Variability of Accreting White Dwarf Binaries and Other Compact Objects

Manuel Pichardo Marcano

Texas Tech University

Thomas J. Maccarone & Liliana Rivera Sandoval

Compact Binaries Surveys

1- SCOVaS: Survey for Compact Objects and Variables

Pichardo Marcano et al. (2021a)

Pichardo Marcano et al. (in prep.)

2- TACOS: TESS AM~CVn Outbursts Survey

Pichardo Marcano et al. (2021b)

Compact Binaries Surveys

X-ray unbiased search

SCOVaS: Survey for Compact Objects and Variables Stars

• HST Archive
• 7 Globular Clusters
• Many Exposures
• Different properties
  • Metallicity
  • Core-collapsed
  • Non core-collapse

SCOVaS: Survey for Studying Compact Objects and Variables

• Focus: Cataclysmic Variables (CVs) with HST
• First Unbiased Survey for CVs in Globular Clusters
  • X-ray faint CVs
  • Orbital Periods
• Spatial Distribution:
  • Looking at the dense Core of Clusters
  • Next: Search in the Outskirts
• Optical Counterpart X-ray/Radio Sources in GCs

Preliminary Results

NGC 6397

• WFPC-2
• March-April 2005:
  • 126 orbits
  • F814W, F606W and F336W
  • Exp time: 500-700 s

Preliminary Results

NGC 6397

• WFPC-2
• March-April 2005:
  • 126 orbits
  • F814W, F606W and F336W
  • Exp time: 500-700 s

A new candidate Redback Pulsar

HUGS catalogue. (Piotto et al. 2015, Nardiello et al. 2018)

Pichardo Marcano et al. (2021a)

X-ray

HST F336W

Radio

Zhao, [...], Pichardo Marcano,  et al. (2020)

A new candidate Redback MSP

Pichardo Marcano et. al (2021a)

• Porb 1.96 days
• Longest Porb for Redback in GCs
• Missed MSP in Pulsar Searchers

Light Curves Known CV Candidates

High and Low state?

Novalike?

Pichardo Marcano et. al (in prep)

New Eclipser?

Light Curves Known CV Candidates

Pichardo Marcano et. al (in prep)

New CV Candidate

Pichardo Marcano et. al (in prep)

New CV Candidate

• New CV Candidate
• Not Detected X-rays
• Potential Porb

  • 5.21 hours 

Pichardo Marcano et. al (in prep)

NGC 6397

• Pipeline to find interesting objects:
  • CMD Position and Periodicity/Variability Searches
• We were able to recover all known CV Candidates
• Found Orbital Period Redback Pulsar
• Potential New, X-ray faint, CV Candidate
• Many more variables to analyze...

Preliminary Results

M 92

• WFPC-2
• 2008-01-25 to 2008-01-30:
  • 76 Exposures
  • F555W
  • Exp time: 10 s

M 92

HST vs Ground-based

Yepez et al. (2020)

Ground-based Data

HST Data

New Variables in the Core

SX Phe

• Good Distance indicator:
  • Strong P-L relation
• Less common than RR Lyrae
• Blue Straggler
  • Product of Binary evolution

P = 1.38 hr

Pichardo Marcano et. al (in prep)

M 92

• New variables in the core:
  • SX Phe, RR Lyrae, AB, ....
• Search for Optical Counterparts of X-ray sources:
  • 1 Pulsar, 4-5 CVs
• Many more variables to analyze...

• Precursor
  • TESS (Duffy et al. 2021)
  • GOTO data
• Echo Outbursts
• DIM with EMT  (e.g. Hameury & Lasota 2021)

TESS AM CVn Outbursts Survey

Pichardo Marcano et al. (2021)

Outbursts

Pichardo Marcano et al. (2021)

PTF1 J0719+4858:

• Similar to Dwarf Novae:
  • Hameury et al. (2020)
  • Rivera Sandoval et al. (2021)

Color Evolution

Pichardo Marcano et al. (2021)

Long-term monitoring

Pichardo Marcano et al. (2021)

• Orbital Periods:
  • 2-minute cadence
• Limits on Recurrence Time
• "Normal Outburts"

SO durations vs Porb

Pichardo Marcano et al. (2021)

Other work with Accreting WDs

• Follow-up eROSITA transient:

• TESS time series analysis

• • Atel: Pichardo Marcano (2020)

  • Paper: Schwope, [...], Pichardo Marcano, et al. (2021)

Caltech

Summary

• GOTO:
  • Time-domain astronomy
    • ZTF, ATLAS, TESS, HST
  • Experience Transients
    • Expand my expertise
• Common interest with Warwick Scientists
  • Compact Binaries:
    • Accreting WDs
• Experience Spectroscopy:
  • IFU: MUSE, VIMOS
  • GEMINI

Extra Slides

TACOS Summary

• Precursors and "Normal" Outbursts:
  • Relatively Common
  • Short Duration (missed ground-based)
• Echo Outbursts:
  • Different morphology
  • Enhanced Mass Transfer
• SO durations overestimated
• Two new candidate periods
• Color Evolution

Long-term monitoring

Pichardo Marcano et al. (2021)

• Orbital Periods:
  • 2-minute cadence
• Limits on Recurrence Time
• "Normal Outburts"

Outbursts

Pichardo Marcano et al. (2021)

Transiting Exoplanet Survey Satellite (TESS)

Caltech

• Porb 20 to ~ 60 minutes (?)

• Superoutburts (SO) and "Normal" outbursts (NO)

  • SO: Superhumps (periodic brightness variation )

• Disk instability model (DIM)

  •  Constant Mass transfer rate

  • Tidal-thermal disk instability model

Outbursting Systems

Empirical Relationships

1. Trec prop Porb^7.35
2. Tdur prop Porb^4.54
3. Delta mag prop Porb
4. Long-term
5. Ground-Based:
   1. PTF
   2. CRTS

Levitan et al. 2015

See also Duffy et al. 2021