chile and Argentina were utilized.


And…?A very exciting LIGO-Virgo Second Observing run is drawing to a close August 25

The Virgo and LIGO Scientific Collaborations have been observing since November 30, 2016 in the second Advanced Detector Observing Run ‘O2’ , searching for gravitational-wave signals, with both LIGO and Virgo instruments operating together since August 1, 2017. Some promising gravitational-wave candidates have been identified by both LIGO and Virgo during our preliminary analysis, and we have shared what we currently know with electromagnetic observing partners: telescopes, gamma-ray and neutrino detectors. We are working hard to assure that the candidates are valid gravitational-wave events, and it will require time to establish the level of confidence needed to bring any results to the scientific community and the greater public. We will let you know when we have information ready to share.

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