50 research outputs found
A Small, Rapid Optical-IR Response Gamma-Ray Burst Space Observatory Concept: The NGRG
After Swift, there is no sure plan to furnish a replacement for the rapidly disseminated, high-precision GRB positions it provides, nor a new type of observatory to probe new GRB parameter space. We propose a new GRB mission concept, the Next Generation Rapid Optical–NIR (near infrared) Response GRB Observatory (NGRG) concept, and demonstrate, through analysis of Swift BAT data, studies of new GRB samples, and extinction predictions, that a relatively modest size observatory will produce valuable new measurements and good GRB detection rates. As with Swift, GRBs are initially located with a coded-mask X-ray camera. However, the NGRG has two distinguishing features: first, a beam-steering system to begin optical observations within ∼1 s after location; second, in addition to the optical camera, a separate near-IR (NIR) camera viewing the same field, greatly increasing sensitivity to extinguished bursts. These features yield the unique capability of exploring the rise phase of GRB optical-NIR emission. Thus far, among GRBs with optical afterglow detections, a peak is measured in only ∼26–40% of the light curves. The rise time for prompt, or pre-afterglow, optical emission is rarely measured, as is the transition to afterglow emission. Prompt or pre-afterglow NIR emission is even less frequently measured. Rapid-response measurements give new tools for exploration of many science topics, including optical emission mechanisms (synchrotron vs. SSC, photospheric emission) and jet characteristics (reverse vs. forward shock emission, baryon-dominated vs. magnetic dominated). The rapid-response capability also allows measurement of dynamic evolution of extinction due to vaporization of progenitor system dust. This dynamic dust measurement is the only tool we know of to separate the effects of star-system-scale dust and galactic-structure-scale dust; it is remarkable that this probe of small-scale phenomena can be used at the high redshifts where GRBs are observed. In this paper, we discuss techniques and the feasibility of these measurements, and give detection rate estimates using only measured Swift performance (without extrapolations). The NGRG will explore two new frontiers: optical and NIR GRB emission measured earlier than ever before, via rapid-response, and potentially fainter, more extinguished GRBs than ever before, via sensitive, early NIR measurements. In an era with little funding for new extragalactic science space missions, costs are important. Our modest NGRG concept will produce new GRB science, while providing crucial access to rapid GRB alerts for the community. An X-ray instrument barely 1/5 the detecting area of Swift BAT, 1024 cm^2, will yield a significant fraction of BAT’s GRB detection rate: more than 65 X-ray detections per year. With a 30 cm optical-IR telescope and modern cameras, more than 19 NIR and 14 optical band detections would be produced each year for community follow-up. In addition, active control of the beam-steering system, via feedback from a fast-read optical camera, would remove the need for arcsec pointing stabilization of the spacecraft platform, for a substantial cost saving and a wider range of potential space platforms
An IR Search for Extinguished Supernovae in Starburst Galaxies
IR and Radio band observations of heavily extinguished regions in starburst
galaxies suggest a very high SN rate associated with such regions. Optically
measured supernova (SN) rates may therefore underestimate the total SN rate by
factors of up to 10, due to the high extinction to SNe in starburst regions.
The IR/radio SN rates come from a variety of indirect means, however, which
suffer from model dependence and other problems.
We describe a direct measurement of the SN rate from a regular patrol of
starburst galaxies done with K' band imaging to minimize the effects of
extinction. A collection of K' measurements of core-collapse SNe near maximum
light is presented. Results of a preliminary SN search using the MIRC camera at
the Wyoming IR Observatory (WIRO), and an improved search using the ORCA optics
are described. A monthly patrol of starburst galaxies within 25 Mpc should
yield 1.6 - 9.6 SNe/year. Our MIRC search with low-resolution (2.2" pixels)
failed to find extinguished SNe, limiting the SN rate outside the nucleus (at >
15" radius) to less than 3.8 Supernova Rate Units (SRU or SNe/century/10^10
L(solar); 90% confidence). The MIRC camera had insufficient resolution to
search nuclear starburst regions, where SN activity is concentrated, explaining
why we found no heavily obscured SNe. We conclude that high-resolution, small
field SN searches in starburst nuclei are more productive than low resolution,
large-field searches, even for our large galaxies. With our ORCA
high-resolution optics, we could limit the total SN rate to < 1.3 SRU at 90%
confidence in 3 years of observations, lower than the most pessimistic
estimate.Comment: AJ Submitted 1998 Dec. 13. View figures and download all as one file
at http://panisse.lbl.gov/public/bruce/irs
Linking optical and infrared observations with gravitational wave sources through variability
Optical and infrared observations have thus far detected more celestial
cataclysms than have been seen in gravity waves (GW). This argues that we
should search for gravity wave signatures that correspond to flux variability
seen at optical wavelengths, at precisely known positions. There is an unknown
time delay between the optical and gravitational transient, but knowing the
source location precisely specifies the corresponding time delays across the
gravitational antenna network as a function of the GW-to-optical arrival time
difference. Optical searches should detect virtually all supernovae that are
plausible gravitational radiation sources. The transient optical signature
expected from merging compact objects is not as well understood, but there are
good reasons to expect detectable transient optical/IR emission from most of
these sources as well. The next generation of deep wide-field surveys (for
example PanSTARRS and LSST) will be sensitive to subtle optical variability,
but we need to fill the ``blind spots'' that exist in the Galactic plane, and
for optically bright transient sources. In particular, a Galactic plane
variability survey at 2 microns seems worthwhile. Science would benefit from
closer coordination between the various optical survey projects and the gravity
wave community.Comment: 14 pages, no figures. Contribution to 12th Gravitational Wave Data
Analysis Workshop. Submitted to Classical and Quantum Gravit
Slewing Mirror Telescope optics for the early observation of UV/optical photons from Gamma-Ray Bursts
We report on design, manufacture, and testing of a Slewing Mirror Telescope (SMT), the first of its kind and a part of Ultra-Fast Flash Observatory-pathfinder (UFFO-p) for space-based prompt measurement of early UV/optical light curves from Gamma-Ray Bursts (GRBs). Using a fast slewing mirror of 150 mm diameter mounted on a 2 axis gimbal stage, SMT can deliver the images of GRB optical counterparts to the intensified CCD detector within 1.5∼1.8 s over ± 35 degrees in the slewing field of view. Its Ritchey-Chrétien telescope of 100 mm diameter provides a 17 × 17 arcmin2 instantaneous field of view. Technical details of design, construction, the laboratory performance tests in space environments for this unique SMT are described in conjunction with the plan for in-orbit operation onboard the Lomonosov satellite in 2013. © 2013 Optical Society of America.This research was supported by the Korean Creative Research Initiatives (RCMST) of MEST/NRF, the Basic Science Research program of MEST/NRF (2010-0025056), the World Class University program of MEST/NRF (R32-2009-000-10130-0), the Spanish MINECO project AYA-2009-14027-C05-01, AYA-2011-29936-C05-01, AYA-2012-39727-C03-01, and AYA 2009-14000-C03-01/ESP, Taiwan's National Science Council Vanguard Program (100-2119-M-002-025) LeCosPA of National Taiwan University, Program of development of Lomonosov Moscow State University and Korean programs NRF 2012-0006632, 20100029390 and Yonsei-KASI joint research for the Frontiers of Astronomy and Space Science Program 2012Peer Reviewe